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How to avoid pinching on concave shapes with the bevel modifier and subsurf?
How can I setup the Bevel modifier to only work on 30 degrees angle and avoid pinching at the same time on convex shapes?

I want to avoid pinching generated on concave shapes to replace the manual edge loops or sharp edges workflow for hard surface models:

It's interesting to have a look at why this happens. This is a transition from  2x Simple subdiv to Catmull-Clark subdiv on a corner beveled with one segment.

It's not 'pinching' in the same sense as the pinching you get at say, the poles of a UV Sphere. It's more like 'leapfrogging'. Under the CC algorithm,the edges of small faces that were next to large faces in their own plane move further than small faces that were next to small faces at an angle to them, to the point that they overtake. This effect is compounded with each iteration, and the smaller the bevel by comparison with surrounding faces, the worse it gets.
I've never been able to think of a solution to fully automate away the need for hand-modified holding loops, or using creases to pin vertices and prevent them from being moved by CC.
Personally I tend to think in 3's, (put in a bevel with 2 segments) and not restrict by angle. Then the extra edge-loops an be 'tied off' (reduced from 3 to 1) elsewhere on the model, if needed. But that's still hand work.

This probably the best answer you're going to get.

The angles of concave and convex edges have a different sign. The bevel modifier just ignores it.

Luckily, the bmesh module has both, a calc_face_angle and a calc_face_angle_signed function. For concave edges, the latter will return a negative angle.

Go into edit mode and switch to edge selection.
Execute the script. (see below)
Now that the concave edges are selected press CtrlE and choose Edge Bevel Weight, then enter 1Enter.
In the bevel modifier, choose weights as the delimiting input.

import bpy
import bmesh
import math

def deg_to_rad(deg):
    return deg / 180 * math.pi

obj = bpy.context.object

if obj.mode != 'EDIT':
    raise Exception("Go in edge selection edit mode!")
bm = bmesh.new()
bm = bmesh.from_edit_mesh(obj.data)
bm.edges.ensure_lookup_table()

for edge in bm.edges:
    edge.select = False
    if not edge.is_boundary:
        angle = edge.calc_face_angle_signed()
        if (angle < deg_to_rad(0)):
            edge.select = True

bmesh.update_edit_mesh(obj.data)

The first import check in the script is edge.is_boundary, where we assure that the current edge is in fact between to face and will have an angle.
The angle is compared in the snippet if (angle < deg_to_rad(0)). You can also modify this line to accept whatever condition.

It would be great if all the select-by-angle features of the Blender interface included a min and max entry, making the distinction between positive and negative angles.

What you need to do is to set the bevel weight to one (blue edges in the picture below) on one edge or edgeloop that originates from the problematic area. This will make the geometry around the edge flow to a new direction, preventing the subsurf modifier to pull geometry over the concave edge's vertices. If the edge you mark lays on a flat surface you don't need to select it's entire edge loop (blue dotted line).

this ultimately was the solution that worked for me. Thanks!

I get around this procedurally using two bevel modifiers (with vertex groups), one for convex and one for concave edges. Adding some edge loops may be needed, just enough so that the vertices assigned to the groups define only the edges wanted.

AFAIK, there are no ways to tell a bevel modifier to work only on a specific angle, he only works on an "equal or greater than X° angle".
Maybe mark by hand the edges you need to bevel, go in edit mode, select the edges, increase their edge bevel weight, then set the bevel modifier to weight mode.

Also, Bevel modifier is being reworked for 2.8. Maybe this issue will not occur anymore: https://devtalk.blender.org/t/gsoc-2018-bevel-improvements

I know this post is from two years ago but I'm still having trouble with it. From what I can find the other posts on this topic are giving the same solutions as here.

Try adding edge split after beveling. That usually works for me


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Translate object using lowest Z value with Python in Blender 2.8
This question shows how to move the lowest vertex of a mesh on the grid, but the script given only works in versions before Blender 2.8: Translate object using lowest Z value python
Here is the script given:
import bpy

# get a reference to the active object
obj = bpy.context.object

# get the minimum z-value of all vertices after converting to global transform
lowest_pt = min([(obj.matrix_world * v.co).z for v in obj.data.vertices])

# transform the object
obj.location.z -= lowest_pt

What is the version of this script for Blender 2.8?
Note: I have intentionally copied a similar title so the users can find the Blender 2.8 version more easily.

For 2.8 replace * with @ for matrix multiplication.

Edited original q with this info.  I see in comments  it was suggested to ask  a new question... I'm not so sure that each question needing this simple change need be a new question.  If you agree consider removing.

@batFINGER I'm not sure about that...if the original answer came from someone who isn't keeping up with the 2.8 project (me), it will be hard to get enough visibility from those who do know the answer to update it. I'm not sure if "duplicate questions" like this has already been addressed on Meta, but it might be worth discussing there as "How to do X in 2.8?" is a common question now.

IMO related to the version tag chestnut. Rather than a version tag the version is being  tagged in the title. A whole new question and answer for what is a one character change seems a bit OTT.  Version tags for answers would be great. Edited your original answer with such.  I see your point, would not have noticed if not for the new question.

@JakeD added https://blender.stackexchange.com/questions/129473/typeerror-element-wise-multiplication-not-supported-between-matrix-and-vect to catch this one.

source: Stack Exchange

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

sort: votes


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Change color of an object depending on camera view (cycles render)
For example I have an object in my sphere. I want the part of the sphere which is behind the object (in the sphere) to be blue and the part which is in front of it to be red.
Is this possible?
Is it also possible to keep it updated if I change my camera view?
Thanks for your help!

I don't know if I understand you right, but this may help you: http://blender.stackexchange.com/questions/27639/how-to-mix-2-shaders-depending-on-distance-from-camera Otherwise consider to use drivers to do it.

It is possible to do that in Cycles using a Camera Data Node
You must use the output of the View Vector socket, separate it into its components with a Separate XYZ node, then pass its Z component through a Color Ramp node to control what colors you get.
The effect might be hard to see at start because the red color would always be off-camera, but tweaking the color ramp node may emphasize the effect.

Should be automatically kept in sync with the camera position

Are the Nodes referring to the Monkey head or the sphere?

Neither, the nodes read from the current camera position, monkey head is  there only for visual reference. The material is applied to the sphere

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


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Is it possible to make half of an object semi transparent and the other half non-transparent?
For example I have an object like a cube. I know that the transparency of my object can be set by the alpha. But is it also possible to just make half of the cube semi transparent and the other half non-transparent?
Thanks for your help!

It is, use a texture to control it, or two different materials.

two different textures/materials. Or dived cube on two object, set two different materials, in order to control both of them in the same time add empty and parent two object to it.

also look this video, might help you : https://www.youtube.com/watch?v=liNGmdXsfbs

Yes, this can be done by assigning different materials to the same object as shown below.

I added a cube to the scene at origin and scaled it to be bigger
Then I added a sphere to the origin which is now located inside the cube
I added a material to the cube as shown below:

I then checked and turned on the transparency and decreased the the Alpha value as shown below:

Then I added a new material and set its color to red as shown below:

Then I switched to edit mode, switched to face mode and selected couple of faces and clicked assigned to the red material as shown below:

Then render and as shown below the grey material is transparent showing the sphere inside while the red material is not:

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


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Need to render a VERY HQ 2.4 meter tall image
Need to render a VERY HQ 2.4 meter tall image for print. How can I achieve this without my computer exploding? :)
Thanks
Logan

More detail would allow us to be more helpful as well as how this question relates to Blender?

The Render to Print addon will let you set the physical dimensions and DPI and calculate the resolution you'll need to render at.

related, possible duplicate question: http://blender.stackexchange.com/questions/58505/whats-the-best-format-to-turn-a-render-into-a-poster/58509#58509

duplicate: How to render a 30K image with cycles?

For print a 2.4 meter billboard you are absolutely don't need it to be in "HQ". Check this answers here.
You don't have to render all in once - you can render layers and then compose them. Explained here
I can presume that if you rendering a work for this kind of printing, you will have to make some post-production work - color correction, text layout etc. So the right workflow is to render the elements you need in blender and than combine them in your preferred editor, trying to make minimum layout work in blender.


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Is there a way to remove all weight paint on an object/armature?
I set automatic weight paint from an armature to an object, but I wanna undo it but it won't let me ctrl+z that far back? So... can I get rid of ALL weight paint without using the subtract brush ? Like just clear absolutely every paint. My character's hair mesh intersects with the arm mesh just a bit, so the paint for the arm bone got on the hair mesh, and it's moving the hair wherever the arm is, and it looks bad, lol.
Thanks for your time.

You can clear the vertex groups (data tab in the properties panel). But be careful : you may have other groups than the groups which handle the weight paint... (the names of the groups you want to remove correspond to the names of the bones of your armature)

Comments are not for answers, please answer the question as an answer so it can be voted on appropriately.  Thanks!

I had the same problem, only way I was able to re-rig with all the old armature removed and start from scratch was to delete the bones that get created on the object itself, one at a time:

Rather than clicking the little minus a ton of times, you can click that little black arrow below the minus and "delete all groups". Learned that the hard way.

You can control bone weights in the Data tab of the Properties window:

Under the "Vertex Groups" section it lists every bone weight. If you go into edit mode, you can assign vertices to the groups directly without weight painting, or remove them from groups. This is great for cleaning up mistakes done in weight paint mode.
It's very helpful to turn on the "show weights" option in the 3D viewport, so you can quickly notice erroneous weights. You can turn this feature on/off in the 3D viewport options ('N' hotkey).

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


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Why is the texture appearing different, and then not rendering?

That doesn't look right at all.
Also,

Why is his face all black?

A few questions before we can help you: what reader engine are you using? Did you UV unwrap the mesh? What shading mode is the 3D view set to?

cycles render, 2. yes, 3. texture

is it because the background of my texture is nothing(trasparent)?

To use any image with transparency (alpha channel) in cycles you need three nodes. Typically a Transparent BSDF, a Diffuse BSDF (or some other color shader) and a Mix Shader.
Here is the most basic node setup for a transparent image texture in cycles.

However that is not what you want, if you use that setup you will end up with you guy's head being see through.
Now the principal is simple, you treat the color data and alpha data differently.
The color data gets displayed, but the alpha gets used as a mask. What it is masking is totaly up to you and your specific nodes.
In my nodes, in the image above, I'm making the alpha completely transparent, with the Transparent BSDF.
However for you, you can use your base color instead of a transparent node.
Here is an example showing the difference between using a diffuse node (left side) and a transparent node (right side) as the base under the image texture.


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How can I Knife Project only selected polygons, rather than the whole object?
So I'm trying to knife project a circle here

See the circle? Well I'm trying to cut it into the blue part. But it'll cut it into the pink and green as well

And even still, the circle doesn't even cut correctly. See?
All I want is that exact curve circle cut into the blue area, that's it. Thanks for your time.

I don't see cutting through the pink part, although it cuts the green one. The Knife Project uses current viewport point of view, so.. where do you look at the mesh from  while executing Knife Project ?

you can hide (H key) the parts you don't want to be cut. Alt+H to see them again.


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I need help as the blender installer is failing
I'm trying to install the most recent blender build on my Win-10 PC and keep getting the error:
   Blender Setup Wizard ended prematurely
Blender Setup Wizard ended prematurely because of an error.  Your system
     has not been modified.  To install this program at a later time, run
     Setup Wizard again.
Click the Finish button to exit the Setup Wizard
I've checked the event viewer and not seen anything generated by this attempt.
Can anyone help me?


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random vertices up-Z/down-Z only..?
I try to ask you..
I did tried randomize resulted: right-X/left-X/up-Y/down-Y
but it's not work up-Z/down-Z..
I want to use random up-Z/down-Z..... only
how do I will do? it's missing?
sorry for my poor English..
thank you

what are you trying to randomize ? Vertices? Objects ? Are you using Randomize Transform?

Note: I assume you want to randomize the vertex positions of a mesh object.
Displace modifier
One solution, that will work on any mesh is to use the 'Displace' modifier.

Add a 'Displace' modifier to the mesh object you want to add noise to. Set 'Direction' to 'Z' and add a texture (use the big new button).

Open the texture tab, and change the type of the texture to 'Noise' (if you want uniform noise, use clouds with small scale instead).

Play around with the 'Strength' property of the modifier, until you get the needed result (Circled in the first image).

Randomize tool
Alternatively, you can use the 'Randomize' Mesh editing tool if all your normals are on ±Z (e.g. a grid). To do this, make sure that you set the 'normal' option to 1.0 (boxed on the image below).

Phew! That was a bit long....

thank you for your TIPS and TRICK! but i have lattice, lattice has not Idisplace... :-(   that is good trick really!! i will use it in mesh but not lattice..

@Manuelsongokuh you should have said in the main question that you want to randomize the vertexes of a lattice.... If you edit it, I think it will no longer be "unclear".


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Gimp's flame plugin for Blender
Gimp's flame plugin is a tool for creating cosmic recursive fractal flames. Could it be done for Blender as some object/mesh/curves with halo material?
It can be 2D. Just so we could animated it. I've made this in Gimp.
This is flame plugin link https://github.com/piksels-and-lines-orchestra/gimp/tree/master/plug-ins/flame

Somewhat related: http://www.blendernation.com/2014/12/24/add-on-attraction/

Thanks. Could someone wrote this flame plugin for Blender. It's open source.


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Same object with modifiers in different layers
How to use the same object with modifiers  applied in different layers ?
I don't want to duplicate object and move it in another layer. I want Blender to use same amount of memory for that object. So that I could use different compositing in another layer but memory and CPU computing should stay optimized as possible.

Do you want it to be assigned to multiple Scene layers ?

Yes, object with same memory in Blender to speed up postprocessing nad rendering. But, object in second layer will be differently made in compositor and rendered at different time. If I hit M on object +Shift to another layer it disappers from current layer.

I don't quite understand how the object dissappears from the 1st layer if assigned  also to 2-nd. It will be present in scene if either one of layers selected. For rendering, as is said in the linked thread, you might want to assign lamps to several layers too, so that object to be seen. If you're talking about Render Layers, then you should also Shift click them too

Yes, my mistake Shift+LeftMB with the camera and light, otherwise it's not rendered. Thanks. So, that method doesn't duplicate the object?

No, it doesn't - assigning it to layers makes it to be displayed on more than one layer, not to be duplicated.


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Seamless 4 camera setup
How to postion 4 cameras and render a scene partitioned in 4 pieces ?
Cameras should positioned seamlessly 2 on bottom and 2 right above.
Then how to setup in compositor that 4 images are merged in 1 bigger image?

I would like more detail on the rendered image. @cetagon I will look into your links. I don't understand it well.

You can achieve this result by duplicating your first Camera and than rotating it:

I reccomend not using seamless rotation. If you have a small overlapping part it is easier to match it up in the compositor.
To match the to renders up you can use the translate node:

The first part of the image.

The second part off the image.

Combined.
First, you take your to images. For demonstartion purposes I use to files on my computer. One file can also be the rendered image. Than scale the images to the right size. Make sure that your scene has the size of the combined image.
Than you need to add these to images together. To get the combined size I reccomend using a mask of scene size. Use a "translate" node to get the images into the right position. Using half your image height is a good starting point. Add the first image on top of the mask with an "add" node. Add the second image with a "lighten" node.
If your images don't overlay you can also use an "add" node.
If your images overlay match up the second image to the first one with the "translate" node. Also add another scale node to make the image in  this case a perfect square. This last step is only neccessary if you have overlaying images.
I personaly reccomend doing the matching up in an image editor like Gimp ore Photoshop. It will save you a lot of time.


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HDRI setup without the .hdr or .exr
Is there a way to make HDRI, a 360 illumination, without world node ?
Just using lamps.
I would like to have a darkened area.
Everything needs to be lit but center object should have small color tinted light.
I would like to save that setup and use it in different scene.
Also, could I have some control to overall rotation of the lamps as in mapping node = rot. along z axis?

Could you maybe explain or illustrate what you're going for a little better? The way I read it you might be better off using regular environment HDRi lighting and then simply blocking the world illumination from your center object via an opaque mesh that is invisible to camera rays (and possibly shadow rays, too) and then set up local lamps behind that "sun screen" But then I might be completely misunderstanding what you're after, which is why I'm not (yet) posting this as an answer...

@OliverGiesen ,
thanks for suggestion. I would like to setup outdoor studio lighting but  dimmed. Only center object gets lit the most. Basically, I would like to setup 360 lighting using only lamps. Also, I would like that this setup could easily be implemented in other scenes and blends.


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How to make HDRI map more subtle?
I'm using one of HDRI from http://www.hdrlabs.com/sibl/archive.html.
I would like to blend/merge it with scene but in a way that the HDRI content is not visible only dimmed and blurred.
How to achieve that but in a way that the lighting is perserved?

To soften/blur the HDRi use Photoshop or Gimp to blur the image (I suggest making a copy of the original ).
To control the intensity in the "Node Editor" select the "World" nodes (Attached is the most common set up I use).
Adjust the strength in the "Background" node (2).
As a side note you can adjust the rotation of the HDRi which affects the position of the light source in the "Z" rotation of the "Mapping" node (3).

If I blur it in Gimp, wouldn't I loose it .hdr properties? I would like to have full lighting only that it can't be seen.

It would depend on the amount of blur. I've blurred them in the past to soften reflections in shiny materials. Worked great for me. I would suggest starting with a slight blur and see what it looks like. Add blur to taste. (Save the original as a back up  and for future use). If you don't to see the HDRi in the final render check off the "Transparent" check box in the "Film" section of the Render Settings.

Btw, how come there isn't blur node in world tag ?

@cegaton Except GIMP, much like the anachronistic leader it models itself in its image from, is strictly display referred. So, even with a deeper bit depth, correct wide dynamic range handling will still elude it.

@Gimp... I use Photoshop. But Gimp is free. So, it's a not so perfect, perfect, alternative for people to use/experiment/learn with.


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Complex light trails as in God of war 3
How to make similar light trails as in
https://youtu.be/IfW1xw2vD-Y?t=10 ?
I have made only in circle motion:
https://www.youtube.com/watch?v=r2togAvQSr4
I don't know how to combine multiple ones. When one stops, the other light trail begins seamlessly.

Related: http://blender.stackexchange.com/questions/24251/how-to-create-motion-trail-in-cycles

Thanks @PaulGonet , that's what I want. I just need to figure it out how to combine multiple patterns of light trails in one combo.


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Pack external data?
I checked pack all into .blend to send a friend the file.
But when he opened it he couldn't load background image.
How to pack everything into blend file so that will be possible?

When packing, you need to save the file after choosing the pack menu item. A quick way to verify everything's packed is to move the saved blend elsewhere and open it.

There appears to be a bug related to saving the directory path for environment images.  I've never been able to get my default scene to remember where the environment textures are located.  They always show up as magenta until I re-point the nodes to the correct path every time I load the default scene.  Also, this happens often when I load any scene, but not always, it's random.  Maybe the same troubled code is affecting you as well.

Unfortunately, there doesn't seem to be an easy way to see which image files are packed into a blend file, except to individually load every file into the UV editor, select the Image menu, and see if it offers the option to pack the file. If it doesn't then it's already packed. If it does then you should select that option, and when you've checked every file, save the blend file to finalize the procedure. You can then reload the same blend file and they should all be packed.


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Different materials for smoke
How to apply diffuse, glossy or glass material to smoke in cycles without using volume materials?

This is not supported atm, it would require converting the smoke simulation to a mesh or some other structure (an SDF maybe). The smoke simulator can only feed Cycles 3d texture data, thus can only be represented as a volume.
Note that if you have access to Houdini or another tool with OpenVDB, you should be able to read Cycles OpenVDB smoke cache (new in 2.77), create a mesh from the cache, and export that back to Blender. But using Blender alone it is not possible to generate the correct data to use smoke sim ouput as a surface.

Will it be added this feature in Bl?

An eventual solution to do this entirely in Blender would likely come from general purpose OpenVDB tools that would allow a smoke sim to be converted to a regular Blender mesh object. Which theoretically could support any renderer. It's all just theorizing at this point though.


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Material index pass on halo
I can't find material index pass for halo in Blender render.
Could you tell me how to set it up?


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Group mirror and armature
I've grouped objects and I would like to mirror them along x axis.
How to do it ?
Then I would like to animate this group as a single object. Do I use armature or something else ?

Related - http://blender.stackexchange.com/questions/2525/array-a-group-of-objects. I don't think you can add modifier to a group of objects like you would to one object apart from linking modifiers' stack from object to object. As to animation it probably should be a separate question.

I've now figure it out that there is not group mirror avaiable. How to apply mirror modifier for all objects? Will mirror double the memory consumption ?

Do you mean to add modifier to multiple objects ? See http://blender.stackexchange.com/questions/319/add-the-same-modifier-to-multiple-objects-at-once. Mirror will increase memory usage afaik, if you concerned about that use dupliframes as stated in the first link.


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Pinpoint the area light to object
I've made an object and put an area light on scene.
I want that area light points toward the object.
I tried to put constraint and PARENT TO OBJECT but that doesn't rotate the light in that specific direction.
How to do it?


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UV restrictions
When you unwrap the mesh, how to restrict some particular faces to apply the texture?
So, some faces will have the texture, some won't.

You can make two similar materials, one with texture, the other without, then assign some faces to the first, the other to the the second. All with the same complete UV map. You can also select some faces and UV unwrap only those, then create a new UV map, invert the selection and UV unwrap the rest of the mesh to the new UV map, but I think it's not useful in your case.


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How to un-mirror the armature?
I modelled mesh using mirror modifier and and skin modifier. After i applied the mirror modifier,than skin, my armature is also mirrored,
meaning everything I do on the left is mirrored on the right.
Is it possible that I remove this property, so that I can pose the mesh as I want?

Are you using pose mode? x-axis mirror is an edit mode option but I don't think there is an automatic mirror option for posing.

Yes, how to change x-axis mirror in edit mode?

Select the Armature, go to edit mode, press T to open the Toolshelf, select the option tab, uncheck X mirror.


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My Textured paint became plain color when I render in Cycles
First of all I Marked Seam and Unwrapped my model and I started to texture paint but the Render is plain light grey color , I also sculpted it but I don't think that it causes the problem .. Here are some pictures to show , the problem.

make sure to assign this texture to the material on that object ( can you show the material nodes )

Ok I'll give you a link , http://imgur.com/j8hIjrD

you are not using nodes,  can you show the material Tab

Ok , can you also tell me how to do the nodes , Here is the link , http://imgur.com/92bYlyf ... Im a newbie btw to texture painting :/

ok minutes and i'll post an answer

the texture needs to be assigned to a material on this object to be visible on the render , and to start using the nodes editor :

select the object
in the material tab click New button to create new material
click use nodes

in the node editor press  Shift+A➝Texture➝Image texture
in the texture node select you image ( the one you painted )
connect the texture node to the shader node ( click and drag the dot to the other one )


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Controlling the direction of face selection?
I may be missing something really simple, but I'd like to know if there is a way to control which direction my selection goes when selecting with  Shift +Alt. A simple example is shown in the attached gif, it is just a sub divided plane object. I just don't understand why I can't control the direction (x or y) of the selection. It seems that I have to figure out the best way each time, and select the leftover faces afterwards.

It really depends on where you click with your ALTRMB.
If you click close to the vertical top or bottom of your face, it will select the vertical loop. If you click on the horizontal area, it will select the horizontal loop.


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Is there a way to use quick explode on a plane object and make it look good?
I'd like to do something very simple, import an image as a plane and use the quick effect 'explode' but it doesn't really work well. I've tried extruding it and rotating it toward the camera to give the illusion of a plane, but the image is distorted. Is there a way to go about this either in BI or cycles? I've only tried in BI thus far. Subdividing also gives poor results. Thanks in advance.


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How would I get brighter color with the voronoi node?
I haven't used the texture nodes much but was experimenting with them today. From everything I have tried, the voronoi node always ends up kind of dark. I like the look of it, but the only thing that comes close in shapes while giving me the brightness I want is the Musgrave node. And it's still not really there. Can anyone help point me in the right direction? My node setups are below for each as well as a low sample Suzanne to help show what I'm talking about. The Musgrave gives much brighter color in comparison. Thanks in advance.

Be warned, the reason it appears brighter is the musgrave texture can return values > 1. In your setup this sort of turns the diffuse node into an emission node, as it will then reflect more light than it receives (which is not very physically accurate).

Have you tried a Color > Brightness/Contrast, Hue/Saturation, or RGB Curves node?  I'd also suggest just making your light brighter.

I would personally use the ColorRamp node. It permits not only to color but also to adjust the brightness of the result. This can help you: When can a Color Ramp be used to create a gradiant in a Cycles shader?


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Check if a mesh has an UV Channel in Python
I want to create a script that checks if the selected mesh has an UV Channel, if not it does a Smart UV Project.

This will do the trick:
import bpy

# Check if active object has any UV layers
if not len( bpy.context.object.data.uv_layers ):
    bpy.ops.uv.smart_project() # Perform smart UV projection

Thank you! Also we don't need to enter in edit mode to do a smart project with scripts.

Well I'll be, you're right - I'll fix the code above.


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Blender adding extra bone when exporting FBX causes problems with Unity & Mixamo
I've been exporting animations from Blender to Unity for a while and I've never had any problems so far. Recently, I tried Mixamo, a free library of animations which uses a specific armature system. The auto rigger they have isn't very good, so I decided to download a model with their own armature in order to use those bones as a base for a better rigging.
The issue comes when I'm finished rigging the mesh and I export it along the armature in an FBX file. Blender adds the armature object itself as a Node in the hierarchy which, seems to break everything. I'm not using custom animations, but instead Mixamo's animations with a different skinned mesh. Therefore, I need the same hierarchy of nodes(as well as the same names) in the armature tree.

The exported custom object is marked in red and Mixamo's model in green. As it can be seen in the picture, the yellow arrow shows the extra armature node (which is the armature object in the Blender scene).
Does anyone knows a way to avoid this addition ?
Disabling leaf bones as seen here : FBX export adding extra bone doesn't seem to solve the problem either. I've also seen a few posts with a similar issue but happening with Unreal Engine, but I couldn't find anything that helped me.

I know it's a year late, but I've just had this same exact issue, so I would like to answer it here in case anyone else comes by this post.
The way to fix this in Unity is, after dragging the model into your scene, right clicking it and selecting 'unpack prefab'. Then, drag your hip object, that is parented by the unwanted armature node, up one level. You can then safely delete the armature node, and the animations should now work as normal.
Hope this will help some people, this behaviour isn't documented well enough for how annoying it is.

For a long time, I have only now come to understand a pipeline. If someone works only through the Animator API or Animation Rigging in Unity itself, it is not so important. The pipeline is: Mesh > Mixamo > Auto rig for animations and avatars from this object.
Hierarchy:

File name (main parent object)

Hips (first bone)
Mesh

Problems:
When opening in other 3D packages, there may be issues with this hierarchy, such as an extra dummy element, as seen in Blender. Reconnecting this armature to a similar mesh in Blender through Data Properties or fixing animations can cause additional problems.
My suggestion is: Mesh > Mixamo (auto rig) T or A Pose > Blender import and export > Mixamo again. This way, we get a dummy container (FBX file name), mesh, and a dummy as a container for fittings where the hips begin.
All animations received from Mixamo for this object will also have the same hierarchy with an "extra" container, the name of which must be followed when editing.
Blender+Unity direction Armature and box Mesh , in Blender select Armature (normally import -Y forward), -90 X axis , reset rot Armature and Mesh , select Armature +90 X axis (Armature 90 , Mesh 0) - export (NONONO Transform experimental )
in Unity must be Case , Armature , Hips . box Mesh all good direction
Import in Blender - Leave Bones - Yes
Export - No , end bones to point but the others good , fbx


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Boolean tool useless for removing an end piece
Been stuck on this for a day now, cannot remove the end circle that is protruding out. Boolean tool doesn't do it. Neither does it work in edit mode. Why does it have to be so complicated?

Could you upload your file using this link? http://blend-exchange.giantcowfilms.com/. Also, what do you want to do: flattening this part along the cylinder or totally remove it?

Please do not ask the same question over again.

Make a loop cut at the center and delete the half with the extra edge made on the right hand (as per the question)
Click on the center vertex and Press Shit+S > cursor to selected in object mode press ctrl+Shift+Alt+C and select origin to 3d cursor . And then add mirror modifier on z axis


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viewport woes : cant hold drag anymore
I cannot use hold up-arrow and drag my model in viewport with mouse anymore.. guess i must have turned on (or off) some settings, but cannot figure it out. Any suggestions?

If the 'up/blue' arrow is not visible, you may have locked Z location. If so, have a look to the object's properties, in the 'transform locks' section.

can you tell me where i find this transform lock ? I have looked at Translate : Constrain axis .. and nothing were ticked there...

Have a look here: https://i.sstatic.net/v3k9r.gif. But not sure this is your problem as you provide few indications...

As a guess if you use Transform Manipulator - http://blender.stackexchange.com/questions/49549/transformation-buttons-disappeared, also maybe http://blender.stackexchange.com/questions/16318/lost-the-move-tool

it was neither of the two suggestions, but i uninstalled Blender and installed it anew.. and that solved my problem.. i have no idea what the problem was, but i am gratefully for you two gentlemens time and suggestions :-)

Go to Properties window > View > Uncheck "Lock to Cursor", it locates above "Lock Camera View". I just faced this problem LOL.


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How make visible grid cell size
Blender view port doesn't display scale (cell size) of the grid.
Grid cell changes depending on zoom in/out (1 mm, 10 mm, 100mm, etc) .
I haven't found an option nor a plugin.
Without knowing current scale it's hard to estimate object size.

Grid subdivision
You can avoid progressive subdivision of the grid by setting the Subdivision parameter to 1. The scale of the grid is in the Scale field: it's a multiplier for your current unit.
You can find the parameters in the Display panel of the Properties panel of the 3D view:

I never heard of a plugin capable of printing the coordinates of the grid. it would probably not be very easy to work with, but there are around lots of plugin/tools that can help you in measuring distances, such as:

Mesh Display Info (edge length, angle...)
Transform panel (for the global/local coordinates),
Ruler/Protractor tool
Measure-it add-on
and many other...

See for example:  How to get selected edges length?

Also if you switch to using Unit scale system the current scale of the grid cells dependant on the zoom will be displayed in the top left corner (below the ortho preset name).


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Bending a ping-pong racket
I want to bend a ping-ping racket.

I tried to use a curve modifier and I faced a problem which I think it's  solvable only in Python scripting. I hope there is an easier solution without any programming involved.
The curve modifier, to make a smooth bending, requires a lot of cross edge loops. It's easy to get them for Mesh objects like a cube or a cylinder using the tool loop cut and slide.
Tutorials about bending, I have found, don't discuss effective ways to doing so for complex objects, created with extruding a bezier curve.
I created a half of the contour of my racked with a bezier curve, mirrored it and extruded. Back and front sides are covered with triangles. I tried to beatify, poke triangulation, etc, but I cannot get faces in form of wide trapezoids automatically.
Subdividing pocked ngon is not good. It enforces to make a lot of triangles I don't need. Such triangulation doesn't give equal distribution. Some places has a lot of faces but others don't.
Here it my desirable ngon trapezoidation (Top view)
    ______
   /______\
  /________\
  |________|
   \______/
      ||
      ||

An idea about limitation of an triangle edge also looks promising, but I wonder why there is no such parameter for the triangulate operation.
I would get a lot of small triangles, but at least vertex density of the surface would be homogeneous.

What is purpose of this model and why not quads?

It should be a 3d printed sculpture.  This is my first day of using blender. How to use quads?

I don't have experience with 3D printing, but as far as I know proper topology is crucial for it. I'm trying to model this one now and I'll post answer in a while.

This case is pretty basic modeling stuff, so I will not go deeper in simple details and just show you an overview not to write full blown tutorial here (it's not place for this). If this is your first day you will need to know some starter pack things like:

Edge Loops and Edge Flow in general (tris, quads, ngons, poles and such),
creating, joining, cutting (Loop Cuts), extruding faces,
adding simple modifiers (Mirror, Subdivision Surface, Curve).

Everything is here, on Blender Stack Exchange as well as on YouTube or any other place with Blender resources (there is topic with them here too).

I'm trying here some new answer technique, so be gentle. I'll expand
  this answer as much as OP will need it.

Overview:

Start with simple Plane at extrude one edge along green curve 9 times (to get 10 faces).
Add Mirror Modifier with Clipping checked.
Fill in faces in the middle of paddle (I don't know how this rubber surface is called).
Extrude bottom face to have a handle.
Add Subdivision Surface Modifier.
Select all and extrude it to gave depth to paddle.
Add Loop Cuts along green curve (the same from first step) and the short one at the bottom.
Add Bezier Curve.
Add Curve modifier for paddle. Important! It should be above Subdivision Surface.
Move the paddle along Curve to adjust it.
Edit Curve to give it bend.

In the blend file, on layer 2 you have 3 models of paddle to study them.

Blend File:
Temporary link (Blend Exchange giving some error with URL):
paddle.blend


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How to create a seamless low poly terrain with displace and multiple planes?
I'm trying to create a large low poly terrain from a heightmap which is divided into multiple squares. Each square is then used as the texture for the displace modifier applied to a plane. However, when I then place the displaced planes next to each other to form the total terrain the edges don't align seamlessly.
Let me visualize this a little bit:
I'm using the following image (512px x 512px) as the heightmap for testing purposes:

This is going to be sliced into four (= 2 x 2) squares. (The final heightmap is supposed to be about 8 x 8 of these smaller squares). Let's just look at the top two:

I have already checked and there are no pixels lost between the two slices.
In the end each terrain tile is going to be in its own .blend file, but for demonstration purposes I'm going to have them in the same one for now.
Now I take two planes, subdivide them into grids of size 256 x 256 and add the displace modifier with the respective texture. (I'm also adding a decimate modifier but that's not part of the problem)

The texture settings are as follows:

Image Sampling is set to interpolate and image mapping extension to repeat (I've tried all extension options already)
The problem is this:

As you can see there are multiple places where the edges of the different planes don't align. I'm guessing that this is probably because each displace is lacking the information for the pixels of the other heightmap slice and therefore can't properly interpolate between the two.
Is there a way to solve this problem and make the edges align seamlessly? Or is there maybe a completely different and easier approach to this whole idea?

After testing a bit: create a vertex group corresponding to the border of one plane. add a shrinkwrap to it using this group. But! you will still have a normals orientation issue

Turn off interpolation in the image sampling panel of the textures.

A solution can be using two additional modifiers:

Shrinkwrap to fill the gap between the two images
Data transfer to align the normal continuously

The vertex group used to that is the following:

You can also use "extend" option on the textures mapping:

Edit
Applying the data transfer modifier won't work if 'auto smooth' is not set, as Blender will recalculate the normals.
So use auto smooth (180°) and apply the modifier:

Thanks for the answer! If I understood it correctly this would require all the adjacent planes to be in the same .blend file though, wouldn't it?

I think you can apply the modifiers, so once done, each part can be saved separately (use 'generate data layer' for the data transfer modifier)... well... just tried, for the data transfer applying does not seem to work...

OK, set "autosmooth" on with 180° for both meshes (data tab). Then data transfer can be applied and will be kept.

Thanks a lot for the follow-up. I'm going to try this out later today, but I think in the end I'm probably going to work around this issue in some other way. My computer is probably not going to be able to handle a lot of planes and the data transfer modifier all at once (It was already struggling with just two).


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How to see python symbolic names of objects on cursor hover of menu items in Blender 2.8
in Blender 2.79 one could hover over a UI element and see the symbolic python name of said element. How would one accomplish the same with Blender >= 2.8?

Python Tooltips needs to be enabled in Edit > Preferences > Interface.

You simply go to Edit/Preferences.../Interface and tap the Developer Extras checkmark.


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Add cubes->add UV textures->union->bake single texture image with Python
My problem is mainly with UV texturing from Python.
I am building a complex model from Python. The model consists of several cubes which have different colors. On top of each cube there's supposed to be an image texture. The goal is to add the cubes from Python, color and texturize them, then union everything with a boolean modifier to get rid of overlapping parts and then to bake the separate textures into a single texture file. In the end I'll upload the 3D model to Shapeways to 3D print it.
In the basic example provided I have 5 cubes. The textures for the cubes are in 5 separate PNG files. The output from my script looks like this:

The output is fine, textures are in the right place and the overlaps are gone. I can now export this to X3D and upload to Shapeways, but on more complex models I'll have 500 separate unoptimized PNG files. This doesn't play well with Shapeways, so I'd like to bake the separate textures into a single texture of 2048x2048. But when I try to do this manually, I get the following result:

This is supposed to be the texture for the whole model, so clearly something isn't right.
The question: How to texturize the top of cubes, so it will survive the Union boolean modifier and Texture bake operation from Python?
My code (I'm 100% sure my approach to applying the Union boolean modifier is wrong, but other approaches I tried didn't maintain the materials):
import json
import bpy
import mathutils
import os
from mathutils import Vector

bpy.ops.object.select_all(action='SELECT')
bpy.ops.object.delete()

# Configurable variables
path_to_json_and_textures = "/path/to/question/folder"
max_model_dimension = 20 # Blender units are in meters
cube_height_relative_to_width = 0.1
overlap_fraction = 0.25 # overlap of cubes stacked on top each other
scale_factor = 0.01

def isJipObject(ob):
    return ob.name.startswith('jip-') and ob.type == 'MESH'

def union_model():
    scene = bpy.context.scene
    web_space = scene.web_space
    obs = []
    # Only union objects made by this script
    for ob in scene.objects:
        if isJipObject(ob):
            obs.append(ob)

    nr_of_cubes = len(obs)
    if not nr_of_cubes:
        return

    # Add some noise, give each object has unique dimensions
    # Boolean modifier doesn't work with perfectly aligned cubes
    boolean_hack = 0.0
    boolean_hack_step_size = float(0.001/nr_of_cubes) # spread out 0.1mm of noise over all cubes

    # Slightly change the scale of all of the cubes, before union
    for ob in obs:
        ob.scale.x += boolean_hack
        ob.scale.y += boolean_hack
        ob.scale.z += boolean_hack
        boolean_hack += boolean_hack_step_size

    # Don't touch current context...
    ctx = bpy.context.copy()
    # one of the objects to join
    ctx['active_object'] = obs[0]
    ctx['selected_objects'] = obs
    # we need the scene bases as well for joining
    ctx['selected_editable_bases'] = [scene.object_bases[ob.name] for ob in obs]
    # Join the objects - this will assign all materials correctly to all objects
    bpy.ops.object.join(ctx)
    # Break them apart again - not sure what happens,
    # but joining and then breaking apart allows to do a union while perserving correct UV mapping...
    # Perhaps it has to do with the origin of the cubes? Joining then separating assigns all cubes
    # the same point of origin, as well as the same location, scale and z dimension
    # The only variance is in the x and y dimension
    bpy.ops.mesh.separate(type='LOOSE')

    prevCube = False

    scene = bpy.context.scene
    # Need to reselect the objects, because of 'separate by loose parts' the objects in obs no longer exist
    for ob in scene.objects:
        # whatever objects you want to join...
        if isJipObject(ob):
            if(not prevCube):
                prevCube = ob
            else:
                modifier = prevCube.modifiers.new('Modifier', 'BOOLEAN')
                modifier.object = ob
                modifier.operation = 'UNION'
                bpy.context.scene.objects.active = prevCube
                bpy.ops.object.modifier_apply(apply_as='DATA', modifier=modifier.name)
                scene.objects.unlink(ob)

    bpy.context.scene.objects.active = prevCube

def makeImageMaterial(index):
    material_name = "jip-material"+str(index)
    if material_name in bpy.data.materials:
        return bpy.data.materials[material_name]

    # Create shadeless material
    mat = bpy.data.materials.new(material_name)
    mat.use_shadeless = True

    # Try, if not exists don't make texture
    try:
        realpath = os.path.join(path_to_json_and_textures, 'cropped', str(index)+'.png')
        tex = bpy.data.textures.new(material_name, type = 'IMAGE')
        tex.image = bpy.data.images.load(realpath)
        tex.use_alpha = True
        # Create texture
        mtex = mat.texture_slots.add()
        mtex.texture = tex
        mtex.texture_coords = 'UV'
        mtex.use_map_color_diffuse = True
    except:
        print("Texture %d not found" % index)

    return mat

def makeMaterial(red,green,blue):
    # return existing
    name = "jip-material-%d-%d-%d" % (red,green,blue)
    if name in bpy.data.materials:
        return bpy.data.materials[name]

    colorName = "jip-material"

    material = bpy.data.materials.new(name)
    material.diffuse_color = (red/100., green/100., blue/100.)
    material.use_shadeless = True
    # return new
    return material

with open(os.path.join(path_to_json_and_textures, "data.json")) as data_file:
    model_data = json.load(data_file)

    # Non-configurable variables
    model_width = (model_data['right'] - model_data['left']) * scale_factor
    model_height = (model_data['bottom'] - model_data['top']) * scale_factor

    initial_cube_height = model_width*cube_height_relative_to_width
    half_current_cube_height = initial_cube_height/2 # divide by 2 because the scale operation increases height towards top and bottom
    non_overlapping_fraction = 1 - overlap_fraction
    current_z = -half_current_cube_height + overlap_fraction*initial_cube_height

    mylayers = [False] * 20
    mylayers[0] = True
    add_cube = bpy.ops.mesh.primitive_cube_add
    prevCube = False
    count = 0

    # Make initial object
    origin = Vector((0,0,0))
    bpy.ops.mesh.primitive_cube_add(location=origin)

    ob = bpy.context.object
    bpy.ops.mesh.uv_texture_add()
    obs = []
    sce = bpy.context.scene

    # Loop over each level and make all the cubes, with color and texture
    for i, level in enumerate(model_data['levels']):
        current_z += half_current_cube_height*2 * non_overlapping_fraction # compensate for overlap in z coordinate
        for element in level:

            copy = ob.copy()
            node_width = element['w']
            node_height = element['h']
            copy.location = Vector(((element['y']*2 + node_height)*scale_factor,
                                    (element['x']*2 + node_width)*scale_factor,
                                    current_z))
            copy.scale = (node_height*scale_factor, node_width*scale_factor, half_current_cube_height)
            copy.name = "jip-" + str(element['nodeIndex']).zfill(6) # leading zeros for correct sorting in GUI
            copy.data = copy.data.copy() # also duplicate mesh, remove for linked duplicate

            material = makeMaterial(element['r'], element['g'], element['b'])
            copy.data.materials.append(material)

            image_material = makeImageMaterial(element['nodeIndex'])
            copy.data.materials.append(image_material)

            # Set image material for top face only
            copy.data.polygons[5].material_index = 1

            obs.append(copy)

    # remove initial object
    bpy.ops.object.delete()

    # Now add them to the scene, adding large number of cubes is quicker this way
    for ob in obs:
        sce.objects.link(ob)

    union_model()

You can download the .blend file, script and textures from here: https://db.tt/dhTMLXe0

rapid reading... but can that be because you need to apply the modified scales before the union ?

Unfortunately the result is the same. Steps taken: Apply scale for each cube. Manually assign all the materials to the bottom cube. Manually apply boolean modifier (union) 4 times to unite with the other cubes. Then in UV Editing window I bake to a newly created image. Same thing happens when I also apply the location.

The UVs from the sides and bottom overlap, is that expected ?

What do you mean by that @lemon? How can I check this? The bottom and side should have the same material and color. But overlapping UVs doesn't sound right... Also, do you mean before the union or the end result?

you are baking all the faces, including the sides. And the sides (UVs) overlap the top picture. So probably the result is dependent on the order (materials) the bake is working

If I just select the top faces (no sides or bottom) and then bake the resulting is still overlapping.

The PNG files were actually cropped form an original large PNG containing all the image data already. So I didn't have to bake to a new file.
This answer focusses on adding the UV mapping via Python.
Join all the cubes (ctrl+j).
With this script I was able to automatically unwrap all the cubes as if doing "UVs -> Unwrap -> Project From View (bounds)" in an orthographic top view.
import bpy, bmesh
from mathutils import Vector

# https://blender.stackexchange.com/questions/32283/what-are-all-values-in-bound-box
def bounds(obj, local=False):

    local_coords = obj.bound_box[:]
    om = obj.matrix_world

    if not local:
        worldify = lambda p: om * Vector(p[:])
        coords = [worldify(p).to_tuple() for p in local_coords]
    else:
        coords = [p[:] for p in local_coords]

    rotated = zip(*coords[::-1])

    push_axis = []
    for (axis, _list) in zip('xyz', rotated):
        info = lambda: None
        info.max = max(_list)
        info.min = min(_list)
        info.distance = info.max - info.min
        push_axis.append(info)

    import collections

    originals = dict(zip(['x', 'y', 'z'], push_axis))

    o_details = collections.namedtuple('object_details', 'x y z')
    return o_details(**originals)

obj = bpy.context.scene.objects.active

if not obj is None:

    # Get the lowest and highest x and y values from the bounding box corners
    object_details = bounds(obj)

    lowest_x_cor = object_details.x.min
    highest_x_cor = object_details.x.max

    lowest_y_cor = object_details.y.min
    highest_y_cor = object_details.y.max

    obj.data.uv_textures.new("map1")
    # Get a BMesh representation
    bm = bmesh.new()   # create an empty BMesh
    bm.from_mesh(obj.data)   # fill it in from a Mesh

    bm.faces.ensure_lookup_table()

    uv_layer = bm.loops.layers.uv[0]

    nFaces = len(bm.faces)
    for fi in range(nFaces):
        face = bm.faces[fi]

        for loop in face.loops:
            # Scale the vertex coordinates into 0 to 1 range
            NewXValue = (((loop.vert.co[0] - lowest_x_cor) * 1) / (highest_x_cor - lowest_x_cor))
            NewYValue = (((loop.vert.co[1] - lowest_y_cor) * 1) / (highest_y_cor - lowest_y_cor))
            loop[uv_layer].uv = (NewXValue, NewYValue)

    # Finish up, write the bmesh back to the mesh
    bm.to_mesh(obj.data)
    bm.free()

This als UV maps the side and bottom faces. It stretches the pixels on the border of top of the cubes down the sides, which I like. To only texture the top I should not loop over all the faces, but instead only the faces with a normal of (0, 0, 1 ).
For this I could use these functions:
# https://blender.stackexchange.com/questions/75517/selecting-faces-in-python

def NormalInDirection( normal, direction, limit = 0.5 ):
    return direction.dot( normal ) > limit

def GoingUp( normal, limit = 0.5 ):
    return NormalInDirection( normal, Vector( (0, 0, 1 ) ), limit )

def GoingDown( normal, limit = 0.5 ):
    return NormalInDirection( normal, Vector( (0, 0, -1 ) ), limit )

To get rid of the internal geometry I found Netfabb (for Windows only) is the way to go if the goal is to prepare for 3D-printing, instead of the Boolean modifier in Blender. After UV unwrapping I export a 3DS file from Blender, then import into Netfabb. Let it do auto repair upon import. Export to 3DS again and import into Blender. The UV mapping is still correct but the internal geometry is removed.


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Union partially overlapping cubes without boolean modifier
My goal is to generate a model composed of many partially overlapping cubes. But I need to get rid of the parts where they overlap, so I have a single mesh without any intersections. One of the purposes is 3D printing. With the boolean modifier I can make it work sometimes, but often the resulting model is totally corrupt (missing parts, weird geometry, non-manifold). BMesh and Carve both have issues. I've had the same experience with the boolean modifier in e.g. Sketchup.
So my question here is how would I manually connect these cubes and remove the overlap? Eventually I will have to do this in Python, but I can't program it if I don't know how to do it to begin with...
Image of example model with partially overlapping cubes:

Image showing inside of example model with internal geometry removed:

Rules:

Each cube has the same height (Z scale)
Each cube belongs to a certain 'floor'
Therefore each 'floor' has the same height
The difference in Z location between two following floors is the same (floors are distributed evenly)
Every cube on a higher floor is supported by at least one cube from the floor directly below it (meaning no cube will float in the air, except for cubes on floor 0)
Cubes on the same floor may intersect each other (I didn't show this in the example images)

Basically it's a tower of cubes with dedicated 'floors', like a building. But each floor is pushed down a little to overlap the floor below it.
The way I think I should tackle this is as follows:

Place all the cubes in correct position, but without pushing down each floor (so no overlap, only touching)
Calculate the places where the faces touch using the Shapely for Blender Python module (using 2D boolean operations)
Cut a hole with the Knife project for each of these parts where the faces touch
Somehow merge/connect the vertices which surround the newly cut hole - this should connect the previously separate floors
Continue with 2, 3 and 4 until finished
Select the faces that face down (except for the faces of floor 0) and pull them down a bit to create the overlap which we didn't make at step 1

I hope I'm on the right track here. I can do step 1 and 2 but from step 3 I don't know how. It sure would have been nice if the Bool Tool Auto Boolean Union would have worked for me but unfortunately that's not the case. I've included a simple example Blend file, as well as a complex one where the Bool Tool fails.
I'm using Blender Version 2.78c.

Turns out Python+Blender is not the right tool for the job. I used Python+OpenSCAD instead and so far I have not experienced any issues with the union boolean modifier. Glad to find out there's an easy solution that just works and that there's no need to do any complex stuff in Blender.
From OpenSCAD I can export to STL and import in Blender if I need to do some manual adjustments.


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Screen corrupting in the blender UI
I'm getting corruption in the blender UI that looks like some of the components are not being drawn correctly, overwriting parts of the screen. I've experienced these issues at various times - usually in the toolbox or other panels - and it was usually nothing more than a minor inconvenience as I could usually simply scroll the panel up or down a bit and they'd go away. However, now I've got the same issue on the node editor window in the compositor and it's making it pretty much unusable. Does anyone else experience this problem and/or have any ideas for a solution? It's sometimes tricky to take a screenshot as moving the mouse or swapping windows to the screenshot utility changes the pattern, but here's a (minor) example of what I'm getting :

Often it's more colourful that that. The pattern changes as the screen is moved around or other elements are selected.
I've tried changing the Window Draw Mode, Text Anti-aliasing, Images Draw Method, etc. in the System preference screen but nothing seems to improve matters.
Any help very much appreciated as this is driving me a bit nuts at the moment.
In case it helps, this is on Blender 2.76a running on Ubuntu on an Acer Travelmate with 2Gb memory - earlier versions of Blender also had the problem but I just figured it was a glitch that would go away with later versions, but it didn't.

Don't know if it's a clue but in this case it seems that the 'Add' node has something to do with it as the image is missing and the 'Add' drop-down is missing its usual decoration.

What GPU are you using? What Ubuntu version are you using? Stuff like that matters. A lot.

No GPU - CPU only. This is on lubuntu 16.04 - but I've been having the problem since much earlier versions.

I've tried searching for additional drivers and it did find one to install - it's now installed and rebooted but the problem still exists. In the preferences for Compute Device it's definitely set to CPU - no option for anything else. One thing I have just noticed is that if I switch off the thumbnail image on the Add node on my screenshot (by clicking on the circle at the top-right) or scroll the node so the image is at least partly off the screen then it's better - it's a reasonable workaround for now :)

lspci reports it as "00:02.1 Display controller: Intel Corporation Mobile 945GM/GMS/GME, 943/940GML Express Integrated Graphics Controller (rev 03)"


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Rotation Animation
This is not a request for help but more an observation that invites other observations related to it. It has to do with rotation animation in Blender.
Please note that in the following the object being animated is at the world center and has no scaling or rotation.

Animating a "cube" seems very straightforward. Set keyframes at desired start and stop frames with 0 and at 360 rotation, respectively. Modify Graph Editor settings as needed. The cube rotates perfectly. Adding an "empty" in this case is superfluous.
Animating a UV sphere, however, can get tricky. Following the same steps as above, the sphere does NOT rotate as one would expect. It appears to start rotating in the desired direction but then stops and begins rotating in the reverse direction. I broke it up into four different rotation steps but that did not help. The only thing that worked was to parent the sphere to an empty and animate the empty.

I even went so far as loading the "factory" defaults to make sure I had not altered something that would cause this. The same thing happens. The fact it can be worked around makes it a low priority thing but it raises a question for me.
Why doesn't the sphere behave exactly like the cube when animating? I assume the nature of the sphere's geometry is somehow involved but a cylinder animates correctly like the cube. Same with the monkey and the monkey is somewhat spherical topologically. So what is it about the UV sphere that makes it prone to this odd behavior?
As far as I can tell, it is only the UV sphere that is giving this odd result. I'm on Blender 2.75 (just released) but I recall running into this problem in previous versions of Blender although I don't recall the details now and I was able to find a workaround.
If anyone tries this, let me know if you see the same odd behavior I'm seeing. The sphere, animated to rotate about 360 in a given timespan appears to rotate in one direction then reverses and rotates in the opposite direction. I thought it might be the rotation itself was fooling my eyes but I watched the "Rotation" values during the animation and those values validate what I'm seeing.

How exactly are you animating it? The way I'm doing it is by typing 360 into the shape properties menu, then keyframing it with I. It works fine for every shape that I've tried. (This is meant to be a comment)

This is because the rotation is local, and not global, i encountered the exact same problem in the game engine not to long ago. What i mean by local, is that as the sphere rotates, so does the axis that it is rotating upon. once it rotates a full 180 degrees, it wants to go the exact opposite direction. writing an answer for you in 3... 2...

that doesn't happen for me !

I tried changing the locality but that did not work. I used both approaches, typing the values in the Properties menu and physically rotating the sphere (just to see the effect). I consider this odd, then. Everything but a UV sphere animates properly when rotated, at least for me in the official 2.75 release. There has to be a reason -- this cannot be due to a graphics card issue. I repeated this earlier today and got the same result. Very, very weird. More research ... repeat: this only affects the UV Sphere, no other object that I can tell.

It sounds like a gimbal lock problem. Set in your object tab of your sphere 'Rotation Mode' to 'Quaternion WXYZ' and delete the old keyframes and reanimate it.


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Smoke simulation - how to make a slow fog
I'm trying to achive a fog effect with smoke simulation. But what I'm getting looks more like a flame and is moving too fast.
Does anyone know how to make it very slow and smooth - as a real fog would behave ?
Here is my example and my smoke settings: https://drive.google.com/file/d/0BxWsWeQP5ugaeHQwQ3owa0t2cEk/view?usp=sharing

'Velocity' value, when set high, then there is more turbulence. If you set the 'density' value and 'temperature' value both low then the smoke will go up slowly. See this https://www.youtube.com/watch?v=pYNr0ZtyD1c

But if you make those values low the smoke doesn't rise and is flat on ground. I want it to be cloudy but move slow.

Then you should increasing the temperature value, to what you like ;)

There are 2 ways and you may need to use a combination of both depending on how slow you want to slow it down:
1) Change the Time: Scale with the CUBE DOMAIN

2)
Slow down the frame rate. E.G. change 29.97 to 120 fps.  Unfortunately it's not a perfect solution- it will change the characteristics of your smoke and you'll basically have to tweak everything from the very beginning.


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Varying focal length camera import problem
I'm trying to import a camera from Nuke to Blender, which has a varying focal length. The camera animation is imported correctly, but the focal length is static - set to the first frame value.
I tried Alembic and FBX, both give the same result. If I reimport to Nuke - the focal length is animated as it should be.
Any ideas how I can import it correctly. Or at least how could I copy the animation values to Blender ?
Thanks,
Lukas

Focal length sounds way to specific to import/export. Read https://blender.stackexchange.com/questions/57531/fbx-export-why-there-are-no-materials-or-textures

Sorry, but I don't understand what you mean. What does camera parameters have to do with material export?

Like materials, camera parameters are application specific properties that can't be easily ported between different software, nor do exchange formats have data structures to store them, as far as I know.

No, camera parameters are not software specific, and they are stored in FBX and Alembic files. Unfortunately it's not possible to import the focal length animation into Blender.


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How to save and load an object position?
I want to know if it is possible and how to save and load the object position using the same script that i used to save and load properties.
Here is the script: http://pastebin.com/aNZATwxX

It'd be better to paste the code directly in your question instead of linking to it because all contents of your questions (thus your script) should be available as long as your question is available, so basically as long as Blender Stack Exchange exists. Here you can see how to mark text as code.

My reputation is too low to comment. But your link to the script is not working.
If the script is writing and reading from an external file, it should definitely be possible to modify it to also save the object position.
Try re-uploading the script.

Your welcome :)

authors: Дмитрий Гуськов


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UV grid only showing on the uv/image editor not the 3d view
UV grid only showing on the uv/image editor not the 3d view- this is what I mean https://i.sstatic.net/WCGKU.jpg

Maybe you have to save the image.

Please provide information about your render engine as settings will depend on that. See related on both Blender Internal and Cycles http://blender.stackexchange.com/questions/5283/how-to-show-textures-in-the-3d-view-editor

Thanks so much, iv been dying to find the answer and it was only because I was using cycles render instead of blender render :D

Judging from your screenshot, you're using Cycles Render engine and Textured View in the viewport. Cycles in this case behaves like this: It will show the image texture node on your model which is at the moment selected in the Node Editor (in the screenshot i marked it in a red circle), no matter if it is connected in the Node Tree or not. If you click another Image Texture Node in the Node Editor, the viewport will show you this one. Not seeing any texture could either mean you have no material set up at all, or an Image Texture Node is selected which does not provide any output at the moment.
The material preview mode on the other hand will give you a representation of the "real" material output, i.e. it tries to evaluate all nodes which are connected and show the result, independent of your selection.

Thanks so much, iv been dying to find the answer and it was only because I was using cycles render instead of blender render :D


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Finding reference images
On Blender I like to model helicopters, guns, cars, tanks. The modelling isn't the problem. The problem is getting reference images of the small details, Most of the things I need I can just search on google and find a picture of it. The problem comes when for example I was modelling a AH-6 Little bird and finding what the avionics and general interior is a nightmare, any suggestions of efficient ways of getting reference images?
Thanks for any help :D

Any of these help? https://www.google.com/search?q=ah-6+interior&client=safari&rls=en&biw=1669&bih=866&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwjP0JfZqrPQAhVh6YMKHciXCNAQsAQIGg#tbm=isch&q=ah-6+helicopter+interior


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Aligning vertices
In the image I want to make the middle vertices out of all the selected vertices align with the 2 other vertices selected. So pretty much I want to know how to make the bottom image look like the top image

you can copy the values for Z and Y of one of the other 2 vertices to the one in the middle

Aside from already added solutions you have many other ways, like changing Pivot Point to Active, selecting vertices to align and lastly - vertex to align to and scale to 0 by Z axis (in this case), or just flatten the edge / face by Z axis.

The easiest way to do that is to turn on vertex snapping.

That will work only if the first and last vertices are aligned with world coordinates.

Simple way to do that is with looptools addon, which can be enabled in the user preferences.
Once its enabled, select the vertices you want to align and in tools panel, Looptools section, select Gstretch, that will make an even distribution of  connected vertices between the first and last one in that selection.

Another way, not stated above, to do this is:

Select the vertice that is the desired height already
Press N to toggle the properties panel.
Copy the Z coordinate
Select the vertice that you want to re-align
In the properties panel, paste the z coordinate


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Vertex paint dirty vertex colors highlighting the wrong places
I tried adding dirty vertex colors to my sniper scope but it didn't seem to like sharp edges, The image of it is down below , any help would be appreciated. Thanks :D

There is probably not enough geometry or detail. Also check your normals.

You could adjust settings a bit.. E.g. set Highlight angle a bit down and Dirt angle a bit up. Also Vertex paint relies on topology, so the problem could be with it.


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Same yet different Y axis?
Iv just found an issue where 2 vertices are on the same Y location yet they are not in the same Y location. And this isn't just me being stupid I have a straight line of vertices along a Y axis yet when I typed the location of the Y axis for that vertices it wasn't the same as the others I had made. I don't see the logic in this

Is it possible you could upload the .blend?

Are there any modifiers on your object? Shapekeys? Animations? Hooks? Does it have any weird transforms or any other thing that me be distorting its shape


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scaling with an equal distance from each vertices
I'm trying to make a machete but when I'm trying to make it have a sharpness I extruded, loop cut the top of it so I could scale the front faces to give it a sharpness but how do I scale it so it moves all the vertices an equal distance away from eachother
thanks to anyone who replies :D

It's a bit unclear from the question what is your desired goal. Depending on the case, scaling is done with - Alt+S for scaling along normals of the faces, S with Pivot Point set to Individual Faces for scaling each group of selected faces up or down.

You can try the Inset tool. related post

I just used the bevel tool, thanks for ur answer :D


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precisely moving faces in different directions
Here is a picture to help show what I mean
Thanks to anyone who helps :D

Click G to grab or translate the face, which you've selected and type the certain distance you want the face to go. You can use the X, Y and Z keys to lock the movement to a certain axis.

To piggy back this comment, you can also hold down shift while dragging to make a more precise selection.

Is it possible to move parts of a model along the selected normals?
TL;dr:
You may also move the faces along the normals.
To do this just change the Transform Orientation.

Doing so aligns the Z axis with the Normals of the selected faces.
After pressing G for Grab Press zz to move along the normals (Pressing once moves them along the Global Z-Axis)
EDIT: Formatting

This would be the better way, if the model is not correctly aligned to the global axis'.

so tell me, did it work out as planned ?


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Face reflects light differently to others
I'm currently working on a Stryker, i'v came across a problem which make it so one of the faces reflects light differently than all of the others.
Thanks to anyone who helps/attempt's to help :D
Here is a picture of it

In case of question about unexpected results of reflection it would be good to include screenshot with that reflection. And if possible a file.

This is a problem related to the normals.  To correct it, go into edit mode and select everything. (This can be done by pressing A once or twice.)  Then, click Shading/UVs > Normals > Recalculate.  If this does not work, select the single face and click Shading/UVs > Normals > Flip Direction.

Thanks for the answer but didn't work :/

Strange . . .  Could you upload your .blend file to http://blend-exchange.giantcowfilms.com/?

If you open up your preference and look under the System Tab you will see Solid OpenGL lights. They are the defaults to help you see 3D surfaces that face different directions - it is just an aid and does not affect the render. If a face goes severely dark then the chances are the Normal's are flipped. In your case nothing to worry about...

If you want to check your Normals though, there is always the button under Mesh Display.

authors: Ульяна Шапарова


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Glass texture restricted to certian parts of the mesh
I've been working on a little bird but encountered an issue, I can't get it so that the glass texture is restricted to the faces I have selected.

I just had to add a second material...solved


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Hard surface modeling issue
While trying to model the Mi8 HIP (Russian helicopter) I came into a few problems as the top view of the blueprint didn't seem to match inside sort of view as shown in the screenshot below, I'm not sure if its me that's making the mistake or the blueprint is incorrect. if anyone could tell me what I was doing wrong that would help a lot as this has had me confused for ages now. This question may not be entirely related to blender it is still related to modelling.
Thanks for the help :D

I believe they match:

Ми-8МТВ-5
Look at the red star, then go up.

I see cross section number 8 like this :

The "turret" is seen in one side view and not in the other views but is there in cross-section 8.
I would use Google to find out what it is then you can decide if you need to have it in your modelor not.


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How can I clone part of the texture?
I'm working on an axe. I've modelled the axe and am working on texturing it. I unwrapped the texture and inserted a picture into the UV image editor and made the mesh fit the picture. The only problem is there is a white gap in the texture, and I want to clone part of the texture to the white gap. I've seen this done on youtube with a texture painting tool or something like that, but when I try it, it doesn't seem to work.
Here is a screenshot of it

https://i.sstatic.net/1r8ee.jpg -
Thanks to anyone that replies :D

For future reference- you can attach the picture when asking a question instead of using a link

k, but can u help me with my question?

Sorry, I'm trying to figure it out. I don't have much experience with uv unwrapping.

To use the clone brush :

Select the clone brush in the paint tools
Ctrl+LMB to set the origin of what to clone from (the 3D cursor is set at this origin)
Then simply paint on the target position

Painting with a strength set to 1 is often better, but it depends on what you want.

If you want to clone from a picture that is not in the current model, you may need to set this picture on another mesh then join the two meshes, as this tool does not handle to clone parts that are outside of the painted mesh.

Slight gotcha that I couldn't find documented anywhere: this tool doesn't seem to work in the image editor, unlike the other texture editing tools.

authors: СаидМалик Мухаммадиев


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texture paint isnt working in certain places
I've been working on an axe, the 3D model is complete and I'm working on texturing. Most of it textured no problem but there is little bits that wont texture whatever I do.

I fixed It I just sighlighted the faces that had the bits of texcture missing and projected them from view and moved it to part of the image with the same colour


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Increase Transparency in Animation for all Materials
In Blender I have been wanting to create an effect where an object with multiple textures disappears evenly. I have figured out how to do this individually, but I would like to be able to decrease opacity for multiple materials. I have just started with blender, Sorry if this is a stupid question.
Thanks,
John

I would do this using drivers.  Have you worked with drivers before?

You could keyframe the transparency value for each material individually, or you can use drivers, as @PGMath suggested.

What render engine are you using?

You can do this fairly easily by using some simple drivers.  Drivers are a way of controlling one property based on the value of another property or properties.  If you have never used them before drivers can seem a bit daunting, but simple driver setups like this are actually pretty easy to set up.
First, add an empty to your scene.  This will serve as a "fader" to adjust the opacity of your materials.  This way you can just animate the movement of the empty, and in turn it will control all the transparency.  (It is not necessary, but somewhat convenient to add a couple Limit Location constraints to the empty to only allow it to move in a straight line like a real fader.)

Next, right click on the opacity setting for your material and select Add Driver.  This will make the field turn pink, indicating that it is now being controlled by a driver.
Now jump over to the Graph Editor and select Drivers under the Mode selector.

Now find the driver on the hirearchical list on the left and select it.  (I am using the Cycles render engine, so yours may be a little different than mine if you are using Blender Render.  Basically it will just be at the bottom of the hirearchy.)
Now look at the panel on the right side (if it's not there just hit N) and scroll down to the Drivers rollout.  Near the top here is a field called expr, this is the expression that determines the actual value of the driven property.  Just type "var" here, as that is the default name of the default variable and it will work fine for us (in more complex situations when you are dealing with multiple variables it is usually good practice to name them something more useful).  Now go down to the variable named "var" and select the empty you added for the Ob/Bone field and select Y Location for the type.

Now as you move the empty up in the y-direction the opacity of all your materials should change accordingly!

There is another, slightly simpler way you can do this (as opposed to my other answer) if you are using the Cycles render engine by using a node group.
A group node is a set of nodes combined into one.  To turn a set of nodes into a group node, select them and hit Ctrl+G.  You can edit a group node by selecting it and pressing Tab, press Tab again to leave the group node's editing mode.

First add a Transparent shader and a Mix Shader node and plug the Transparent node into the top input of the Mix Shader.  Then select the two nodes and hit Ctrl+G to group them into one.  This will automatically bring you into edit mode for the new node group.

You will notice that there are two more nodes inside the node group, a  Group Input and a Group Output node.  This is how information is passed into and out of the node group.  By default the node has no inputs or outputs, making it pretty useless.  To fix this, drag a node wire from the socket on the Group Input node and plug it into the bottom socket on the Mix Shader.  Then connect the output of the Mix Shader to the Group Output node.

This group node can now be added to any of your materials under the Shift+A > Group menu.
Now you can add this group node at the very end of all your material node trees.  When you go into the group node and adjust or animate the mix factor it will adjust the opacity of all the materials you have added this node to.


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Unable to see smoke, and still see faces of object in Wire(Maximum Draw Type)
I am working on making a rocket in Blender using this tutorial
https://www.youtube.com/watch?v=4pQc0qIy33A
but I am unable to see my smoke effects in render mode, but I am able to see them in Solid view. Also for the cube I am using for my domain, I am still able to see the grey faces on the cube, even though I changed Maximum Draw Type to Wire.
I apologize if this is an obvious question, or if I am not describing my problem well, if you need anymore information then I would be more than happy to supply it.
Thanks,
John

Please post a blend file here. Most likely your material is not adequate.

not sure what went wrong.
to make smoke first decide your render engine Cycles or BI.
Next on the 3 screen hit space, type quick smoke
you'll get something to start with, keep in mind smoke requires light as well and settings how thick it will be can be tuned, and viewport might not reflect cycles but be just some aprouch to it.


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Why a scene render might have many very dark triangle artifacts?
It was imported from obj and the scene has some environment light and a lot of sun light (the only way to make shadows more contrast I found).

.blend file: https://yadi.sk/d/UEUud0Y93HWBUH
Thank you!

In edit mode press A, so that the whole mesh is selected. Then press Ctrl+N (this fixes the normals of an object, normal essentially tell the render engine which way the face is facing). Then press W and select delete doubles.

Thank you, works like magic! Could you please also specify name of an operation that is performed when you do Ctrl+N?

wonder why this answer might not work here; it seems like they do very same things

I'm sure though, I"m not the best with python

@Ben Usman CTRL+N is the shortcut to (edit mode) mesh > normals > recalculate outside


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Mark faces to use different textures
I'm traying to make a material for the leaves of an ivy, and i got 2 different images of leaves.
I would like to keep all the leaves as a one object, with one, material, and somehow mark the faces to use different images and get a better result.
Is it possible, or do I have to select random faces, separate in a new object, and use a different material?
I could use the same material and object id to switch texture, but if possible, as said, i'd prefer keep al the leaves in a single object.

Look at this thread. Also randomizing leaf color probably could be useful.

You can use different material settings in 1 shader and mix them.

Here you have 2 diffuse shaders using different textures. The mix shader uses as factor a random objet info to choose wich one to use. the color ramp, set on constant, allows to use only 1 one them, not a random mix of the 2 (constant) and the Position at 0.5 allows a 50% mix, but you can have more or less of a material moving the slider left or right.

As far as i know there is no direct mechanism to control different textures on a per face basis, however you don't need  to separate into different objects to use different textures or materials.
Either setup two similar materials each using different textures and use different material slots for each (you can use random select to assign materials to randomized faces), or if you really need only one material merge your two textures into a single image file with both leafs and use uv map offset for each face to show whatever leaf you want.

Yeah, i considered this, but for each leaf i have diffuse, normals, and specular map, so there would be 3 double-sized image files.
For now i made 2 object with different ObjID.
Thanks anyway for the help!


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Trouble controlling where to add Faces on my model
Problem:
I have a curved edged wire model that I have developed that needs to have a Face applied to it, whilst keeping other "holes" within the model "Face-free". It's like a wire mesh but the wires are much thicker and flat.
How I created it:
I initially used curves to create the model as can be seen below then converted it to a mesh. Then I selected all the edges and pressed "F" to create a face. I hoped that the long flat curved wires would get faces, leaving the middle "holes" empty. Unfortunately only the middle "holes" became Faces and the flat wire sections were left, albeit somehow linked to the middle Hole faces.
My only other option is to individually select each face in straight groups before pressing "F" but this would take days as the model is pretty large.
Any help would be appreciated.
Image 1: Pre-Face. I want the thinner parts to have Faces and centre "holes" to be empty.

Image 2: After adding Faces this is the outcome with Faces where I don't want them.

Image 3: After selecting the Hole Face and deleting it the Face icon (the black dot) disappears but there still seems to some form of Face present that is no longer clickable.

The problem is that you're creating one big ngon with that mesh. Blender doesn't work well with ngons and wants tris (three-sided faces) or more preferably, quads (four-sided faces).
Break your mesh down into smaller segments that accommodate Blender's needs. If I were you, I'd just make one big plane and then subdivide it enough that you can form the same mesh by angling rows and columns of vertices to get your desired pattern, and then delete the faces that you don't want. Your mesh pattern is repetitive, so you only really need to create one section of it and then duplicate it as much as you need and merge them all together into a larger mesh.
Here's an example I threw together for you. You can bevel the angled edges to make them more rounded before you duplicate and merge the meshes together into a larger mesh.
http://www.pasteall.org/blend/42020

Excellent. Thank you for the advice. I'll give it a go and let you know how I go. :)


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Armature doesn't stay connected when moving mesh in object mode
Problem: I have created an armature that attaches to my mesh, but when I move the mesh in object mode, the armature doesn't come with it after parenting with automatic weights. This is obviously due to the parenting position (Mesh to Armature) but I don't know how to get around it. Parenting the Armature to the Mesh doesn't give the Armature Deform options, so I can't do it that way.
Here is my model. The armature works correctly with the mesh like this, as it's parented correctly with automatic weights.

The problem arises when I want to curve my mesh into a circle using the Curve Modifier. I added a Bezier Circle and using the Curve Modifier to the mesh, attached the circle. I then merged the ends of the mesh so there are no gaps. The problem you can see is that the armature doesn't keep its position with the mesh, and grossly distorts the mesh if I leave it where it is. I would prefer not to add the armature after adding the curve modifier as that would be very time-consuming, so much easier doing it flat to start, or so I thought.

How can I get the armature to remain inside the mesh after moving it (or making it into a circle shape) in Object mode? Thank you.

Armature Deformation usually works from bone to mesh, not the other way around. There is an option to use a shape key to deform the mesh, and then parent a bone to some of the vertices, but it will not be applicable to your situation. Depending on the rig itself, there might however be a workaround.
Given that the bones have to deform the mesh, what you need to achieve then is to reposition all of your bones in Pose Mode so they form a circle. To do this, you can try the following: Set the rotation mode to individual origins with the button on the bottom left of the screenshot:

This will apply the rotation to each child of the bone individually, instead of just rotating the upmost parent. The bone chain in my screenshot is one single chain, so all bones are in a parent/child relationship. If you now select all bones, and then activate the rotation tool, constraining the rotation to Z-Axis only, you should be able to achieve this:

Rotate it until the circle closes and you're done. In Edit Mode the chain will still be straight, also if you disable the armature modifier visibility you're back to a straight chain.
The logic is: The first bone rotates by X degrees, its first child by X degrees again, the child of that child by another X degrees, and so on. That's why you get a circle in the end. This method is sometimes used when animating fingers curling. If that works with your current rig has to be tested, but I believe there is a chance it will.


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Texture paint on animated cloths
i'm trying to figure this out for a while...
I want to texture paint 3 animated objects plus background in one go with the option to keep animate them after painting (just like spray painting irl)
presumably I would need all these objects to be joined? any ideas? I have managed to do it with one cloth and a background

but now I want to do it w/ 3 objects.
Thank you!


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composite glass
I'm trying to composite an image with glass but I don't know if there is a workable solution for the scenario I have in mind.
The set up consists of two parts:
the first in itself is a composite of the following:
A scene of 4 figures with their own lighting composited with a world scene.
the second part is a water glass standing on a low wall.
Ideally I would want the glass lighting to be a combination of the world lighting and a point light, but to display the right (or close enough) refractions.
My best shot so far is this:

The other scenes are:

Any help making this better is appreciated! will try to upload a file but my internet is bad atm.

Why do use different scenes to do this instead of one? If the reason is only to isolate lights to specific objects, we have light linking to do that.

yes, only to isolate different light sources to different objects. Never heard of light linking during my research. will look into that. Thanks!

This 1min long video could be useful: https://www.youtube.com/watch?v=excz9dfRycQ

thank you, it's a good solution!


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Full script for fitting the camera view to the only object in a scene
I have found an answer in this stackexchange website that is supposed to do exactly this:
 for area in bpy.context.screen.areas:
     if area.type == 'VIEW_3D':
         override = bpy.context.copy()
         override['area'] = area
         bpy.ops.view3d.view_selected()
         break

assuming a model imported from an *.obj file is selected now. When I run it, nothing happens. However, Shift-C + OpenGL Render does pretty much what I need.
The context: I need to render many models from many viewpoints, but all models have different scale, so I wonder if there is a command that could move camera so that object regardless of its original size fits given specific viewpoint, like, direction in spherical or cylinder coordinates, for example. view_selected() and view_all() seem to do that.

Okay, this is a working script in case anyone might need similar thing:
import mathutils
import bpy
import sys

model_path = '/input/path/file.obj'

scene = bpy.data.scenes.new("OurScene")
camera_data = bpy.data.cameras.new("Camera")
camera = bpy.data.objects.new("Camera", camera_data)
camera.location = (-4.0, -5.0, -1.0)
scene.objects.link(camera)
scene.update()
scene.camera = camera
bpy.context.screen.scene = scene
bpy.data.cameras['Camera.001'].clip_end = 10000
bpy.ops.scene.new(type='LINK_OBJECTS')
bpy.context.scene.name = 'model.obj'
bpy.ops.import_scene.obj(filepath=model_path, axis_forward='-Z', axis_up='Y', filter_glob="*.obj;*.mtl")
bpy.context.scene.camera = camera
bpy.context.scene.render.filepath = '/output/render.jpg'
bpy.context.scene.world = bpy.data.worlds['World']

# look at origin
loc_camera = camera.matrix_world.to_translation()
direction = mathutils.Vector((0., 0., 0.)) - loc_camera
# point the cameras '-Z' and use its 'Y' as up
rot_quat = direction.to_track_quat('-Z', 'Y')
# assume we're using euler rotation
camera.rotation_euler = rot_quat.to_euler()

bpy.data.worlds['World'].light_settings.use_environment_light = True
bpy.data.scenes['model.obj'].render.alpha_mode = 'TRANSPARENT'
bpy.data.scenes['model.obj'].render.image_settings.color_mode = 'RGBA'

for obj in bpy.context.scene.objects:
    obj.select = False

for obj in bpy.context.visible_objects:
    if not (obj.hide or obj.hide_render):
        obj.select = True

for area in bpy.context.screen.areas:
    if area.type == 'VIEW_3D':
        for region in area.regions:
            if region.type == 'WINDOW':
                override = {'area': area, 'region': region}
                bpy.ops.view3d.camera_to_view_selected(override)

bpy.ops.render.render(write_still=True)

sys.exit(0)


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Strange rotations in vertices of mesh
I was just in mid of editing a mesh I copied with ctrl+D and moved elsewhere, as I recognized that all vertices are strangely rotated and not all in same direction. Few are rotated same but others are completely different. I have no idea how this could happened and using ctrl+A to apply rotation didn't help at all.
I hope somebody has an answer for this and can help.
Thanks for the attention.
And if somebody by the way could explain how to make the ctrl+ things look like buttons I would appreciate that help too. :D

Do you have a modifier that is affected by the grid?

The only modifier I did use was subdivision surface and I did use a tool named booltool, with which it's easier to use boolean to seperate or connect meshes. Nothing else.

The image is showing that 'normal' axis are displayed: look at the bottom bar

Thanks; I once set it to normal and forgot to set it back, now everything is fine again :)


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Keep selection while switching through edit and object mode?
I wonder if and how the above questioned action can be done. Because for me now it would be a lot easier just to pick the desired mesh in object mode, switch to edit mode while still having it selected.
Would be awesome if someone could help with an answer. :)
Thanks for your attention.

In my experience, if I'm working on something in edit mode, and have one or more blender elements selected, and then switch to object mode, select another object, go to edit mode, and work on that object in edit mode, then go back to the first object, switching to edit mode, the elements that I had selected when I left, are still selected when I return. So I'm not real clear what your asking. Please, might you give more specific details?

I mean the mesh I have selected in object mode would still be selected in edit mode to work on with it if needed.

again in my experience, the mesh selected in object mode is still selected in edit mode, otherwise you would not be able to edit the mesh.

Sorry for long time not responding, I wasn't online last time. So, to light up the mistery of my strange thinking: Yes, you are right, the selection is kept when changing to edit mode, so you can edit this specific mesh, my thought was more to already have all faces/edges/vertices already selected without having to select them with B tool, or by hand.


text:
Wrong material shown in Viewport
I have just created a mesh and tried giving it a material which I gave to many other meshes in the same file and now for any reason it is showing the wrong material in Viewport, but the correct material in the Node Editor. If someone has any idea how to solve this problem I appreciate any help.
Thanks for the attention.

Is the material "Material.002" assigned to mesh faces?

Umm, I always picked a mesh in object mode and picked material and got done, so I think so. But when I have chosen a single face from the mesh it showed the actual shown material, but it did not help to change it for this one face, it remained white.

You may be confused about the workings of assigning materials to a mesh , this may be relevant https://blender.stackexchange.com/questions/516/add-different-materials-to-different-parts-of-a-mesh