text:
Animate like in Real Life in Blender (Stop Motion?)
Is there an approach or a way on animating scenes in blender like we do it in real life with stop motion? Adding and changing objects in between the shots.
I know that there a shape keys for example, but you can't "add" objects or vertices, as far as I am informed.

There was a Key Mesh project in that direction https://www.youtube.com/watch?v=jPvLQH17Y2Q&ab_channel=askNK but as I know it was abandoned

this might interest you : https://youtu.be/noexK8EIwzg. I just typed "Blender stop motion" on youtube.

You indeed can't add vertices. But you can just have different objects available, and animate their visibility.
Though that's the manual repetitive way.
Ideally, you have a rig with different models (for example, different face models), and there is a controller in the rig that will drive which model is visible. So that for each frame, you can choose which face model to show for example.

You can add and remove geometry in animation if you use either generative modifiers or geometry nodes and this applies to character animation too. In the production of Sprite Fright, the sprites had geometry nodes and the geometry count was animated. This may also be useful in realistic animation if you use adaptive subdivision for example.

We are not talking about generating in-between geo nor particles. We are talking about having literal different models.

I was just making a remark on you saying "you can't add vertices" which is not completely true. I assume Edit Mode modifications was implied which is why you gave that answer but there are other ways.

I see, but I posted an answer to a question, not a broad statement with no context :P


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Extruded area is not filled
I have a single sketch with multiple vertices and faces. Once I select one face, and press A to select all faces and extrude, the extrusion happens but the volume in between is not filled. The reference photos are attached:

Your mesh has been extruded already. I mean, you pressed E to extrude then canceled the operation, but when you cancel "extrude and move" you cancel only "move", but not "extrude". So you have 2 copies of vertexes that exactly overlap each other.
Simplest way to fix this - select all, then press M -> By distance. It will remove overlapping vertexes and only clean geometry will be left

source: Stack Exchange

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

sort: votes


text:
texture on wrong side, normals are good

Ive created a procedural texture shown in the middle, and baked it to a texture, tried multiple uv mapping methods, reseting vectors and the baked texture always obeys the lighting of the face normals as id expect based on the blue normal face map. However when applying this texture to the model it displays about half it on the wrong side of my mesh.
Anything I can try?

OH, I realized that the model was using an old baked texture stored in cache, that texture was baked with a different uv map. All i did to fix was save my new bake, disconnect the image texture from the render node, then reconnect the texture

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


text:
properly UV unwrapping "edge loop" geometry?
Think of a geometry like this (blend attached):

Now imagine you have a texture image such as this, which you want to have tiled horizontally on that selected surface (polygons).

To get a result akin to this:

How can you do that without starting from scrach?

PS. Cylinder unwrapping only works to a degree, the texture gets noticeably stretched at places compared to other places.

First remove doubles (W-->Remove Doubles) and apply transformations (Ctrl+A-->Apply Rotation, Scale). Then hide the non selected part of your mesh with Shift+H. Mark seams (select edges as pictured below and press Ctrl+E-->Mark Seam). Then select it with A and unwrap it U-->Unwrap.

Now straighten the UV islands ( How do I straighten UV maps? ).

Actually, you do not have to straighten the islands out by hand, the command Mesh > UV Unwrap > Follow Active Quads is perfect for quad strips like these.
Basically, follow all the previous steps:

Remove Doubles, so your mesh is contiguous again (it will merge vertices together that are in the same position, you can also enter a tolerance value that will then get points that may be a little off, too)
Mesh > Vertices > Remove Doubles
Mark your Seams with Mesh > Edges > Mark Seam
around the lid and in the fold front and back should do fine
Go to Top View, Select the lid by hovering the mouse over it and pressing L, then, in the Operator Panel, select Delimit by Seam. This will keep your Face Selection limited to the area you just defined.
Since it is flat, you can unwrap it easily with Mesh > UV Unwrap > Project from View. If you want to avoid clutter, you can now go to the UV/Image Editor and move your unwrapped island off the 0 to 1 Square. This is just to keep the other islands from landing on top of them when you unwrap them next, so skip it if you want.
Select one of the strip parts by hovering over it and pressing L. This will select Linked Face. Put the Delimiter in the Operator Panel on "Seams", just like before.
To make sure the Unwrap works properly, I recommend first resetting the unwrap first with Mesh > UV Unwrap > Reset
Then, first deselect one of the faces on the island you want to unwrap and immediately re-select it. You will notice, its color is different from the rest of the selection. This is because this face is now the Active Face.
Now unwrap the strip with Mesh > UV Unwrap > Follow Active Quads
Usually, Length Average gives the best results on strips, but you can toggle through the option to see if you can get a better fit.
You should now have a perfectly rectangular strip of quads in your UV Map. It may require a little scaling along the X- or Y-Axes, but it will make texturing very easy.

Side Note here: one of your strips has a hole in it that is made up of N-Gons. This does not go over well with Follow Active Quad. I would suggest you model that shape with quads. Otherwise, you will have to stitch those faces in by hand or straighten all those UVs by hand.
To ease that pain, take a look at the UV Squares-plugin. Just search it in the Plugin List in Blender, I think it is part of the trunk.

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


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UV unwrap: separate maps for separate faces problem
The problem is:
I have 1 mesh.
I want some faces of the mesh to be in one map (faces A) and other faces of the mesh in another map (faces B).
Now when I unwrap faces A, there is no problem, I get a UV map only with these faces.
When I unwrap faces B to a new UV map, there is faces B and faces A on that map. While on the first map there is only faces A.
Is there a possibility to only get faces B on the second map or can I just move the faces A away?
EDIT:

In the file there is a plane. I first picked some vertices and unwrapped them with U -> Unwrap leading to UVmap1.
Afterwards I picked some other vertices, created a new UV map with the + and then unwrapped them. Now if you select all and switch between the maps you will see that UV map 1 contains only the first vertices and uv map 2 contains the first and the second ones.

Jonathan, perhaps you might be so kind as to upload a copy of your Blend file to Blend-exchange, or a similar site. Please do not use Pasteall, or other sites which arbitrarily delete your file after some length of time. You can have multiple UV maps on the same object, but seeing your blend file would help those wishing to help to explain the process more clearly.

@brasshat, well I didnt think that it was necessary, because it is a fairly simple issue. but sure, no problem, I'll upload a file, so you can visualize it better :)

Jonathan, the simplest questions sometimes have the most complex answers, furthermore, what the questioner thinks is a simple question is sometimes not simple at all, it only seems simple to the questioner because he or she hasn't the background to understand all of the implictions of the question.

@brasshat I definitely understand what you mean.

Yes you can have separate textures for separate faces.
One technique is to scale the vertices of unwanted faces by zero to the median point. Scale 0.  The area of the faces are now zero. Zero area signals no mapping is attempted.  I hope the single dot on the uv map is acceptable to you.

mark seams so as to partition faces into group A and group B

First UV Slot

uv unwrap case 1 and move unwanted faces to the side of uv map. The texture repeat must be set to [clip].

Second UV slot

uv unwrap case 2 and move unwanted faces to the side of uv map. The texture repeat must be set to [clip].
The combination of faces of the uv map and repeat set to [clip] should achieve your goal

Keep in mind advanced users may be able to simply use one uv map with texture painting.  You are the advanced user.

Thanks for your answer, though I knew all this and I wanted to know if there is a way not to "move the unwanted faces aside" but rather to not have them on the UV map at all. I dont know about the texture repeat though and how to set it on clip maybe you could explain this? Oh yeah and I dont want to just use one uvmap because there are faces which exist twice in different layouts, I will use a slighty transparent texture on top of a non-transparent one.

When I look at the original post I see one sentence with a [?].  I selected that as the question which I attempted to address.  Please consider changing your original post with a new question.  See the note above please.

yes, I know you responded to my question about texture set to clip. Btw I just try now to put the islands I dont need off the picture and scaling them down f.e. Thank you! :)

Successful or Not Succesful?

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


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Blender automatic weights distorting mesh
I Need help with blender automatic weights. When I click automatic weights it moves parts of the head that doesn't have weights example on the last image, also when I do automatic weights it doesn't cover the correct area for the mesh example image 2.
Problem 1

Problem 2

Distortion often appears when the vertices of the mesh are improperly assigned to the bone. It looks like some parts of the head are assigned to the upper arm causing deformation. Please take a look at this answer:
http://blender.stackexchange.com/questions/21480/how-to-fix-armature-distorting-my-mesh

Thanks but is there any video to fix this ? thanks

Sorry, but tutorial requests are off topic (unfortunately) I suggest weight painting by hand... Err.. mouse.

oh BTW this is the retop , on the original , it works fine =\

Fix It ^^ . I just Click Automatic Weights to the Skin Modifier Mesh , and then transfare the weights to the retopo and it worked ^^ .


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BGE: Add object actuator spawning bullet on wrong angle
I'm trying to make a turret in blender game engine,

(the small red object is the laser)
As you can probably tell, this is a laser turret(top right), but the lasers (nothing special, just a red cube reshaped) are pointing the wrong direction.
I can't really say much more other than give a screenshot of my logic bricks.

What fires this object is a empty. And it's called to fire it by the turret you see it's self. No need to show the logic bricks for what calls it, unless needed.
I truly apologize for any mistakes. I tried to look this up, and found no results, and it's 1:47 AM and i need to wake up early tomorrow.
A link to download the .blend: https://www.dropbox.com/s/4psdrb2zf8xcs7x/Cube%20assault%20%3B%29.blend?dl=0

The problem is the rotation of the laser. go to the laser, rotate it 90* on the z axis, then Ctrl+A>apply rotation. this should solve the problem.

Thank you, you answered my question, although it was 90* on the z then the x as well for it too work. :)

okay, hard to tellfrom just the screenshot

There is a download the .blend but anyway, thanks. :P

okay, sorry, i don't really have time to go through them all. :P

Ensure that the emitter and all of it's parents have a scale of (1.0, 1.0, 1.0).
If not you might want to apply the current scale to mesh Ctrl + A,S.

I've got all the scales set to 1.0, 1.0 1.0, already. :/

The only other option would that the emitting object is rotated at the moment of adding the object. Maybe you post a demo file showing the problem.

Vincent Scalia answered the question, thanks for the help anyway. :P


text:
Why are the size and shape are different in edit and object mode?
When I change the mode, the mesh looks different. Edit mode-skinny, object mode-fat. Before I made the skeleton, everything was fine.

have you parented the armature to the mesh assigning some weight (maybe automatically?), check the mesh in weight mode, some of the bones could be influencing the mesh shape

As I see, all bones have effect only on the correct bodypart. In weight paint mode its also fat. When I render, also fat. Only in edit mode, i can see the real shape.

You applied an armature on your mesh. This effects the mesh only when you are not in edit mode. In edit mode you can see the original shape and in all others the deformed shape (the same when you apply other modifyers on your mesh). Your rigging was not very succesfull, as already mentioned. You have to apply the sam scale on the armature and the mesh and make sure, that they both have the same origin. Otherwise it looks a bit creepy after parenting them, like in your case.

Make sure that before you do automatic weigthing, that you apply the scaling to both your mesh model, and you rigifie armature  [CTRL + A]
once all scales are applied it shouldnt deform, i see this happen often with people who begin with this.


text:
Why is a piece of this mesh stuck in pose mode?
When I grab the right foot, I have a glitch. The point where these 3 bones are connected is not moving.

Is it a bug? Or can I fix it, somehow?

weight painting issues, not a bug

you are right, thx

@VincentScalia Can you whip up a quick answer.

Uh, yeah! un momento por favor

The problem is that the particular vertex is not assigned to the bone that you are moving. Fix it by going into weight paint mode and painting that vertex red!
Unfortunately, weight painting disagrees with my computer so I can't post an image. :( I will try to have someone put one in for me


text:
How do I create this arch in the middle of a cube?
Also, are there any techniques to do these kind of shapes in Blender?

Edit: Second part of this Q was removed. It has a new thread here

I couldn't picture what the arc you build has to do with the roof in the images above. Can you clarify?

no both are totally different images! In my model, I generally have to do such kind of shapes and I have trouble doing them hence put it up for reference. I am searching for an easy method to do it. only if the edges could be magically turned into curves so i could dip them, my life would be so much better

Blender has build in addons like Archipack and Archimesh and also Extra Curve addon can generate some arch type of shape. It really depence what specificaly you need to achieve. I'm not sure what do you mean edges to curves. You can Convert Mesh to Curve, but it depence what exactly you need to result with. If answers doesnt covers your Q edit your Q with more mockups.

You should use the Array modifier with an Object Offset:

Create a 8 vertex circle.

Only keep 1/8, create an empty at the same point as its origin.

Give your circle an Array modifier, Count > 8, deactivate Relative Offset, activate Object Offset, choose the empty as object, rotate the empty 45° on the Z axis.

Model the object.

Extrude it down, flatten the bottom with SZ0.

Since others started to react to my oftopic comment here, I asked them to delete comments and move to chat to keep your answer clean. Thanks :)

I would say possible with three modifiers.

create a segment
(circle 8 sides, fill triangulate, keep 1/8)
add Solidify modifier (to get hight)
add Sphere
select segment add Boolean modifier > Difference (object Sphere)
add Empty, rotate 45°on Z axis
select segment add Array modifier > Count 8 / Object offset ON - Empty

Tips:

by moving and scaling Sphere you can shape curvature of segment
to get nice topology following roof shape, direct top of sphere to center of segment

vklidu, our responses are slightly different, it would be worth if you gave a more detailed answer

@moonboots ok you got me :) I was ready to delete it, since your version was even better with topo, at the end I compensate this handicap a bit with Sphere rotation. BTW still one of us could spent time with another Q :) Cheers


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Glass behaving like mirror issues
My brown cosmetic bottle seems good on view port, but as soon as  I render it on Cycles it becomes like chrome
Viewport

Rendered

Original file on Google Drive

What blender version are you using?

First image looks like it's reflecting an Enviroment and the second image look like there is no enviroment to refflect except for the white plane, did you add an HDRI for you Render? viewport shader's HDRI are not visible on the final render, you need to add one to the World shader.

There are several problems in your objects:

Your floor has overlapping faces, it creates Z fighting and it will render black, merge the vertices:

You've assigned a bad material to the inner faces of your bottle, give them the good material:

The green color of the Glass node is too dark, enlight it:

The IOR value of your glass object is much too high, bring it back to about 1.5:


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UV maping a sphere to have stripes runing between both poles?
I tried to map a country flag on a UV sphere, but I could not get it laid out the way how I wanted to see it. I used the Poland flag.
I wanted to map it exactly as you can see in picture 1.

But what I got was a result as you can see in these pictures.

The flag was looped at least 8 times on each half side of the sphere.
I could double that, but I could not go half of that, or less.
I wanted the flag to show up just 1 time at each half side of the sphere.
or maybe twice at each side, but not 8 times.
as you can see on the third picture, I tried to resize the UV map, but also then it would never go under 8 repeats.
How can I change this?
Here is the Poland flag texture.

http://blender.stackexchange.com/questions/3315/how-to-get-perfect-uv-sphere-mercator-projection

thanks again for a fast replay
but the result is not the solution to the question as you can see in picture 1 that i showed at the beginning.
i added now a new picture with the result for you to see how is the difference.
i even tried to rotate this UVmap 90% but that didn't do the job.
i already tried all of the UVwrap possibilities
but non of them seems to do this very simple basic task.
there must be another way to get it right.
also youtube has no tutorials about it, i looked everywhere..
am i missing something ?
http://tinypic.com/view.php?pic=2n1azoj&s=8#.VPPqxNzyBFw

Your image doesn't fit the UV map in UV editor select all 'A' and scale it down 'S' + mouse movement.

any image size i try has the same result , no matter the size.
the result of horizontal flaglines came from
project from view (bounds).
but to unwrap it in sphere projection make the flag lines go vertical , just as i want them to be,
but unwrap there has the problem of having scrambled poles as you can see in pict 5 that i added now.
http://i62.tinypic.com/j9wx9u.jpg
in pict1 that i added earlier , you can see the poles look clean .
how do i get the vertical flag texture poles clean without scrambling when using unwrap in sphere projection ?

are you looking to have just one red and one white stripe on the front of the sphere, without any of the curved distortion?

hello david , i want the final result exactly as i showed in picture 5 , http://tinypic.com/view.php?pic=j9wx9u&s=8#.VPSDj9zyBFw, but with clean poles in stead of them having scrambled. i hope you know a way , hope to hear from you soon , thanks

While you could unwrap the sphere and then texture it, in this case it will be easier to just use a generated texture.
The first method simply differentiates the colors based on the selection. You can easily select the edge loops with the method in this answer. You will have to manually select the few faces at the poles.
Here I put a white material on the ball, selected the faces that should be red then added another material and hit Assign. You could also use vertex colors with this method.

The second method uses only one material, it creates the stripes with a gradient texture. Here are the nodes used to make the stripes in cycles.
Using object coordinates as the vector, a Gradient Texture node set to Radial creates the base for the stripes. The ColorRamp node set to Constant colors the stripes and makes the stripes distinct.

Here is an example ball rendered using the above nodes.

it is beautiful and perfect for a result how i want it, but in this way i will never be able to quickly change between several textures while searching for a better jpg , or change the amount of the vertical color lines .

i tried to find another way and simply deleted the poles , than made a UV map from this sphere without poles.,
then putting the poles back by E for extrude. en S size to "0"
in this way you can repeat the texture as you desire,also less then 8 repeated loops , which was not possible before.
you can even export this as an object and import it in other projects.
 the problem here is that it works for certain simple textures only , but  for complex textures it would still look uncomfortably scrambled at the poles.


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Can or How do Animation nodes play an action by name with a delay or start time
Q:
Can or how can I call a keyframed action on an object and play it at a later frame time instead of its current dopesheets or NLAs playheads start?
Explainer:
Im trying to animate a sequence of objects when they reach a condition for a fake collision simulation. In this example multiple balls falling with paint, so two objects ball that bursts and paint object that splashes.
I thought I could setup up some keyframed actions and remove them from the object and later call them from nodes on conditions but found no node way to do this.
So then I limited the animation to keeping one animation action on the object and thought I could delay it at frame 1 by feeding it frame zero until its ready to play in full with a stopwatch. But found no node that did that either.
So now all im trying to do is call the one action without a name via the "action from object" node and delay it but that does not seem to work at all. I have tried unhooking all orders but nothing seems to respect what I was expecting, attached screenshot is a simple example
I also can not figure out how to make a stopwatch to feed a time value to a lerp but did see a post about that subject

As you can see the cube animation is from 0 to 20.
By the node setup the delay is 40, so the animation starts at frame 40.
you can do it with this node setup:

Thank you this worked, I think the play activation was broken as well! I did figure out how to also do a delta time via script, which all post in an answer

Glad I could help

As stated above that worked, I also figured out how to store a delta time on the object itself and feed it frames using a custom property.
HOWEVER I encountered a logic issue for INVALID NETWORK that ill ask in another post
selfObject = bpy.data.objects[watashi.name]

if x > 0 and selfObject["hasPopped"] == 0 :
    selfObject["hasPopped"] = 1.0
    selfObject["startTime"] = timein

#outtext = watashi.name
#hasPopped = selfObject["hasPopped"]

hasPopped = selfObject["hasPopped"]

timeout = selfObject["startTime"]

deltaTime = timein - selfObject["startTime"]
if selfObject["hasPopped"] == 0 :
    deltaTime = 0


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Decimate mod breaks apart model
I just started using blender and don't really know my way around everything just yet.
I wanted to use the decimate modifier on my model. It worked fine, apart from highlighting a few areas. I thought it would go away if I applied the modifier, but it then deletes the highlighted part of the model as soon as I do that (or maybe makes it invisible? I can't tell).
What did I do wrong, and how do I reverse it?
Thanks in advance

use Ctrl+Z to undo or File > Revert to recover the last saved version or File > Recover > Auto Save to restore the autosaved file.

Have you checked the normals of the mesh? The mesh should not vanish if you apply the Decimate modifier. It's not invisible but broken :(

Thank you @Blunder! I will try to check everything again to see where my mistake was, but at least I was able to recover an autosave. :)


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More complex shapes/beams of light
Hello fellow Blender users.
Recently I work for a client that manufactures lights and I am making a video showcase of those lights. Today he asked me if it is possible to make a video sequence where the lighting source (1 rectangle light) will change its diffusor (there are 6 in total) and it will light up an empty room with only 1 table and 1 chair. It needs to make beams of lights that follow this specific information:

I may be using Blender for a long time but I am no specialist, do you know if there is a good way to make lights like this? Should I use 2 lights in 1 place,(1 weaker and 1 stronger) or is there any specific way to make lights this way? Also, it needs to be done in Eevee not in Cycles due to how long this video is.
Also the one problem is that I cannot use Cone light sources due to rectangular shape of the lighting source that basically looks like this:

Lighting sources are those tiny little cubes and the big white rectangle at the bottom is the diffuser that will change into 6 different types of materials

Hello :). You might want to look into IES light textures like here. There's a dedicated IES Light node.

Hmm but the IES node works only with Cycles so this is not the right way unfortunately

Few years on TODO list https://developer.blender.org/T68472 ... But in your case I'm not sure about the goal since you run point light through rectangle diffuser in a middle of a room I don't think you can get any light beams to be visualized.


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How do I lay objects on the surface of a sphere with Python?
Just started Blender (and Python) about a week ago, so please bare with me. I apologize ahead of time for confusing/misused terminology, etc.
I am working on a research project and I need to:

create a hemisphere with smaller objects laying flush on the
circumference of it in precise locations.

I've been able to do this manually using shrinkwrap modifiers, but I need to be able to do it mathematically and through coding.
So far, I've been able to generate the location where the objects need to be made (I am using simple circles and will replace these with the objects that I need once I get the code working), but my issue is that I can't get the circles to have the correct orientation such that they follow the curvature of the hemisphere.  I've spent a good deal of time looking online looking for solutions and reading about rotation matrices, but I can't seem to sort it out.  To get the orientation correct, I ended up trying out a rotation_difference function based on something I read online but it didn't work (see below images).
If someone could review my code and advise me on how to possibly proceed, I would greatly appreciate it.  Since my understanding of Blender and rotation matrices is not great, a written explanation with some snippets of example code would really go a long way to helping me out.
Here are some images to help clarify:
Here's the hemisphere with the circle translation locations in place:
Here's what happens when I try to get the correct orientation of the circles (I made the larger radii circles on top of the smaller circles to make it easier to see for explanation purposes):

And the code:
#Imports.
import bpy
import numpy as np
import math
from array import *
from mathutils import Vector
from math import degrees

#Definitions

# Calculates Rotation Matrix given euler angles.  Need angle in radians.
def eulerAnglesToRotationMatrix(theta) :

    R_x = np.array([[1,         0,                  0                   ],
                    [0,         math.cos(theta[0]), -math.sin(theta[0]) ],
                    [0,         math.sin(theta[0]), math.cos(theta[0])  ]
                    ])

    R_y = np.array([[math.cos(theta[1]),    0,      math.sin(theta[1])  ],
                    [0,                     1,      0                   ],
                    [-math.sin(theta[1]),   0,      math.cos(theta[1])  ]
                    ])

    R_z = np.array([[math.cos(theta[2]),    -math.sin(theta[2]),    0],
                    [math.sin(theta[2]),    math.cos(theta[2]),     0],
                    [0,                     0,                      1]
                    ])

    R = np.dot(R_z, np.dot( R_y, R_x ))

    return R

#Variable Initiations.
maxYaw = (75) #degrees
maxPitch = (65) #degrees
radius = 0.3 #degrees

#variables
hemiRadius = 0.3
hemiSegments = 16
hemiRingCount = 16
hemiLocation = (0, 0, 0)
dropRadius = 0.03
dropVertices = 16

bpy.ops.mesh.primitive_uv_sphere_add(segments = hemiSegments, ring_count = hemiRingCount, size=hemiRadius, view_align=False, enter_editmode=True, location=hemiLocation)

#cut sphere in half vertically
bpy.ops.mesh.bisect(plane_co=(-0.3, 0, 0), plane_no=(0, 1, 0), clear_inner=True, clear_outer=False, xstart=494, xend=1343, ystart=384, yend=384)

#conversion into radians necessary for rotation matrix function
maxYaw = (maxYaw/180.0)*np.pi #now in radians
maxPitch = (maxPitch/180.0)*np.pi #now in radians

#locations of needed circles
rollPointsDeg = [[0, 0, 0],                #0 center
                [0, maxPitch, 0],          #1 top mid
                [0, maxPitch, maxYaw],     #2 top left
                [0, 0, maxYaw],            #3 mid left
                [0, -maxPitch, maxYaw],    #4 bot left
                [0, -maxPitch, 0],         #5 bot mid
                [0, -maxPitch, -maxYaw],   #6 bot rig
                [0, 0, -maxYaw],           #7 mid rig
                [0, maxPitch, -maxYaw]]    #8 top rig

#results from rotation matrix: where the needed circles locations correspond to on the surface of the hemisphere
rollPoints =    [[-radius, 0, 0],   #0
                 [0, 0, 0],         #1
                 [0, 0, 0],         #2
                 [0, 0, 0],         #3
                 [0, 0, 0],         #4
                 [0, 0, 0],         #5
                 [0, 0, 0],         #6
                 [0, 0, 0],         #7
                 [0, 0, 0]]         #8

#the rotational matrix variable
rotMat = np.array([[0,0,0],[0,0,0],[0,0,0]])

#Rotation Matrix Loop.

i=1
while i < 9:
    rotMat = eulerAnglesToRotationMatrix(rollPointsDeg[i]) #converts the rotMat into the rotational matrix
    rollPoints[i] = np.dot (rotMat, rollPoints[0])  #dot product of rotMatrix and rollPoints[0]
    i += 1

print("rollPoints:")            #####
j = 0                           #
while j < 9:                    # simple loop confirming the values of the rollpoints
    print(rollPoints[j])        #
    j += 1                      #####

v0 = Vector(( 0, 0, 0))  #Set for rotation axis global
v1 = Vector(( 0, 0, 0))  #default initiation for RollPoint locations
rollAngles =    [[0, 0, 0],         #0
                 [0, 0, 0],         #1
                 [0, 0, 0],         #2
                 [0, 0, 0],         #3
                 [0, 0, 0],         #4
                 [0, 0, 0],         #5
                 [0, 0, 0],         #6
                 [0, 0, 0],         #7
                 [0, 0, 0]]         #8

#code to generate appropriate angles orientations that correspond with rollPoint locations
i=0
while i < 9:
    #start loop
    v1 = Vector((rollPoints[i][0], rollPoints[i][1], rollPoints[i][2]))
    rollAngles[i] = v1.rotation_difference( v0 ).to_euler()

    print( [ degrees(a) for a in rollAngles[i] ] )
    #this should provide output or angle rotation in each axis: [ #, #, #]

    i+=1
    #end loop

#comment out this line if getting errors from blender about <<operation cannot performe in edit mode
bpy.ops.object.editmode_toggle()

k = 0
while k < 9:
    bpy.context.scene.cursor_location = (0.0, 0.0, 0.0)
    bpy.ops.object.origin_set(type='ORIGIN_CURSOR')

    bpy.ops.mesh.primitive_circle_add(vertices=16, radius=0.04, view_align=False, enter_editmode=False, location=(-rollPoints[k][1], -rollPoints[k][0],-rollPoints[k][2]), rotation=(-rollAngles[k][0], rollAngles[k][1], rollAngles[k][2]))

    bpy.context.scene.cursor_location = (0.0, 0.0, 0.0)
    bpy.ops.object.origin_set(type='ORIGIN_CURSOR')
    k +=1

#currently, only the translation values seem to be correct, the orientation of the circle is NOT
#unsure how to fix this

No need for translations? Simply create all the circles at radius(hemisphere) and rotation 0,0,0.That is to say, at the North pole of the hemisphere.  Then  rotate them into place about the world (& hemisphere) origin, and they will naturally wind up tangential to the hemisphere?

Hi. I have tried to improve the title of the question to make it clearer what you're actually asking. If I have mistinterpreted your question you can use the [edit] link below it to either edit or roll back my changes.

Thank you very much for your assistance.  I actually worked through the problem today and I have resolved it.  My orientation values were the same as my original rotation and I was able to use them successfully as one of my rotational axis was constant zero so it didn't require building a secondary matrix.  Finally, my hemisphere was orientated in an odd way which made the smaller circles seem misaligned.  I changed the orientation of my hemisphere, then added pi/2 + rotation of one of my 3 axis and the model fit fine.  Thank you again for your assistance!

If you have a solution you should post it in the answer box below.

The pose (location and orientation) of the circles was already contained within the math.  The reason why the code wasn't adding the correct orientation (only location) was because of my poor coding.  After I coded it, I re-coded some portions and didn't adjust the math properly.  Specifically, I bisected the sphere at a different location to be able to better visualize the row/rings of the sphere mesh as they contacted my circles and, due to this, my x, y, z orientations were swapped up (in relation to the location of the bisected sphere).
I went back and bisected the sphere such that the orientation matched the orientation of the rotation matrix (and changed the index order and sign of the index back to its regular conditions (for example, -A[1], -A[0], -A[2] changed to A[0], A[1], A[2])).  I then discarded the 'rotation difference' function and added the rotation values as my original rotations values.  This worked because one of the three original rotation values was constant 0.  If this value was not constant 0, then I would have had to create a second rotation matrix to determine the orientation values.
Thanks for the input everyone!


text:
Boolean difference not cutting all holes correctly within for loop (python script)
I have a strange problem with a python script. I am generating an object with holes cut out of it in specific locations.  The script works well for all of it except for one specific and weird problem.  I run a loop for a boolean difference operation and it works for every hole except for my first hole.
I've gone back and stopped the code before the first boolean cut occurs by adding an extra edit mode toggle (to break it) and tried to manually add the difference boolean to generate the hole and it doesn't want to work manually either.  I have no idea what is going on - especially since it works on all the other holes and also since it won't even seem to let me do it manually.
My code is attached below.  I have no idea why it won't build my first hole - all assistance will be greatly appreciated.

#imports
import bpy
import numpy as np
import math
from array import *

#Definitions
# Calculates Rotation Matrix given euler angles.  Need angle in radians.
def eulerAnglesToRotationMatrix(theta) :

    R_x = np.array([[1,         0,                  0                   ],
                    [0,         math.cos(theta[0]), -math.sin(theta[0]) ],
                    [0,         math.sin(theta[0]), math.cos(theta[0])  ]
                    ])

    R_y = np.array([[math.cos(theta[1]),    0,      math.sin(theta[1])  ],
                    [0,                     1,      0                   ],
                    [-math.sin(theta[1]),   0,      math.cos(theta[1])  ]
                    ])

    R_z = np.array([[math.cos(theta[2]),    -math.sin(theta[2]),    0],
                    [math.sin(theta[2]),    math.cos(theta[2]),     0],
                    [0,                     0,                      1]
                    ])
    R = np.dot(R_z, np.dot( R_y, R_x ))
    return R

#Variables
hemiRadius = 0.3
hemiSegments = 25
hemiRingCount = 25
hemiLocation = (0, 0, 0)
dropRadius = 0.03
dropVertices = 16

#Variables for hole placement.
maxYaw = (75) #degrees
maxPitch = (65) #degrees
radius = hemiRadius #degrees

#Sphere
bpy.ops.mesh.primitive_uv_sphere_add(segments = hemiSegments, ring_count = hemiRingCount, size=hemiRadius, view_align=False, enter_editmode=True, location=hemiLocation)

#Cut sphere in half vertically in the correct plane
#Change plane_co("X", 0.3, 0) to '0' to make it a perfect half of a sphere, increase 'X' to allow more of the other half of the sphere to be present
bpy.ops.mesh.bisect(plane_co=(0.03, 0.3, 0), plane_no=(0.999995, 0.003263, -0), clear_inner=False, clear_outer=True, xstart=681, xend=683, ystart=715, yend=102)

#add subdivide meshes
bpy.ops.mesh.select_all(action='TOGGLE')
bpy.ops.mesh.select_all(action='TOGGLE')
bpy.ops.mesh.subdivide(smoothness=0)

#increase thickness
bpy.ops.object.modifier_remove(modifier="Solidify")
bpy.ops.object.modifier_add(type='SOLIDIFY')
bpy.context.object.modifiers["Solidify"].offset = 0
bpy.context.object.modifiers["Solidify"].thickness = 0.02
bpy.ops.object.editmode_toggle()
bpy.ops.object.modifier_apply(apply_as='DATA', modifier="Solidify")
bpy.ops.object.editmode_toggle()

###At this point, Hemisphere is built

#Conversion degrees into radians
maxYaw = (maxYaw/180.0)*np.pi #now in radians
maxPitch = (maxPitch/180.0)*np.pi #now in radians

#locations of holes
rollPointsDeg = [[0, 0, 0],                #0 center
                [0, maxPitch, 0],          #1 top mid
                [0, maxPitch, maxYaw],     #2 top left
                [0, 0, maxYaw],            #3 mid left
                [0, -maxPitch, maxYaw],    #4 bot left
                [0, -maxPitch, 0],         #5 bot mid
                [0, -maxPitch, -maxYaw],   #6 bot rig
                [0, 0, -maxYaw],           #7 mid rig
                [0, maxPitch, -maxYaw]]    #8 top rig

#location of holes
rollPoints =    [[-radius, 0, 0],   #0
                 [0, 0, 0],         #1
                 [0, 0, 0],         #2
                 [0, 0, 0],         #3
                 [0, 0, 0],         #4
                 [0, 0, 0],         #5
                 [0, 0, 0],         #6
                 [0, 0, 0],         #7
                 [0, 0, 0]]         #8

#the rotational matrix variable
rotMat = np.array([[0,0,0],[0,0,0],[0,0,0]])

#Rotation Matrix Loop
i=1
while i < 9:
    rotMat = eulerAnglesToRotationMatrix(rollPointsDeg[i]) #converts the rotMat into the rotational matrix
    rollPoints[i] = np.dot (rotMat, rollPoints[0])  #dot product of rotMatrix and rollPoints[0]
    i += 1

#comment out this line if getting errors from blender about <<operation cannot performe in edit mode
bpy.ops.object.editmode_toggle()

#Loop adding circles in precise location and orientation
k = 0
while k < 9:
    bpy.context.scene.cursor_location = (0.0, 0.0, 0.0)
    bpy.ops.object.origin_set(type='ORIGIN_CURSOR')

    exitStatus = bpy.ops.mesh.primitive_circle_add(vertices=16, radius=0.03)
    scj = bpy.context.scene

# The added circle will be the active object after it is created
    ob = bpy.context.object
    me = ob.data

# If you want to move your object, simply set its location thus:
    ob.location = ( rollPoints[k][0], rollPoints[k][1],rollPoints[k][2] )

# And you can rotate the object the same way
# Note that you need to use radians rather than angles here
    ob.rotation_euler = (0*(np.pi/2), (np.pi/2) + rollPointsDeg[k][1], rollPointsDeg[k][2])

#Now apply shrinkwrap after orientations are correct
    bpy.ops.object.modifier_add(type='SHRINKWRAP')
    bpy.context.object.modifiers["Shrinkwrap"].target = bpy.data.objects["Sphere"]
    bpy.context.object.modifiers["Shrinkwrap"].wrap_method = 'PROJECT'
    bpy.context.object.modifiers["Shrinkwrap"].use_project_z = True
    bpy.context.object.modifiers["Shrinkwrap"].use_negative_direction = True
    bpy.ops.object.modifier_apply(apply_as='DATA', modifier="Shrinkwrap")

#weird prep-stuff needed to make boolean operation work correctly:
#moving circles within the sphere to allow proper difference boolean operation

    bpy.ops.object.editmode_toggle()

    bpy.ops.mesh.extrude_region_move(MESH_OT_extrude_region={"mirror":False}, TRANSFORM_OT_translate={"value":(0, 0, 0.09883128), "constraint_axis":(False, False, True), "constraint_orientation":'LOCAL', "mirror":False, "proportional":'DISABLED', "proportional_edit_falloff":'SMOOTH', "proportional_size":1, "snap":False, "snap_target":'CLOSEST', "snap_point":(0, 0, 0), "snap_align":False, "snap_normal":(0, 0, 0), "gpencil_strokes":False, "texture_space":False, "remove_on_cancel":False, "release_confirm":False, "use_accurate":False})

    bpy.ops.object.editmode_toggle()

    bpy.ops.transform.translate(value=(9.31323e-010, -2.09548e-009, -0.0348931), constraint_axis=(False, False, True), constraint_orientation='LOCAL', mirror=False, proportional='DISABLED', proportional_edit_falloff='SMOOTH', proportional_size=1)

#boolean difference operation

    hemmy = bpy.data.objects['Sphere']
    bpy.context.scene.objects.active = hemmy

    bpy.ops.object.select_all(action='TOGGLE')
    bpy.ops.object.select_all(action='TOGGLE')

    bpy.ops.object.modifier_apply(modifier="Auto Boolean")
    bpy.ops.btool.auto_difference(solver='BMESH')

    k +=1

https://blender.stackexchange.com/questions/3212/how-can-i-create-a-hollow-sphere-with-regularly-spaced-holes

https://blender.stackexchange.com/questions/34781/boolean-modifier-not-working/

@DuarteFarrajotaRamos: thank you for the links.  I'll review them and post an update on my progress thereafter.

I rewrote my code such that cylinders were generated instead of circles.  This simplified the code and I was able to then perform the difference boolean operation on the cylinders and it worked.  Looking through the example links you posted helped me do this.  So, I was able to make my model correctly, HOWEVER, I still haven't figured out why the boolean operation would not work correctly...on only one of my circles.  I would like to know as it will help me learn and develop my skills further.  If anyone has ideas, please don't hesitate to comment.  Thanks!


text:
How to get back to scene view after opening python console?

So, I'm very new to blender. I am trying to do a batch scripting project for a friend, so I'm just trying to learn the scripting/console environment. I already know python pretty well.
I found out you can press SHIFT+F4 to open the console... but after that, how do I close it? I want to see the changes I've made from the console on the scene in blender, but I can't find a way to go back to the default starting view--with the cube and the lamp and stuff. Pressing SHIFT+F4 again doesn't seem to help... I'm on a Lenovo thinkpad so I actually have to press SHIFT+FN+F4, if that makes any difference.

Also, in addition to my answer below, I highly suggest you get a full-size USB keyboard if you really want to dive into Blender. You also might want to download one of the many Blender Cheat Sheets that float around the web. Some of them have the most common shortcuts listed, others come with the complete set.

In Blender 2.79, you close Areas by dragging them by their split widget towards the area you want to close.

By pressing Shift+F-Key (F1-F12), you switch the Area to a different Editor. You can also do this by clicking on the area's pop-up menu button and select a different area from there.


text:
How to render interlaced video (2.8)
How can I render my scene to interlaced video, I don't want progressive.
I use latest blender version 2.8. In 2.7 there was a "Fields" option somewhere but I cant find it in 2.8

Apparently they removed the option. It was an option of old crt tvs. but even today there are broadcast channels that use 1080i. Other programs like Cinema 4d still have the option. Professional camcorders still record at 2160i. It is still a useful option to decrease the data flow. I don't know why they removed it.


text:
MakeHuman model not retargetting correctly to mocap bvh file
I am involved in a research project where I collected mocap BVH files from Kinect (converted CSV to BVH files) for yoga poses and I am making synthetic humans animation for yoga poses. I am using Blender for rendering animations.
I am facing issues with retargetting the BVH fie to my Make human model and it is not giving a very nice animation.
In this image the skeleton is an imported BVH file and another is a retargetted Makehuman character for the same BVH file:

You can see the strange behaviour among the rig of the MH model and the mesh and other objects such as clothes.
I am not sure what the problem is, I am unable to figure it out. Can you guys help me out with some important steps while creating animations with Makehuman, Makewalk and BVH files? I am using .mhx2 files for the character model.

I also experience that. The motion is not smooth

did you solve the problem when you faced the same issue? @IsraelBamidele

No. What I discover is that the Mocap BVH is having too much keyframes. Trying to simplify the Keyframes makes it even worse. So I do prefer Keyframing it myself rather than using Mocap BVH

Bunny would you be able to share your code for converting csv to bvh?  I am using OpenFace https://github.com/TadasBaltrusaitis/OpenFace   to caputre facial 3d landmarks data and need to convert it to bvh.  Thanks.

hi @dan, since i was working on the project under a university professor, he has not allowed me to reveal the code yet, i can provide you the github repo https://github.com/meshonline/kinect-openni-bvh-saver which helped us in the project. code for Conversion of CSV to BVH is used from the same repo with some edits.

@Bunny Thanks for the info!


text:
MakeHuman model vertex coordinates after retargetting with Mocap?
I am writing a script which takes makehuman model and bvh files aS input and create animation. i also want to get coordinates of each vertex in image space after rendering, i write this script
for f in range(0,tracking_frames):
                #updating frame number for tracking coordinates of vertices in image space
                bpy.context.scene.frame_set(f)
                pointTracking(curr_scn,person_name+":Body",bpy.data.cameras[0].name,f)

def pointTracking(scene,person_body,scene_camera_name,frame_number):
    # needed to rescale 2d coordinates
    render = scene.render
    res_x = render.resolution_x
    res_y = render.resolution_y

    obj = bpy.data.objects[person_body]
    cam = bpy.data.objects[scene_camera_name]

    # use generator expressions () or list comprehensions []
    total_vg = len(obj.vertex_groups.items())
    #print(total_vg)
    #print("inserting")
    tracking_data = []
    for j in range(total_vg):
            track_per_group = []
            vg_index= j
            vs = [v for v in obj.data.vertices if (vg_index in [vg.group for vg in v.groups])]
            #print(vs)
            vertc = (vert.co for vert in vs)
            coords_2d = [world_to_camera_view(scene, cam, coord) for coord in vertc]
            #print(coords_2d)
            # 2d data printout:
            rnd = lambda i: round(i)
            rnd3 = lambda i: round(i, 3)

            #limit_finder = lambda f: f(coords_2d, key=lambda i: i[2])[2]
            #limits = limit_finder(min), limit_finder(max)
            #limits = [rnd3(d) for d in limits]

            # x, y, d=distance_to_lens
            print('x,y,d')
            print("Vertex_group for:",obj.vertex_groups.items()[j][0])
            track_per_group.append(frame_number)
            track_per_group.append(obj.vertex_groups.items()[j][0])
            for x, y, d in coords_2d:
                track_per_group.append((rnd(res_x*x), rnd(res_y*y), rnd3(d)))
                #print("{},{},{}".format(rnd(res_x*x), rnd(res_y*y), rnd3(d)))
            tracking_data.append(track_per_group)
    with open("Point_tracking_"+bvhName+person_mhx2+".csv","a") as f:
        writer = csv.writer(f)
        writer.writerows(tracking_data)

how to verify that this code is updating locations of vertices after each frame, since when i checked in software itself, the object world matrix does not changes after updating frames because it shows that mhx model is fixed at origin as it was initially therefor locally vertices coordinates are also same after updating each frame.

location after retargetting bvh file changes which is shown in this picture, what i think is that as the mhx model body is fixed and therefore obj.data.vertices[0].co is producing same coordinates for all the frames.
if i did not explained it very clear please let me know! i know its hard to explain for me. Thank you in advanced

The vertices are moved by the armature modifier. The object matrix won't change. Python by default gives the undeformed positions. You need to make a copy with the modifiers applied each frame.

@Sazerac did you mean something like this https://blender.stackexchange.com/a/3463/75100 , since i am new to blender i never used blender before this project,  will you please exaplain it more!

Yeah, I think that should be what you need.

@Sazerac but that answer also mentioned that it does not track same vertices always, indices can change after modifiers applied so the tracking coordinate of vertices miss lead

Depends on the modifiers, so long as none change the vert count you should be fine. Might need to remove subdivision if it is there.

@Sazerac what you mean by removing subdivision? as i am working with bvh armatures as modifiers, will it be fine ?

Check that the mesh doesn't have a subdivision modifier. I can't remember whether the makehuman importer adds one of not.

@Sazerac i write the code same way as mentioned in https://blender.stackexchange.com/a/3463/75100  and i set camera at 3 unit distance from the origin where mhx model is set initially before retargetting, after retargetting my output z-coordinate for vertices is also fluctuating around 3 unit.. that means still the mesh is at origin, it is not translated by armature, in rendering animation there is no problem at all.


text:
Dynamic detail with smoothing
Is there a way for the sculpted area to smooth as you sculpt dynamic detail on it. I might be missing something obvious, but as you sculpt with dynamic topology, smaller polygons are added, but the surface is not smoothed, creating that jagged shading. I think this behaves the same way when using a Subsurf modifier put on "Simple" instead of "Catmull-Clark".
In blender:

However, Sculptris on the other hand smooths the surface and there's no problem adding more detail.

I find it that only the Snake and Smooth brush are working fine for this. Is there a way to sculpt with smoothing somehow?

If you hold down the Shift key while making a brush stroke, the Smooth Brush will become active until you release the Shift key.
Sculptris uses what people call auto-relax smoothing.
I don't believe that Blender currently has anything analogous to that feature.
There is a thread hosted on Blender Artists that has been going for a couple years now and it's topic is Dynatopo sculpting.
There are many tips sprinkled here and there if you read through the whole thing.
http://blenderartists.org/forum/showthread.php?264568-Dyntopo-tests/page249&highlight=sculpting

I just found this link - https://nicholasbishop.net/?p=474 - where a blender developer or something like that mentioned "Surface relaxation (to fix blocky appearance after subdivision)" in the section of the things that are yet to be done so now it's obvious that this is not yet supported in Blender. Thanks for the answer :)


text:
Glow with depth in Blender?
What would be a way to create a glow in Blender. For that purpose I've been always using the compositor. However, that is pixels work, which means it is a 2d work. To make a 3d one, do I have to use particles, nodes or maybe some simulator? Because the compositor deals with images, which will make the glow to be out of perspective (flat). is there a way to make a glow with depth in Blender? Here is what I mean (If we assume that the blue color is a glow, it is clear that like other objects it is part of the perspective of the 3d view, which means that it has depth) -

And if possible, how to make one in cycles?

Do you want volumetrics?

I was about to update the post, sorry. What does volumetrics does anyway (never used it before)?

Basically .. fog.

Thanks. Basically the kind of glow that fades out of the object, so maybe fog is not what I need.

Maybe, but volumetrics interact with light http://wiki.blender.org/index.php/Dev:Ref/Release_Notes/2.70/Cycles

This could be of use to you: http://blender.stackexchange.com/a/3640/3127

Oh wait, what I meant by "to fit in the environment with light bouncing and such", I meant it literally, 'cause I don't know if linking objects or scenes from internal to cycles will be with lighting effects from the Internal (which I don't want). If linking means that it will render as if the feature was in cycles, then I would go with linking.

@Vladimir I don't see where linking between scenes is involved..?

Cycles has volumetrics now, and the compositor works on both render engines.

I know (thanks however), but in the post I didn't asked about volumetrics ("someonewithpc" maybe assumed I did). Anyway, are glowing effects available in Cycles?

@Vladimir Yes and no. You can simulate the light on other object, and there are some hacks to create the color glow, but there is no robust method.

Such blooms/glares are created inside the camera/lens in real life, so it makes sense for them to be done in the compositor. The closest you can get without composting is volumetrics (or putting a "lens" in front of the camera object), but I would use the compositor anyway.

You can use volumetrics and procedural gradient textures to create a glow effect:

The setup:

This works by defining two spherical gradients which are infinitely long (making them cylindrical), and using those to create the hard white part and the soft colorful bit.
The gradients are defined in object coordinates, so they will stay with the object when it's animated. Note that because of this, the origin of your blade object will make a big difference. If it's centered it should be fine.
A third gradient is used to fade the cylinder gradients out before they get to the tip of the blade object. This will have to be configured depending on the length of your object and the location of it's origin. It should look something like this:

Provided that your origin is centered, all you should have to do is tweak the Z location value in the mapping node until the gradient is in the right place.
Note that your blade object should be a bit fatter than you might make it normally, as it has to contain the glow. Also note that it doesn't actually have to be a cylinder, as the cylindrical shape is defined in the material nodes.

This is actually pretty much what I was looking for back when you answered my question (http://blender.stackexchange.com/a/3640/3127).  Of course, back then, we didn't have volumetrics and I wasn't totally thinking of making it material-based instead of compositor-based.

@kizlink Ha, I was thinking of that when I wrote this one.. Glad you found it :)

Absolutely astonishing! The result looks hilarious ... yep, node tree is not that easy ;). Thanx for the .blend file so we could see the action - for sure I will use it in my WIP now!

...it could not be used for bent objects (only straight) so very limited usage - sadly.

authors: Хазрет Шафиев


text:
How to change object orders?
I was wondering if I can change order of objects because of my animation exporter script only exports their transformation data with their index number -not names. I do it for efficiency in my game, in that way instead of using dictionary classes I use arrays.
I tried copying, deleting then pasting back but it didn't work. I need a simple way of doing this but if someone can show me a script to reorder it's also appropriate.

No, if you rely on a specific order you will have to sort on export.

Looks like it's gonna be huge headache...

I'm facing same problem.  I'm using blender for both my 3d scene, and a 2D GUI overlay.  For the solid GUI objects, I can just set the object's depth value, and let the z-buffer sort it out.  However, this trick does not work for semi-transparent objects (alpha-blended), which causes nasty artifacts.
I found a workaround, but you're not going to like it:
it is possible to re-order objects in the outliner, but this doesn't help, since they are still exported in alphabetical order.  So the only solution that works for me, is to rename all my objects to the letters of the alphabet, in the order that I want them rendered.


text:
Why does a black box appear in the render instead of a window when using the Archimesh add-on?
My window looks fine in the viewport. But when I go into into rendered mode, its just a black box.
Viewport:

Rendered mode:

click the wall and in the tool shelf -> create -> archimesh -> room tools -> click auto holes

I have the same problem in Blender 3.4.1 - I see a black box in the viewport instead of the Archimesh when using Cycles in render preview mode. I see the Archimesh item in the viewport as expected in render preview mode when switching to Eevee.
The Archimesh item is rendered as expected in a proper render when using Cycles, so this issue is in the viewport in render preview mode only.


text:
Why does a box appear when I try to make a window hole in a wall using Archimesh?
I get this weird thing when I set auto holes on the wall. It should boolean a hole for the window.

Try selecting the item the hole is in (e.g., wall) then go into and out of edit mode (Tab key).  Sometimes this resets the boolean.

Look at the settings for the "CTRL_Hole" object: if that object is renderable ("camera" icon in the last column not grayed out), you'l see it in the render. The hole for the window will be present, just hidden by the Ctrl_Hole object.
You could also try the other 'solver' option in the boolean modifier.

My holes didn't work because I did't set wall thickness.

One sentence rarely does make a good answer. Please read How do I write a good answer? and Why and how are some answers deleted?.

I don't know what else to add. If you are trying to use auto holes you already know how to make walls and the thickness property is just right there.

Happened to me when I forgot to assign thickness to walls. Try that :) Also the auto holes function loves to randomly stopping working, but comes back if you just click it again ;)


text:
Using Empty Object Coords for shading (Multiply Vector by Matrix)
I'm making a setup that reduces the complexity of shading by replacing the Normals with coordinates from an object. If you take Object Coords of an empty and plug them into the normal socket of a shader, you end up with the object being shaded as if it were a sphere. If you make some edits to each axis, then you can change the shape more. In this setup, the sphere is distorted quite a bit to give the shading I want for the face:

So this all works quite nicely. The problem is when the head moves:

What we see here is that the altered normals are masked only to the face, with the real normals still in use further up the forehead. As the head rotates, you can see the shading desync. It rotates with the head, instead of the light moving over it. This is because the Empty is parented to the head bone. I'm not sure exactly what's going on, but its something to do with the coords of the object being in the wrong space (world or object). I've tried Vector Transform node, but it doesn't help.
If the Empty only copies the location of the head and not the rotation, then there's no problem. But that only works if the head only rotates on Z, and never tilts or rolls. So it's not a proper solution.
I'm looking to understand why the coords from the empty are behaving wrong in the first place, and what can be done to make things stay properly synced up as the head moves. Someone has suggested that they might need to be multiplied by the Matrix of the object. I could get the Matrix info via drivers, but I'm not sure what to do with it after that.

The solution was to multiply the Vector by the empty object's Matrix. I built this group with some help and a lot of trial and error. The values are driven by the Matrix World of the Empty from the Data API. I'm not sure I have the component nodes of the matrix laid out properly or not, but this is working.


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Black lines where a transparent mesh intersects

I have a simple piece of geometry with a cloth simulation on it (a tube). I have a second piece of geometry rigged to it with a bone chain. I need the cloth simmed piece to not render, so I made it fully transparent. However, in areas where the two pieces intersect, I get black lines. How do I prevent this?
Normally I would use a mask modifier to hide the simmed geometry, but that causes the bone chain constrained to it to get messed up as the geometry it is constrained to no longer exists.
Disabling rendering of the cloth object entirely isn't an option as other parts of it need to render, and it's running off a mesh cache, so I can't alter the object.

You can send that part as an example file here for much better diagnosing.

No backface culling in Cycles, and setting the backface to be transparent as well is redundant with just having the whole thing transparent.

Seems and impossible task with out at least a pic of the cycles node tree for both the tube and the cloth... can you please post? a pic of these node trees?

I don't think the problem is with the number of light bounces. I created a character using Make Human and imported it into blender. The part of the hair and eyebrow (that have alpha channels) that intersect with the main body of my character actually allows me to see inside his head (that should be completely opaque). I put on a point lamp inside of his head and sure enough the parts where I was getting dark edges now glow white. I think that the intersecting shells actually confuse the renderer somehow and make wrong parts of the mesh transparent. I also have no idea how to fix this if someon

It is definitely a small bias of cycles. I believe that it is caused by cycles internal unit system. I tested the same thing in 3ds max with Arnold renderer and it works fine without black lines.
Blender's default unit is meter which could lead to precision issues in close shot rendering. However you just cannot tweak this.
The only fix to this is that you scale everything up 100X then the black lines will not be apparent in your renders however the downside is that lighting will be a big trouble.
If you only want to hide some part of the mesh, then you can use vertex group and mask modifier to mask out some part of the mesh.
This has been an issue for years but no one from Blender tried to fix because most of people didn't notice this.
It probably not a problem for most of the case but if you render close shot of transparent objects intersect with each other, it is a huge problem.
Hope it get fixed in the future. I think it is not hard like eevee has alpha cut out, cycles deserve a cut out shader as well.

Up the Max bounces under Render > Light Paths > Transparency to a high number, even numbers like 48 or higher. The more overlapping transparent surfaces there are the more likely to get black artifacts if the transparency bounces isn't high enough.
If that doesn't work, perhaps check the normals aren't getting inverted mid-way, but it's likely the former.
You could also disable the cloth rendering completely by unticking everything under the Object Panel > Cycles Settings, which should speed up the render.

Turning up the transparent bounces does not change anything. The normals are fine :(

Mmm... maybe the Blend file would be useful. But on a side-note, if the cloth (assuming it's the object seen behind the tube) is set to fully transparent (full white), why is it visible in the render? I'm trying to simulate it, but whenever I get artifacts, upping the Max/Min bounces on transparency fixes it on both full render & ambient occlusion pass. I haven't tried your full bone rig.

The material isn't on the whole object, only on the part I need to hide. The cloth object is brought in from Marvelous Designer with a .mdd cache. Some of it needs to render, some of it doesn't. MD can only do cloth and doesn't handle things like cables or other items that you don't want to wrinkle very well.

Is the image an Ambient Occlusion render, or normal render? I'm asking because of that shadow bleeding out on both sides of the relatively narrow tube. If you can't share the blend, perhaps post an image showing the viewport or such so we can see where/how the transparent cloth is positioned.

@Drudge Again, why not uploading the example file here? It would be much much helpful for others to help you. It is enough to send the problematic objects only.

Seems like it's just the AO doing what it does. Maybe disable transparent shadows on the visible material?

I do confirm having same issues with transparent meshes intersecting. And the more meshes intersect the more artefacts we get. Cranking up the Max value for Transparency Light Paths gives no effect with these complex scenes. I've tried up to 900 with no luck in my scene.
Solution for my situation was moving from Transparent Shader to switching off the rendering for the objects in the Outliner. I can still use them and they are visible in the viewport. However, they do not have any effect on the final render. This may seem the same as transparent shading but it's different for the Cycles engine.

I am speaking for Blender 2.82. Under Render Prop.>Light Pass>Max Bounces I raised the transparency bounces a bit and it cleans the artifects well for the hair meshes I am working on.


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Why doesn't selecting a UV island select the corresponding vertices in the model?
I have a model and I selected an island from my UV map with L, but those vertices didn't get selected on the mesh. Why is that?
Is there any way to quickly select UV islands on the mesh?

This is a follow-up question to Where is the "sync selection" option?

@RayMairlot I think the question is specifically about selecting islands, not just faces. The comments on this question might help provide some context: http://blender.stackexchange.com/q/27298/599

This is now possible as of this commit. Will be in 2.75 or any recent development build.
To use it, enable Sync Selection, switch to face select mode (⎈ Ctrl↹ Tab), and enjoy ;)

By default, only the vertices you select on your mesh, in Edit mode, will be visible in the UV editor, and what you select in UV editor has no effect on the mesh selection;
however, if you enable the Selection sync, found in the UV editor's header, you can select vertices in either editor and have the selection sync in the other one.

if you enable sync you cant select only one island the whole islnads will be selected

yes because there is no island selection on the 3D view and it need to be identical ; you can see that selection modes change when it's enabled

You can select islands with 'L' from the object if you're in face mode and marked seams. (Blender will use the seams as island bounds, not the unwrapped UV islands if they are different)

If you enable sync selection and then try to select an island, blender will give an error.


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A shape of cubes has "dangling edges"
The shape I made consists of several hundred cubes (generated via Python), with some stacked on top of others, and all joined into one shape using Ctrl+J.However, if I attempt to slice it using Skeinforge/ReplicatorG, it says that there are "dangling edges".
Is there any probable cause of these "dangling edges"? I have tried all of the Mesh > Clean up tools, but to no avail.
Thank you!

Here's a part of what the mesh looks like so far:

Edit: here's the .blend file:

Did you select all geometry before proceeding to Mesh > Clean-Up tools ? Aside from that I think you should post some screenshots of mesh/-es in Edit mode and upload the file.

Welcome to the site. You might want to take the tour and review the help center. To provide for the best chance at getting help, you might want to post a copy of your ~. blend file to a site like Blend-Echange, and edit a link into your question.

@MrZak, I believe I did. Thank you for your advice; I posted a screenshot and uploaded the file.

Terminology may vary, but what Skeinforge/ReplicatorG is calling "dangling edges" refers to one specific type of non-manifold geometry. It is the kind where an edge is shared by more than two faces. In other words, this is bad:

It is an infinitely thin shared edge, because even though each cube has a volume, they are joined in a way that is impossible in physical reality. Imagine if you were to perfectly line up two tables so that their corners touch in a similar way - would you have one table or two? You would still have two tables, of course. With this kind of non-manifold geometry it would be analogous to having the tables inseparably stuck together at the corner where they touch, even though they are only connected by a few molecules. A 3D printer doesn't know what to do with that.
Here is another example - infinitely small corners. Or if you prefer, "dangling vertices".

So what are your options? Well, you can either separate them:

Or you can create a very small area where the cubes touch that joins their volume:

3D-printable edge connection:

3D-printable corner connection:

Now that you understand the nature of the problem, your challenge will be coding into Python a new way of generating your geometry that is manifold. Have fun. :-)

Thanks so much for the explanation! When I keep this in mind, everything works perfectly.

@416E64726577 Glad to hear! Happy blending.

Revised Answer
I downloaded and examined your ~.blend file, and then read your question more thoroughly. I think there is an issue with the way you constructed your "shape of cubes". Generating cubes in Python, and joining them with CTRL-J will generate a large number of duplicate vertices, edges, and faces.  After downloading your file, when I attempted to select non manifold edges, using CTRL-SHFT-ALT-M), nothing was selected. After removing doubles—the report was 22641 vertices removed—and attempting to select non manifold edges, most of the object was selected. Since this is for 3D printing, the interior vertices may be an issue, too. If it were me, I'd look for an alternative method for building your initial mesh, perhaps one based upon extrusion that does not generated unnecessary internal geometry, or alternatively, add logic to your script that would merge vertices together, where appropriate.
Original Answer
In the absence of a ~.blend file,  one thing to try in edit mode, choose face select option, limit selection to visible, and using circle select tool, highlight all faces you can see, and hide them with the H  key, rotating the scene so you can select from all views . If you do this repeatedly, you may see edges or vertices which are not part of faces, and be able to select and delete those.

@Mr Zak, if there is an unintended edge between one vertex through the center of the cube to the opposite vertex and one uses CTRL-L, this edge will not be isolated. Doing the select-faces-and-hide method does isolate such edges.

It won't be, but it will be detected with Select Non-Manifold operator (and loose geometry too). However this won't help with the problem in the question.


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How can I export a Blender Animation as a Video?
I am a newbie to blender. As a part of my coursework I have to do an animation video. I have created  a model, rigged him but now I wonder how to export the animation (pose mode) as a video. There was no proper explanation on it in youtube,vimeo,dailymotion,google.
I am not satisfied with previous below question answer
How to save animation as a video format [duplicate] (How to save animation as a video format)
Can someone guide me to a video lecture on this or someone please help in rectifying my current situation

Can you add a few details as to why the question you mention didn't help you? Otherwise, I'm afraid this question is likely to be marked as a duplicate.

Hi I learnt how to export animation as video .In that Previous question it was mentioned exporting each frame as png. What after that is not explained in that question.
A clear explanation is given in layman terms in below tutorial
https://www.youtube.com/watch?v=1qDnZroK28c

Can someone help me I got another issue. Under Animation Screen layout when I position camera towards my model and render the image.It's not as I expected.
Example: Suppose If I lift my right leg in Rendered Image is showing as left leg. Further if I need to see right body of my model I need to place camera on left side.Help me in rectifying it.

Please ask new questions for these issues.


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Shadow objects appearing in render
I'm having another rendering issue that I can't seem to figure out.  I have a video that, when rendered on my local machine, turns out as it should.  However, the company that I am submitting the .blend to renders in the cloud, and when I receive the rendered PNGs back, there are faint black objects overlaying some of the scenes (similar to another question I asked about a Blender Internal video a month ago).  This occurs in areas where scenes overlap in the Video Sequence Editor (as I am using a separate scene to composite multiple scenes).  To allow the scenes underneath to show through, I've tried both editing the scene strips to have the "Alpha Over" blend setting and using "Alpha Over" Effect Strips.  Both produce the same results. Currently, I am using the Effect Strip method.  I'm curious if this is a common problem in the Video Sequence Editor, or if there is something wrong with my scenes.  I'm using Cycles, and I'll post a shortened version of my .blend below.

This is the result of rendering in the cloud.  Notice the black shadowy cube that is present on the left side of the frame.

This is what I want my render to look like.  The black shadow cube is not present.

This is what my Video Sequence Editor looks like when using Effect Strips.

This is the other method I attempted in the Video Sequence Editor, specifically changing the blend mode of overlapping scene strips to "Alpha Over."
Both set-ups yield the same result when rendered in the cloud.

Always make sure to mute underlying Strips that have an Effect Strip applied to minimize side-effects.

Doing so causes areas not covered by the effect strip to no longer be visible when rendered.  Also, even when I don't use an effect strip and simply change the blend setting of my scene strips to "Alpha Over," this issue still occurs.  So I doubt this is related specifically to the use of an effect strip.  I'll upload another screenshot with the method I described above.

The Effect Strips have to have a Blend Type of Over Drop or Alpha Over if you want to have it "on top" of other Strips. Those other Strips of course don't have to be muted, only the original Strips where the Effect Strip is applied on.

The only strips in my scene are the original strips and the alpha over effect strip that I created from them.  So muting only the original strips means I'd be muting all of the strips except for the effect strip.  And doing so, even with the effect strip set to "alpha over," still renders all areas the effect strip doesn't cover empty.  I was hoping I could use alpha over as a means to connect two strips between their transition so that the bottom strip is visible through the upper strip's alpha channel.

Yeah, never mind. My tip doesn't apply on Alpha Over Effect Strips. I'm looking at your Blend file and it's quite a Setup... The Black Shadow Cube comes from messing around with Render Layers and Masking and Blackhole Nodes and stuff... that's pretty complicated, no wonder something appears that shouldn't be there ;-)

When you turn Backface Culling on in the Viewport you can see, that this Black Shadow comes from the inside side wall of your Box... You really messed around with those Faces and Backfaces... Probably there's a Problem in your Shader, but I can't really understand it why you stitch everything together like this...

Related somehow: http://blender.stackexchange.com/a/5104/2843


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display face normal direction in blender 2.8
How can I know if the normals of an object are flipped or not? Because in version 2.8 both normals have the same color and I can't identify if it's a flipped normal, unlike the previous versions where there are two colors of the faces: white is a real object, while light purple is a flipped normal.

In 2.8 it's different now, to preview normals orientation you have to use Overlays menu and enable preview mode there. See https://blender.stackexchange.com/questions/119408/how-to-show-the-normal-of-a-face

Both methods are available in Blender 2.8x.

Go into edit mode

Select the overlays drop down and click on the button shown in the picture below

You will see blue lines in the direction the faces are facing

An even faster way to quickly check is to check the box that says Face Orientation. It'll color any flipped normals to red from blue.

Also in blender@3.2.1 (y)


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How can I change a Text color in Blender?
I did in Object Mode > Add > Text
Now I want to change the text color to red. Now it's in gray.

If there is no material, add one and set the diffuse colour to red. Note that configuring materials varies depending on which render engine you select.

there is nothing off topic about this question.  He's asking how to change the color of his text.  what's wrong with that?

@Millard that comment has been migrated of [SO]

oh, that makes sense. :)

You are using an older version of Blender. You should download a newer one, however, you should still be able to follow this, because it's basically the same in your version, except your tab icons are on the top, instead of the side of that panel, as below.
Change tabs and add new shader

Click the default white color for a pallet wheel

Choose you color

Don't forget to change the view to Preview/Render, else you will not notice the change in color https://i.sstatic.net/zCSg5.png


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Blender scripting: Circle Selectiong in the "3D View"
In Blender2.74, I want to circle-select the vertices in the "3D View", using this: circle_select(x = 300, y = 400, radius = 30).

I found this question. So I know how to get the xy positions in the camera coordinate system.
Now I don't know how to use the API "bpy.ops.view3d.select_circle()".
When I used the command in python console, the following error occured.
bpy.ops.view3d.select_circle(x=500, y=500, radius=10)
Traceback (most recent call last):
File "<blender_console>", line 1, in <module>
File "C:\Program Files\Blender Foundation\Blender\2.74\scripts\modules\bpy\ops.py",
line 189, in __call__
ret = op_call(self.idname_py(), None, kw)
RuntimeError: Operator bpy.ops.view3d.select_circle.poll() expected a view3d region

Can I use this API in the "Python Console?
And, I will probably have to convert the xy positions in the camera-cood to those in the "3D View". Please teach me this also.

you'll have to use location_3d_to_region_2d to get X and Y and do the selection with math ( if P inside the circle ? ) , otherwise you have to be in the right context to use select_circle

thx. In my goal script, select_circle will be called many times. So I think it undesirable to check if each vertex in in inside the circle with Python. If possible, I want to use the API, which is called when I use the selection(circular region) in the GUI. But, I don't know its name.

You have to override the context to be able to call this operator outside of the 3d view :
import bpy

for area in bpy.context.screen.areas:
    if area.type == 'VIEW_3D':

        override = bpy.context.copy()
        override['area'] = area
        override['region'] = area.regions[4]

        bpy.ops.view3d.select_circle(override, x=300, y=150, radius=300, gesture_mode = 3)
        break

Update : Finding the camera corners coordinates
import bpy
from bpy_extras import view3d_utils, object_utils

scene = bpy.context.scene
cam = scene.camera

for area in bpy.context.screen.areas:
    if area.type == 'VIEW_3D':
        viewport = area.regions[4]
        rv3d = area.spaces[0].region_3d
        P1 = (0,0)
        P2 = (viewport.width, viewport.height)

        depth_location =  view3d_utils.region_2d_to_vector_3d(viewport, rv3d, P1)
        p = view3d_utils.region_2d_to_location_3d(viewport, rv3d, P1, depth_location)
        P1cam  = object_utils.world_to_camera_view(scene, cam, p)

        depth_location =  view3d_utils.region_2d_to_vector_3d(viewport, rv3d, P2)
        p = view3d_utils.region_2d_to_location_3d(viewport, rv3d, P2, depth_location)
        P2cam  = object_utils.world_to_camera_view(scene, cam, p)

        cam_width = int(P2[0]/(P2cam[0]-P1cam[0]))
        cam_x = int(-1*P1cam[0]*cam_width)

        cam_height = int(P2[1]/(P2cam[1]-P1cam[1]))
        cam_y = int(-1*P1cam[1]*cam_height)

        print(cam_width, cam_height, cam_x, cam_y)
        print("\nP(0,0) at (%d, %d) and P(1920, 1080) at ( %d, %d)"%(cam_x, cam_y, cam_x+cam_width, cam_y+cam_height) )

Oh, thanks you very much! How can I get the positions of the red circles, or what property should I use to calculate these positions?

@reosa what is your selection based on ( on the final image or the current view ?)

It is based on the current view, "3D View". I want the positions of the red points(circles) in the "3D View".


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Unwrapping a gun
Im trying to get a user friendly unwrap for a weapon, ive tried many methods but they all either return complex texture maps or distorted mapping, what techniques can I use to make the unwrapping a little bit easier or more user friendly?
I made the gun in multiple parts as per real life (receiver, stock, etc)
The gun will be re-texture-able by the community so it needs to be easy to read
here are two examples of the most common problem I am facing

You need to show us more. How mesh is looking (wireframe), where did you placed seams?  Preferably upload .blend file to: http://blend-exchange.giantcowfilms.com/ then you can recieve some answers.

You have way too many seams. Every 'closed' seam generates another island in uv map. Especially those seams in holes. Mesh is looking a little bit messy, ngons, tris, quads. Where you want to export this model? Game engine?

the seams are arranged so the main sides are the sides of the gun, the top, and bottom of every part, the game engine is Roblox, which supports multiple separate parts per gun, and using a single texture file for all

UV unwrapping a mesh so that others can use it for re-texturing usully means a lot of editing by hand in the UV editor.
For your gun, I would suggest that you go into side view and then use the Project from View option from the UV Mapping menu.
It makes things a little easier if you start the UV unwrapping before applying the mirror modifier.

When editing the UV islands use a grid and the enable Area Stretch from the UV properties panel.

Don’t be surprised if you find that you spend more time editing the UV’s than you spent creating the actual mesh.

Thank you for that detailed answer, just to clerify, this also works with asymmetrical guns?

Yes of course. Just means more work for you.
Edit mode,  Side view,  Face select mode,  select one face of the part you want to unwrap followed by the L key, that whole part will now be selected. U to open UV mapping menu and choose the Project From View option .
In the Uv editor move that Island aside so that you have an empty UV space for the next part you will be unwrapping.

In the 3D editor switch to view the opposite side and repeat the UV unwrapping.
Do this for the other two or three main parts of the model. Then start moving, scaling and editing those islands’ in the UV space.
When you have these big parts correct you can go back to the model and start unwrapping and UV editing the smaller parts.


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Weird glitched material
Honestly, I don't know what this is anymore, I have never seen anything like this before. It is not a UV map issue (this object doesn't even use UV, only basic color).

Anyway, I have tried to recalculate normals, tried to UV unwrap it, just in case, changed materials and I don't know what more... Odd thing is that this only happens in Cycles, not Eevee:
This is in Eevee

Also, it is bad only from this one side. The other side is fine:

Does somebody know what else could cause this? And why is it only visible on one side of the object?
File:

Are you using an AMD GPU?

FWIW it looks fine in Cycles with my NVIDIA/I7/Windows 10/2.93.5 setup.  I'm guessing GPU.

Hi everyone, after a short while, I discovered that I forgot one thing, origin... I realized that the origin point is for some reason way too far away in the deformed normals... So I set the origin point in the middle of the mass and it was solved... didn't know that the origin point can cause something like that


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Export material values (metalness/roughness) to WebGL
I would try to find the answer myself but time is against us.
I and my colleague are working on WebGL for the webpage. I'm making the 3D parts of this process and he takes care of the coding.
Does somebody know if values like Metalness, roughness (no textures, just values like 0.7 and 0.5) are possible to export in glb, or does this need to be setup again directly in WebGL by my colleague?
If both options are possible, which one is better in terms of time and difficulty?
Thank you

The glTF (.gltf or .glb) format includes a metal/rough PBR material that does support metalness and roughness properties — either values or textures — like you're describing. In Blender, you'll want to choose the Principled BSDF material, configure those properties, and export. The Blender glTF documentation has more details on which material configurations are supported for export. Common WebGL engines like three.js and Babylon.js will handle these materials correctly.


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Blender 2.83, Cycles, can't get pointiness to work
Guys I'm in a pickle here - regular scene, cube, uv unwrapped, cycles renderer selected and yet for a love of me I am unable to get pointiness to work.

Top left view - is a rendered image, looks exactly the same in rendered view.

pointiness wont work on just a cube. there is no curvature for the node to work with.

Oh damn @Timaroberts you are right, what I missed is tad of geometry more. Post it as an answer so I could accept it.

working on it, just a bit :)

By the way you don't need to UV unwrap your geometry to use the pointiness attribute

@Gorgious yea I figured out I'll just start trying all the stuff that came to my mind as I could not replicate the pointiness which I know I used long ago lol

And it doesn't work in Eevee, if you're ever wondering :)

As mentioned in the comments, on a cube with no curvature,or any type of bevel, you will see no result from  the pointiness output of the geometry node.
Pointiness as defined in the manual:

An approximation of the curvature of the mesh per vertex. Lighter values indicate convex angles, darker values indicate concave angles. It allows you to do effects like dirt maps and wear-off effects.

You can see this clearly in the following example:
All objects have the same basic node setup including the default cube on the left.

Click to enlarge
The node seteup used:

What will help is having some decent subdivisions. Use Cycles, and use Rendered Shading mode.
This cost me over half a day to figure these out. They are often not mentioned in tutorials.


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Object folding in on itself
I am working on a bedroom project in Blender while following a tutorial. I'm not sure what I did wrong, but while attempting to color the walls of my bedroom, I realized some of the parts were- folding in on themselves?
I'm not sure how this happened, I recently merged the vertices by distance to fix a different issue; would that have anything to do with it?
Here is the blend file: https://blend-exchange.com/b/OsmXJW7G
I feel a bit silly asking another question only minutes after my last got resolved. I'm just not sure what else to do.
Help and advice very appreciated!

Hello, for the moment you still have overlapping vertices, so you need to Merge by Distance, and also you have a Bevel modifier, which creates bevels, but I'm not sure what you mean by "folding parts" (but I can't select these half faces like you show)

I think I figured it out! I removed the Bevel modified then re-added it, but instead I set it to "by vertices" rather than "edges". Thank you for the help!

oh ok yes it's the Bevel modifier that created this effect for some reason

Well, are you sure you want to bevel the vertices? What was the problem with the edge bevels?

check your face orientation and repair it -> if you click on "overlays" -> check "face orientation": red means: wrong orientation.

To repair, select red object, TAB -> edit mode -> A (select all) -> Shift N
if all is blue...

delete double faces -> select object, TAB -> edit mode -> A (select all) -> M -> merge by distance

after that your problems should be gone.

You have internal faces which is considered non manifold geometry and messes up the Bevel Modifier causing your distorted geometry.

And don't forget this side as well. Once you have deleted these internal faces, your Bevel Modifier will work perfectly :)

+1 This probably happened because you Extruded > Changed your mind > right-click canceled the move (Leaving the extruded geo in place) > Decided to inset > Inset the now doubled face you had selected. Remember that when you press E to extrude you are actually doing two things at once: Extruding the geo and then moving it. When you right-click to cancel you only cancel the move part. Be aware of that.


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Certain part of object showing up black in Cycles rendered view
I'm currently working on a bedroom project in Blender while following a tutorial. I thought I was completing all the steps correctly. But when I entered rendered view, specific parts of my wall showed up as black. I have lighting and I do not have any textures added to my scene. None of the other objects are doing this. How do I fix this?

Hello and welcome! Can you share your blend file https://blend-exchange.com. Most likely you have duplicate vertices or objects overlapping each other.

I think this is it: https://blend-exchange.com/b/OsmXJW7G - Let me know if that works!

You wrote you have no textures added, but textures ≠ materials. Are there no materials on the objects? Because if you start modeling with the default cube for example, this usually has a basic material - a Principled BSDF with 80% white color plugged into a Material Output. Let's say you have this basic material on the object, delete the Principled BSDF but leave the Material Output - this would look exactly like that. But everything else is just guesswork without any screenshots of materials or the file.

Here is the blend file: https://blend-exchange.com/b/OsmXJW7G
I don't believe I have any materials or textures added to the cube. It also only appears as black in Cycles, not Eevee.

Yes, I've seen it, no need for double-posting (writing my comment overlapped with you posting it) - by the way, on the download site it says "Share this file: Add this text into your post:" and you can edit the whole text into your question.

i have just confirmed it is really the duplicate vertices. just select the object and go into edit mode then press a then m then Merge By Distance. solved :)

Omg thank you so much!! You're a life saver, I hope you have an awesome day. Thank you so much for helping me!

@HarryMcKenzie That's right, you're quicker than me. Post this as an answer so one can see it is solved, because many people have problems with duplicate vertices.

Okay, thank you! :D I just signed up to this site so I wasn't sure about that. It's solved now- I just had to merge the vertices by distance. Once again, thank you very much for your assistance.

alright! hey no problem! glad we were able to help! :)

Seeing black textures in Cycles rendering is commonly caused by either overlapping objects of the same geometry or duplicate overlapping vertices. These scenarios cause the render engine to mess up the calculation of lighting. In your case it is duplicate vertices. To solve this just select the object and press tab to go into Edit Mode and press A to select all vertices then press M and choose Merge By Distance.


text:
How to pass command line arguments through Blender without IndexError thrown?
I am trying to execute my command with two arguments in terminal:
blender -b Scripting_Testing.blend -P background_job.py -- 1 2

I have used:
import sys

try:
    index = sys.argv.index("--") + 1
except ValueError:
    index = len(sys.argv)
sys.argv = sys.argv[index:]
....
....
foot_position = sys.argv[1]
angle_movement = sys.argv[2]

(Used from Here)
I get:
IndexError: list index out of range

All the parameters before "--" (+ 1 makes it inclusive) have been skipped here. The second line overrides the sys.argv to hold only items that go after "--", which is an array of length 2 containing [1, 2].
index = sys.argv.index("--") + 1
sys.argv = sys.argv[index:]

Array indices start from 0. You are trying to access a third parameter here
angle_movement = sys.argv[2]

This causes the out of index exception.
Should be
foot_position = sys.argv[0]
angle_movement = sys.argv[1]

Thank you for your help!


text:
Is there a hotkey (or a way to hotkey) to cycle grease pencil brushes?
I Ctrl+Tab to the draw mode. Shift+Space to select the draw tool. Is there a hotkey to select the brush I want or cycle through them?


text:
How to render single frame instead of repeating frames?
I have an animation that has three(3) still images in it. Each image stays for 3 seconds and then switch to next image. I don't want to render same image for 3 seconds(That is 180 frames) but in animation video that same frame should stay for 3 seconds.
Any suggestions?

Just render your three images into picture files, then import them into your favorite video editing software and make them last any time you'd like.


text:
How do I set multiple settings with one button?
How can I change a viewport shading settings from one button?
I am creating a toolbox I put in the Right panel. Everything's Ok exept for this. I'd like to get my settings in one click.
Anyone?
bpy.data.screens["Scripting"].shading.light = 'MATCAP'
bpy.data.screens["Scripting"].shading.color_type = 'SINGLE'
bpy.data.screens["Scripting"].shading.show_xray = False
bpy.data.screens["Scripting"].shading.show_cavity = True
bpy.data.screens["Scripting"].shading.show_object_outline = False

Are you specifically looking to do this with Python or did you just include that code as a reference to what settings you want to change?

yes I want it in python because I want to use it for my addon. The code here is the one given in Blender for that but it does not work probably because it's 3d view dependant. I don't know how to do that

Make an operator
For the most part a button in blender calls an operator.
Using the simple operator template, here is a quick edit to hardcode in some settings.

I have made the operator poll only in the 3d view area.
Haven't sanitized name.

Since your addon panel also resides in this area, it is simply a matter of adding
self.layout.operator("object.simple_operator")

into your panel's draw method.
import bpy

def main(context):
    space = context.space_data
    space.shading.light = 'MATCAP'
    space.shading.color_type = 'SINGLE'
    space.shading.show_xray = False
    space.shading.show_cavity = True
    space.shading.show_object_outline = False

class SimpleOperator(bpy.types.Operator):
    """Tooltip"""
    bl_idname = "object.simple_operator"
    bl_label = "Simple Object Operator"

    @classmethod
    def poll(cls, context):
        return context.area.type == 'VIEW_3D'

    def execute(self, context):
        main(context)
        return {'FINISHED'}

def register():
    bpy.utils.register_class(SimpleOperator)

def unregister():
    bpy.utils.unregister_class(SimpleOperator)

if __name__ == "__main__":
    register()

Further to this, for saving multiple settings

there is the preset system for saving an operators, or some tools settings to a text file. How to use presets for operator properties?
A collection of settings can be defined as a property group. Multiple can be saved as a CollectionPropery the "current" as a PointerProperty

Basic guide script considering Blender 2.80 is still evolving. (Tested on 2.80.35)
import bpy

my_areas = bpy.context.workspace.screens[0].areas
my_shading = 'SOLID'
my_light = 'MATCAP'
my_color_type = 'SINGLE'
my_show_xray = False
my_show_cavity = True
my_show_object_outline = False

def chngviewptshader():
    for area in my_areas:
        for space in area.spaces:
            if space.type == 'VIEW_3D':
                try:
                    space.shading.type = my_shading
                    space.shading.light = my_light
                    space.shading.color_type = my_color_type
                    space.shading.show_xray = my_show_xray
                    space.shading.show_cavity = my_show_cavity
                    space.shading.show_object_outline = my_show_object_outline
                except:
                    print('Setting invalid')

chngviewptshader()

thank you! What if I want it to affect only the area where the button is clicked?

@LoranozorGraphitz batfinger's answer is already setup for only affecting the area in which the operator is called. You may want to include the shading type being set or checking for it to be equal to solid in the poll since some of the settings like shading.light = 'MATCAP' are not available in all shading types.