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Animation Nodes - instance objects over time
I am trying to create an animation where torus's emanate from a centre at regular intervals (like the RKO Pictures radio wave animation).
This means creating new instances over time.
I have managed to create expanding instances of a bezier curve, which is sort of the effect, but not really.

What I am looking to do is loop the expansion of a master circle over time.
Any ideas would be very helpful.

The wave/scale effect is controlled by the scale of an empty (simply animate it the way you want).
The node setting is in two parts:

Main part:

Get empty scale and generate a set of scales from it.
Duplicates the model (a curve).
Put the result in the resulting curve.

The scale is limited between 1 and 5 in this setup but you can change it as you want.
The next nodes are making an array of scale.
Say current scale is 3.19, we want the array to be [1.19, 2.19, 3.19].
This is done using the float range node.

Sub loop:

The loop is done over the precalculated scales (above).
For each scale duplicates the input vertices and scale them.
The result is merged (reassign to the output).

The result is cumulated in a "reassign" node which is also set as output.
The model input is set as copy as we want a new circle at each iteration.

Thank you Lemon. That is just what I am looking for. It is going to take me sometime to understand how you got there as I am a real newbie. Many thanks again. Christopher

I have found that when I try to add rings and space the distance between rings, the system breaks. Therefore, I have found that having the same integer number in the 2 maths nodes after the vector separate node and the Float Range node, solves the problem.

@ChristopherLowden, I've considered that the distance between ring can simply be changed changing the size (in edit mode) of the model curve (or you could also do than within nodes).

Edit mode works for me.Thank you

The floor division of the scale of the master circle with some parameter controlling the density of the circles gives you the amount of the circles. You can use this amount in a Float Range node to get a list of scales for your circles, you can then use to do the replication:

Alternatively, you can use a start-end sequence to make the circles appear in the center:

Thank you Omar. A very interesting way of doing it. The problem is that the replication adds at the outside of the circle and not the centre. I am really looking for a water ripple animation. So it has the same issue as the node set I did.

@ChristopherLowden I can't really imagine what you are saying. Can you elaborate?

In your version, every new instance is added to the outer edge of the circles at it grows. What I am looking for is a ripple where the each new instance starts in the centre.

@ChristopherLowden Added another method to the answer.


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build modifier - perpetual loop
I am trying have a mesh build and then unbuild in a perpetual loop. I tried to key frame the build parametre, tried animation nodes to drive the parametres, tried the nla, without success.
The looping animation will be linked to other scenes, so I am prefer a solution that works with linking. Any ideas are most welcome?
If the build modifier is not appropiate, is there a way to replicate the mesh build with animation nodes?
Thank you

Duarte's solution is the best solution I can think of. However, it will not work for more than cycle, meaning it worn't repeat more than once. To solve this, Animation Nodes can be used to automate setting the start frame and reverse options of a single build modifier.
Build Modifier
Lets say we want the length of each build to be 30 frame, then for the first 30 frames, Reverse will be False and Start will be zero, for the next 30 frames, Reverse will be True and Start will be 30, for the next 30 frame, Reverse will be False and Start will be 60, and so on. This pattern can be easily achieved using floor division, if we floor division the time by 30, the output will be 0 for the first 30 frames, 1 for the next 30 frames, 2 for the next 30 frames, 3 for the next 30 frames and so on. If we multiplied this output by 30, we get the Start value, which is $0, 30, 60, 90, \dots$. If we modulo the output by 2, we get the pattern $0, 1, 0, 1, \dots$ or in other words, $\text{False}, \text{True}, \text{False}, \text{True}, \dots$ which is the required pattern for Reverse. So we can imlement this and write the values using the Object Attribute Output Node as follows:

Which results:

Animation Nodes
Let me, in addition, show you how to replicate the build modifier in Animation Nodes. All we have to do is slice the polygon indices list using the Slice List Node, where the end index starts from zero, goes to the full length of the list, goes back to zero, and so on. The Repeat Time can be used to create a ping pong pattern where the output goes from zero to 30, then back to zero, and so on. If we divided that by 30, it will be in range $[0, 1]$, if we multiply it by the length of the list, we get the required pattern, and the node tree becomes:

And the result is exactly the same as the build modifier:

@ChristopherLowden Please accept the answer if you find it useful.

Add two Build modifiers, one after the other.
Set the second one to Reversed, and adjust its Star frame to start some time after the previous one ends.

source: Stack Exchange

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

sort: votes


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After exiting blender, texture I was painting shows up black
So I didn't save it, as I didn't know you had to but in this screenshot is what I have. You can see in the UV selector menu thing it shows my texture, highlighted in red.  Now how do I restore it?

Related: http://blender.stackexchange.com/q/13407/599

In Blender, when you texture paint in Blender, it doesn't save the images when you save your file or close Blender (unless you have Blender pack, or save, all images into the .blend file).
It keeps the slot (that's what you observed) because the texture is being pointed to by your materials, but if you don't save it externally, you've lost your textures.

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


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Mouse wheel rotates instead of zooming in
My mouse wheel is suddenly rotating around an object instead of zooming in. What hotkey did I accidentally press, and how do I get it to zoom again?

That generally happens if you press Ctrl + Alt + Scroll Wheel or Shift + Alt + Scroll Wheel by default.
The fact that it is doing it by default may mean that you either changed the keyboard shortcuts in Blender preferences, you have a stuck key in your keyboard, or something else is interfering with which key presses are being sent to Blender.
As far as I know there is no keyboard shortcut to permanently set this behavior by default.
Check what hardware is currently plugged into Blender. Some input devices like drawing tablets, pads, game controllers or 3D Mouse may erroneously send keystrokes or simulate keypresses that confuse Blender or alter its behavior. if in doubt disconnect them all, restart Blender and see if behavior changes.

I was using a Wacom tablet, which I unplugged. That's when the mouse wheel started rotating instead of zooming. I rebooted blender and now everything works as it's supposed to! So technically, it was a stuck key, if you consider a tablet to be an additional set of keys.

Ah I see, possibly some input conflict then.

You can always reload factory settings to start fresh....

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


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How to separate texture-alpha without premultiplying the color?
I want preview some game assets via Cycles for the game Space Engineers. The game uses packed .dds textures where the color and alpha channels store unrelated information: diffuse color + metallness, normal map + glossiness (roughness, inverted).
I think my problem is this documented behavior of image-texture nodes:

Color output:
  RGB color from image. If the image has alpha, the color is premultiplied with alpha if the Alpha output is used, and unpremultiplied or straight if the Alpha output is not used.

The result is that my shader nodes produce some strange artifacts when I use both image-texture outputs:

If I extract the alpha-channel of the textures into separate files and plug those in, the problem goes away. But I don't like doing that because it introduces an otherwise unnecessary conversion step to my workflow.

Here is what I already tried:

Making sure Alpha is set to Straight for each image. I think that only affects how Blender treats the data it reads from file, though.
Load the .dds into two separate image-datablocks. The first image has Use Alpha disabled and provides the RGB channels. The second one has Use Alpha enabled and provides the Alpha channel. This resulted in largely the same problem because it seems Blender optimizes internally and loads the same file only really once. I think that because toggling Use Alpha seems to affect the image-data of both images (without reflecting that in the UI).
Use a MixRGB node: Add the color (0,0,0,1) to the color output and clamp the result. This shouldn't change the color (because adding black does nothing) and remove any transparency (because 1 + anything is 1 when clamped). Sadly, that didn't do anything.

Am I out of luck and using the alpha output simply cannot be done without affecting the color output?

Can't you just devide by the alpha to undo the premultiplication (use math nodes)

Hm, now that you mention that, I wonder if what I'm seeing is the automatic reversal of premultiplication. Although the red parts are non-metallic, i.e. the alpha-channel is completely black (0.0) in those places and should destroy all color information.

Workaround: Duplicate each Texture Input node and get the RBG value from one, and the Alpha value from the other input. Yes, suboptimal, I'm discussing it at irc://irc.freenode.net#blender currently

The workaround WorldSEnder mentioned above is the only solution:

Duplicate each Texture Input node and get the RBG value from one, and the Alpha value from the other input.

The stance here seems to be that texture-files are simply not expected to contain unrelated information. The optimization to pack several unrelated channels into one texture-file to improve memory-locality on the GPU is just not that relevant to Blender to warrant a change to the behavior of Texture Input nodes.

That's strange, I get the exact opposite behavior here. Unrelated data stored in the alpha channel only works when both color and alpha are connected, otherwise the premul kicks in. Take a look at this file, it renders correctly here, but will get weird colors if you disconnect the alpha>roughness noodle: http://www.pasteall.org/blend/36709

I've had a look and I can see your problem. I can't be certain that this is the same issue, though. At least what I'm experiencing is in line with the documentation. Your issue is the exact opposite of what the documentation says. Maybe it would be best to avoid using this kind of textures with Blender entirely.


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How can I register the same keymap item for different space types?
I have for example:
bpy.utils.register_class(RENDER_OT_set_fps_increase)

    kc = bpy.context.window_manager.keyconfigs.addon
    if kc:
        km = kc.keymaps.new(name="Timeline", space_type="TIMELINE")
        kmi = km.keymap_items.new('render.set_fps_increase', 'W', 'PRESS')

And I want to register the same key for GRAPH_EDITOR and DOPESHEET_EDITOR.
But I couldn't find a way to do it. The only thing left to try was to create two extra classes, but I want to believe there is a simpler way to do this.

Have you tried repeating what you have using another space_type?

Yes, it was the first thing I've tried, but didn't work, maybe I made a mistake somewhere? I'll try again.

Made a mistake indeed, I was duplicating also the register class... perks of a noob. Thanks!


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Is it possible with Python to code G key to move channels up and down in the Dopesheet editor?
Just like we are able to translate most elements in Blender, it would be really nice to be able to do it there. Is it possible?

Well, in the form you've asked it, the answer is "yes," but that's probably not what you're looking for. Incidentally, the answer to any question that starts with "is it possible to write code that would..." is almost ALWAYS "yes." It is possible. A better question is "would it be worth it." The BEST question would be "What Python command sets a new hotkey in Blender," or "how do I get my Blender script to listen for a keypress without it just running all the time?" Try to be specific.

Actually, "yes" would be enough, thank you! Sometimes I think something is possible, then look for a way to do it, and after a lot of time invested, turns out it isn't possible. Also, every little usability improvement is always worth it if you repeat the same task every day, even if I have to expend a ridiculous amount of time figuring out how to implement it. P.S.: I'm sorry if the question bothered you!

Are you asking if you can use python to make dope sheet channels drag+drop with the G key to change their position in the list?

You can move the position of channels within each Action group up and down using the Page Up/Down keys, not sure if you already knew that.

I know about the keys, I want indeed to drag+drop with G key.

Yes, the default keys are ⇞ Page up and ⇟ Page down, the setting can be found in keyboard input under Animation Channels.

The python path is bpy.context.window_manager.keyconfigs.active.keymaps['Animation Channels'].keymap_items['anim.channels_move'] with the property type being the key used, properties.direction is the direction the selected item is moved. You will want to loop through the keymap_items as you will find four keymap_items['anim.channels_move'] entries, up one line, down one line, to the top and to the bottom.
You should look at adding keymaps to an addon to make the changes properly.


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using bpy.ops.*.view_all
I have this at the end of a function, so every time I execute it, I would like to use view_all for those three area types from whatever area is active. But I get an obvious context error.
        bpy.ops.action.view_all()
        bpy.ops.graph.view_all()
        bpy.ops.timeline.view_all()

So, how can I use all three from a single context area?

See http://blender.stackexchange.com/a/35038/1363 and linked questions. You need to override the context (supply a custom context).


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Where can the stats at the main bar be changed?
I would like to hide some of the "mesh info stats". Looked into space_info.py, but it only contains the menu items.
Thanks.

Those are defined in C in /editors/space_info/info_stats.c, they are not editable at all from/with python.


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Vertex color values over one
Is it possible to paint vertex colors that are higher than one?
Vertex colors are exposed through the python API as floating point numbers. If this is how they're stored, they should happily accept any value without clamping to [0-1], even negative values.
Potential uses include per-vertex light emission or material hardness.

It is probably supported internally, but the UI doesn't seem to allow doing this. At least from my quick look at it, but I don't use vertex paint often. Maybe through scripting or the API you can do that.

Attempts to modify the brush color (bpy.data.brushes["Draw"].color) with Python seem to instantly clamp it to [0-1]. This is probably impossible without modifying blender.

In the page you linked to it does say float between 0 and 1 so I guess it's not supported at all

You can add  a custom vertex float layer as outlined https://www.blender.org/api/blender_python_api_2_77_0/bpy.types.Mesh.html?highlight=vertex_layers_float#bpy.types.Mesh.vertex_layers_float  http://blender.stackexchange.com/questions/36710/create-ui-slider-for-each-member-in-a-custom-vertex-layer-floats?s=1|1.3640

How would that make sense, color-wise? 0 is the lowest-possible value while 1 is the highest-possible value. Setting for example all R,G and B values to one will produce white, all set to zero produce black.

@metaphor_set Emissive colors can be any positive value--this is why lamps have an 'Energy' property which can be well above one. Literally all that property does is multiply the lamp's color.

Yes vertex colours are exposed as three floating point values, but in the background they are stored as three integers that are clamped to values between 0 and 255. You can see the actual code doing that here.
This would be a decision made to conserve space, a floating point value uses 4 bytes of RAM while the integer used fits in 1 byte, that saves 9 bytes for each vertex. This leads to being limited to the 16.7 million colours that can be stored in a 24bit RGB image when using vertex painting.
Blender supports image formats that store float values, so you could look at using an image texture to get more variation in your materials.

But that´s a blender limitation right? what about an fbx or obj?

@Badjano yes it is how blender stores the data. If fbx or obj export vertex colours as float values they would be clamped to 0-1 when imported into blender, and as blender only holds the 0-1 value it will always export in that range. This still applies with v2.83


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Unable to prevent self intersecting geometry?
I'm working on a cap for a little device, but whatever I do, I cannot seem to avoid self intersecting geometry from being generated.
I fiddled with the order of modifiers and solidify parameters, to no avail.

blender file

First thing, move the Solidify mod above the Sub-D mod, then change the settings in the Solidify mod to "Edge Data -> Rim -> 1.0"
And check your crease values, there are a few of them, especially around that corner, that are not 1.0, this will screw up the Edge Data.

This will fix most of the problem.
After that, there will be a small issue left that is caused by the edges near that corner being a smaller distance away from the corner than your solidify value (1mm) This means that when Blender tries to offset them, they overlap. Simply move them away a little to fix the corner. Use GG to slide them away.
(These verts)

Remember, Blender is not CAD! There are a whole different set of rules to learn and follow! :)

Swapping solidify and subsurf in the modifier stack and setting edge data->rim to one changes the model in quite a number of ways: the round hole becomes hexagonal, and the rounded edges end in sharp corners at the bottom of the model, which is not what I have in mind...

So it does, but it did fix the issue you wrote the question about. You will need to apply the Solidify mod and deal with the crease edges around your other geo. Sometimes, we just need to apply our mods, they are not always the best way of modeling. Your model as a whole is not a good way to model it. I came from 20 years of professional CAD before I started Blender, and I had to over come the problems, mindset and realizations you are facing now. :) It does get easier mate! Stick with it! :)

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


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How long does the RAM continue to hold Prefetching for whilst motion tracking?
I looked through similar questions but can't really find anything on it.
When you prefetch a video in motion tracking, it stores it on the RAM for quick access, that bit I get.
My question is, how long does the RAM continue to hold it for?
I noticed last night I was working on tracking and adding my mesh into the scene and my RAM was still being used for the prefetch, this was a good 3 or 4 hours.
Secondary bonus question: Is RAM at risk of being damaged if used all the while we are editing in vfx/layout mode?

Hi Please use a title that reflects the content of the question. It should be descriptive but succinct, unique and identifying, summarizing the issue so that users can at a glance understand what your post is about. Use the [edit] link below your post and avoid anything not strictly essential to the post. Remember, your title is the first thing potential visitors will see, and makes your question findable for future users. See "What is the problem with posting an image or link and asking “How do I do this?""

Your PC will hold that data in memory pretty much as long as feasible.  It's possible if your PC was running low on memory Blender would be told to relinquish it.
RAM stores voltage in capacitors which are actively maintained by refreshing the voltage levels many times per second.  This is fundamentally different from an SSD which has the capacity for long term storage and uses a self-destructive method out of necessity.  Electrons are shot through a membrane which can store them even while power is disconnected but this will wear out the membrane eventually.  This is why SSDs have a write limit, and it's why SSDs go through the trouble of "wear-leveling" so that the entire drive wears out around the same time.
RAM suffers no such damage from regular use, and will only fail with age (hours used) or electrical damage like any other solid state PC component.


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World Scene Lights On, No Texture

Blender version 3.5.1.  I made an ocean. I appended a unicorn model into it.
When the world scene light is on the unicorn loses its texture but not colour.The texture's there with the world scene off. It's the same in rendered preview and material preview.
Any ideas why this is happening?

Screenshots or even GIFs would help understand your question. Or even your file if you think it might be hard to get what's happening. Please consider sharing your .blend file with use, you can do so by uploading it to Blend-Exchange and add the provided text into your post.

I did put an image in but I guess I did something wrong. It worked this time.

Can you share the blend file? ( plz remember to pack the images)

It's because of your HDRI, it's very bright on its whole surface, if you have lights 360° around your object you won't have any shadow, while the Material Preview HDRI selected has the light coming from a more defined direction. If I take your current HDR and paint on it to make the light comes from a direction, here is what it gives:

In the new file that you share, the HDRI image is still the same, it is called Sky1.png, which is bright all around, it will prevent any shadow and therefore you won't be able to see any fold on your plastic object, to fix that you need to choose another HDRI image:

If you want a different HDRI for the reflection, so that the sea is affected by an HDRI and the object is affected by another HDRI, you can mix 2 HDRIs and use an Input > Light Path > Is Reflection Ray as Factor:

Thanks. I'm pretty new at this and I can't figure out what you're talking about. How do I fix this? What window should I be in and what do I adjust?

You need to change the HDRI you're using, open the Shader Editor, switch it to World instead of Object, and in the Environment Texture node, load a new image (or paint on the image that is used, as I did)

I did what I think you said and it just darkens everything. I added a 100000w point light and it still won't get clear with good highlights. Even what you did, the image is still dull with no highlights like in the first image. I've used this exact same water with other appended objects and there's no problem. How do I get the unicorn to look like the first image? Thanks for helping.

could you please pack your image (File > External Data > Pack Resources) and share again?

thanks, I've edited my answer, you have not change the HDRI image, you need to upload another one, the current one won't create any shadow as it is 360° bright

When I change the HDRI image it changes the colour etc. of the water. I have that water in too many scenes to change it now. Thanks for your effort. (o:

@Schming In that case maybe read my edit


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Hexagons and Pentagons UV map
How I can create UV map with pentagons in center and hexagons around? But without gap between hexagons and pentagons.

Thanks, now, how can I make all the hexagons have all the pages be equal?

Open a UV workspace and..

On the 3D side, select a pentagonal face, and ShiftG Select Similar > Polygon sides
CtrlNumpad + expand the selection to include surrounding Hexagons
Edge Mode, Header Select Menu > Loops > Select Boundary Loops and ..
Right-click, > Mark Seams

With those faces selected, U unwrap. This will unwrap the pentagons and their surrounding hexes to separate, identical islands. If you want them all overlapped, those can be snapped together, or ShiftS to the  cursor.. but I must say, haven't figured out a way to do them all simultaneously.

This leaves a ribbon of hexes between the islands, so I (CtrlI, by inverse) selected them, and U > Reset those.. it all depends what you want.


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Exporting render image into Photoshop and still get material distortions
Apologies if this question has already been asked.  I'm completely new to Blender and I want to use it to create 3D objects for compositing in Photoshop.
I don't know if this is even possible but here goes.  I've created a basic model that has arms and legs.  I've set it to be transparent so it looks like glass in Blender.  With another object behind my model you can see the distortion this glass material creates.
I open the blender file (.3ds) in Photoshop which treats it as a 3D object.  Doesn't look pretty to begin with.  What I notice straight off is that a photo  I drop in behind my 3D object layer isn't distorted at all.
Does anyone know if this it's possible to have 3D objects distort a 'normal' photo layer in Photoshop?

I think you'd be better off rendering out the normals pass and trying to use that to distort the image in photoshop, or even better, importing the .psd into blender as a 2D plane behind the object. Photoshop has no way of knowing that the object is supposed to distort the image for a whole slew of practical reasons..

I stitch together an HDRI environment map backplate first with no movement and add it in as an environment map. I then add the footage as a shadeless material on an image-as-plane in cycles and place it behind the element, parented to the camera. (Make sure to remove any lense distortion from your footage so that distortion added to the camera doesn't compound the footage distortion. That's a huge tell.) I then add additional reflection plates behind the camera filmed in front of a green screen to simulate ambient backround activity. An alternate method, if you can afford it, is to buy a 360 camera and film cars, actors, etc to the rear of the camera, along with a few frames of empty environment. Use those last few frames to mask out unwanted background elements, maybe even photoshopping them a little. Then create the shadeless plane as before. Either way, you need an environment map or you'll wind up with grey artifacting. If I make a tutorial, I'll post it.


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I'm trying to save an Image that I rendered and can see in the UV/Image Editor
As the title states, I am trying to save an image that I can see normally in the UV/Image Editor. I have done some compositing to it, and everything works inside Blender, but when I press F3 and save it to my desktop, the file that shows up there is blank, transparent. I have 3 render layers, all being affected by my composite nodes. In the layers tab at the bottom of the UV/Image Editor screen, I have Composite selected. It looks great inside of Blender, and I don't see why this isn't working.
Any help would be much appreciated, thanks!
If any extra info or screens are needed to try to help me solve the problem, please request!

Can we see the node setup (compositing) please?

http://i.imgur.com/4JnZbrt.jpg

Anything useful come up yet?

It's hard to tell, because the image resolution is not enough in this case. Is that Render Layers node in the bottom right, just above the nearest spaceship wing? It's showing there's no infromation.

It actually does have a render, but is a really light slipstream type effect, and if I zoom in enough, you can see it slightly http://i.imgur.com/0lUG2L4.png

How about uploading the Blend? As far a I can see, nothing is wrong with the nodes in the image. As you can see the backdrop is rendering properly.

Here's the blend itself, sorry for it being so cluttered. https://www.mediafire.com/?bh9o9p120pw5b4m

The problem is that the image you are saving is entirely transparent except for the lights on the wings. You can't see this in blender because you have selected the RGB display mode, which disables the effect of the alpha channel. If you select the RGBA display mode in the header of the image editor, then the problem becomes clear:

As a quick fix, you could disable Use Alpha on the composite node and then save the image as RGB instead of RGBA.
However, in case you want an alpha channel, then the cause of this lies in your compositing setup (Be sure to select RGBA in the header here too, so you can see what's going on).
Mix/Add nodes don't handle alpha very smartly on their own, so you'll have to handle alpha for them, or use some alpha over nodes.
Also note that add nodes literally just add the values of all the pixels together. As a result your spaceships are coming out a few times brighter than they would be.
Here I've remade your compositing setup, working from the bottom (here the bottom is the background, which goes under all other elements) to the top (lens flairs/bloom effects generally go above all other elements):

Compositing things in this order makes a lot of this alpha handling unnecessary, and generally avoids extra headaches.

Thanks a bunch! I am gonna try doing this now and I'll tell you the results I get.

I tried it out, and when I went to save it as a RGB it gave me the same black background with white light spots where the headlamps should be, could you send me that blend you fixed up please? It would be much appreciated.

@Cold999 I forgot to mention that you'll still need to disable Use Alpha. Otherwise the alpha channel will still affect the output, but will appear as black instead of transparent. I've uploaded the .blend with the reworked composite nodes

Thanks a bunch! Really helped me out and it works like a charm!


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python error in addon "Load Obj Sequence as Shape Keys"
error in Python script?
The imports all load bbut no shape keys--on Mac -here is my error message--I really appreciate any help! G.E.
(line 59):
sknames = [sk.name for sk in target.data.shape_keys]
TypeError: 'NoneType' object is not iterable
script link follows:
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&ved=0ahUKEwi5qY2yrOTNAhVF2D4KHU86DfAQFggvMAM&url=http%3A%2F%2Fwww.blenderinmotion.com%2Fresources%2Fio_obj_as_shapekey.py&usg=AFQjCNFNzLkGqWM1QGdP3-Qgdv8251JtsA&sig2=X319gVkvLZFd7O283UVzuQ&bvm=bv.126130881,d.dmo&cad=rja

I wrote this addon. I saw just saw you posted in the BlenderArtist thread, but for some reason I wasn't subscribed to it so I didn't get any alerts. Are you using the mac version of the script?

Well, the first thing to notice is that
target.data.shape_keys.key_blocks

is a null or empty object at the point of the error and thus the script cannot execute the for loop to fill the sknames object.
Upon looking into this further it seems the issue is with the file path that references the location of the obj files around line 56 (at least it did for me).
Replacing this:
for f in files:
    fp = spath[0] + "\\" + f

with this:
for f in files:
    fp = os.path.join(spath[0], f)

seemed to solve it for me.


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Geometry Nodes sample texture attribute and materials
Using Blender 2.93 Geometry Nodes; I have a sample texture attribute used for scaling multiple point instances. Is there a way to use this "scale" to control the material color(s) on these multiple points? I am unable to find a similar example in tutorials and any help is much appreciated..

https://blender.stackexchange.com/questions/217474/can-you-use-geometry-node-data-to-affect-the-material-of-instanced-objects-e-g
I should have seen this first/closest possibility ..thanks again

You didn't specify if you wanted to work with Eevee or Cycles but right now it seems it only works with Cycles.
You'll need an object with sufficient geometry since the material attribute will be linked to the geometry.
I used a subdivided cube.

After that, create a Geometry Nodes Modifier that initializes a custom attribute and an Attribute Sample Texture.

Tweak the settings of the texture as you wish.

I used a very simple Material setup to plug the custom attribute in. Use an Attribute node set to Geometry and type in your custom attribute name.

Result :

Note : Cycles Only
Adressing the second point of the question : Instancing.
Add a Point Instance node before initializing the attribute.

Result :

Thank you so much--I was perhaps not clear/ i am trying to translate the sample texture attribute that is scaling many points to the "field" of points, so that, for instance; the small-scale points are black and then the range flows or gradates to white where the points are largest, corresponding to the texture below...


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morph and/or blend multiples in geoNodes

I am using Blender 3,5Beta--cannot figure out how to add in a third object for blending like the two in the screenshot (all the same number of vertices).Any help/suggestions much appreciated!

why don't you just add another mix node after your mix node and do another join + object info + sample index?

THANKS, yes, did that! though i am trying to find a way for 1 "slider" or factor to control combos of all 3 meshes..

This could work with simple geometries but complex meshes would produce very jumbled results, no? If simple geometries is enough for you, detach this Set Position from where it currently is, link one of your objects to it, and then link that to Join Geometry. Your factor will control this third, new blend between them. Is that what you're after?

thanks! yes, just fiddling around with the math because first mix is not equivalent to second: first the mix of mesh 1 + 2, then the result gets added to 3rd mesh so its never .33-.33-.33.

This link is to a thread where there is a geometry solution. The file to download is called wave3 and it was created by sozap. It's collection based so the index order will be from the  top of the collecrion to the bottom . Enjoy and please reward him with a like . https://blenderartists.org/t/crashing-wave-rig/1469696/25?u=benny7770


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Curving an existing flat plane
Normally, when one creates a curved surface, I understand that you
would add a curve, finalize the shape and then extrude it. I'd like to
convert an existing surface to a curved one - in this case, the selected area of a
furniture leg piece that I'd like to curve inwards. Ideas? thanks

You may use a Lattice Modifier. The adequate solution to the one you're asking for is here: http://wiki.blender.org/index.php/Doc:2.6/Tutorials/Modifiers/Lattice/Shaping_a_Fork

..Or create two identical curves of desired shape, place them on the same width as the width of the mesh, convert curves to mesh and join them. You can then substitute mesh parts with those curves and create faces with Bridge Edge Loops.

@Gonzou - thanks.. love the lattice modifier

@MrZak - do you have a link to somewhere that demonstrates the technique? thanks

Of course, related to your question - http://blender.stackexchange.com/a/5625/1245. The last thing to do will be to join made shape with your furniture piece.

@RoyM you'll love it even more when you know all its possibilities ;). I'm glad I helped.


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why is my image texture with texture not displaying properly?
i am trying to render a one of the mesh primitives, specifically a cube, with an image texture that has texture paint on it.
i succeeded in rendering my cube with the image texture by checking 'face textures' in the found in the 'options' section of the 'materials' tab, but when i added my texture paint over the image Blender rendered a black cube.
why and how could this happen?

the second image is the desired result

Could you upload a .blend sample file? Maybe with the texture packed

What render engine are you using?

did you save your texture paint image? (in the UV editor)

Blender render engine

To make our life easy blender can remember an image that you choose in the UV/mage editor while uv unwrapping or that you create while texture painting and use it when drawing an object in the 3d viewport. This only happens in the viewport with the right settings but does not carry over into the final render, to use an image texture in the final render you need to setup your material properly.
Recent versions of blender added the ability to add images to paint onto, when using blender internal the texture is normally also created, in cycles when needed a material and/or an image texture node can be created but it doesn't get connected up, you need to do that yourself.
If using blender internal you need to ensure that the texture is added and setup to use the image. For cycles you need to ensure the image texture node is connected to the shader node that you want to use.

You may want to mention also that (in case of Cycles) one needs either to unwrap the mesh first or connect Texture Coordinates nodes if using another texture mapping mode (as it uses UV mode by default).


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Auto-Run disabled? should i be concerned with this error?
i am just getting into rigging in blender, and in the graph editor with the properties panel open i get a error message saying "ERROR: Phyton auto-execution disabled." Another thing that i noticed is a message on the top menu bar saying "Auto-run disabled."
I am in the graph editor because i want to create a driver for a simple but convent 2d ball rig, and i was wondering will be a problem for me later down the road. Also, what the heck should i do about the message. I don't like "ERROR"  sign being thrown at me.
Thank you,
Chris

I just click on a sign that said revert to trusted, and i lost all of my current progress, sigh!.

This is a feature of Blender that tries to prevent you from running (possibly) malicious code when opening a file.
Animation drivers are actually Python statements (if I recall correctly, there is a way to make them multiline), which normally serve to control l parameters in some advanced ways; rigs tend to have a few drivers, since it's just easier to make work properly that way. However, if someone wanted to, they could, for instance, delete all your files, capture and send private information like passwords, keys and tokens, possibly, without you even noticing.
If you open the file from within Blender, there is an option to mark a file as trusted and thus run all scripts inside. Use at your own risk.
Another option is, in the User Preferences (CtrlAltU), to allow scripts, from all files, to run; if you don't save the user preferences, they'll only apply to the open file. You can also exclude some directories, if you want; if you do this, I recommend disabling it for your  "Downloads" folder. Again, use at your own risk :P

yeah but how does that relate to rigging or animation or any thing else beside malicious code. Besides, what purpose could malicious code serve to software like Blender

yeah this answers my question, but does this mean i am running  malicious code right now on my computer?

When i clicked "revert to trusted" why the heck did it destroy my current session in blender? as i was in the process of creating a rig.

I am currently doing the same process all over again, but ever since i click the revert to trusted button i am not getting the "ERROR" message any more, Why is that?

No, it is disabled to prevent that. If your creating your own drivers then, arguably, it should realise that you entered it and want it to run, but that would be a  "bug" which should be reported to the tracker. For bow the solution is to change the preferences as shown in the image, but to also exclude downloads, just in case.

Thar I do not know... It might be new or I just didn't notice it, but I've never seen such button


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how does one add accessories to a sculpted mesh?
i am a novice modeler who i looking for some a modeling advice.
here is an image of a creature that i would like to model, (IMAGE BY ALEX CHEN, found on creature spot dot com)

this is my sculpted progress so far,

i just can't figure out how to add the wings and the armor like material for the chest and arms. As you can see from my mesh i tried to use and array modifier, along with shrink wrap, and subdivision surface modifiers but so far i am not getting the results that i want.
Your (the viewer reading this question) answer can really help us novice modeler in the long run. What is the best approach to adding accessories to sculpted mesh?

I'd say one of often used approaches, at lest as for adding accesories, is by duplicating adjacent part of sculpted mesh and editing it so to make it look like desired. This is applicable to clothes/armores most, though. As for wings, it seems it would be easier to model from scratch

Consider using a Shrinkwrap modifier as well

if i model the wings by themselves they will be a static mesh, which is not what i want because i am going to make an animation out of this character. (it will spread its wings)

Add an armature for the wings as well (assuming it is being added for the character). No matter in what order you will model them, to animate the result you still need to have something to animate

notice the wings, how curved they are. Let assume the wing can represent a flag. how does one achieve that shape. I mean look real closely at the wings on the concept are, those folds, how, just how? sculpting would be too exhaustive. Modeling, maybe! but are there some modifiers that i can use to get the shape of the wing. Maybe a  beizer curve! i just don't know, i have spent the longest time just looking at the model, simply staring at it. Any help, much appreciated!

the wings could represent a plane, which has a subdivision surface modifier. Then i could dynamically sculpt the rest of the detail, such as the tears in the wings, but interns of the curvature. Would bezier curves be the solution. They might, but how!!!!

This process will work for parts that are attached permanently to the creature only. You only see gear/armor swapping in game design, because it is streamlined to be that way. If you want to be able to switch out gear quickly, you're working with the wrong program.
But you can change the materials and look of the parts easily, as I will show you here.
Make sure you are in Cycles and have created a UV for your model. In your node creation create three materials, one for the creature, one for the armor, and one for the wings. Put all the node groups into one material, link them together via a mix shader governed by a black and white texture. Make sure the texture is high resolution to avoid ambiguity in the border between the materials.
You can later come back and tweak the materials without having done any destructive editing.
Note: if you will share the .blend I can give you more specific instructions.


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why can't i change the setting of primative mesh objects in object mode?
When ever i try to change the setting of my mesh primitive in object mode, the panel with the configuration setting is visible, but i can't click on it. It seems that the only way i can get access to the configuration panel for primitive mesh objects is by going into edit mode for any mesh, deleting it, then adding a primitive object, which enable me to have access to the configuration panel for said mesh primitives.
problem:

(unpractical) Solution:

I really need an alternative. I wish to find a method or setting configuration that will allow me to have access to the primitive mesh setting as i add it in objects mode, and NOT have to go into edit mode, delete object, then add primitive(this is disruptive to  my workflow.)
all solution are considered, thank you!


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Apply scale when adding UV texture, why? why not?
should i apply scale when adding a UV texture to a mesh?
If i don't, will the distortion of my uv texture be the only consequence of not doing so?
Thank you!

The one reason, another one that you have already mentioned


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why is my texture split and not one image?
All i did was add new material to a plane mesh, then i applied a image texture. why does it look like this?

maybe you need to UV unwrap it?

if I'm not mistaken U then UV unwrap?

you got it man! why don't you post and answer so i can 1+ it!

Thanks to Glady's comment i have discovered that my mesh what not UV unwrapped. This done by going into edit mode click U on the keyboard, followed by selecting "UV unwrap."


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why is my mesh not moving correctly with weight paint mode?
here is my an image of my mesh.
For some strange reason i red weight paint is not working. how can i fix thi

Yes, sometimes the Automatic weights creates issues and don't work properly. Most of the time I have to go over each automatic weighted vertex group and modify it to work the way I intended. Happy Blendering,

You should check each vertex groups directly if you can. While doing a project my problem was the weights were added. Ex: the left feet's weight were mixed with right so I had to paint the left feet's weight influence to zero for the right

I Managed to find a solution.
Go into 'object mode' select the figure mesh(not the armature), and look at the vertex groups assign to that specific mesh. My problem was that my vertex groups were all out of alignment (The vertices were spread in placed i didnt intend to put).
So i deleted all of my Vertex groups, and stated assigning new one with the correct vertices.


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Network Rendering textures
I have a mix-match of computers and want to network render to them.  The problem is if I make a material with an image texture, that texture is not sent to the slaves.  I don't have the ability to network the image path (I do, but its unreasonably complicated). I just want to have the image file cloned to the slaves so that they can use it in the same way  the bake files are sent over.
I tried this in python, but can't find the mechanism to find where the textures should be stored on each local slave.  This means if the client texture map is at c:/tmp (on a windows machine) and I send it to a Linux slave, I'll have to jump through flaming hoops to make it save the texture map to c:/tmp on Linux (permissions issues).  I'm assuming that it should store them to // on the Linux slave (or any slave) but where is it in perspective to python UserPreferencesFilePaths?
I'm also finding that my motion blur isn't working on network, so I want to tweak the .py file so that it moves over extra bake files (assuming it reads the previous bake file to generate a vector, if the batch is 5 files, it should send over 6 files so that it can properly generate the blur).
I guess what I'm asking is if there is a non-script, non-network-path way to resolve me rendering problems or if there is a scripting way to do it.
Thanks
James

Yes, there is.
You need to pack the external data.
It's simple!

Click file, in the info panel.
Select External data.
Press Pack All Into .blend.

Or you can simply check Automatically Pack Into .blend so that it will automatically save the external data (like images) into the blend file.
Note: this will make your blend file larger. You may not want to do this for every revision, otherwise your file sizes will quickly stack up, because each file will store the images.

About motion blur in network rendering, I don't think that feature is supported yet. However you can try the experimental feature set, and I think it may be enabled, just not "stable". I'm not sure whether they have it there or not though.

Final note.
To pack a single image, in the image editor select "image", "pack as PNG".


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How can I create a crashing wave effect?
I have a scene with a stormy ocean, and I am trying to create this effect:

I've been looking for tutorials on "crashing wave" or "ocean spray" without much luck. As such, I've run up against a wall.
Can I get tips on how to accomplish this? Should I use a particle system or fluid sim? Material recommendations (cycles)?
Or perhaps I have missed a good tutorial somewhere, to which someone could direct me.
Thank you for any help you can offer.

I guess fluidsim could do that but not quite easily... it is a hell complex fluid motion you see there... you will need a lot of experience and computing power.. and if you need the ocean, I would suggest separate tools, ocean simulator for the general look, and some fluidsim for the spray. Professional (movies) CG is a lot about cheating, is to do what look best, cheaply as possible.

@m.ardito I've got the ocean set up nicely, and the scene is such that I don't need to see the "origin" of the wave, just the big spray. Is fluid sim the best way to do the big spray? Or is there a better option?

@Peridigital Yes, fluid sim is the only way to get the splashes. If you want to add some fine mist spray as well you can use a particle system.

see also this http://blender.stackexchange.com/questions/1634/ocean-modifier-foam-spray

This might be possible with the new point density textures.

I'm kinda of inexperienced, but you could try using metaballs with particle systems. If you set up the materials right (and have a powerful enough system) it may work.

A simple solution to get you started is to use a particle system and the smoke simulator.  Initial testing on my end used a camera set high on the Z axis facing down to the emitter object within the smoke domain.  Track the smoke within the domain to the particle system.  Emit for about 20 frames with a lifetime of 20 on the particles. the object I used was an icosphere cut in half with the rounded side facing the positive Z axis also the object emitted from the faces.  Under Emitter velocity, I set the Normal to 15, initial velocity on the particles per axis at X & Y = 0, Z = 5.  As the particles move out from the emitter, the smoke will follow their path.  As for the crashing of the waves exploding onto the dock, use an object within the domain as both a particle obstacle and a smoke collision object under the physics tab.  Within whatever render setting you should be able to control the material and or color of the smoke to simulate water and foam.  Run the animation and tweak to your needs. Hope this helps.

I would use a fluid physics simulation. Set a domain (just a cube) around the scene in which you want the water to flow. Keep in mind that the bigger the domain, the longer the bake times. You can also adjust the size the domain cube would be in real life so I would do that if you want realism. You can either create an inflow object for the wave (and give it initial velocity) or you can use an animated obstacle underneath the water to create a wave. I suppose you could fiddle with the smoke effects in blender to do it. Keep in mind that realism in any 3D program involving water is going to take a ludicrous amount of computing power to bake within a reasonable amount of time. Blender hasn't really got the "whiteness" of crashing water to work correctly, though. Large scale water isn't that great at this point.
Other programs are also a solution. I've seen people create good fluid crashing effects on programs like RealFlow.


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How to control many tiny lights
I've been modeling in blender for several years now, but only recently started doing some animation.
This thing I'm currently working on requires controlling hundreds of little lights turning off and on. If I was just doing a couple, I'd merely animate the emission materials as needed. But for something of this scale, having tons of individually animated materials seems rather impractical. They also need to be animated in patterns, which depending on the solution could make it harder or easier.
This is a rough example of what I'm going for in terms of shape and number

Thus far, my attempts at google have resulted in nothing, and so I turn to the ever helpful boards. If any more experienced animators had any tips or recommendations, that would be lovely.
I'm working in Cycles if that matters.
Thanks!

Having hundreds of light objects is probably gonna kill your performance and render times and result in very noisy images, not to mention being very impractical to manage.
Not being at all an animator myself I would probably go with some sort of image sequence/animated video texture driving an emit shader strength, with whatever patterns you want your light grid to display.
Probably model a single lamp as a mesh and use an array modifier to populate the grid. Manually adjust UVs in the texture nodes to match the number of lines and columns of the array.
The texture can be of relatively 'low resolution' as in one pixel per lamp (it is either in or off), and your can animate it easily elsewhere with black and white textures or objects drawing whatever patterns you need.

Thank you for your answer! The trouble though is that the lights are the main focal point of the animation, so they have to have 3d definition. Also, the noise is fairly easy to do deal with.

Maybe my answer wasn't clear enough, I suggested actually modeling the lamp as a mesh object with all the needed detail for a foreground object. The 'low resolution' texture is only meant to simplify the animation process without having to individually control each lamp. You will never actually see the "big pixels" as they would cover each whole lamp, they are meant only for controlling if each lamp is 'on' or 'off', you will never actually see them individually.

Well don't I look silly. I see what you are saying now. That's certainly a stride or two in the right direction.


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How to disable material preview icons?
Very often when i have a lot of materials in the scene and switching to materials tab, blender starts to rendering that materials to make a preview icons. This procedure taking a lot of memory and is cause of crashes when you have many materials(specially complex materials) and low RAM.

are you talking of the "preview" panel in the "material" data tab in "properties" editor? if so, did you try to collapse the "preview" panel, so that the image is not visible? (not sure that helps...)

no, i am talking about that small icons that you see on the left side of material name.

I've had the same problem for awhile, especially when working with complex material setups. I think I have found a work-around.
Try switching the Properties panel (on the left) to another tab. ie. Anything except the Material Properties tab. This should stop the preview of the material from being re-rendered in the background.


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Blender Cycles quickly renders animation just black
After making some improvements to a project that I have not previously had any problems with I proceeded to set up my render settings.
I then realised that I had been working in blender render instead of cycles. I don't know what the difference is between them really apart from I was able to do a lot more in blender render than in cycles.
So I made the changes I needed to make now that I was in cycles render and tried to render the animation. And this happened!!!!

Press "shift + Z" to go into render preview mode, still black? Add a new lamp and a new object to the scene. Render again, still black?

Is it possible you could upload your .blend? Also, note that it's generally not recommended to render your animation directly to a video file, see http://blender.stackexchange.com/a/4881/599

After much searching and reading the advise here I eventually found that I had two boxes selected in Post processing which should not have been.

Cycles Render uses a different node set-up for the materials then Blender Render. (You can check that for both Cycles Render and Blender Render by opening the Node Editor, with 'Use Nodes' enabled) After switching to Cycles Render,  it doesn't contain the materials you have set up in Blender Render. You must make the new materials in Cycles Render yourself.


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Is there a way to visualize border edges of meshes?
When editing a mesh, it sometimes happens that two faces are seemingly connected by an edge, but these are actually two edges on top of each other. Often enough I only notice this way later. For example when moving one of the faces, revealing the hole in the mesh.
In Maya there was an option to highlight border edges. Does Blender has something similar?
Or this there another workflow in Blender to detect gaps?

would an wire frame help? here is a link to a tutorial https://www.youtube.com/watch?v=kAaToapgBxQ

A screenshot (or a gif of mesh close-up revealed) probably could help since "these are actually two edges on top of each other" seems like simple removing doubles would be enough. There is selecting borders tool, select all and run Boundary Loop from Edges menu.

Did you mean check non-manifold?
Type select non manifold in search-bar (F3 or Space) in verts select mode(edit mode) when selecting nothing.
It will help you to select something not manifold including separated holes

This is a neat feature, how come it’s not listed in any menu? Or am I just blind?

This is a very handy function, and quite close to what I'm looking for. I tried it and as expected it will select a lot more parts than just border edges.

@mic.. It's under (Header) > Select > Select All by Trait > Non-Manifold. It's also worth checking the options in the operator, to narrow the selection.

Thanks for the tip. I’m gonna be using this a lot :)

Please don't just add thank you as a comment, upvote the answer instead. If you feel it completely solved your problem consider marking it accepted

Manifold is a special trait that we always want. A lot of algorithm in 3D need a manifold mesh to operate. It is a common thing in computer graphic, and there should be a similar one in others program.

A quick option is sometimes Select Similar in Edge Mode. Select an edge known to be on a boundary to nothing, and ShiftG > 'Amount of Faces Around an Edge' to select the others.

So I need to have a border in order to use this function. Other than that this is what I'm looking for. Is there something like 'select border edges'?

@mic it's one of the check-box options in Select Non Manifold  as described in the other answer. The settings will persist on repeat usage, in any one session, until you change them.


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Parachute animation
I'm trying to use cloth physics with this parachute animation but I tried all the variables and I cannot simulate something that could look real.

Blender file
Viewport animation

looks nice!!! what do you expect?

Instead of having users go through links and external sites please use the builtin tools to embed images in your post. See How to upload an image to a post?

I ask the same question as @Chris.  Yours looks a lot better than mine. (here) - https://blender.stackexchange.com/questions/183341/how-to-attach-a-rigid-body-to-a-cloth-simulator/183477#183477


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How to turn off the (auto)terminal output while rendering blender file in headless mode?
I'm using blender rendering with my own python script in headless mode. Some how when blender rendering in headless mode, it automatically print the rendering process it went through. The terminal print out a lot of information about blender rendering.like:
"Fra:0 Mem:27.60M (Peak 52.27M) | Time:00:00.19 | Mem:8.04M, Peak:8.04M | Scene, ViewLayer | Updating Scene
Fra:0 Mem:27.60M (Peak 52.27M) | Time:00:00.19 | Mem:8.04M, Peak:8.04M | Scene, ViewLayer | Updating Shaders
Fra:0 Mem:27.68M (Peak 52.27M) | Time:00:00.19 | Mem:8.05M, Peak:8.05M | Scene, ViewLayer | Updating Procedurals
Fra:0 Mem:27.68M (Peak 52.27M) | Time:00:00.19 | Mem:8.05M, Peak:8.05M | Scene, ViewLayer | Updating Background
Fra:0 Mem:27.68M (Peak 52.27M) | Time:00:00.19 | Mem:8.05M, Peak:8.05M | Scene, ViewLayer | Updating Camera
Fra:0 Mem:27.68M (Peak 52.27M) | Time:00:00.19 | Mem:8.05M, Peak:8.05M | Scene, ViewLayer | Updating Meshes Flags
Fra:0 Mem:27.68M (Peak 52.27M) | Time:00:00.19 | Mem:8.05M, Peak:8.05M | Scene, ViewLayer | Updating Objects
Fra:0 Mem:27.68M (Peak 52.27M) | Time:00:00.19 | Mem:8.05M, Peak:8.05M | Scene, ViewLayer | Updating Objects | Copying Transformations to device"

There are too many of them that i can not see my own python script print output,it is so difficult to understand where i was in the whole process. It became a big problem when i need to test and debug the program. How do i turn it off? without turning off my own script print output?
I'm using command
./blender -b  D:\gitproject\smi_data_generation\release\tsr_1.0_win\tsrscene_V6.blend --python D:\gitproject\smi_data_generation\release\tsr_1.0_win\pipeline.py
for headless rendering.


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Trying to model character's t-shirt. Duplicating faces does not work as expected
I am trying to create shirt for my first character.
When I press ⇧ Shift +  D to duplicate faces, it gives me that weird thing below the character that you can see on the second screenshot.
Any reason why?
I am on Blender 3.0 + Windows 10.
I use Mirror Modifier + Subdivision Surface (occasionally as it is performance heavy)

That is most probably because you have an active mirror modifier with clipping enabled and the merge threshold is rather large
I'd advise you to reduce the merge threshold in the mirror modifier to a lower value, like, say 0.01m


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how can i remove the current UV image texture off a mesh?
I am currently using the blender render engine and i have a mesh with an UV image texture, but i don't want it anymore. How can i remove it?

You can do that by hand (just don't press Shift if you don't like to completely remove image from file) or using Python.

Do you want to remove the image from the .blend? Or just from the object? If you just want to remove it from the object, how is it associated with the object? (does it appear in the render?)

go into the texture panel with the object selected, and find the texture with the image you want to remove, then click the X on the top right and the texture/image will be removed from the object


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What is the is the difference between object and data link for while creating materials?
What is the difference between the two options provided when creating a material while using the blender render engine?
heres an image.

related answer http://blender.stackexchange.com/q/32665/2217

Borrowed from iKIsR from different question:

Linking a material to Data (to mesh specific data) is ideal when you want a mesh to always have the same material, while linking a material to an object is when you want to have different materials on objects that share the same mesh.
Short explanation: If connected to the object, you can have several instances of the same Data using different materials. If linked to mesh data, you can't.

You should add the link back to iklsr's answer.


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Is adding a lot of loop cuts bad?
Im creating a mesh, or more specifically a very detailed robot. I look for modeling suggestions to the following concerns.(see below)

is it suggested that i use a lot of edge loop (for definitions sake), while also using a subsurfice modifier.
for some reason i feel like all of my edge loop are going to bite me right back later on. (has this happened to you? if so what do you suggest)

p.s I'm box modeling.
Thank you!

It depends a lot on the situation and what you're modeling.
Generally, I try to get the main shape of my model in before adding in the subserf, and then once it's to the point where I need extra geometry, or smoothing, I'll add in the subserf, and start to add in holding edges.
If an edge loop isn't adding anything, get rid of it. Every vertex should have a purpose.
If you're getting to the point where you think that it's becoming a bit too messy, it could be a good idea to retopologize your mesh to streamline the topology.

Yeah, i think I'm  loop are going to turn on me because there are tons of vertices that "Don't serve a purpose."

Yeah, you'll probably want to do some retopology then. Good luck! :)


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can i lock my zoom in position while sculpting?
I have a tendency to zoom in a lot in blender, but while trying to sculpt this "zoom in" habit can get annoying. Is there a way that i can lock the the zoom in position while sculpting in blender?
Thank you!

You can temporarily disable Zoom event in the User Preferences.
Zoom in/out to position you'd like so to work comfortable. Then open the window with Ctrl Alt U, type Zoom in the search input textbox and look for the event in the 3D View, to disable/enable simply check/uncheck that option (exact option depends on the type of zooming that you use so frequently):

You may want to leave the User Preferences window opened while you work so not to search for options you've changed.
Note that still you will be able to zoom with other ways in the 3D View window, and using any way in other windows.


text:
Rendered preview stopped working
I'm not sure what happend... I had CUDA enabled so long as I opened Blender as root, but not only has that disappeared, my "rendered" preview no longer works. For example if I open a brand new project with just the cube, switch to cycles, and select rendered, I get this:

If I actually render the project by clicking the render button, it works... I just can't preview it anymore.

Blender 2.75
OS: Linux Mint 17 Cinnamon 64-bit
Cinnamon Version: 2.2.16
Linux Kernel: 3.13.0-24-generic
Processor: Intel Core i7-2600K CPU @ 3.40 GHz x 4
Memory: 15.7 GiB
Graphics: NVIDIA Corporation Device 13bb

I haven't changed anything outside of some automatic system updates. Any ideas?

Just so you know, the name of your graphics card isn't "NVIDIA Corporation Device". You should probably actually look up the name of your GPU

Well that's what it says in the system info. It's the PNY Quadro K620 if that helps.


text:
Mesh different objects uniformly
I want the maximum polygon size to be the same for all my objects. I am using the remesh modifier to generate many faces, but I would like to specify how dense the mesh is globally, rather than relative to the object's size.
Example:

Here are the settings I'm using for all objects:
ob.modifiers["Remesh"].octree_depth = 5
ob.modifiers["Remesh"].scale = 0.99
ob.modifiers[0].mode = 'SHARP'

I was thinking I could play with the scale? How would I adjust scale appropriately to get polygons of the same size? Not sure how to go about this..

I do not currently have a Blender here to test my theory, however I am pretty sure, that applying scale would solve your problem. Check the three scale values in the properties panel. If they are not the same on the two objects, that could be the problem. hit ctrl + A and select apply scale so the scale is set to uniform one.

If you join all the objects, go into edit mode and remove doubles --specifying the maximum polygon size for when to remove a "double" -- you may get you're desired result. You could then separate all objects by "loose material" to return objects back to original state.


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How to voxelize and extract blender data?
I am trying to use Blender as a CAD tool for electromagnetic simulations. I have modeled the geometry, but now would like to export it to a format that I can read for the simulation (external Python program). To do this, I compiled bpy as a python module, and am creating and loading .blend files from Python directly. The constructed objects/files are viewable when loaded in Blender.
My goal is to be able to query the space (any x,y,z point) and return which material the point belongs to. This sort of information would be used in a 3D FDTD simulation. Is there an easy way to do this? -- I could not find any, so I decided the next best thing would be to grid/mesh my simulation domain into voxels.
Looking around, the closest thing I could find is the Add-Cells plugin, but it is written for Blender 2.48, and I don't think it works with the current version 2.74.
(http://wiki.blender.org/index.php/Extensions:2.4/Py/Scripts/Add/Cells_v1.2)
I was hoping to voxelize all the objects in the scene, and then export to a 3D NumPy matrix. I imagine this will consume a lot of memory, but I am happy as long as it works. (Ideal case would be to just query points in space and have it return the material).
Thanks in advance!

Have you tried using the Blender Python API to create an internal Python Script (as opposed to an external Python program)? It seems like a lot of unnecessary extra work. https://cgcookie.com/blender/2011/08/26/introduction-to-scripting-with-python-in-blender/

Did you try to update the Cells_v1.2 Python script? I'm sure you can update some of the old functions with some of the new functions (I assume most of the logic still holds).

i'm trying.. but there are so many differences! so, its still a work in progress. also don't know if its working since many of the types/properties are different.
for example, do you know what property of object.data i should return for "mesh.faces" ?
this is the object type: http://www.blender.org/api/248PythonDoc/Object.Object-class.html#getData
i found the vertices (ob.data.vertices instead of ob.data.verts), but not sure about faces?

Mesh.faces is now Mesh.polygons as seen here: http://www.blender.org/api/blender_python_api_2_74_0/info_gotcha.html#info-gotcha-mesh-faces . More info on Mesh.polygons can be found here: http://www.blender.org/api/blender_python_api_2_74_0/bpy.types.Mesh.html#bpy.types.Mesh.polygons . If you're using the latest Blender version, then you should use these Blender Python Documentations: http://www.blender.org/api/blender_python_api_2_74_0/contents.html . Does this help? (Also, I'm willing to help translate the Python file, if you need any help.)

I was working through it, but it seems overly complicated. I think the same functionality can be created via the remesh operator (cubic). I'm trying to implement this, maybe you could help? http://blender.stackexchange.com/questions/33138/how-to-access-center-of-polygons-after-remesh

I just read your question statements and comments.
Generally your approach is fine in my opinion. I try to supply some details here. Hope them help.
External or internal?
Luis B suggested in his comment:

Have you tried using the Blender Python API to create an internal Python Script(as opposed to an external Python program)?

I think an external script may be more suitable in this case.
The conversion from a geometric representation(which is created by Blender) to computation representation(i.e. something like Eulerian grid) should be coupled with your simulation, not Blender.
For example, the computation grid may be staggered, or you want to use adaptive grid(such as an octree rather than a uniform grid), etc.
All of these requirements depend on your simulation's setting.
How to do the voxelization?
I assume you are using mesh geometry to represent elements and boundaries in your simulation.
Then in this case you need to traverse all meshes and decide which mesh the point belong to.
For convex mesh you can shoot one ray and check the intersections with the mesh. Two intersections means a point is outside this mesh. Also you need to handle the special case which a point is just right on the surface of mesh.
This process will be slow. But I think it is ok since you only run it once for each simulation configuration.
If you do want to optimize its performance you can consider using some data structures like BVH(bounding volume hierarchy), kd tree or spatial hash.
Things get much simpler if you can use procedural objects. For example you model a sphere using distance field function like $x^2+y^2+z^2-1=0$ rather than polygons. Then it is easier to decide whether a point is in a geometry(evaluate the distance field function and a negative value indicates the point is inside).


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How to access center of polygons after remesh
I'm working on a method to compare distances in a space in Python. I am only using the GUI to check my results; all operations are done via a Python script.
I am using the remesh operator to increase the number of faces of a given primative, so that I can find a pseudo-accurate distance to the object by finding the closest face.
I was able to get the remesh to work. However, I'm having trouble accessing the new polygons. It seems there are only the original centers available.. although I am able to see when loading Blender that the number of faces have increased. So, the number of face-centers should also?!
Before:

After:

In the console:
>>> ob.data.polygons[:]
[bpy.data.meshes['slab'].polygons[0], bpy.data.meshes['slab'].polygons[1], bpy.data.meshes['slab'].polygons[2], bpy.data.meshes['slab'].polygons[3], bpy.data.meshes['slab'].polygons[4], bpy.data.meshes['slab'].polygons[5], bpy.data.meshes['slab'].polygons[6], bpy.data.meshes['slab'].polygons[7], bpy.data.meshes['slab'].polygons[8], bpy.data.meshes['slab'].polygons[9], bpy.data.meshes['slab'].polygons[10], bpy.data.meshes['slab'].polygons[11], bpy.data.meshes['slab'].polygons[12], bpy.data.meshes['slab'].polygons[13], bpy.data.meshes['slab'].polygons[14], bpy.data.meshes['slab'].polygons[15], bpy.data.meshes['slab'].polygons[16], bpy.data.meshes['slab'].polygons[17], bpy.data.meshes['slab'].polygons[18], bpy.data.meshes['slab'].polygons[19], bpy.data.meshes['slab'].polygons[20], bpy.data.meshes['slab'].polygons[21], bpy.data.meshes['slab'].polygons[22], bpy.data.meshes['slab'].polygons[23], bpy.data.meshes['slab'].polygons[24], bpy.data.meshes['slab'].polygons[25], bpy.data.meshes['slab'].polygons[26], bpy.data.meshes['slab'].polygons[27], bpy.data.meshes['slab'].polygons[28], bpy.data.meshes['slab'].polygons[29], bpy.data.meshes['slab'].polygons[30], bpy.data.meshes['slab'].polygons[31], bpy.data.meshes['slab'].polygons[32], bpy.data.meshes['slab'].polygons[33]]

Clearly more than 33 polygons! Any ideas?
I've tried:

after remeshing
bpy.ops.object.origin_set(type='ORIGIN_GEOMETRY')
bpy.ops.object.editmode_toggle()
after remeshing ob.data.update(calc_edges=True)
when reading bpy.ops.object.mode_set(mode='OBJECT')

For one thing, you're not going to see the faces of the centers in object mode.. You'll need to be in edit mode to view these.

After applying the modifier, you can convert the object into a mesh:
How can curves be converted to meshes?
This will "flatten" the results you expected from the modifier into the mesh and you will see the transformed vertices and be able to select them in edit mode.

Good deal, I realized that I was applying the mesh in the wrong mode. Fixed with:
bpy.ops.object.mode_set(mode='OBJECT'); bpy.ops.object.modifier_apply(apply_as='DATA', modifier="Remesh");


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How can I scale a set of vertices to the size of another set of vertices?
I have a mesh that is shaped like a frame. Basically I cut a hole in a plane by selecting knife project in edit mode.

Now I would like to animate this mesh with the help of shape keys. I want to take the four inner vertices and scale them up so they are in the exact same position as the outer ones (effectively making the frame disappear). Scaling itself is not the problem but I cannot figure out a way to scale it just the right amount. Unfortunately I can only manipulate the position values individually (in the pane to the right) but not the scaling. Does anyone know of a way to do this?
Any help would be greatly appreciated!

@MrZak You beat me to it!

@MrZak That should be an answer not a comment.

@MrZak You can make a shape key

@NoviceInDisguise nice catch! I even didn't think about that

Wow, excellent! That worked flawlessly, thanks!

In the begining, create shape keys you'll use for animation (as NoviceInDisguise suggested, thanks):

Then, in Edit mode you select the vertices you'd like to scale. To not mess up pivot center, select only vertices located on one plane. Turn on snap during transform with Shift + Tab, set the Pivot Point to the median with Ctrl+<:

In this case you don't need to remove doubles, and now it's possible to use shape key, created before. In Object mode drag the slider and test how it works:


text:
Does Blender allow to perform operations on multiple objects at once?
Let's say five objects are parented to the same 6th object. Is it possible to remove the parenting links at once. Selecting all children and removing the parent doesn't work:

Only the "active" object is un-parented.
That's curious since the inverse operation, parenting multiple objects to the same parent, is possible at once.

with alt P > Clear Parent

You are not doing inverse operation to parenting. Modifying a parameter of active object (properties display active object) only influences that object.
Operators can operate on selections, like Ctrl+P and Alt+P do.
If there is no operator to do it on multiple objects then RMB on the field > Copy to Selected. Works on most parameters in general.

So 'Copy to Selected', or, but only when available, a specific menu entry working on multiple objects, like 'Parent Set' / 'Parent Clear'. What is implicit in your answer (thanks) is that 'Parent' field setting and menu entry '3D>Object>Parent>Object' are NOT equivalent, contrary to usually a bit quickly explained. They are working on different sets of objects. Those subtleties increase the difficulty to learn Blender, I believe.


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What is a paint slot (compared to an image with a UV mapping)?
Learning texture painting mask with the help of Blender official User Manual... nah... just kidding ;-)
In the Texture Paint mode, "painting slots" are displayed in the tool shelf of the 3D editor (1). Entries seems to be images (3) associated with material textures (2), provided they have a UV mapping associated with.
If this is the case, is there a reason for having them listed at two locations under two different names?

I see a possibility to associate a different painting mask to each "painting slot" (masking is actually the topic I'm trying to understand). But as it would be possible to have this mask defined in the Property editor without adding another concept, I'm a bit perplexed...
Using 2.79.

I've read this page, but it doesn't help for this question.

Paint slots are not datablocks listed in the Properties editor > Materials tab. There can be one material listed in the Properties editor. But there can be multiple paint slots listed in the Toolshelf for that material. In other words, paint slots correspond to image textures you have in one material. But you can have multiple textures for one material, as well as multiple materials with multiple textures for each of them

@MrZak. Thanks. I think this is what Craig wrote in the first paragraph of his answer.

A texture painting slot is how you can control which is the active target for paint without having the node editor open to hunt and find that corresponding image node to click it to make it active, nor having to find the corresponding texture in the material texture properties.
The origin of the texture slot panel was actually a GSOC adaptation of the Texture Paint Layer add-on that offered similar functionality in the N Panel, and it also gave the ability to not need the properties editor to be open to determine which image texture was to be the target.
Masking is much more than the Stencil type that is normally used between image textures, and the actual mask tool is very powerful and I have explored it a few times on my youtube channel. You can utilize a different UV projection for masking, or you can use the same as the existing UV mapping for the target image.

Ok, that makes sense. After a few exercises, the slots benefit is obvious. One more question... what do you mean here when you say: "There is more than just that..."? While I've not doubt I'll see more in the video linked to your answer, I don't get the difference between the painted mask at the beginning and the mask loaded from the file (women face). Nice channel by the way, thanks for sharing your skills.

"More than just that" referred to using more complicated images as masks, and also that you can use different UV mappings that orient based on a different image texture slot already available, or maybe a view projection or even a uv reset that then places all the faces in one place so that the mask exists per face. Any image loaded into the UV Image Editor or into the texture slots can then be called up as a mask to be used to paint through.


text:
How does changing 'Dimensions' fields at once exactly work?
For related X, Y, Z fields of Location, Rotation  and Scale in the Transform panel of the 3D view 'N-Region', there is a possibility to change the 3 fields at once. It can be done with the mouse or with numerical input.

But it seems 'Dimensions' fields behave strangely (entering individual values works as expected). Sometimes the value is lost after being entered, sometimes only two fields are changed. An example:

When using the mouse, Y is left unchanged (expected: All values adjusted in proportion).
The final dimensions X and Z are different (expected: Final values are starting values times the same factor).
When entering the value 5, the result is 2 (expected: 5, whatever the scale value).

Is this a bug?
If not, what is the reason to prevent this single input?
Using 2.79b.

Good catch, Probably classified as a bug or over site.   C.object.dimensions = (5, 5, 5) in py console works as expected.

It is not a bug, it is a known limitation, dimensions values are actually a hack and don't work with click-drag

It is not a bug, it is a well known limitation of the current system, as you can see in the bug repot.

Object dimensions are broken and an abuse of RNA, IMHO - the same
  problem happens from Python and we had it reported too.
Basically they rely on one axis being set, then updating - before the
  other values are set.

Thanks. A more recent activity here. Too bad the UI allows something that is known to be broken. RNA presentation can be found from here.


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What is the difference between Set Render Border and Set Render Border Camera Only?
In version 2.79b, and when in the 3D Editor area, two shortcuts call view3d.render_border with a parameter camera_only:

ctrlB sets the parameter to False
shiftB sets the parameter to True

The later shortcut is actually assigned to two functions in the user preferences:

so, for the purpose of this question, I've disabled temporarily "Zoom to Border", to allow "Set Render Border" to be called. The configuration is:

My understanding:

Those two Set Render Border shortcuts allow to define a rectangle in the one of the 3D view (not necessarily Camera view).
The result is visible in the rendered image (F12) and/or in the 3D view but only when in shading mode "rendered"

In practical, when using any of them:

In the 3D view, only the rectangle is shaded in "rendered" mode, the rest is shaded in "solid" mode.
In the rendered output, only the rectangle is rendered, the rest is empty.

My question: What is the difference between the two shortcuts? Or is shiftB (camera_only = True) an unintentional leftover?

SHIFT + B lets you select a portion that you wish to see in the final render image or in the camera view.

CTRL + B lets you select  a portion you wish to see in the render view mode. to then delete the border is CTLR + ALT + B

while CTLR + B works also in camera mode, SHIFT + B if is not in the camera view mode acts as a zoom tool.

CTLR + B does not affect the camera view or the final render. unless you are already in camera view

Please read after "In practical, when using any of them" where I explain I see the same result, so the question. No need to explain "zoom to border", I've disabled it to be able to compare both versions of "set render border".

I dont know how you compare them to see the same results, but again CTRL + B lets you have a preview box of your render view mode. thats not the same as the final render.  if you make a preview box with CTLR + B in the render view mode that wont affect your camera view nor your final render.

try it yourself. clear the border in your camera view so there won't be any confusion. then use the CTRL + B in your 3D view (not camera view as in camera view they do the same job) to preview an area, then go in camera view or just do a render. you will see that you will have the full render resolution

Ah you're right! The difference is not visible when marking the border with (ctrl)(B) in the camera view, but as soon as the rectangle is created in another view, the rendered image is complete, but not with (shift)(B)

After some experimentation... Sh-B (camera only = true) is valid in camera view (no effect in other 3D views -- calls Zoom To Border if it shares the same shortcut). Its effect is to partially render the camera view, and to limit F12 render to the same area. Ctrl-B is similar to Sh-B: It partially renders the view in which it is defined, and limits F12 render (so it's identical if defined in camera view). It can be used independently in camera view and other views (two distinct areas can then be defined and cleared individually: one for the camera view, the other for all others views).


text:
How to quickly select the 3D viewpoint among Front, Top, Left, etc., and customized ones?
I thought the 3D-view viewpoint could be set equally according to predetermined directions (six standard views: Left, Top, Right...) and also camera directions. But it doesn't seem to be the case:

It turns out the correct procedure to select a camera viewpoint is two-fold, as explained in the selected answer to this question:

Switch the 3D-view mode to "camera" (in the menu above, or using the shortcut Numpad 0)
If the current "active camera" is not the one you want, select the correct one using the scene "camera" setting. You may also select the camera object in the 3D view and make it the active camera (using the submenu shown above or the shorcut Ctrl-Numpad 0), but this can be a bit difficult in general, as the camera can be hidden by actual objects.

To make it short, I'm surprised by this quite laborious procedure, which has also the side effect of changing the camera used for rendering ("active camera"), something that seems unrelated to working in the 3D view:
Looking at addons shipping with Blender, I see none able to simplify this.
Question: Is there a method to simplify the 3D-view viewpoint selection, where any viewpoint, standard (e.g. Front) or user-predefined (e.g. a camera, but not limited to cameras) can be selected in a couple of clicks?
If not, what would be the script required to add this feature to Blender's view menu?

There's a getaround in GiantCowFilm's answer here

@RobinBetts: Thanks, an ingenious way to deal with a stubborn UI, I must say :-)


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How to properly manage the center of rotation of the view when painting in 3D editor?
When in Texture Paint mode, and painting in the 3D editor, the center of rotation of the view is not anymore a fixed point (viewport center, selection center, 3D cursor) like it is in Object and Edit modes.
My understanding from experimentation is the CoR is close to the current cursor location.
For simple cases, like say... painting a donut :-) in the 3D view, it is useful to have a fixed CoR at the center of the object. But this seems not possible.

After rotation, the new faces to be painted are now located closer to the point of view, so a zoom-out and a translation are necessary to relocate the object at a better position.
This will repeat until done, or the death of the artist, whatever comes first ;-)
A workaround seems to relocate the CoR using Ctrl-LMB.
Is that right? What else needs to be known on this topic? What is the usual practice? (though the latter question may be a bit subjective.)

I have my settings to use rotate around selected, turntable, and I often use a shortcut I made for myself to utilize the align view to top of selected face. That shortcut enters and exits edit mode to use the option that is available there for face selection, and I often use it with face selection masking.


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How to access the operator instance members?
I'm testing Blender's scripting, with this simple operator from the documentation:
def main(context):
    print("OPNAME"+":", len(context.scene.objects), "object(s) in the scene")
    print(*[obj.name for obj in context.scene.objects])

class SimpleOperator(bpy.types.Operator):
    def execute(self, context):
        main(context)
        return {'FINISHED'}

In the first print instruction, I'd like to replace "OPNAME" by the name of the operator (supposedly bpy.types.Operator.bl_label). However main is not an operator's class method, so I can't access the variable directly.
When execute is called by Blender, what's the executing context? how can I access the operator instance (excluding passing the value to main)?

How about SimpleOperator.bl_label or pass the operator (self) to main, or make main an operator method.  Note: the method main is only used by way of example is not mandatory. Could also look at context.active_operator.

@batFINGER: SimpleOperator.bl_label will work if main is only called by this operator. context.active_operator is None.

Yes am aware of both counts.  Needs to be a registered and invoked operator for context.active_operator.  As mentioned would simply pass self to get the instance.  ie def main(op, context): and call via main(self, context)

@batFINGER: I agree the example with a standalone method not receiving a reference to the operator is not a good choice, it makes sense to have everything in execute or use a parameter. I'll keep this question just for learning purposes.

Disagree re choice. Can either call main from the  operator.  or  import the main method from the module to use elsewhere.  Listing the context objects is a  pretty simplistic example... but that's the idea.


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How to use 'Set Vertex Colors' properly?
I'm trying to set vertex colors per faces. I already did it successfully, but obviously now I'm missing something and after numerous trials, I give up.
I use this procedure:

Select a face in Edit mode
Switch to Vertex Paint mode
Select a color and execute 'Set Vertex Colors' from Header menu.

Instead of changing the color of the selected face, all faces are recolored.
Can you tell me what I'm doing wrong?

Done with Blender 2.79 (and both Blender Render and Cycles).

https://blender.stackexchange.com/questions/31160/is-it-possible-to-paint-only-on-selected-vertices-in-vertex-paint

In your Properties > Material > Options, have you enable Vertex Color Paint option? Otherwise you can't see the result in Solid mode, only in Texture mode.

@TryingGuest: Thanks, it was the problem. I guess the question can be closed as duplicate. I did it here, but didn't appreciate the use of this button at full extent.

@moonboots: The option was selected, but you're right to mention it, it can be forgotten easily.


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Snap to vertex projection while sliding an edge
I have made a staircase by creating a simple mesh with two faces per step. The general volume of the stair is a rectangle as visible in the top-left editor. Then I extruded the top of each vertical face horizontally to create a small overhang for each step (see bottom left editor below).
When extruding along the normal of the vertical face, the added face doesn't match anymore with the general rectangle limits, there is some variable inner/outer offset (as visible for the selected edge).
I now need to adjust the overhanging corners. Each vertical edge must be slid to a vertical position given by the overall rectangle.

I can likely create a customized orientation for each step and then snap without using the slide operator, but that seems very inefficient.
I have two questions:

About the slide operator: Is there a possibility to snap to the external rectangle?
About the method itself: Is there a better method than using the slide operator?

You can't snap when edge sliding. There seem to be far more modular approaches to this https://blender.stackexchange.com/questions/66716/how-to-create-a-half-turn-staircase

@DuarteFarrajotaRamos: This is possible to use the same stair model for an helical staircase, but not in my case where each step is unique. I hope some approach still exists, as it took me a lot of time to align the extruded face corners (mostly using the knife tool, possibly a noob's choice...).


text:
How to merge a loose edge into coplanar faces?
I created this edge by linking the two vertices directly (Make Edge / Face):

Now I would like to split the quad face below along this loose edge. What is the solution for the general case where the edge crosses multiple coplanar faces?

AFAIK, there is no way to use an edge (without even a plane) to divide a face.
What you need to do is delete the edge (x->edge) and then join the two verts, by selecting them and hitting 'j'.
If you've made a bunch of edges not realizing what you were doing in some other model, you can use mesh->cleanup->delete loose to delete all these edges, but I don't believe there's any way to transform them into cuts.

Actually you don't have to delete the edge first. With the loose edge selected J will still cut the underlying face, turning the loose edge into an edge between faces. You can use Select Loose Geometry to find the edges you want to fix.

@sambler You don't have to delete the edge first, but you do have to delete the edge.

Right you are, easy to miss two edges in the same position.


text:
Using different materials on each instance of an object with a mirror modifier
Is it possible to have each instance of an object with a mirror modifier using different material? An example would be a door modeled only on one half, but where each side would be in a different color:

Or is applying the modifier permanently the price to pay in order to be able to do this?

You will have to go around the mirror modifier and create 2 copies of the door each with different material, but with the same mesh they share between each other:

Get rid of the mirror modifier.
For each material slot set it to be linked to Object:

Make an instance of the door with Alt+D. This will duplicate the object, but link the same mesh between them. More on this can be found here:
What is a Duplivert, or a Dupliframe, internally?
Scale one object in the axis you want to -1 to mirror. Arrange them accordingly.
Assign different materials to the material slot(s).

Exactly the solution I needed, the linked question's answer is also very useful.


text:
Switch between modes
I seem to have trouble switching between modes. I have to open and start a file in sculpt or I can't use the sculpt feature. For example, I start model and get the basic shape then go up to modes, choose sculpt. My object is there but nothing happens. I can't use any brushes or anything. But if I open a new sculpt file, the sphere is there and I can use all the brushes on it. What am I missing?

I believe that the issue is arising from either one of the situations below.
1) When you switch to Sculpt mode, the sculpting tools will only act on the previously selected object. Switch back to the Layout mode and make sure that you've got the sculpting object selected.
2) Your object may not have enough geometry to be sculpted on since the sculpting brushes act by moving the existing vertices of the object. So if you are attempting to sculpt on the default cube, for example, the brushes only have the eight corners to work with. You can add more geometry to the object by subdividing it. Alternatively, you can enable Dyntopo located in the header bar while in sculpting mode. This will add additional geometry as you work.

I never thought about not enough geometry. I'll try that. Thank you.

It was not enough geometry. Thank you.


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time-animation of a latitude/longitude observations - best approach?
I'm trying to develop a skill to display space-time data in 3D Blender space.  In general, the X and Y dimensions would be longitude and latitude, and the Z dimension would be any one of dozens of numeric float variables.  All of the data would typically display on a map, with observations at irregular (not evenly gridded) positions to create a "sheet" (like an elevation map) of hills and valleys.  One sheet would be a snapshot of a point in time, and I would have many (hundreds) of sheets of sequential snapshots in time that I would like to display as animation.
At the moment, for technique development, I'm working with daily high temperatures at ~2500 US weather stations across 365 days.
I've been working on this pretty much full time for a couple of weeks, trying to do this with Blender Python scripting and csv files, with great progress, but in the last 2 days I've gotten stuck.  Rather than post my code, or a simplified version of it that anyone could run to show where I am stuck, I'm rethinking that maybe I'm thinking about this animation problem completely incorrectly, so I'm asking anyone here for reactions and comments.
My python/Blender code right now, trying to animate thru 365 days in a year, is creating 365 sheets or maps, and they are all stacking up in a "thick" pile (like a sandwich of data).  I have 365 keyframes created, but I cant see any movement because the top and bottom surfaces of the sandwich are enclosing any movement that might be going on in the stack of (Jan 1 to Dec 31) daily sheets.  FYI, I used Delaunay triangulation elsewhere in Python to create face triangles that connect the discrete points (irregular spatially though fixed and complete across time, not sparse).
So my question - how to structure this animation problem in a Blender script - is an either/or choice: 1) should I try to fix my 365 keyframed sheet approach, or 2) should I restructure the approach completely....with ONE sheet / surface of connected triangles "deforming" in time as the z-values of the vertices evolve?
If my original/current approach 1 is correct, I can either share the code of the core, or simplify then share it as a 15 line program that is self-contained, but if approach 1 is obviously wrong, I can abandon it and start re-structuring now to approach 2.  Is it obvious what is the right approach?  I'm still too inexperienced with animation to know.
Thanks loads, and I apologize in advance if this is not understandable.  OK for you to say that if true.

At the moment this reads  akin to "I have been working (paid?) on this for two weeks and have nothing to show.. Can I do better?  Please show me"

Thanks for commenting.  It's unpaid.  Just me.  I finally found something insightful and high quality late last night which helps my understanding.  The person codes 3 level, nested loops for x, y, with object creation inside the middle loop, then in inner third loop, moves the object progressively, keyframing that object with each movement.  Not sure whether it is a best practice, or one of several ways, but it is disciplined and rigorous.  This was the insight I was seeking, whether you animate “scenes”, or each object within scenes.  Seems to be latter.  Comments or suggestions welcome.