text:
object deforms strangely when using the subsurf modifier
I am trying to make an axe and stomped upon this problem...having no idea how to resolve it.
1st photo is with subdivision.
second is without.

It basically the Ngons that are causing the problem, as Cegaton stated best to use 4 vertices to a face. So keep it even and one way can be using edge loops to create more faces evenly.
Sample solution can be like this, for example:

Fixing up the model to create quads
Summary:

Use the Knife Tool to create Quads i.e remodel the geometry
Use Dissolve Edges to keep faces, but remove edges

A Quad is just face shared by four vertices, just making that clear.

Now, you have edges lines going each of the corners vertices select them and go delete X > Dissolve Edges. This will delete your edges but keep your faces as shown here:

TIP: Use Edge Select to make this easier
Now use the Knife Tool to create quads, what I did was use an existing vertex and created another one which creates an edge as well between the new one and the existing one. See the rectangles I'm making between those vertices, those are the new quads. Press Enter to accept knife changes.
Repeat for the rest geometry/vertices that don't have quads.
Hope that is enough :)

can i solve my problem in this stage?Or how can I use only 4 vertices because i ended up there by just using basic blender tools!

Yes you can still fix from what you have here. I might edit my answer to show you how.

So?any idea how to solve it?Thanks btw for all youre answers!

See my edit above for the method

I think I'm dumb...after that complex explanation I still dont get it...so I disolve some of the vertices so i remain with 4 for each "shape" but for some of them it's just not possible and with the knife tool I dont understand how to use it...Thanks for the answer

Knife tool lets you cut geometry by selecting a vertex, edge or point on a face and selecting another line, edge or point to create a 'cut'. For example if I have a plane and select one corner and then select the opposite corner I create two new faces and make an edge along the diagonal. Also, It okay if you don't understand the tool at first, google and the docs are there to help. here is the docs for the knife tool

Yep, he did not have enough support geometry.

You have N-Gons and are using subdivision surface. N-Gons and subdivision surface don't work together unless the N-Gon is flat and surrounded by a quad loop. This is not the case in your model. See this post for more details on when Ngons are okay to use.

Now I have this! https://i.sstatic.net/aoKgh.png

Subsurf needs quads but also objects created with Spin and proportional editing to have the desired effect without extra work. A bowling pin is an example of sich an object.


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How to create photo-realistic complex plastic material in Cycles?
I want to create a plastic material with proper bump and reflection. Something similar to the first image. For bump I used Voronoi texture, but I am having trouble adding small silver dots. And I am not sure that Voronoi texture suits best for plastic.
How to achieve more photo-realistic material?

That is what I have now:

It might be a problem with your lighting. Try adjusting the size and strength of different lights. I think the flat look of your material is caused by a lack of highlights and contrast. hope this helps.

source: Stack Exchange

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

sort: votes


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Creating Sapling Tree in the Python Console still not working
I encountered an error adding a tree using sapling in the python console, see here:
Creating Sapling Tree in the Python Console
and the suggested solution was to use INVOKE_DEFAULT.
However I tried using the INVOKE_DEFAULT and although it adds the object, it does not use the parameters I passed in. It is using the default settings for the tree_add. How do I get it to use my parameters?
I should also mention I tried the other execution contexts and none gave the desired result. (Asking this question in a new thread as requested).

Same issue, new user here.

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


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Bezier Curve - Cant select anchor points
This is a really simple question but I am new to this.
I just started using blender on my Mac and I created a Bezier curve while following along with a tutorial.
I have toggled to edit mode, and am trying to select the endpoints in order to manipulate the curve. However, I am unable to click the endpoints to select them. I can rotate (using R) and move the curve (by pressing G) but I can't select the endpoints to drag them around or the tangent lines.
Is there a quick fix for this? I am totally stuck :(
Thanks!

You can only select vertex and handles directly, not tangents or segments. Clicking on them should suffice. Why are there small numbers near your cursor?

In blender select objects by right mouse button instead left mouse button. Left mouse button is used to place a 3d cursor.
If you want to change it - you can do this in file -> user preferences -> input tab. But it is recommended to stay as it is

Crantisz, thank you so much! I appreciate your help


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Kelvin temperature from heat attribute
When simulating fire, the heat attribute gives a scalar representing the heat, but the blackbody node, which converts a temperature to a color requires the heat to be specified in Kelvins, and the heat scalar is not in Kelvin.
My question is, therefor if there is an unambiguous way of converting the heat scalar to kelvin temperature if I already know what type of combustion this is (ie. is it a flame of a candle or burning barrel of oil)

Yes. Multiply it by 1000.

Temperature
Gives a scalar defining the temperature of the volume. Values in the range 0..1 map to 0..1000 kelvin. This may be used to render physically-based fire with the Blackbody or Principled Volume shaders. All three outputs are the same.

From https://docs.blender.org/manual/en/dev/render/cycles/nodes/types/input/attribute.html
So the attribute node gives the temperature in Kelvins in the range [0,1000] mapped linearly to the range [0,1]. To change it back, you can simply multiply it by 1000.
Interestingly, what seems to refer explicitly to "Temperature" is actually referencing the "heat" attribute. using "temperature" in the attribute node simply returns 0, as if it were any undefined token.

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


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distance to camera as text
I would like to render 3 dimensional text which both includes unchanging text, and automaticly calculated distance to camera (in the units specified under the scene tab), which should look something like this:

is there any way to do this in 2.78, are there any third party add-ons (for Blender 2.78) which allow me to do this or is it possiple to achive this through blender python scripting?

I would recommend using animation nodes (https://blenderartists.org/forum/showthread.php?350296-Addon-Animation-Nodes)
As an example how easy it is to create this with animation nodes, see the node setup below.
Blender file here

It works just as well as my (text counter plugin) solution, but this feels more general purpose.

Turns out the Text Counter Plugin can be used to solve this problem; this plugin was made to animate text counting up/down, but using drivers it can also display distance to another object (or any property which can be used in drivers really).
After installing the plugin, add text, go to the text tap and find and activate text counter
If desired change »padding« »decimal«, and use suffix and prefix to write what will be before and after the distance displayment.
Then add a driver to counter value

finally go into the graph editor and change type from graph editor to drivers, select the current driver; find »drivers« tap in the disebar to the right, if driver type is not scripted expresion, make it scripted expresion; under variables add new variable (if one does not already exist) change type to distance and as object 1 and 2 select camera and the text.

then change expresion to
var*scale

where var is the name of the distance variable, and the scale is the scale between blender units and the desired units; in this scene i have 100 meters for each blender unit, and i want distance to be displayed as kilometers, therefor my scale is 0.1:
The text now automaticly calculates the distance as the camera and the text moves around the scene.
Unfortunately the suffix and prefix of the text can not be multilined (not even by typing in \n) and only one changing number per text object is supported


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Help forming an aircraft cockpit

Hello,
I am trying to extend the lines on the body of the aircraft I am working on, see photo below.
I have used a combo of both scale and moving by the z axis so far, but I am unsure how to apply the lines of the model so they overlap the top line of the cockpit, having tried so far, it causes the bottom lines to bulge out over the bottom of the plane which I have already set, as seen in the pic.
Thanks for any help.

I'd probably go about it like this:

And I'd likely keep the cockpit cover itself separate:


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Multiple objects/parts are selected in object mode
As noted in the title, when I switch into Object mode, several separate objects are highlighted as one. Is there any way to make them separate?

You have joined all of those parts into a single object, as can be seen in the outliner where it shows only one object is selected.  You need to go back into edit mode and separate the objects if you wish to have them become separate parts.
In edit mode, select one part, perhaps by island select; (shortcut L) box select; or other means and separate them. (shortcut P and select Selection.)

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


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How to import a map image from OSM to Blender?
How could I import an image of a map from Open Street Maps to Blender? I'm not talking about 3D buildings or terrain. Rather, I'm talking about importing an image from the map itself into Blender as a flat surface/plane. 2D basically.
To give an example, I'd like to import the OSM map for Lexington, Massachusetts. So anything within its marked borders including labels and names. Is that possible?


text:
What identifier of operator must be entered for assign shortcuts
I have a couple of questions:
To configure a border selection to a left mouse button click and drag, I used the following example of parameter "Tweak".

After making these changes when I run this command, the subobjects selection occurs, those who fall within of the action zone the frame.
But now there is no possibility to make the deselection of certain parts of geometry (subobjects) by frame selection.
What do I need to do to deactivated part of geometry (subobjects) via hotkeys Alt +LMB?
And one more question:
In another post, is said that: The RNA value comes from the operator named above. Were you have entered "rotate view" needs to be the name of the operator to be run when the key/mouse combination is pressed. The standard operator to rotate the view would be view3d.rotate.
To get the value of a custom operator, you need to use the value of bl_idname defined in the operator you wish to use.
I do not understand exactly where and how should I use the value of "bl_idname" to get the value of the main operator?
Identifier of operator for the transformation tools (move, rotate, scale) has following view: "transform.rotate", etc.
However, to assign hot keys such tools as Move, Rotate and Scale must enter the following value: "view3d.enable_manipulyator". Why "enable_manipulyator"?
If I want to assign a hotkey to the "occluded geometry" button, What values do I need to enter?

Please make different topics for each question
For border select you will have to create several entries for selection and deselection with tweak mouse with all the desired modifier keys, like Alt+Tweak+Left or Shit+Tweak+Left, ect. for example.
After that you have to additionally expand the Border select modal key map bellow any of the entries (they are all the same) and manually configure all options for selection, deselection, and canceling the operator.

I use a similar setup myself, and it is a sort of a chore and a bit hit and miss manual work.
Word of advice, don't directly use Left Mouse or Right Mouse in your keymaps, when possible use Select Mouse or Deselect Mouse so the custom keymap remains dynamic and responds to general switch of selection with left or right click. Also make sure there are no conflicts as they may inexplicably make some key assignments nor work
Best way to know an operator name is to Right Click a button and choose one of the following options and search for hints there

Copy Python Command
Copy Data Path
Online Python Reference
Assign Shortcut (does it automatically)
Edit Source

Some times it's also useful to search for that operator in the keymap list and see if there's one already assigned you can copy from.
Some buttons don't use an operator directly though, some times they need contexts, or toggle variables or call menus.
For toggling occluded geometry the operator has to be wm.context_toggle and the context is space_data.use_occlude_geometry

authors: Савелий Макашоа


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Maya to Blender
I am currently looking for a way to export from Maya 2017 to Blender.
In most instances, Collada (.DAE) and FBX have proved reliable for what I'm doing, but with these files it appears to be different
Currently, Exporting with Collada (.DAE) results in missing bones, but only when I import into Blender. Re-importing into Maya shows that the bones are indeed still there, so I'm assuming it's something with Blender's Importer.
Exporting with .FBX results in the following error:
"Unsupported FBX Version (7500), Binary Format is Uncompatible!"
I'd like to know if there is any other way to Completely transfer data between the two programs (or if there is a fix to either of the two issues listed above)

Try exporting an earlier version of FBX, you can select the FBX version when exporting.

I have no experience with this but did understand Alembic was the answer for this. https://wiki.blender.org/index.php/Dev:Ref/Release_Notes/2.78/Alembic


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Collada Importer Issues: Missing Bones
Whenever I import Collada/DAE files into Blender, they're always missing bones. However, if I import them into Maya, the bones are clearly there.
Would anyone know what causes this and any solutions there are to it?
Also, a side note, I would use FBX, but Blender seems to lack support for the 7.5 format, so Collada is the only way I can transfer between Maya and Blender.


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Using Cubemap/Mirrorball Texture on a material
I'm looking for a way to create a cubemap effect that mimics that seen in Source Engine materials, either through use of the cubemap faces or the mirrorball/sphere that is included in some of the textures, seen in this image patched together from one of Valve's cubemaps

I would prefer to be able to replicate the cubemap effect that works like a cube with inverted normals but on a per-material basis and regardless of UVs, but at minimum I'd like to replicate the effect of using the sphere as a matcap, which I'd assume would be WAY easier

Does anyone know how to accomplish this? I know there are built-in reflection functionality, but the goal of this is to be able to use pre-existing textures that likely aren't formatted for blender's current forms of environment mapping

Cubemap

Add a Cube, Shade > Smooth
Assign two modifiers - Subsurf > Simple = 4 (to get more geometry) and Cast modifier > Sphere > Factor = 1
under Object Properties > Visibility > disable Shadow
create a material just with Glossy shader > Roughness = 0, add Image texture node (disconnected but selected - Active) with a New one

under Render Properties > Bake

Mirror ball
it can be rendered directly with blender's camera ... in Camera Properties set type Panoramic > Mirror Ball ... if you need to have it as a part of Cubemap texture you would have to merge them in Compositor.

Cubemap /Mirrorball example file ...

To generate CubeMap without UV ... assign each side of Cube individual material with individual Image Texture (again this node has to be Active in each material to be succesfully baked).

Do you know how to control render settings using the bake method?  For example, the exposure seems different from a standard render, and the Scrambling Distance option seems to be ignored in Blender 3.1.

@SO_fix_the_vote_sorting_bug ... Bake is controlled by the same parameters as regular render. Previously some features wasn't available (like denonising), that is possible now thanks to rewritten Cycles to version X, that is merge in 3.x now. I'm on Mac so I can't confirm Scrambling Distance feature for Optix, but it is possible it is not available for baking ... and that is why you see also differences in exposure. Denoising, especially in combination with low Samples, makes a huge difference in a result.

Very nice ideas. Wouldn't it also be possible to use 6x 90º FOV cameras, one for each face of the cube?


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Fixing Boolean issues between objects with matching edges/vertices
I'm currently working on a project for 3D printing that involves a bunch of subdivision and multiple parts, and for those who are familiar with 3D printing, usually a solid, single volume mesh is required to avoid issues with printing. I figured using boolean modifiers would work best, but I ran in to some problems.
When using union, my mesh does not properly form into a new, single volume because of edges that are similar
Offending Edges (Second set hasn't been subdivided since applying boolean applies all modifiers from the target)

What happens

I can create the result I need by moving one set of offending vertices, but then the clean edge I needed is destroyed in the process

I can't join the parts together manually because presubdivide, the subdivision modifier obliterates the edges/shapes I want (yall know how it goes with edge creases)
This happens multiple times throughout the rest of the parts. Is there any way to circumvent this issue, or is the only way to fix it is to manually fix any issues afterwards? I'm fine with doing the manual work (I'd rather not risk a print messing up, as this is going to be a massive multiple piece print so failed prints would be costly), but just wanted to see if anyone knows a workaround.

Okay so I found one way to fix this

Duplicate one of the two offending meshes
Apply remesh to the new duplicate
Separate a part of the mesh that included the offending vertices from the newly remeshed mesh
Delete the offending vertices and vertices that overlay with the new piece from the old mesh
Stitch together the old mesh and the newly remeshed part

The reason I needed to restitch the old mesh with the remeshed piece is because the remesh destroyed edges and faces that didn't fall along the remesh grid (aka curves and diagonals)
Still looking to see if there are simpler/less destructive ways around this though

Boolean isn't good for 3D printing at all, it often creates a lot of errors. Iam using multiple objects, joint them and after Iam done I use voxel remesh, which makes it one object in topology and solid.


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Hide Floor overlay from viewport render in Blender 2.8
In 2.79 Floor grid hides automatically when doing viewport renders, but stayed in place for solid view.
How can I obtain such behaviour in 2.8? Manual unchecking Floor from Overlays is a bit annoying

I'm afraid it's one of the features that have been dropped from 2.8+. I don't know of any setting that allows to do that either. You're going to have to hide the grid floor manually like in one of the two answers.

It's not automatic but I've spent a good amount of time searching for this myself and found out that you can toggle on/off all overlays (grid, outlines, etc) by clicking the overlay icon.

I know this is pretty late but I figured I'd post this in case. It's still annoying but it's better than having to uncheck/check each overlay.

If you want to hide only the grids, but keep other overlays, you can expand the Overlay Icon and uncheck Grid, Floor and Axis :


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Why were default camera settings changed in Blender 2.8?
Default settings:
v2.79:
Lens 35mm, Sensor 32mm
v2.8:
Lens 50mm, Sensor 36mm
Just out of curiousity what is the reason for that change?

Mhhh, that's what I've found: https://developer.blender.org/rBc6a4b469e3ac8844dfd66ad03cee38a746e0e01a

I feel I heard somwhere (blender today?!?) that they changed the defaults to something more similar to the real world (36mm sensor is the full frame format and 50mm is one of the most often used lenses and is not deforming the objects as much as the 35mm).

In this video https://youtu.be/z6B2gt5PWdQ?t=131, Gottfried Hofmann from Blender Diplom explains his thought about those default.

And here's the commit of those changes: https://developer.blender.org/rBbcf6cc1f6b5f16ec37651ff6b0964fd91a60a59b

Same default in Maya

50mm lens is much more versatile and allot closer to the "human eye lens". For beginners that don't know about the lenses yet it can also be quite frustrating when things look off.


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Ambient Occlusion Map dots
I'm trying to create an AO map for my object. This is the result

As you can see the image is like created from little dots. The color isn't homogeneous. I don't know how can i describe better . . . it seems scratched.
It's my fault or this is the best result i can achieve? How can i improve my AO map?
These are the stats used

EDIT: Oops, I assumed you were using the Cycles renderer. For the Blender Internal renderer, it's a little different.
This is also sometimes called "grain" or "grainy" which might help your research.
Not to worry, you CAN get a better result. This is just because you've not rendered enough samples. The AO bake gets its quality settings from the "gather" section. Increase the number of samples and you will have a better result. Try adding 5 to the number of samples, and if it's still grainy, add 5 again. Keep adding 5 until you either get a good result, or the bake takes too long ;-)
There's even more information in the Manual:

Samples
The number of rays used to detect if an object is occluded. Higher numbers of samples give smoother and more accurate results, at the expense of slower render times. The default value of 5 is usually good for previews. The actual number of rays shot out is the square of this number (i.e. Samples at 5 means 25 rays). Rays are shot at the hemisphere according to a random pattern (determined by the sample methods described above); this causes differences in the occlusion pattern of neighboring pixels unless the number of shot rays is big enough to produce good statistical data.

authors: Дмитрий Сорвачев


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mesh is distorted due to armature
I created a mesh and made it a child of an armature.
once I did that, the mesh has been distorted.

When I changed the Pole Angle to 90 deg (it was -90). the mesh was fixed but then the IK went the wrong direction..

How can I fix that?
Thanks!

I just edit the IK after rotating the bone.


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Is it possible to get a rigid body to bounce off cloth?
I am doing something very basic: trying to simulate a rigid body (a sphere) falling onto a large cloth. Right now in my simulation, the object falls, the cloth deforms, and then the object just comes to rest on the cloth. It would look more realistic if the sphere were to bounce a little bit (and maybe roll around) before coming completely to rest. I have tried changing the physics properties of the cloth and the rigid body, with no success. I know rigid bodies can bounce off of each other: is there any way to get them to bounce off of a cloth before coming to a stop?

Related: http://blender.stackexchange.com/q/989/599


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How to create an all-around night sky in Cycles?
So I created a night sky following this video https://youtu.be/9vbq6HOgA2w
It was going pretty well until I noticed that only half of the world actually looks decent. The bottom half/ middle is this plain ugly color I want to get rid of but I'm not exactly sure how I would do that.

In the video,he use the sky texture node as a base,which create this sort of effect,instead you can use a solid color as a base.

In the beginning he added Mapping node which allows moving texture coordinates by some axis, and he used that for changing location of horizon by Z axis.

Usually, the bottom half is invisible if your scene has a ground. So, this is kind of ok.

I usually use an HDRI from NASA's SVS: Deep Star Maps.
You can get a full sphere OpenEXR image in 4k that is very usable, or you can get 8, 16, or even 32k versions.
Here's my world shader for using HDRIs.  It allows you to rotate the map as you need.

Just download the NASA maps, replace your world shader with something like mine, and plug the OpenEXR image into the image node.


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How do I apply color with Cycles Material Nodes with No UV?
After many attempts I can't figure out how to make the ends of the lemon green.
Here's my latest attempt. I've tried mapping, etc.

Try this: do an UV unwrap of the lemon, then add a texture coordinate node, and plug it into the gradient texture node you already have using UV. Then in UV/imagee ditor rotate the uv map (if necessary)

was hoping I could accomplish this without UV. May not be possible, dunno.

I think it's either that or using XYZ, see my answer here: https://blender.stackexchange.com/questions/82405/lab-color-sphere-as-cycles-material/82411#82411

Is this an interesting node experiment or is there some larger purpose?  Why not use a quick texture paint?

I don't know how to use texture paint. I was following a Sardi Pax tut on using procedural textures. Some of us are still learning.

Nodes using Generated Coordinates
No UV

Nodes Use Generated X Coordinates.  Image above.    Cleanup Pending. We think these are better attached to vertices and survive rotation as the image shows a translated and rotated lemon. See axis orientation.  Please test and confirm.  Artistry not considered.
Please improve these nodes.
Deprecated Nodes of Lemon Quality abusing the X position of fragment.

Cycles Render.  Less Green.  X Coordinate used. Object Centered at Origin.  Image Above.  Keeping some old nodes until cleanup.

More Green.  Nodes showing use of X Coordinate.  Left and Right value made equal via Absolute Value Node.
The Multiplication node controls the spread.  Its value is keyframed.
Do not eat lemons like this.

My lemon mesh is not aligned with the xyz coords. It's rotated on the z axis. No reason for that, it just was left that way after modeling. I guess that's why it's showing a "diagonal" yellow/green? Hey, I'm trying.

@NeverGiveUp I do not think I can interpret your results without an investigation.  So I cannot agree or disagree.

@NeverGiveUp  Do you understand at least 50% of the nodes above?


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Auxetic Foam Cell Structure
I want to create a Auxetic Foam Cell Structure with this technique:
Create a sphere in sphere (with boolean diffrence)
Generate particles with add particles and replace with mesh sphere in sphere
for grid distribution la morphologie est obtenu de cette forme
Note: The interference between spheres with holes is equal to the thickness of spheres.

But, if i want the distribution of meshes (sphere in sphere) to be random (50 spheres), how can i do that?
Ex:

http://pasteall.org/blend/index.php?id=50818

Can you show a simple example with Boolean Operators?  Are you stating one case is easier and one case is more difficult.  Is this for a single image or a dynamic image sequence?

it's a cube that contains these spheres with holes

We do not understand each other.  That happens sometimes.

it's a bit difficult with me : http://pasteall.org/blend/index.php?id=50818

Related (different technique but similar visual result) : https://blender.stackexchange.com/a/81396/29586

The sponge have a thickness with circle or ellipsoid section, with a texture volume is difficult to obtenain this forme same with tissue add-on.

I have moved your Blender File link from the comment to the question.  There probably is a better way to do this, which you may have noticed from other people who include Blender File links.

Yes, but this for only the grid distribution

I am working on a new feature that will make this process much easier, basically a new voronoi node inside the geometry nodes system: you can find it in here: branch It depends on voro++ library, Currently the build system does not search for voro++ automatically. You need to change the CMakeList to register that to the builds system

version Shader
Probably would be good to know the purpose of your needs. In some cases could be enough and probably looking better simple Volumetric material with texture type Voronoi or Musgrave.

Under Properties > Render > Geometry > Volume Sampling > Step size decrease value to something like 0.0100. In Blender 2.79 are some changes on Volume Shader, I don't know how to colorised foam to get the same result.

version Mesh

add Cube
use addon “Destructability Editor” or official “Cell Fracture” to crack cube into Voronoi shards

Join all shards Ctrl+J
in edit mode - “Remove Doubles” (W)
select all outer faces and choose delete "Edges"
than delete “Only Faces”

add Modifiers - Smooth (here with Factor 2)

Switch to "Edge" select
Select "Random" from menu like 20-50% and delete selection

Subdivide (W) like 2-4

This created net you can render by adding "Skin" modifier, but its very heavy for calculation, so I used here to add Mball to the scene and add Particle system to the net with "Render" > "Object" > "Mball".

Good vklidu, as for the first solution, the problem is that I can not take the thickness containers. The second solution is a good solution. Can you add a cross-sectional method to obtain sequential images, which are in two colors (voids and texture yellow)?,

Contact me on blenderartists.org . I didn't understand your comment. It isn't the best place for discussion here :) Thanks

Is an approach like this one equivalent to what you describe?

Using a Rigid Body simulation with collision, pour a bunch of balls into a box:

Choosing a stable frame at the end of the simulation..

CtrlA Apply visual transforms to the balls, and in the Tool Region > Physics, remove them from the simulation.

With the pivot set to 'Individual Origins', scale the balls up to your
interference margin, apply the scales,  and reintroduce the inside surface of the box,
flipped, sealed, and scaled.

Using the Bool Tools shipped add-on..

Make a union of the balls..
and subtract them from the box

The thickness depends on the scaling of the spheres before union..

Good idea, but the problem that this technique does not give shape with desirable thickness. There is a script that can generate random spheres, the technique is to create a sphere in sphere, then we replace the spheres generated with the script by this sphere, here we can adjust the thickness of the sphere, but the problem is how to assemble the interference between these spheres after replacement to get the foam. Note: in the script it is necessary that the spheres is interferent with each other with the desired thickness.

@saded (see edit)  I'm pretty sure, if your intention in the OP is to subtract the sphere-shells entirely from the cube that encloses them, then  this arrangement is the exact equivalent. The physical collision places the sphere-centers at the same relative position as they would have with 1/2 interference/shell thickness, and the scaling makes up the other 1/2? Or do you want the solid to comprise some other constituents?

@saded ahhhh! do you want the solid formed by the intersection of the shells?

Yes, It is only the shells that overlap between them, with thickness equal R-r


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Why are the mesh faces different colors?
In the 3D View window the mesh I am modeling appears with two different colors.  The final render has one color.
it's my first day learning blender and I'm following a tutorial to create a house model. In the tutorial the different faces of the house are all the same color, but my faces are having two different colors. I'm wondering why was there a color applied and what does it mean? When I render the model it's all the same color.

http://blender.stackexchange.com/questions/3606/why-are-some-faces-in-my-mesh-darker

While I can't tell you why they're in this state currently, as there are many possible reasons, these colors indicated the direction in which the face normals point. To fix this, you need to recalculate your faces' normals, by pressing Ctrl + N. Alternatively, this can be done from the toolbar (whose visibility is toggled by pressing T),by pressing Recalculate found in the Shading/UVs tab of said toolbar.

Make sure your [normals] are consistent.
In the image above the 3D View is in edit mode.  Normals are displayed as thin blue lines and you see the panel to show this with the word [Normals].  You can see one Normal has intentionally been flipped/changed.  The material panel is shown so I know I have only one material.


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How to make particle grains move across screen on render?
So for a video I'm working on, I'm trying to achieve an older film effect so I followed this tutorial:
https://youtu.be/-1zr1zFQawA
I worked out surprisingly well for the most part but I noticed that neither the vertical lines or grain move across the screen in the video like they're supposed to.

Generated grain always looks fake. For a believable result I'd suggest use real film scans.

Watch closely from 43:30 - he adds a keyframe to some node values and then adds a noise modifier to the the keyed value.

A little later about 47:05, he adds a translate node and keys the x and y values to get some parts moving across the screen.


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How to cancel Constraint "Track to" for a specific keyframe
So I'm having my camera follow my spaceship around and at the end of the scene I want it to stop. On that keyframe, I want it to stay at the view it was positioned at before I cancelled it but when I do, it just goes wherever and I have to manually position it, which doesn't get too good of a result and looks funny when I put the image strip in video editing.

If you set the camera to the final position first, before adding the Track to constraint, there is a solution. On the Track to constraint, there is a slider labeled Influence: (shown below). It decides how much control the constraint has over the camera's direction.

Turn the Influence: to 0 and position the camera how you want it on the final frame. Turn it back to 1. Move the cursor in the Timeline panel to the frame just before the one where you want the camera to stop moving. Hover over the Influence: slider and key I; it should change from grey to yellow. Move to the next frame in the Timeline panel. Move the slider down to 0. Hover and key I again. The slider should change color from green to yellow.
A sample of the method used (note how the slider changes):

The .blend with the cube can be found below.

Track To constraint has a value slider called Influence, that goes from 0 (no effect) to 1 ( full effect) you can keyframe this as much as any other value in Blender.Selecting the camera, go to Constraints panel, go to the last frame you want the Track To constraint to have effect in, mouseover that value, press i it turns yellow and adds a keyframe, go to the frame you want to elliminate the constraint's effect in, change the value to 0, and repeat the previous operation to add a keyframe.


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In video editing, how to fade scenes out, with next starting immediately after?
So this is my first using the video editor so I'm not really sure how to do this. With my animation, I want to add an effect where 1 scene would start to fade out and the one after it would start immediately after the first starts fading. I thought the cross effect would work but it justs makes the first one start fading and the second just stays frozen until its time to start. I would move the stripes around to test it but I have this synced with music so there's not much there I can do.

How-to
To acheive this effect, use the Gamma Cross Effect Strip.

To begin overlap your videos, so it looks like this(it does not matter which channel the videos are on).
Next, select which video you want to fade out with the RMB(usually the first video). Then, using SHIFT RMB select the next video.
Finally press SHIFT A and navigate to Effect Strips... and click on Gamma Cross. The cross duration should be the length of the overlapping videos. You cannot change the length of the gamma cross directly, you must increase or decrease how much the videos overlap.

Reasoning
If the videos are directly next to each other, but not overlapping, you can't have the second video start right away because how can the second video start if the first video is still going and they are not overlapping?

Reference : https://www.blender.org/manual/editors/sequencer/strips/types/effects/cross.html
Reference Video: https://www.youtube.com/watch?v=T_PRXTZoHtI&list=PLjyuVPBuorqIhlqZtoIvnAVQ3x18sNev4&index=14
Audio Reference Video: https://www.youtube.com/watch?v=beWj_mw0M-I
AudioAs for the audio do as RobinsSea suggested in his answer, insert keyframes along the timeline concerning the audio level of the videos. To do this select the audio track and navigate to the properties panel "N". Make sure your timeline is where you want the audio to begin fading out! Over in the properties panel go to the volume area and hover your mouse over the volume. Then press "i" to insert keyframe. Do the same to complete the fade out, just set the volume to 0 and the timeline where you wish to end.
Happy Blendering!

Could you also show the fading of the volume out and in? I think that your answer is very valid, however it seems to be lacking the audio part of the question :)

I have found you can do a video cross-fade using keyframes together with opacity settings for two overlapping video clips... I tend to use a black colour as base. This technique is a wee bit quicker than (although perhaps not quite as visible or flexible as) Gamma-Cross. You would do the audio cross-fade the same way, inserting a keyframe and setting volume at 1.0 where you want the fade to begin, go to the end of the clip and set volume to 0.0 and insert a keyframe there. In the second clip, start volume at 0.0 (set keyframe), then go to the end of the first clip and set volume of the second clip to 1.0 (set another keyframe). Hope this all makes sense.


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Vertex paint not working after sculpting with dyntopo on
I started painted a low poly island model some weeks ago.  Today I modified the mesh with sculpt mode and when I activated Dyntopo, I got this warning:

Then I tried to vertex paint the new vertices but it is not working, the new vertices don't get painted. Here you can see my settings:

What I am doing wrong or missing to do? I will appreciate any help.

Dyntopo sculpting mode removes all data related to mesh since it regenerates it, vertex paint included. It won't prevent from vertex painting though rather only remove previously existing one. As to painting see https://blender.stackexchange.com/a/126566/1245, looks like you have masking turned on

Blender is a complex application. I don't know exactly what I did, but at the point when I wrote my question, for some reason I had changed the Draw mode to Add instead of Mix. Once I put it back to Mix, it worked as expected and I was able to keep working in this project.


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How to share shaders among different materials
In order to model a better quality Earth without distortion at the poles, I decided to use a cube, subdivide it 3 times and then to-sphere it. It works much better than a UV Sphere and than an Ico Sphere for the same reasons. All the faces are squares of similar size and if you use a cube projection, you will have no distortions and best texture quality.
As the material properties of the ocean and the continent are different, I used a Principled BSDF shader for each one and mixed using a texture of the ocean mask.

My problem is that as I need 6 images, one for each side of the cube, I duplicated the same material and just changed the texture. But if I work on the shader of the ocean, only one side is affected.  I want that all sides share the same ocean and continent shaders since only the texture is side dependent.

How can I do it?  Thank you in advance for any hint.

Related: How to get perfect UV sphere Mercator projection?

In your image, you're using an image texture (py.png) as a mix factor to mix between two different Principled BSDF.  And you have six different materials.  How to make your edits to one, affect all, without having to use the same texture image?
In this case, the simplest thing to do is to node group your two principleds and your mix shader node.  Leave the image texture mix factor outside of the node group, feeding into it as an input.  Copy/paste that node group into your other 5 materials and set each of those materials to use the appropriate image texture for the node group mix factor input.
Node groups are all linked copies until you unlink them, so when you edit a node group, you edit all materials that use that node group.
This is the simplest technique for what you're demonstrating.  There are other possibilities.    You could mix between six different textures on the basis of some bit of face data, like an extra UV map, within a single material.  You could bake your six textures to a single texture on a different UV, so that you could use a single material.

Textures are assigned by face, to make the ocean all one texture you would need to make one for the ocean, then make all ocean faces that material. If your contents were on one texture with the water areas alpha, then you could make one for the ocean, then overlay the contents over the ocean.
It may not be hard to edit your map image in a program to make an image with the contents and alpha water.


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How to avoid obstruction of supposedly parallel sun light?
I am trying to make a Solar System scene. An obvious lighting for this scene is the "Sun" light, but it is obstructed by a big object even when the position of the light is outside that big object, as illustrated with the following images:

This is how it should look

This are the position of two sun lights, both outside the big object.

First, I don't get why this happens since the lights are located and pointing outside the big object.  Second, I'll appreciate any suggestion to solve this problem. Blender 2.8.7.
Thank you in advance for any help.

Hello :). Sun light is different from other lights. It only has a direction. No matter where you put it, it'll always shine from infinite distance.

Jachym, I know, exactly that is the reason I am using it for this simulation. That doesn't explain why it is affected by a nearby object outside its way.

Ok, I was not really understanding Sun light. You were right, sorry.

A 'Sun' lamp is so called because it simulates the light of the sun as perceived on Earth.
Its rays are parallel, from infinity. It has no position, and so no falloff with distance. (Good for you, in that respect.) The position of the lamp's gizmo has no bearing on its effect; only its direction makes any difference. All objects will cast shadows on other objects 'behind' them in that direction.
A quick solution to your problem, either in Cycles or EEVEE, would be to use one Sun lamp, anywhere you like, (inside the Sun object if that seems logical) pointing parallel to the Sun > Planet direction, and with 'Cast Shadow' or 'Shadow' switched off in the lamp's Properties panel > Data tab.
This would also mean planets do not cast shadows on one another.
If you want more particular effects, the answer will vary, depending on your renderer. For example, if you're in Cycles, you may want to prevent planets bouncing light on to one another, using a Light Path node. Or if you wanted the planets to go round the sun, you could use a shadowless point-lamp at the sun's position, with its falloff adjusted if necessary.

That solved it, just turn off Shadows!  Thank you very much! :)

@user2309000 Great!


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How can put a mesh into a different position?
I have meshes of human dental jaws in the image below. I would like to put them in correct anatomical position.  I would also like to rotate them in correct anatomical fashion.  How can I achieve these two goals.
I'm trying to overlapped and solidify object in a simple example, to plan maxillo facial surgery.
The idea is to put the jaw with the teeth into an other position during the surgery.
So I would like to "tell" to the lower jaw that I just cut to "move into this position and to stay there".
In this exemple, I would like the teeth from the back to overlapped the teeth in front of them (mirroring lower jaw in the good position).
Is it possible to do it by selecting region of interest (like the top of the teeth of the back) and show to Blender the similar point in the mirroring teeth?

The second question is during the occlusion of teeth. When I want to close the jaw (if the CT scan is not in occlusion), I would like to solidify the teeth of the upper jaw. Like that, when I'm trying to close the lower jaw, I would find the contact with the teeth, and not passing through the upper jaw...

Thank you again for your help! Blender for ever!

In your images above I think I see the same jaw twice. That does not seem reasonable to me but I am not a surgeon. It seems correct placement would require the cranium visually to be present to obtain a context for correct placement.   A screen image from you showing more cranium would help.  I think your questions are not difficult and you or your workmates may need to see a tutorial series about blender   Link    https://www.youtube.com/watch?v=lY6KPrc4uMw&list=PLda3VoSoc_TR7X7wfblBGiRz-bvhKpGkS.

Are the upper and lower jaws and cranium already three separate objects?

What do you mean by saying "solidify"? And is this a question only about modeling (put polygons in the right place) or rigging also (assigning constraint between polygons, such as hinges, pivots, rotation restraints...)?

Align identical object by a twin tris
Let's suppose you have an object and another one, very similar to the first, and you want to overlay the two.
If they are not perfectlty identical, you should probably start an iterating computation that would progressively guess the function that best fit all the vertex positions...
...if instead they are identical (as in your case), but with different transformations applied such as in the picture below:

the problem is much more simple. If you'll get able to align one triangular face to the corrispective one, the whole mesh will be aligned. I would suggest to use the Precise Align add-on.
Basically you have to activate edit mode of both object (one at time), select the same triangular faces by selecting the vertices in the same ordere and than create a parented empty with the add-on command:

These two empty are now associated with the mesh. All you have to do is to match position and rotation of the empty object and the two jaws will follow their trasformation:

Overlapped!

Limit object's rotation
Easiest way to set up a moving jaw is to first of all add an empty that would represent the rotation pivot and than parent the upper jaw to it.

Now the jaw will follow empty's transfrormations.

Add a Limit Rotation constrain to the empty and assign min e max angles to limit the rotation of the jaw to a given range too.
Credits: jaw's model by lucasfalcao from Blendswap

As to your second part, have you looked at RigidBody and RigidBody Contstraints?
http://wiki.blender.org/index.php/Doc:2.6/Tutorials/Physics/Rigid_Bodies
https://www.blender.org/manual/physics/rigid_body/constraints.html
For the first part though, I'm very new to blender but I think it would probably be easier to export your models to something like Unity, you could then run clever scripts and colliders etc. to do the detection of areas and move parts accordingly. Although saying that there may well be a way to do it in Blender.

Press G ,  to grab and move the mesh.
Press  R,  to rotate the jaw mesh.
Press  Numpad 1, 3, 7 to see your model from different viewpoints.


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How to copy position, size from one armature to another?
I have a armature A and made Copy armature B and C;
I went to editmode on B and moved arms bones a little down and made head bone bigger;
How to I apply same changes on C without manually moving the bones or without creating a new armature (ctrl+d from B)?
I was hoping for some button to copy armature from one to another (the bones structure is exacly the same even same names)
this is a quite challenging question, I don't expect an exact answer but directions to help me do what I want
thanks

While we can easily copy a pose from one armature to another I don't think there is a way to copy edit bone changes from armature to armature. This would mean creating a python script is the way.
As editing bone data in bpy.data.armatures[x].bones doesn't seem to work, we can go into edit mode to collect the bone data from the source armature, then apply that data to each destination armature in edit mode.
So getting close to an exact answer would be the following script, you should only have to change the rig names at the top.
import bpy

source_rig = 'metarig'
dest_rigs = ['metarig.001','metarig.002']

############

bone_data = {}

def edit_rig(rigname):
    bpy.ops.object.mode_set(mode='OBJECT')
    bpy.ops.object.select_all(action='DESELECT')

    bpy.data.objects[rigname].select = True
    bpy.context.scene.objects.active = bpy.data.objects[rigname]
    bpy.ops.object.mode_set(mode='EDIT')

edit_rig(source_rig)
for b in bpy.data.objects[source_rig].data.edit_bones:
    bone_data[b.name] = (b.head.copy(), b.tail.copy(), b.roll)

for arm_name in dest_rigs:
    edit_rig(arm_name)
    for b in bpy.data.objects[arm_name].data.edit_bones:
        b.head, b.tail, b.roll = bone_data[b.name]

bpy.ops.object.mode_set(mode='OBJECT')

For the movement itself ("moved arms bones a little down"), you can copy/paste the keyframes without any problems, with the copy/paste button, on the right of the 3d windows (arrow down / arrow up, in pose mode).
I can't test right now, but I wouldn't be surprised if it copy paste the bone scale datas too...
In any cases, you need to go to pose mode, and not edit mode for that.
On another hand, but I assume this is not a satisfying answer, as you don't want to duplicate, but why don't you simply duplicate the original armature (A) to a new one (B), make the desired changes to B, and then copy B to C ?


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How to render gummy - jelly like movement in character
I want to render an animation of character which is a bit jelly like. You know, it has that lulling like movement when its moving around.
Sometimes you see that in games when fat character walks there is this bouncy, lully movement on its torso.
Any ideas how to do it?
Maybe fluid simulator?
The idea is to have this effect a little bit , but not overdo it.

probably more soft bodies than fluid simulation...

yes soft bodies seems promising


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Why mirroring and not rotation?
I'm doing some basic tutorial from https://youtu.be/LCghBIUZyuM?list=PLWO2DQFscvE-CYIjCIYUZ71RAhYNgmwg6&t=440
Author uses mirroring on the x axis. I'd like to ask why? I understand that to show us the function of mirroring. But is there any other meaning to use it and not just rotation?

The tools are not the same. Mirroring object is scaling its vertices' coordinates by -1, so it inverts object; rotating won't give such result. Create some more complex mesh than default and experiment. See related - http://blender.stackexchange.com/questions/1093/understanding-mirroring-and-inverting-an-object

In the particular case of the teddy bear in the tutorial referenced by the original poster, because the leg and bottom of the leg objects are approximately symmetrical around the center axis of the leg, mirroring the object, and rotating the object will have similar results, except that it appears that mirroring may result in the normals of the faces of the object being flipped. With a more complex mesh, however, mirroring and rotating the objects will not have the same result. An example of this would be an exterior rear view mirror on an automobile, such as this one:
[
In this case, duplicating the object(s) and using the mirror tool (CTRL - M) will yield a right side rear view mirror. However duplicating the object(s) and then rotating it 180 degrees will not have the same result; instead the right side mirror will have the glass facing forward, and the mounting surface in the wrong orientation.
Note 1: Original photo at https://upload.wikimedia.org/wikipedia/commons/thumb/f/f7/Wing_mirror_with_indicator_light.JPG/297px-Wing_mirror_with_indicator_light.JPG


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How do i add material/textures to only one face of an object?
I just got Blender and I don't know how to add textures to only one side. I've tried finding an answer but i can't. It adds the texture to all sides of the object.
I just want the blue on one side of the square. BTW i don't know where anything is in blender so if you have an answer please include pictures.

If you want to add a different material to a different face of your cube see how to do it here: http://blender.stackexchange.com/questions/516/add-different-materials-to-different-parts-of-a-mesh

See this answer http://blender.stackexchange.com/a/36023/15366

How do i select a side of the object?

@Funshine  your last comment had a question which is probably best answered in a video tutorial series.  Here is one example of a series https://www.youtube.com/watch?v=lY6KPrc4uMw

In Edit Mode select a face (using a face selection [Ctrl+Tab-->Face]) you want a texture to be projected on. Then press U-->Unwrap. In Uv Editor open your image texture.

Add a new material to your face (using a + button) and press the Assign button.

Then go to the Texture header. Add a new texture and change its type to Image or Movie. Open an image and change its coordinates (in a Mapping panel) to UV.

Result:

Followed these instructions but the 3d view doesn't show my texture. Blender 2.79b

@ether_joe Have you tried to change Viewport Shading to Texture Mode (It's Solid by default)?

Eventually I realized I needed to hit U -> unwrap after assigning the materials. Now working.

I was banging my head over this for a while. Thanks!

I am struggling to follow these instruction on blender v2.91. after creating a material, how do I add a texture to it? I do not find the texture header.

This desperately needs updating for the newer blender versions after everything got moved around in 2.8/9

@Kai After adding the material click on the dot next to "Base Color" and choose "Image Texture". Then add your image.

What a huge overkill to do this simple thing :-(. I'm missing a way, which is common to all other modelling programs. Just select a face, choose a texture and choose a scale or rotation.


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How do I fix camera weird mapping quirk?
I've run into a bit of a problem when trying to do some camera mapping.
This is what happened:

As you can see, the mapping is not working well. As far as I know, when you project to view, it should work every time, is there something that I'm missing? I have tried remaking the plane, and resizing it, it seems that the bigger it is, the less accurate it is. Please help me, I want to finish this.

Nevermind, I just realized that I had to subdivide the plane because if you don't have enough polygons, project from view will produce bad/inaccurate results.


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Dopesheet selecting multiple objects at once
So I have 7 objects that are all moving in unsion, but I need them to animate one after another. The problem is that when I am trying to select them in the dopesheet, no matter what I do, every single one of them is selected at once.
Here's a picture of what I've got right now:

I've tried doing many things to stop them from being all selected, including the show only selected filter.
The objects were seperated in edit mode, which may have something to do with it.

If you separated objects after they were animated then they will share the same animation, which will be shown in the Dopesheet.

Okay, but is there a way to make it so that when I select one it doesn't select them all?


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Animation not exported to COLLADA
I have a model consisting of 4 meshes: 'base' and 3 'electron'.
electrons are quads with a transparent electron texture. Both 3, have an animation of quad rotation.
When I export to COLLADA, object exported, but without animation.
PS: I guess Blender export to COLLADA is crippled. Is there any other tool which loads .blend and exports .dae, with better COLLADA support?

Why not use FBX?

Because I am hobbyist and I use open technologies.
I made the assumption that because COLLADA is open, open software like Blender support it 100%.
No. This assumption was wrong!

Blender's collada export is indeed in a delicate state to say the least. I am not sure about exporting animations as collada, but I can say for sure that nothing in this world besides Blender can open .blend files. They are basically brain dumps. Trying another format could be your best strategy.


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Geometry Nodes: how do I use the location of a point as the position for Set Handle Positions node?
in geometry nodes I'm trying to make an alien sunflower type plant, I have a dish that copies the rotation of the sun, and a point attached behind the dish that moves with it. basically I have everything working how I want it to except that the top of the stem doesn't look like it's attached to the base of the dish. I made the point behind the dish because I was hoping I could use that point's location as the position of the curve handle, but I can not get it to work. the setup I have currently lets me manually move the set handle position with the offset so I think something is wrong with my transfer attribute node set up
sorry my nodes are kind of a mess. I've been all over the internet looking for a solution, I can only find confusing explanations for how the position and transfer attribute nodes work just saying to use them together. any help would be great thanks

In order for your question to be answered quickly and satisfactorily, please be kind enough to share your blend file with us (https://blend-exchange.com/). This will avoid misunderstandings, allow for faster and more accurate answers, and not force anyone to rebuild the node tree and possibly provide an answer that may not be what solves your problem. Thank you!

...but just a basic tip that might help you: Maybe it helps if you switch the node Transfer Attribute from Float to Vector.


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How to see polygon's local axis in Animation Nodes?
Sometimes it is very handy to visualize local axis to debug polygons' rotation (like 3D Viewer for location of points). Is there any default solution for this task?
This is an Axis type of displaying particles and I'd like to build something similiar in Animation Nodes:

While the local axis of a polygon is not exactly defined, one can generate a possible transformation for the polygon using the Extract Polygon Transforms node:

Thanks! That is exactly what I want. Are colored axis only present in Blender 2.8? Mine from AN v2.1 in Blender 2.79 are simple empties

@SergeL Yes, colored axis are only in Blender 2.8.


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How to properly setup linear deformation in Hook modifier?
The goal is to make right mesh (with orange outline) to look exactly straight like on the left side. But these horizontal loopcuts are completely destroying Hook setup. As you can see falloff is set to Linear and it is still has curvature.
Left side mesh has all vertices asigned to hook except top two. Right side - all of them.

This setup you can easily build using armature deformation, but not Hook. But if you want to use hooks, try vertex group setting in hook modificator:

I draw vertex group using weight gradient:

When add  weight group into modificator settings:


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Highlighting of compositor nodes?
How to use it? Checkbox in compositor's N-key panel is enabled, but I see no difference in behaviour.
My PC is Win7 64 bit, 4gb RAM, card ATI HD4670 500mb.
Anyway, assuming it is working, what information can I get from it? Collateral indication of nodes' memory consumption? For example, nodes which will be firstly highlighted are less memory consumption and so on.

It tells you which node is executed when. When enabled in heavy compositing trees, you can see the nodes highlighted one after the other in the order of execution. The idea behind is to identify nodes that are slow to execute.

So, is it working only with heavy setups? Does anybody have a screenshot of nodes being highlighted by this option?

Weird. I remember this worked a while ago for me, but I haven't used it in quite some time. I'll keep investigating this. All resources so far, even in the manual and the tooltip, say the same: It highlights the node currently executed. But it doesn't show up for me atm.

From the Blender Bug Tracker:

This feature was disabled in the code but not in the interface.


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Convert rotation from sign switching to continuous in Animation Nodes
Plane is simply rotating on Z axis around origin from 0 deg to infinity (linear interpolation), AN extracts this rotation from polygon. Extracted motion looks fine but it isn't calculated as cumulated/continuous value. Every 180 degrees it is switching sign from + to -.
Look at Z value here:

Can this rotation be recalculated to match input motion? I was planning to change some values inside material in [0-1] range using growing angle, but unable to do it with current behaviour.

This signed representation is called a Directed Angle. To convert that to a non-directed angle, simply add $2\pi$ if the result is negative as follows:

This is assuming you angles are in radians, if they are in degrees, you should be adding 360 instead.

Good to know it has a proper name. So, to go beyond 360 I should store every negative appearance and add another 360? Or is there anything easier than that?

@SergeL Take the modulo with the maximum range, $\pi$ or $2\pi$ depending on when you perform the modulo.


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Why rotation with snapping is not working?
I am trying to snap edge in edit mode to selected object and can't do it easily though. It only snaps in one view.
I've tried to enable/disable "Align rotation with snapping target", but still without good result:

I am not looking for other ways like modifiers, etc, because it is quite limited in some cases.

This might seem a bit long-winded, but... a variation on this..

Set snap to 'Active' and 'Vertex', and in the snap panel, set it to affect rotation
Set Pivot to '3D Cursor'
Set Transform Orientation to 'View'
Establish one end of the snap. With all selected, make the vertex at one end of the source (moving) object active, and snap it to the corresponding end of the target edge. ShiftS > send the 3D cursor to the same spot. It will be the center of rotation.
Establish the plane of rotation. ShiftD duplicate the vertex at the other end of the source object, and snap the duplicate to the other end of the target. With all source vertices selected, F create a temporary triangular face, and ShiftNumpad 7 align the view to the face
Delete the duplicate vertex, (and the face, with it)
With all source vertices selected, and the loose end vertex active, R rotate it into place.

This takes longer to describe than it takes to do.. usually there are convenient faces / whatever already hanging around.. you wouldn't have to create them specially, as in this example. Maybe, instead of using the View orientation, you would create a Custom Orientation from a selection of vertices, edges, or faces (either existing, or temporarily created for the purpose).

Hm, so this snapping design is strictly view dependent? Very strange, that you can move to snap to any point in perspective, but can't with rotation.

@SergeL No.. snap is not view dependent, but on the whole, it does need to work in the X,Y or Z of a given orientation I only chose the view orientation for 1-off convenience. You could, for example, have created a Custom Orientation from the triangular face, and then, with that orientation active, the command would have been RZ to rotate about the normal of the face, whichever view you were in, and whether or not the face still existed. The orientation is implicit when 'View' is selected, with Z out, X across, Y up, and you can see what you're doing.. but any aligned orientation would do.


text:
Strange specularity in Blender Internal reflection
Cube is standing on mirror plane and Lamp without diffuse lighting produces strange specularity in mirror's reflection. It is strange, because actual object doesn't have such specularity. Is it normal?

Stranger still is that the lamp set to Specular should create specular in the box as well as the reflection of the box - tested an added Suzanne, and also same thing - reflection has specular, but mesh doesn't.

The reason you can't see any specular reflections on the cube is because they are just that, reflections. Since the cube's faces are flat planes, you will only see specular reflections if you are at the opposite angle of your light source.
The reason they show up in the reflection is because the light is bouncing off of the face of the cube, (just away from the view/camera which is why you can't see it) and then reflecting off of the mirror.
I tested this on some other objects as well, all using the same materials. The mirror reflects the specular light based on where it reflects off of the object and then off of the mirror.
What it comes down to (as far as I understand) is that we expect the light to behave like diffuse light (the mirror reflects what we see exactly) but instead the light bounces off of the object, then off of the mirror and into the camera, we just can't see when it bounces off of the object since we are at the wrong angle.
You can test this in the real world as well, by using two perpendicular mirrors and a light source. When set up like you have it, you will only see the light source in the horizontal mirror.


text:
Shading Problem

How can I correct the shading?
Can someone pls help me with this because I don't know what's going on!

Being in Edit Mode select the whole mesh (A), then press Ctrl+N to recalculate normals.

@Gonzou why not add it as an answer? :)


text:
How can I create a random walk animation with animation nodes?
The idea is to have a bunch of objects that are animated given a random vector each 20 frames. Something like this video:
https://vimeo.com/75135375
The problem that I´ve found with Animation Nodes is how to somehow store the previous positions of the objects that sometimes could be 20 frames away. For the first animation I can use the ID key, but as long as the animation continues I can keep it consistent.

[For the first animation I can use the ID key, but as long as the animation continues I can keep it consistent]   .   [consistent], What does that sentence mean?

Currently there is no very efficient way to do this.
If you only have a few objects this solution might work for you:

Essentially you generate the whole path for each object in each frame.

I see. This is one of the few weak points on AN.  How to make objects aware of their previous states.


text:
Materials information on a file Blender Internal Render
I'm trying to get information from a Blend File, but I've just hit a wall.
We are referring to Blender Internal Render. Not Cycles Render.
I'm new to Blender basically, so I really don't have a clue of neither scripting or Python whatsoever, so I really don't have a clue of what do I have access or what can or can't do via Python scripts on Blender, so I was thinking: Is it possible to take the material information from a Blend file or from within Blender, specifically, what files they are using?

In this example, thanks to Blender, I know the files the Metal material is using are these, but is there a way to output, let's say:
Metal:
- nomad_a1_diff.tga
- nomad_a1_norm.tga
- enviroment.png
And this, with all materials? Thank you in advance!
EDIT
What I'm basically trying to get is this

Name of any materials of a mesh.
Listing the textures of that single material.

Example
Material: Metal Textures of the Material Metal: nomad_a1_diff.tga, nomad_a1_norm.tga, enviroment.png
These three are the materials for that Metal material on the image.
I want to do this with every material on the model. Thanks to this script, I've got the name of all the materials, however, instead of listing all the textures per material, it lists all the textures of the model, I don't need that.
UPDATE
Thanks to atomicbezierslinger for the script, he helped me to get a step on the right direction!
I've run your script, but it gives me just the name of the textures. I've done some research and found a function called bpy.data.materials so I decided to add it to the script and now it looks like this
import bpy
import datetime

def inspect_textures():
    for t in bpy.data.materials:
        print(t.name)
        for t in bpy.data.textures:
            if isinstance(t, bpy.types.ImageTexture) and hasattr(t,'image'):
                x = t.image
                if hasattr(x,'filepath'):
                    print(t.name, type(t),t.image.filepath)
        else:
             print(t.name, type(t), "?")

inspect_textures()

This is the output from the code above. Now it gives the name of the material and the name of all the textures of the model, when all what I need is the texture names of the specific materials,  is there something else it can be done or does it need another import? Thanks so far for the help!

It will be better form if the first variable (t) were change to the letter (m) since that would semantically be close to the word (m)aterial.  Change the second line to match.   Actually I think your use of material is incorrect.  That outter loop should be deleted.

It would be useful to add two statements to your requirements as bullet points. Example.  01 Please include X, Y, and Z. 02 Please exclude T, U, V.  Currently I do not understand what the I need to understand.  Please explain and rewrite .... [specific materials]

Editing post

I've edited the post with the points, thanks for pointing it out

A Text Editor window containing a Python Script.  Filename indicated has the suffix [.py].  Line numbers and Syntax Coloring enabled. Yellow arrows from left to right show, Window Type, Name of file, Buttons for line numbers and syntax coloring, Button to Run Script.  Image Above.
Only copy the newest software code sample.  The images above have older software.  But they address questions that may apply to you which are not letter by letter code specific.
NEWER
import bpy
import datetime

print("-" * 88)
print(datetime.datetime.now())
print("-" * 88)

def inspect_m_textures(simple_sleek):
    print(bpy.types.ImageTexture, " Preferred")
    for m in bpy.data.materials:
        #print("M ", m.name)
        b = False;
        for ts in m.texture_slots:
            if hasattr(ts, 'name'):
                b = True
                continue
        if b:
            print("M ", m.name)
            inspect_t_textures(simple_sleek, m.texture_slots)

def inspect_t_textures(simple_sleek, slots):
    #print(bpy.types.ImageTexture, " Preferred")
    n = 0
    fs = "%03d" # format string
    #for t in bpy.data.textures:
    for ts in slots:
        #print(t.name)
        #print(type(t))
        #n += 1
        if not hasattr(ts, 'name'):
            continue
        t = ts.texture
        if isinstance(t, bpy.types.ImageTexture) and hasattr(t,'image'):
            n += 1
            ns = fs % (n,)
            if hasattr(t,'image'):
                x = t.image
                if hasattr(x,'filepath'):
                    print(ns, t.name, t.image.name,t.image.filepath)
                else:
                    print(ns, t.name, "Incomplete", "Incomplete")
            else:
                print(ns, t.name, "No Image")
        elif not simple_sleek:
            n += 1
            ns = fs % (n,)
            print(ns, t.name, type(t), "Other No Match")

inspect_m_textures(True)

OLDER
import bpy
import datetime

print("-" * 88)
    print(datetime.datetime.now())
print("-" * 88)

def inspect_textures():
    for t in bpy.data.textures:
        print(t.name)
        #print(type(t))
        if isinstance(t, bpy.types.ImageTexture) and hasattr(t,'image'):
            x = t.image
            if hasattr(x,'filepath'):
                print(t.name, type(t),t.image.filepath)
        else:
             print(t.name, type(t), "?")

inspect_textures()

Python for Cut and Paste.  Code Block Above.  Inspect, Verify and Improve. You can delete comments and extra print statements and extra print arguments.
Open or use text editor window. New Text. Name Textures.py  . Copy and paste the text above.  Make sure the formatting is retained.  Execute from Button or Keystroke indicated on Tooltip of Button. The console window has the textual results. Toggle the visibility of the Console Window from the menu.  In the [Info] window Menu/Window/Toggle System Console

Console Window on Windows 10.  Console allows Copy and Paste.  Python allows Standard Out Redirection.  Image Above.

Toggle the System Console. Image above.

Thank you very much for your help, I've updated the post with your code and added some information about what I found using another bpy. Thanks so far!

Suggestion. Vote up if the proposed answer is useful. Vote down otherwise. Vote answer if applicable.

This is not that difficult in the grand scheme of things.  The filepath for the image for the texture in slot one of a selected object is:
C.object.active_material.texture_slots[1].texture.image.filepath

To do what you would like, you would just need to iterate over the objects of each scene, and each texture slot in each material.  You will need to check for when there is no material or Texture.  This is a super inflexible way to do so:
import bpy

for i in bpy.data.scenes['Scene'].objects:
    print(i.name + ":")
    for mslot in i.material_slots:
        print("\t" + mslot.name + ":")
        if not mslot is None:
            if not mslot.material is None:
                for tslot in mslot.material.texture_slots:
                    if not tslot is None:
                        print("\t\t" + tslot.name + "=>")
                        if hasattr(tslot.texture, 'image'):
                            print ("\t\t\t" + tslot.texture.image.filepath)

Not the most pythonic code ever, I was in the middle of something else.

import bpy
import datetime

def time_stamp():
    print("-" * 88)
    print(datetime.datetime.now())
    print("-" * 88)

class material_texture:
    def __init__(this, name_fp = "?", texturetype_fp=False, image_fp=False, filepath_fp="?"):
        this.name = name_fp
        this.texturetype = texturetype_fp
        this.image = image_fp
        this.filepath = filepath_fp

    def __str__(self):

        return self.name + " , " + str(self.texturetype) + " , " + str(self.image) + " , " + self.filepath

def texture_line(tl):
    n = 0
    fs = "%03d" # format string
    for t in tl:
        n += 1
        ns = fs % (n,)
        print(ns, t)

def inspect_m_textures(simple_sleek):
    print(bpy.types.ImageTexture, " Preferred")

    for m in bpy.data.materials:
        tl = inspect_t_textures(simple_sleek, m.texture_slots)
        ftl = tl
        if (simple_sleek):
            ftl = [t for t in tl if t.texturetype]
        if (len(ftl) > 0):
            print("M ", m.name, "-"*8)
            texture_line(ftl)

def inspect_t_textures(simple_sleek, slots):
    n = 0
    tlist = []
    for ts in slots:
        if not hasattr(ts, 'name'):
            continue
        t = ts.texture
        if isinstance(t, bpy.types.ImageTexture):
            n += 1
            if hasattr(t,'image'):
                x = t.image
                choice = True;
                if (choice):
                    if hasattr(x,'filepath'):
                        x = material_texture(t.name, True, t.image.name, t.image.filepath)
                        tlist.append(x)
                    else:
                        tlist.append(material_texture(t.name, True, True, "Incomplete"))
                else:
                    tlist.append(material_texture(t.name, True, t.image.name, getattr(x, 'filepath', "Incomplete")))

            else:
                tlist.append(material_texture(t.name, True, False, "Incomplete"))
        elif not simple_sleek:
            n += 1
            tlist.append(material_texture(t.name, False, False, "Other No Match"))
    return tlist

def test333():
    time_stamp()
    inspect_m_textures(False)
    time_stamp()
    inspect_m_textures(True)

test333()

Just a low priority alternative to the above selected answer.  Some of my test textures were not that well groomed and thus more tests to  avoid missing data issues.  Also I wanted to use other tests for personal purposes.  There is a separation of data query and presentation now.  Small testing software rig. The accompanying explanations are in the original selected answer.


text:
Store unique vertex ID in vertex color
Script from this answer encodes polygons ID to vertex colors:
import bpy

obj = bpy.context.object
obj_data = obj.data
group_name = 'face_ID'

#check for existing group with the same name
if None == obj_data.vertex_colors.get(group_name):
    obj_data.vertex_colors.new(name=group_name)
color_map =  obj_data.vertex_colors[group_name]

#get faces' number
count = len(obj_data.polygons)

for poly in obj_data.polygons:

    ID = poly.index / count  #for normalized results
    color = (ID, ID, ID)
    for loop_ind in poly.loop_indices:
        color_map.data[loop_ind].color = color

Can this be done with vertex indices as well?
I've tried to change poly to vert and obviously script doesn't work.

Using bmesh.
Similarly to this answer loop thru the face loops and set the associated vertex to a color based on its index.

result on default uv_sphere, cube and torus
import bpy
import bmesh

context = bpy.context
mesh = context.object.data
bm = bmesh.new()
bm.from_mesh(mesh)

color_layers = bm.loops.layers.color
color_layer = color_layers.get("color") or color_layers.new("color")
L = len(bm.verts) - 1
for face in bm.faces:
    for loop in face.loops:
        x = loop.vert.index / L
        print("Vert:", loop.vert.index)
        loop[color_layer] = (x, x, x, 1)
bm.to_mesh(mesh)

Note: for large meshes could make a a look up table for vert and color to avoid calculating for same vert per face loop.
LUT = {v : v.index / L for v in bm.verts}


text:
Is scaling to absolute zero a bad way to hide an element?
Usually if I'm going to scale a polygon (for duplifacing) or a whole Object in order to reveal it smoothly during animation, I set 0 value as a float 0.0001.
It is still invisible for the eyes but annoying to setup in keyframes/drivers.
Should I continue to limit it every time or I can put a real 0 without a doubt and won't get any problems with rendering or exporting?

What have your tests told you about rendering or exporting for you current methond?

Interested to hear your results.

In my opinion, you are fine to use zero for a scaling factor for objects - those scaled meshes will simply be reduced down to a point, but with no actual loss of geometry; increasing the scale factor again will restore your mesh and while scaled down to a point will not be visible in your render.
However, for scaling faces, you will lose geometry by scaling down to zero in Edit mode - since all vertices will exist at the exact same point so there is nothing to 'scale back up'. Note though, that in this situation, even scaling down to a very small scale (but not zero) may introduce rounding issues with the vertices in your mesh when you scale back up again. The exception to this is if you are scaling the faces using a modifier (such as an Armature or Deform modifier) since the underlying geometry is not actually affected and so can be restored without distortion.

Would a  point shapekey  be another exception?

@batFINGER A shapekey would be OK as it’s effectively a deform modifier - so the underlying geometry change can be undone and the original geometry restored (so the acale to zero can be undone).

Interesting thing that duplifaces' inherit scale is limited to 0.001


text:
Limiting precision level in Animation Nodes?
Is there a perfomance wise way to limit decimal numbers for all values inside NodeTree?
Sometimes I don't need that many decimal numbers, especially for comparing values to get desired boolean result. Limiting values like Vectors, Eulers is a waste of resources as they need to be separated to floats and recombined after. Any tips are welcome.

Non list types are represented using python objects, so you can't really change the precision.
Vectors types lists in Animation Nodes (i.e. Vector3DList, Vector2DList, EulerList,...) are composed of float typed numbers, which is the smallest possible type, so you can't have smaller precision than that.
A float list in Animation Nodes is actually composed of doubles, so you can reduce the precision by using a FloatList instead.
An integer type in Animation Nodes is a long, so you can reduce the precision by using a ShortList, a CharList, or an IntegerList. Though I believe two of them might have the same precision on some systems/compilers.
Finally, I think it is unlikely to get a performance boost out of this, at least in the context of AN. So I think you are better off optimizing your node tree somewhere else.


text:
How to compare values properly with expression in Animation Nodes?
Such simple task goes wrong somehow (result of comparing inside Expression is far from expected):

What did I overlook here?

Floats in general have a limited precision and most real numbers can not be fully represented using a float. So when you set the input float node to 0.1, it is actually represented internally as 0.100000001490116119384765625. See this answer for more information. Python's representation of 0.1 is different from blender's representation, python's is more accurate 0.1000000000000000055511151231257827021181583404541015625. Hence the result you see in your setup.
In general, don't try to compare floats as this may yield some unexpected results. You can use something like isclose() function to compare floats, this function is the standard math module.

Well, a man can easily end up in asulym trying to assume that not every 0.1 is equal to 0.1. Thank you, Omar!


text:
Can Animation Nodes extract data from dupli-instances?
By dupli-instances I mean dupli(verts/faces/particles/frames). I was thinking that once vertex snapping is working with duplies in 3d viewport, then you can somehow extract vertex location and poly's in Animation Nodes, like from normal mesh.
Is it possible or not?

I don't think the API provides such access. However, it is very easy to generate this information yourself based on the data already given by blender. For instance, vertex dupli-instances data can be generated as follows:

Similarly, we can do that for polygons, edges, particles, and frames.

Thanks for the answer! I don't see Transform Mesh in my AN 2.1 of 2.79 Blender in Mesh section, only via search bar (moreover there is no "Join Meshes" option?). I assume this node is like "Instancer", but joins all meshes in one object with this checkbox checked?

@SergeL Not all nodes are available through menus, it will probably be added to the menu soon. The Join Meshes option appears when the input matrices are a list. Yes, when your input transformation is a list, it works like this.


text:
Bezier curve between faces of different meshes
Help me please to set up nodes, so that curve will be instanced between every two faces of different meshes.

Faces should be selected by index, like 1-1, 2-2, etc.
Curve should be directed along faces' normals.

I've replicated something partly similiar to my needs from this answer, but it is limited to only 2 faces inside one object.

Loop over both the polygon centers and polygon normals of both mesh and create some between each two centers using the normals as handles:

Or by using the Instancer node:

Thank you very much! But can it be done using Instancer, rather than one object with many curves?

@SergeL Edited the answer.


text:
Are there any critical drawbacks of rendering animation on per frame basis?
I have a scene, where rendering is controlled by python script which takes a still image on each frame. After test run I can't name any "problem" except inability to abort rendering without crashing Blender.
Will animation output (image sequence) be the same as with default "Animation Render" or it's not that easy?

No, if you render all your frames individually the result will be the same of pressing "Render Animation". This button is only iterating over all frames and sending the render command for each of them.
As for the render crash, you could use a modal operator that checks if you press Esc (for example) and aborts the render without making Blender crash


text:
Do Custom normals work in Animation Nodes?
Generally I want to direct polygons along custom split normals, or at least get them work in AN. Can it be done?

You can get access to loops normals using the following expression:
[loop.normal for loop in [obj.data.calc_normals_split(), obj][1].data.loops]

Which calculates the split normals data and returns the normals. To set vertex normals to a mesh, you can use the setVertexNormals method, which take a single vector list representing the normals.

Thanks for this answer. I have been banging my head against a wall trying to get custom normals with [loop.normal for loop in obj.data.loops] and just getting an array of zero vectors, even though the object has clearly visible custom normal data. Would love to know why the normals can only be read in this way.


text:
Relative size for blur in VSE
Is there any way to have relative size instead of absolute in Gauss strip?
Final output is 4K, while I am working with 30% preview. It is very annoying to switch between render sizes just for tweaking correct amount of blur.

There is no built in functionality for this. However, you might be able to achieve what you want using drivers. Use the Render resolution as the variable. Perhaps you could define a custom property for the total blur value?

How did I forget about power of drivers? Nice solution.

Sorry its incomplete as I was rushed this morning.


text:
Do procedural textures have MIP maps?
I am talking about integrated textures like Clouds and node setups in general.
It is working by default or not? And can it be enabled without baking textures to images?

Procedural textures don't have MIP maps. They are calculated whenever they are needed. But if you're planning to use those textures in any other engine, you should bake them, and therefore you can create your own MIP maps.


text:
How to avoid vertex sorting after using Offset Polygons in Animation Nodes?
AN v2.1 for Blender 2.79b
When I link Polygons Offset node to transform input mesh, it overrides original vertex sorting (Wire view mesh with orange outline is original array, small planes - result of AN transform):

How can I avoid that?

The Offset Polygons node doesn't just transform the vertices/polygons of the mesh, it also splits polygons if they are connected. So it is impossible to retain the order of vertices in most of the cases, and in cases where it is possible, it is not worth it to consider it as a special case.
So if you want to retain the order of vertices, manually loop over the polygon indices, transform the vertices and write them to their respective locations in the vertices list. Let me know if you want more details on how to do that.

Expression [x for y in a for x in y] converts Polygon Indices (list of tuples) to list, that can be later used as sorting list to relocate vertices. Whole tree (note that Mesh Info node is not in default menu, so search it via Space):

Why is this needed sometimes? For example to correctly join new mesh as shapekey, because this process relies on element order.


text:
Normal map does not work with tangent shading?
I bake normal map from Cover1 to Cover in Blender (in "Tangent" space). Then applied it to Cover_normal object.
Quick render is OK with basic shading, but acting very strange with tangent shading enabled.

.Blend file

Do you check Tangent in Shading rollout to get metallic look or for some other reason ? Tangent space normal maps do not require Tangent shading.

Yeah, enabled it only for the matter of look, but i guess it should work regardless of shading properties.


text:
How to know that object is fully shrinkwrapped?
Let's assume that I have a Plane moving towards a Sphere. When they are close enough, Plane is using Shrinkwrap modifier to stick to a Sphere. Now I want to add a Driver which depends on situation: is the Plane fully shrinkwrapped or not?
I do not want to use distance between objects as input for the Driver, because their movement is a kind of random.
So, how can I get such information from the Shrinkwrap modifier?


text:
Does decimate modifier decrease render time or memory usage?
Because I have completely opposite result during this render. Cube was subdivided 10 times in edit mode + 3x subsurf modifier = more than 40k faces. And 582 faces after Decimate

I made similar experiment and render times match the expectations. The shortest time with default cube. The longest with Subsurface, shorter with subsurface and decimate.Almost back to the shortest after applying both modifiers(so the last render is of cube with 16 faces).

Decimate modifier is single-threaded and slow. On high-poly meshes it takes ages to compute (sometimes more than it takes to render). Modifiers are computed at pre-render time in the phase "Synchronising object". Apply the modifier. There is only a small vertex count range where the modifier will actually speed up anything non-applied.

Principally, the decimate modifier reduces face count. A smaller geometry leads to less memory usage and a shorter render time.
BUT: The modifier is slow. Really slow (Don't blame it, reducing geometry isn't a simple task). Before rendering, all modifiers are "applied" so that they can get rendered in the "Syncronizing object" phase as Jerryno said. This will add some overhead to your rendering time.
If you can afford it, apply the modifier. Then it will calculate once and for all instead of at every render. Eventually back up your object somewhere else just to be sure.
Also please keep in mind that the decimate modifier is a "I messed up the polygon count" quick fix. If you need it, in most of the cases that's a hint that you made a mistake somewhere. See here for alternative solutions.

Thank you, I get it. It was a quick test, but my main project is animation with transforming, so applying is not for me. So I will stick with rendering to EXR files and then "compose only" process.


text:
How to disable vector pass calculating on unwanted frames?
I have an Internal Render animation more then 2000 frames and for 150 frames there is some postcomposed vector blur. All is good, except that calculating of vector pass taking about 10 seconds.
So to not wasting time, I've tried to drive the Vector checkbox in Render Passes tab, but it is working very buggy - sometimes it fails to produce decent vector.
Is there a decent way to avoid unwanted calculations?

To use vector information for frame 10, information from frames 9, 10 and 11 are used. This make sense, because to get a sense of speed, Blender needs to compare the positions of objects before and after the current frame with the position in the current frame.
Lets say that you want to use vector info for frames A to B. Is it the case that you get weird results for frames A-1, A, B and B + 1 only? In that case I would simply manually re-render those frames with the vector checkbox ticked.
It might be possible to use a math node in the compositor to automate the
influence of the vector pass in your node setup, taking 0 as the input to the vector pass node for the frames I mentioned and the actual vector values for the other frames


text:
How to separate animation of materials in Blender Internal?
I have a non-node material with some animation inside texture slots. When I hit Plus symbol to make a new material from original, full copy appears sharing same animation block.
I think there should be something like Make single user (U) for meshes, because simple Clear keyframes with left mouse button destroys data in both materials.
So how can I clear animation data inside copied material and keep it safe in original one?

You may have copied the material but the property that you keyed is part of the texture, so looks like both materials are using the same texture.

I've had this problem and found it's best to press the UPPER plus symbol, not the one indicated.  This will create a new material slot accessible to the object selected and one which is independent of those already there.
Back in the 3D window get into edit mode, switch to "Faces" and select those surfaces you wish to allot this new material to.
Go back to the UPPER panel (to the left of the upper plus sign) and make sure the new slot is still highlited.  If it's not, click on it.
The unnamed material will also appear in the slot next to the lower plus symbol.  Click in there (NOT on the plus sign) and give it a name.
Only when both the desired surfaces (in EDIT MODE) AND the material slot in the upper panel are highlited should you press the "Assign" button a little below.
The assign button will connect your highlited faces to the new slot.
You should see those surfaces/faces immediately react and change colour.
There should be no keyframes in the dopesheet for this new material either.  Any you do create later will only affect the new slot and  those surfaces you've just assigned to it.


text:
How to maintain interpolation when keyframing F-curve?
Inserting keyframe ruins Bezier interpolation. There is an option Sample keyframes, but it inserts keyframe for every frame - this is too much for me. How to do it without additional handwork?
Top to bottom: original curve, single keyframe inserted, sampled

This sounds like a bug in blender.  To preserve the curve shape the control points must be adjusted according to exact formulas for subdividing a bezier curve.  https://www.cs.mtu.edu/~shene/COURSES/cs3621/NOTES/spline/Bezier/bezier-sub.html

Can I ask what you aim to do? I ask because if you want the exact same curve, why do you need to add a keyframe?

Lemon, because in my real project I have a curve (about 2000 frames) which is already fit in whole animation scene, but now I want to behave it differently from frame 500 to 650 without affecting outside values. Basicaly, I would like to put bounadaries with this keyframes at 500 and 650 frames


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Is there a way to combine keyframes in groups?
Let's say, I have multiple keyframed objects.
Selecting necessary keyframes from necessary objects in lengthy Dope sheet is very tedious.
For easier manipulation with the timeline, I want them to be grouped in "chapters" or somehow binded to Markers or whatever, is this possible?

You can separate certain bits of animations into Actions. Then you can take the NLA and combine those into your final animation.

Generally this task is demanded to Bone Layers: you can put a group of bones in a Bone Layer, then select that layer, select all bones and set keyframes.
In the dopesheet you can set the visibility to all, only selected, multiple objectes, etc with the little buttons on the header of the dopesheet window.


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What is causing n-gon to have smooth shading with unexisting bevel weight?
I accidently found that Bevel modifier with weight option somehow improves n-gon after subsurfing, but don't understand what does it actually do. There is no real bevel weight applied to the edge.
Decimate modifier draws same amount of faces either Bevel is turn or off. Normals also behave similiar, but shading is smoother.

File to play with:

It maybe a problem caused by the non correct update of vertex normals. By the way it's not strictly related to the Bevel modifier, you can for example force the update by switching to edit mode (https://i.sstatic.net/ujZZF.gif) or use another modifier that interact with the faces (wireframe, simple deform with zero factor, triangulate...)

Can you check whether in the Mesh Tab under Normals "Auto Smoothing" is active?

Auto Smooth is "Off"

I think Carlo is right, I played with that creased edge that you have around the top and when I push its crease value back to -1, it behaves like it should at 0. My guess is, that somewhere along the way, these value get overwritten.


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Why is glass shadow blocky in viewport render?
Raytraced shadow was set to be smooth (Point lamp: 6 samples, 2 size) and solid material produces fine results, but enabling any transparency gives strange blocky parts inside smooth area.

Appears to be a viewport issue. Render is fine. You shouldn't rely on the viewport for render view. (I am aware that this doesn't answer anything.)

I was thinking about viewport rendering to radically reduce rendertime, but can't stand such things