How can I apply exact texture measure (cm) in uv mapping?

The room to tile with 75cm x 25cm tiles:

1: Create or resize a tile texture.
It should have the same proportions as the 75cm x 25cm tile, thats to say 75/25 = 3:1. To keep things simple I like the idea of having 1pixel to 1mm. In the example below the tile texture size is 750px x 250px.

2: Open this texture in Blenders UV Editor:

3: Next is to UV unwrap the four walls A, B, C and D.
Before doing this it may make things easier if all all the surfaces that are not going to be tiled (UV unwrapped) are hidden (H key). Doing this will make it easier to select each of the remaining walls.
Select Wall A and in orthographic front view (numpad 1) UV unwrap using the Project from View option.

4: Hide wall A. Switch to the Back view (CTRL + 1), select Wall B and again UV unwrap using  Project From View.
Repeat for walls C and D. It is very important that you do not change the zoom in or out when selecting before each unwrap.

5: Unhide the Walls (Alt H)
With the four walls selected, in the UV editor the four islands may appear squashed in the Y axis so to correct this select all four islands and scale up by 3.

6: Next we need to get the lower left corner of each wall island snapped to the lower left-hand corner of the UV space. This is done for two reasons,  a) to have all  the walls lower edges aligned and b) so that they can be all scaled up together from the same single point. (X=0 Y=0).
In the UV menu enable the Constrain to Bounds option then select each island in turn and drag it down so that its lower left corner is snapped at X=0 Y=0.

7: Uncheck the Constrain to Bounds.
Assign pivot point to 2D cursor and check that the 2D cursor is at X=0 Y=0. Select all four islands and scale them up until the right-hand edge of the Wall A is aligned with the right-hand edge of the UV space (X=1).

8: Now we are ready to do the final scaling. The length of Wall A divided by the length of the tile 6000mm/750mm = 8.
With the pivot point (origin of the scaling) still using the 2D cursor and all four islands still selected scale them up together by a factor of 8.

Now when the tile texture is applied to all four walls it should be correctly aligned and correctly scaled.

Another way to do this could be to use the Mapping node in the Node editor, adjusting the X and Y values to suit. In this case the UV Unwrapping (mapping) method would be Project from View (Bounds).
Because the length of Walls A and B are not the same as Walls C and D the scale of Y value would be different. This would mean having to use two different materials.


How to randomize pixels in image/movie (size 12x12 pixels)

Tile Randomizer

How does it work? Faces of one plane (tiles) are mapped through Explode modifier to randomized faces of a plane with Build modifier.

Create a Plane and UV unwrap it, then loopcut it or subdivide to match desired columns and rows amount (final facecount = rows * columns). This is Randomizer object
Duplicate Plane ALT-D and add material with image. This is Image Plane object
Add Build modifier to Randomizer, check Randomize and drive a seed with expression #frame. May add Stepped interpolation modifier for a driver to control time interval before switching seed (step size is 5 for GIF in example).
Add Particle System to Randomizer, set particle count to match facecount, enable modifiers stack and set particle/face ratio to 1, also choose Keyed physics.
Add Particle System to Image Plane, and link same particles set as for Randomizer. In Physics tab press "+" button and add Randomizer's particle system as a target key.
Add Explode modifier to Image Plane.

Test file done in 2.79 for Blender Internal engine.


Low lying fog bounding object rendering as solid

As an alternative to smoke you can use volume scattering.

In an example like this:

Add a mesh that uses a volume scatter node as the volume.

Using a gradient and a color ramp you can control the height and density of the fog.

Using additional textures to affect the transparency of the volume scattering you can get a less homogeneous mist.

To move the fog animate the mapping used on the textures.

Here's the file:


One way to do this is by beveling, then extruding:

What I did in the gif:

Enter edit mode (Tab)

Enter face select mode (CtrlTab> Face)

Select a face on the surface that I want to select, then press CtrlShiftAltF to select the entire surface.

3D view > Header > Select > Select Boundary loop:

Bevel (CtrlB)

Extrude and cancel transform (EEsc) See this question for details on what pressing Esc does.

Press AltS to scale along the normals.


Possible to not make light blend colors?

Ok, so this is going to be pretty extensive and difficult to explain through text and images but I'll do my best.

Make sure you're in cycles render

Begin by deleting everything in your scene, add in your text and center it

Now lets create our layers, name layer 1 and layer 2 (name choice is up to you). Make the first layer associated with layer 1 and the second layer with layer 2

Add a camera into your scene, press 5 and then 7 to enter top down orthographic view, and then Ctrl+Alt+0 to move the camera to your current perspective

(you can then modify how close the camera is to the text with g and then z, or using the axis arrows).

Move to the second layer and create 3 planes (one will be the red light, white light and colour of the text) Make sure that these three planes are spaced out along the z-axis to ensure that they aren't intersecting. From here, enter edit mode and manipulate the vertices to match the shape you're trying to create for the lights.

You should have something that looks like this:

Select one of the planes that is representing a light, select the object settings and under Cycles Settings deselect diffuse. Do this for both planes representing lights.

Go into the node editor, select one of the planes representing a light and create this node setup:

Once you have done this for both light planes, create a similar node setup for the plane that will represent the text's colour. Should look like this:

(The emission colour will effect the text's colour)

Tick the transparent option, shift select both layers and hit render.

After rendering go into the compositor and create this setup:

This is pretty much the final result, now all you need to do is animate the colour ramps to emulate the lights, crank the white value closer to the black and that will remove your issue of the colours blending.

Hope this helps and resolved your issue, sorry if any of this is hard to understand. If so, just let me know and I'll do my best to reiterate what I was trying to say. I will also attach the .blend file so that you can dissect what I did if you get stuck.


Understanding Texture Projection and UV Mapping

Since a texture is a 2D image that's supposed to be wrapped onto a 3D object, there needs to be some way of converting a 3D position of each point of the surface into a 2D coordinate to use for the texture.  Since x, y, and z are already used for the 3D coordinate, u and v are used for the texture coordinate, hence, they're called UVs.
There are several methods for converting between XYZ and UV, each of which are options on the Texture Coordinate node.  For example, "Generated" automatically converts the XYZ coordinate of the surface to a UV texture coordinate, and "Normal" converts the surface normal into a UV texture coordinate so that any points facing the same direction on that object will share the same UV coordinates and thus be colored the same (if you're using a texture to color the object as opposed to something else).
Each of the automatic options work great depending on what you want, but if you need precise control over how it converts XYZ to UV, you'll need to use a UV map.
When you unwrap an object, it takes each vertex on the object and automatically converts it to a UV coordinate.  Then, you can adjust the conversion in the UV editor.  For example, if one vertex by default maps to the UV of (0.3, 0.2) which would be 3/10 horizontally along the texture image and 1/5 vertically along the texture image, by moving the vertex in the UV editor, you can change it to map to a UV of (0.2,0.2) or anything else you want.  That way, you can get precise control over how the image wraps around your 3D model.
When you unwrap an object, it gives you several different options or projections for how to unwrap the 3D model, but these are just starting points.  Ultimately, it doesn't matter which one you choose, but choosing the right one can help reduce how many tweaks and edits you have to make in the UV editor.
The main projection options are:

Unwrap which just does a default unwrap.  If there are seams (see below) on the object, it will account for those.  Otherwise, if it's already unwrapped, it will do nothing.
Smart UV project which splits the object into several different shapes based on the angle between the surfaces
Cube/Cylinder/Sphere Projection which work well for their respective or similar shapes
Project from View which just takes how the object looks from you're current perspective and copies that over to the UV map (kind of like placing a projector right where your eye is and shining the texture onto the entire object.  It works well for that particular view, but often doesn't look very well from the side)
Project from View (bounds) which does the same thing, but it scales everything to fit the texture more nicely.

For the default unwrap option, if you first mark certain edges as seams, it will split the object along those seams as it unwraps the image.  For example, notice in the image below how the edges of the islands or groups of connected vertices correlate with the red lines (seams) on the object.

And that's the basics of UV mapping.  Now to answer some of your specific questions:

You only need to unwrap and object when you're going to use a texture on it, and even then, you can sometimes use the other options on the Texture Coordinate node.
You only need to set up one UV map per object
See above
Usually, but not necessarily.  For example, maybe you created the UV map for a modifier but just want to use the "Generated" option on the Texture Coordinate node for the material.  Or maybe you want one texture to use the UV map you created and another just to use the "Generated" option.  But usually you'll just use the UV map option if you already created it
Honestly, I'm not 100% sure how these projection types on the Texture Coordinate node work, but it seems that "flat" is the best option with UV maps, and the other options work best with the "Generated" option on the Texture Coordinate node.

Let me know if you have any other questions.


Relative distance 3d cursor on the right axis

If you want to snap all the vertices of the rim to the surface at once, you could assign them to a Vertex Group, temporarily P split the hatch off into a separate object, and give it a Shrinkwrap modifier, affecting only the vertex group, targeted on the surface.

If you align the hatch object-axes down the edge of interest,then you can use the modifier to project all the vertices in the desired direction. Apply the modifier, rejoin the objects.


How to cut extrude inwards like in sketchup?

Starting with blender version 2.9 there is a way to Extrude Manifold
(Alt+E)

This tool is very similar to Extrude Faces but enables Dissolve Orthogonal Edges by default. This causes the tool to automatically split and remove adjacent faces when extruding inwards.


How can I run a add-on from a python script

Imagine there is an addon installed called "my addon". It has a couple properties to control in the toolshelf, and an operator.

The properties are all in bpy.context.scene.

In your script/addon, you can access all these properties.

You can set properties by

bpy.context.scene.my_addon_string = "hey"

And call operators

bpy.ops.object.my_addon_op()

So with a combination of editing properties and running operators, you should be able to run the addon from another addon or script.


I'm sure there's a more intelligent way but here is one:

Create your P shape from a 64 vertices circe.
Convert it to Curve.
Create a plane, it will be your profile shape, don't forget to put vertices close the corner so that it will sharpen the edges.
Convert it to Curve.
Now select your P curve, go in the Properties panel > Data, in Shape choose 2D, in Geometry choose the plane as the Bevel Object, and enable Fill Caps.
The profile appears along the P.
If you play with the End value of the Geometry you'll see that it will progressively fill the P shape. You'll use this value and some keyframes to animate the appearance.
Duplicate your P shape to build your logo shape.
Don't forget to Smooth the shapes.


# When your add/remove vert(s) in your mesh. You need add
bm.verts.ensure_lookup_table()
# to your code

# When your add/remove egde(s) in your mesh. You need add
bm.edges.ensure_lookup_table()
# to your code

# When your add/remove face(s) in your mesh. You need add
bm.faces.ensure_lookup_table()
# to your code


Ho do I write a script to remove loose geometry from all objects?

Set the active object:

bpy.context.scene.objects.active = o

and you should check wether the object is a mesh object:

if o.type == 'MESH':
    ...


Driver expression: #frame
You can use drivers with #frame expression.
It's basically feeding the field with the value of the curret frame. By using a multiplying factor you can set the pendency of the curve.

It's also easy to edit: just right click the field or type in to override the expression.


How can I add a texture with an alpha channel without affecting the base materials opacity?

You are so close!

Delete the transparency node and make suitable adjustments.

Above the nodes overlay color.
The nodes select color by alpha channel.
There is no desired transparency in the final material.
There is no need for any transparent shader.
Selecting color and final material transparency are different.


Ok, after quite a bit of experimentation, this is what I came up with:

The green group (which is duplicated, because I couldn't get it to work otherwise) creates  half spheres, which I then append to the ends of a cylinder. As of now, changing the node setup is made so that the cylinder is aligned with the Z axis; you can model your object that way, to start, and then rotate it around, remembering not to apply the rotation. Also, changing the Z Cylinder Scale input value in the material allows you to scale the whole construction.

You can get the blend file here.


How Do I Lower My Polygon Count In Blender 2.8?

Select your object. Go to the modifiers tab (the one with the wrench icon)
and set ratio to 0.5 (50%) with the option collapse active.
That means that whatever your polycount face is, will be reduced by half that number.


The color of your cup depends on the color of the background, how much light you have in your scene, and the amount of objects you have in your scene. If you add a lamp or an object emitting light and set the value to at least 5, you will get a white mug


Since the color management applies at the very end of the chain, the sRGB transform curve modify the RGB values.
You will see a perfect match if you set the color management to linear (display device to none) save it as tiff with the checkbox save as render enabled, this way you can visualize a linear render without transformation.

But remember for real light condition you need to set the display device to sRGB (if you have a sRGB monitor) otherwise you'll not see the light like in real life, due to all the transformation operating during the chain.
So depending of what you are doing exactly (you don't provide a lot of infos about your workflow) you need to choose the correct way of doing things depending if you want to display or work with your image and how you would mix different footages.

Here it's becoming a bit complex, remember real light intensity is linear, but the eyes apply a contrast curve (a bit like sRGB transform curve), so to see an image like we see the world with our eyes, we need to display a linear image with the monitor.

The chain is like this:

The render is linear
We save it with a sRGB transform curve (not linear anymore)
The monitor transform it the opposit way, so the image is linear again
The eyes apply a contrast curve and we see it like really world

Light intensity is linear but we don't see it linear. It's a really interesting and hard topic to dive in.
Hope I have spread some light in.


Bad looking motion blur with cycles motion blur and vector blur

Your particles seem to be rotating a tad in-between the frames (bug in particles?)

The solution is to turn on rotation for the particle system, and leave the values at 0.

As for having different results between render and animate, try baking the particle system.


If Blender API document doesn't provide enough information of a function or class, what should we do?

The API is for the programmatic options and things.  What is happening in that line of code is a new node is being created of the type 'R_LAYERS' in the Compositor. In short, it just makes a Render Layers node. To know more about the node, you would need to look in the manual, not the API. Render Layers Node


Grease Pencil and also curves don't appear

One reason for missing annotations can be the fact that they are disabled in viewport;

Check your 3D viewport upper right corner menu, see if annotations is checked or not.
Or change Active workspace tab - Layout and Modeling tab for example show annotations by default.


It is possible to use Antialiasing in Multitexture mode?

Make sure Blender's interface is set to "Blender Game" (usualy in the top of the blender window):

Then go to the "Render" settings in the properties panel. Under "Standalone Player" you can set the antialiasing samples:

If you also want to enable Antialiasing in the viewport, which also affects the embedded player, you have to set it in the user preferences. Press [Ctrl+Alt+U] to open the User Preferences window. Then go to System and set Multisample to your desired AA factor.
You may have to restart blender for this setting to take effect.


What's the difference between the various Open Subdiv compute types?

The difference relies in in which device the actual calculations are done. CPU and OpenMP are run on the CPU, while GLSL Transform Feedback and GLSL Compute are run on the GPU.

  CPU - single threaded CPU implementation. it is mainly useful in cases when GPU compute is possible and threaded CPU option causes artifacts (it is unlikely to happen, but still possible).
  OpenMP - multi-threaded CPU implementation. It is similar to threading model of old subsurf code. Use it for maximum performance in cases when GPU compute is not available.
  GLSL Transform Feedback - uses GPU to perform calculations, has minimal requirements to video card and driver.
  GLSL Compute - uses GPU to perform calculations, supposed to be more efficient than Transform Feedback but also has higher requirements to video card and driver.

From the wiki r (archived version).


A function that returns True if all the properties of mod1 match mod2

def mod_equality(mod1, mod2, ignore=["name"]):
    return all(getattr(mod1, prop, True)
             == getattr(mod2, prop, False)
             for prop in mod1.bl_rna.properties.keys()
             if prop not in ignore)

Edit: added an ignore list.

Simple test in console, Cube with Subsurf modifier and copied.

>>> m1
bpy.data.objects['Cube.001'].modifiers["Subsurf"]

>>> m2
bpy.data.objects['Cube'].modifiers["Subsurf"]

>>> m1 == m2
False

>>> def mod_equality(mod1, mod2):
...     return all(getattr(mod1, prop, True)
...              == getattr(mod2, prop, False)
...              for prop in mod1.bl_rna.properties.keys())
...
>>> mod_equality(m1, m2)
True

A method to see if one object has same modifiers, all with same settings and in same order as another object

def same_modifier_stack_ordered(obj1, obj2):
    return all(mod_equality(m, obj2.modifiers[i])
                for i,m in enumerate(obj1.modifiers))


How can I export or print coordinates of each selected vertex?

Open up a new Text window and copy and past the following.

import bpy
import bmesh

# Get the active mesh
obj = bpy.context.edit_object
me = obj.data

# Get a BMesh representation
bm = bmesh.from_edit_mesh(me)

bm.faces.active = None

# Modify the BMesh, can do anything here...
for v in bm.verts:
    if v.select:
        print(tuple(v.co) )

Make sure you are in Edit mode with the required vertices selected and click "Run Script"

The coordinates of each selected vertices is now printed in the System Console.

If you can not see the System Console select Toggle System Console in the Window menu.

To get this code I used the Bmesh Simple Editmode template from the Templates/Python


The issue with the white dots is solved, I used different node setup, now it looks much better with hemi light as well:

Here's the node setup I used:


edges missing in wireframe view, but visible in edit mode

It's a feature from the past to save performance. Object Mode does not draw all edges by default, but skips them here and there. You have to tell Blender to draw all edges.

Go to Object tab, and tick Draw all Edges in the Display panel

.


Is there a faster way to close these holes

You should add a boolean modifier to merge the two objects. You might have a few new vertices in your mesh but it will be far easier to clean up once you have deleted the inner faces created in the operation.


Script meant to randomize camera position does not point the camera back to the object. What script do I need to point camera back at object?

Global Coordinates
Recommend you work in global coordinates
camera_location = camera.matrix_world.to_translation()

and set the cameras world matrix.
import bpy
from mathutils import Vector

def point_camera(camera, point=Vector()):
    point = Vector(point) # recast len 3 iterable
    cmw = camera.matrix_world
    direction = cmw.translation - point
    M = direction.to_track_quat('Z', 'Y').to_matrix().to_4x4()
    M.translation = cmw.translation

    camera.matrix_world = M

# test call

point_camera(bpy.context.scene.camera, (0, 0, 0))

Also at play here if pointing to an object is the objects origin can be anywhere... so if using a track to constraint may be easiest to track to an empty, and place the empty at objects bounding box centre (for example)
Given a mesh object ob its global bounding box centre location would be
bbc = ob.matrix_world @ sum((Vector(v) for v in ob.bound_box), Vector()) / 8

Note: Object constraints, drivers and keyframes all work together to create an objects world matrix.  Keep this in mind, as code above that sets the matrix world may produce strange results on constrained (or otherwise set) objects.


Press Ctrl+Alt+U to bring up User Preferences. Then go to the Input tab. Then expand Image, there you'll find UV Editor. Expand that and scroll down to the bottom and click on + Add New button.

In the identifier, input this: wm.context_toggle. Then in the context attribute, input tool_settings.use_uv_select_sync.

Finally select an unused keyboard shortcut. I used ` in this case. Select to Save User Settings so you don't have to do this every time you start Blender.


Copy animated viewport color to another object

You can do this by either copying the keyframes themselves or by sharing Action data in an NLA strip. Using NLAs means that changes made to the shared Action on one object will also be reflected in the behaviour of the other object.

Method 1, Duplicate Keyframes:

Select only the Viewport Color keyframes from your source object in the Dope Sheet.

CTRL+C to "Copy".

Notice that the Transform keyframes/channels are not selected.

Add a single dummy keyframe to Viewport Color on your destination object.

Select only the Viewport Color keyframes from your destination object in the Dope Sheet.

CTRL+V to "Copy".

Delete the dummy keyframes if they're still there.

Method 2, Shared Actions:

Place the keyframes for Viewport Color specially in their own Action datablock, and then push that Action onto an NLA track for both of the objects:

You can now add another NLA track or active action to keyframe the other properties of either object.


How to control animation speed and direction in BGE

I could not find any info and this, so since i figured it out, i would post the answer. I used logic block and a python scrip. The example is not for a follow path, but just a simple cube animation.

The game goes as follows:
Press space key to start animation, press again to stop the action.
Press the F key to speed up the animation, and press the S get to go slower.

I included some images.

import bge

def main():

# max frame of animation
maxFrame = 100

cont = bge.logic.getCurrentController()
own = cont.owner

frameAct = cont.actuators['Frame']

currentFrame = own.get(frameAct.propName)

# limit speed to between 1 and 10
speed = own['speed']
speed = max(1,speed)
speed = min(10,speed)

speedInc = (0.10*speed)

currentFrame = currentFrame + speedInc

if currentFrame > maxFrame:
    currentFrame = 1

frameAct.value = str(currentFrame)
cont.activate(frameAct)

main()


Those look like artifacts created by the denoiser. Use more samples to render and lower values for denoiser.

Or you might want to try the Intel Open Image Denoiser instead of the built in one.

Related links:

Type of Denoiser built into Blender

How to avoid noisy renders in Cycles?


I dont have enough rep points to comment, but, to comment, I did what you wanted, just with CTRL+B, not sure where the problems is with your bevel. Maybe, CTRL+A first ? scale / rotation / location....

OP edit: SpaceKat had recommended resetting my settings. Which I did by reinstalling the latest version of Blender 2.79B, the original version I used was 2.78. Using the newer version of Blender fixed the issue right away no problems at all. I wanted to give SpaceKat proper credit so I edited the post.


Looking at the PDB file of 1AD4 here, it looks like the PDB does not contain hydrogen. So you wouldn't see any Hydrogen atoms in the render.

As for colouring different chains, you can import each chain by itself, and then use a surfacing algorithm (MLP or EP) to generate a surface, once you have the surface, it should be easy to apply the material yourself.

If you want to create something simple without fiddling with Blender as much, take a look at MolecularFlipbook.


Editing different meshes together -- Bezier curve and Circle

You can never enter edit mode in two objects at the same time, this is a fundamental part of Blenders design philosophy
If you want to edit two meshes at the same time join them together with Ctrl+J. Have in mind that this may have undesirable effects, and will mess with modifiers.
Knife project doesn't require entering edit mode in two objects at the same time, only the object to be cut. You may be confusing it object mode Boolean operations
Knife project will not work well for what you are trying to achieve. It only works when the "knife" object is a flat shape or fundamentally bi-dimentional

You may want to use the Boolean modifier or edit mode Boolean Operations instead. The former requires two objects, but no edit mode, the later requires you yo join both objects.

Have in mind that both Knife Project and Boolean operations are discourage modelling tools. Booleans are very prone to errors, and both will produce low quality meshes, with bad topology, duplicate geometry, artifacts, hard to texture and bad for animation.


The answer is easy. Blender has no idea which edge loops you consider to be connected. In Blender, connected means there have to be edges between the verts. Your top and bottom edgelines are not connected and logical, implied connections do not count. The local symmetry of the topology of your eyes isn't picked up by the selection tool.

You can use Box-, Lasso- or Circle Select or you can add to the selection using Loop Select more than once, SHIFTALTRMB. If you needed a certain selection a lot, you could even assign the verts to a vertex group and select them that way. But Loop Select will not bridge gaps. Your topology is not to blame.


The CM panel is somewhat confusing due to some unfortunate labelling.

  Now it seems to me that I have two options for Display Device in the
  Color Management Panel, either sRGB or None. I guess the color space
  for the monitor will be sRGB when I chose sRGB ?

Display Device is nothing more than a collection of View transforms. Think of it as a grouping.

  What happens when I chose none ? Will I see the linear color space

Close but not quite. You will see whatever the reference space sees. If you assign a different colour space to an image in the UV Viewer for example, you will see whatever you have set the image to, as transformed to reference. If you properly linearize a display referred sRGB to display linear via a correct transform, you would see those values dumped directly to display. In the case of a typical LCD panel however, we have to remember that such electronic displays, though they operate almost strictly linearly, will have a 2.2 power curve baked into their lower level hardware. So the not-so-simple answer is that you would be seeing display linear values dumped to a 2.2 power curve in all likelihood.

  I guess under normal circumstances there are no reasons to correct
  exposure or Gamma ? When would this be useful ?

One could correct exposure via the exposure control, however in most typical situations, the two controls are used to check compositing. Bending values can reveal problematic keys, comps, and other details, as well as previewing looks / creative grades, and how materials respond.

  When choosing "Default" this means "Does no extra conversion besides
  the conversion for the display device.". That seems fine to me.

Default is simply a label. It is the sRGB specification's transfer curve. While default, the sRGB transfer curve was never intended for rendering, and has many implications. See some of my other answers on wide dynamic range for further information.

  Is this about rendering image sequences ? Or video editing ? I am not
  sure what is meant here.

This is a byproduct of the VSE being hacked around how OpenColorIO was designed to work. It is how the VSE sees image data in its reference. That is, it is a hack around how OCIO was designed to give the VSE a unique reference space.


In "Edit Mode" select The bottom vertices and one edge and mark them as a seam by pressing CTRL + "E" and selecting mark seam from the drop down menu. Then in the UV Editor while in "Edit Mode" select all of the vertices
and unwrap them by pressing "U" and selecting Unwrap from the drop down menu.


How can I remove shading on a plane but still allow shadows from other objects to be cast on to the pane?

The simplest solution I can think of is to use the default Principled BSDF setup (using base color, not emission) and change the type of the light source to Sun. This way, neither cube position, nor Plane position, will change the colors on the plane (other than the colors of areas that go in or exit the shadow).

The reason your examples don't work is that in one case the image is the light, so it can't be shadowed, and in the other you're using a light type with a falloff - simulating the fact that the closer a pixel is to the light source, the more photons from the light source hit that pixel - for the same reason the Sun heats ground the most at noon on Summer. You can lit a surface equally, if it's a fragment of a sphere, with the light source in the center of the sphere - same logic as with curved PC monitors. As you increase the sphere, given the fragment's surface remains constant, it will be closer and closer to a flat surface as it gets further and further from the sphere's center:

If you want a perfectly flat surface, you need an infinitely far light source, and that's what the Sun light type represents.


It seems that the original add-on has been discontinued. However, there's a community supported branch of the add-on available at https://github.com/animate1978/MB-Lab/wiki


why is add skin data used in skin modifier? I found it always inactive

It's used in a very specific cases when you change mesh data on object with Skin modifier (from dropdown if you select other mesh data in Data tab). Then you click this button so Skin modifier updates. Was added after this issue (link).


Is there a way to designate a vertex group *without* weight painting?

In edit mode select the vertices you want, the weight you want, and use "assign" in the data properties:


You may use some IK (invert kinematics) and some constraints to do this kind of things.

I did a very basic model to show that :

I presume you know how to parent a mesh to an armature, but if not, please leave a comment and I could complete that.

The body is parented with automatic weights.

The gun is parented too, but all the weights are given to the root bone.

The right hand has a IK constraint with a chain length set to 4 in order to end at the shoulder (the yellow line you can see in the gif above) :

The left hand is done the same but it target an empty indicated by the green arrow :

The gun now : its root bone has a constraint in order to follow a little bone of the man armature parented to its right hand. This allows the gun to follow this hand :

The empty has a constraint too which makes it follow the gun extremity, which is the bone indicated by the arrow in the 3D view below :

So, to summarize :

The gun follows the right hand
The empty follows the gun extremity
The left hand follows the empty

But in some situation surely, you want to free the left hand, because the man position needs it. So simply lower the influence of the left hand constraint to allow it to come back in place. You are also free to move it independently :


Rounding a spinner on a British Spitfire

Here are the steps I would take to model that:

1: construct a base set of vertices from one side of the rounded top, like so:

Add a screw modifier: (make sure it is lined up to the axis for this part).

Then finally add a subidivision surface modifier to make it higher poly:

I hope that is what you are looking for. You can just adjust the vertices (or line them up to your image) to get the curve you want. When you are done, you can apply the modifiers and put it on your plane.


Align rotation with the snapping target users interface?

Its pretty straight forward in blender

Option 1:
Please Go to;

User preference -> Themes -> 3D view -> Object selected

You may change the color to your own choice

Don't forget to save user settings at the bottom

Option 2
Alternatively you may fully change the theme

User preference -> Themes - Under presets there are lots of good ones


Workflow and image/video formats for rendering high quality photos as animations?

It is more common to save the output of blender rendering as a set of PNGs.  You can turn up the compression in the Render > Output section, but I can not predict if it will save space compared to the OpenEXR.

Making a VSE output to compressed video (as you do) is very common, and almost required if there is any sound involved.  The settings you use for the final video render will vary depending on

how much bandwidth you are willing to allocate for streaming
resolution of video (3.75Mbit/s MPEG-2 is CableLabs VoD standard for SD.  You will want 4-9Mbit/s for H.264 1080p video)
what formats are supported by the client software (motorola DCT-2000 -vs- iPhone)
does the container support the codecs you want (MPEG-2 program stream doesn't support AAC and blender does not seem to support transport streams)

Some more reading is at http://wiki.blender.org/index.php/Doc:2.6/Manual/Render/Output/Video


BLENDER RIGIFY ERROR (Generation has thrown an exception: 'bpy_prop_collection[key]: key "ear.L.004" not found')

I saw your file. The ear bone is there but it was not un-parented from the other bones for some reason
You have to parent

ear.L.004 to ear.L.003
ear.R.004 to ear.R.003

Parent with Connected.
Also your metarig has Scale that has not been applied so most likely you'll have to press CTRL+A > Scale (in Object Mode!)


Distance from the surface as an input node for use with volumetric materials

You can use an OSL shader that measures the proximity of the mesh from within a volume. It works by projecting out rays from each point in the volume to probe the surrounding mesh. Be warned that this will be extremely CPU intensive as it has to trace multiple rays from each point within the volume which is significantly extra CPU work.

Here's the shader in action, varying the emission color based on depth :

Here's the code :

shader volume_meshproximity(
    vector Point = P,
    int Iterations = 1,
    output float Min_Distance = 0.0,
    output float Max_Distance = 0.0,
    output float Avg_Distance = 0.0
    ) {

    float x;
    float y;
    float z;
    vector rand;
    float scale = 5000.0;
    float sum_dist = 0.0;
    float max_dist = 0.0;
    float min_dist = 0.0;
    float Distance = 0.0;

    for (int loop = 0; loop < Iterations; loop++)
    {

        rand = noise(Point*scale,loop*scale);
        x = rand[0] - 0.5;
        y = rand[1] - 0.5;
        z = rand[2] - 0.5;

        if(trace(Point,normalize(vector(x,y,z))))
            getmessage("trace", "hitdist", Distance);
            //getmessage("trace", "N", Normal);
            //getmessage("trace", "hit", Hit);

        if (loop == 0)
        {
            sum_dist = Distance;
            max_dist = Distance;
            min_dist = Distance;
        }
        else
        {
            sum_dist = sum_dist + Distance;

            if (Distance > max_dist)
            {
                max_dist = Distance;
            }

            if (Distance < min_dist)
            {
                min_dist = Distance;
            }
        }
    }

    Max_Distance = max_dist;
    Min_Distance = min_dist;
    Avg_Distance = sum_dist / Iterations;
}

To use it, make sure you're using a version of Blender compiled to include OSL support and enable the Open Shader Language checkbox in the Render properties.

Create a new Text block and paste the above code. Name it something like 'surfaceproximity.osl'.

In your Node Editor, add a Script block and select the 'surfaceproximity.osl' text as its source. This should give you a node like this :

The 'Iterations' control how many 'probe rays' are projected out from each volumetric point - more rays will provide slower renders but sharper results (since it will sample more internal geometry of the mesh). Point is the location in World space for the origin of the probe rays (pass the Object texture coordinate through a Vector Transform node to transform the point from Object to World coordinates). The resultant 'Min', 'Max', 'Avg' are the minimum detected distance (ie, the closest point) the maximum detected distance (the furthest away point) and the average distance of all probe rays (gives an indication of how 'enclosed' that part of the volume is (a thin section of mesh will tend to have a smaller average, a wide open section will have a larger average - when compared to the min and/or max).

The 'Min_Distance' can be used to indicate the depth from the surface of the mesh. For example, it can be used to control the density of volumetric Scatter/Absorption to give Suzanne an internal skeleton as follows :

Here the OSL shader is set to project 16 probe rays (Iterations) from each point within the volume. This controls the density of the Volumetric Scatter such that closer than 0.1 blender units (the Greater Than node) it is transparent (density 0) whereas further in than 0.1 blender units it is opaque (density 30). An Emission shader makes the 'skin' of Suzanne surrounding the 'skull' visible to show the effect. Adjusting the 0.1 in the Greater Than node will vary the thickness of the 'skin' (ie, the depth at which the 'skull' begins).

This produces the following results :

Blend file attached.

Similarly, you could use a Less Than node to create a 'Solidify' effect (the inverse of the above example) or drive the Volume density directly from the output of the OSL node to vary the properties smoothly - as mentioned in the original question.


A relief can be generated using shrink-wrapped plane over the object.

Procedure (tested on Blender 2.79)

Add the object to blender and a base plane. Position the object over the plane.

Add another plane over the object and the plane on the bottom.

Subdivide the plane until the mesh is relatively fine.

Apply the shrink-wrap modifier to the object. Set the mode to 'Project', set the target to the object name (in this case 'Suzanne'), set the auxiliary target to the base plane (in this case 'Plane').


I solved this by using a displacement map. Using Blender 2.8, I used a space shuttle thermal tile texture to influence the height of a displacement node and plugged that into the Material Output displacement. You also need to enable "Displacement and Bump" in the Material Settings -> Surface -> Displacement settings.

I realize this isn't procedural, as I originally asked, and it's not the exact texture shown above, but it solves what I was trying to do in a relatively simple way.

Here's the texture I created, in case anyone wants to use it in their work. It's made from several images of NASA's Space Shuttle thermal blankets.


How to combine Hair and Rigid Body physics?

As far as I'm aware, Rigid Body and Particles don't work together - this is the case for hair and also for particle collisions - the particle simulation mostly ignores the state of the rigid body (for collisions and hair, although it strangly does work for particle emission, just not hair). It's not likely to be fixed by the developers due to the current and planned re-development of the physics simulations (which will hopefully support such cross-simulation interaction anyway). The only solution at the moment is to select the Rigid Body object and 'Bake to Keyframes' so that it is no longer a Rigid Body simulation - then the hair simulation should work fine.

Update
Just found https://developer.blender.org/rB342a6b5f9339c31931f4d2c87d9f47b88307e8cc, which mentions a recent change to how the modifiers (which includes collision and particles and hair) are applied in the sequence of applying the various simulations. With the Rigid Body Collision set to 'Base' your hair (with Hair Dynamics enabled) should follow the rigid body - without having to Bake to Keyframes.
I put together a crude example to demonstrate (Blender 2.83.6) :

Note that after changing your RB settings to 'Base' you will likely need to free and re-bake your hair simulation (or invalidate it by performing another change on the hair properties or base mesh).


How do cycles' emission strength values relate to real-world units?

From the documentation: "Strength input: Strength of the emitted light. For point and area lamps, the unit is Watts. For materials, a value of 1.0 will ensure that the object in the image has the exact same color as the Color input, i.e. make it ‘shadeless’."


How to straighten edges along an axis point

I'm hoping this is the situation:

.. you have a good reference top edge to the plane containing the skew loops.

Create a Custom Orientation from the top edge by using the little '+' in the Header > Transform Orientation dropdown, and set Pivot to Active Element, then:

(above) Bottom edge selected, with its good reference vertex active,
in the new orientation,SShiftY0 make the bottom edge parallel to the top edge.

Left edge, all verts selected, Loop Tools > Space make them regular

Same for the right edge.

If you're missing the good reference points in this answer, let us know what else you need to fix before following these steps.


Getting the color of a movie clip under a tracking point

You can extract the color directly under a Tracker like this


Translating the center of a group of objects to the world origin

Use the matrix world.

  is there an alternative to my approach to move the center of a group
  of objects to the origin?

An objects matrix world gives us access to global coordinates.  Hence could look at all the global coordinates of objects, get the mean and subtract it from each.

import bpy
from bpy import context
from mathutils import Vector

obs = context.selected_objects

o = sum((o.matrix_world.translation for o in obs), Vector()) / len(obs)

for ob in obs:
    ob.matrix_world.translation -= o

On parenting. In the UI we are used to seeing child coordinates such that the parent inverse matrix is identity.  To do this in code would set the matrix local of each child to be in the object space of the parent.  To do this we multiply its world matrix by the inverse of the parents.

Taking up script above, from mean calculation

bpy.ops.object.empty_add(location=o)
mt = context.object
mwi = mt.matrix_world.inverted()

for ob in obs:
    ob.parent = mt
    # alter ob.matrix_local
    ob.matrix_local = mwi @ ob.matrix_world
    # instead of
    # ob.matrix_parent_inverse = mwi
    # which retains matrix_local

mt.location = (0, 0, 0)
bpy.data.objects.remove(mt)

Note the difference here is that the local coordinates are being altered directly to what is the result of setting parent inverse (and keeping local coords same).

The latter is the reason the objects would return to original location when parent  removed,  parent inverse isn't used in calculations.


How to slice a disc, and yet keep the pieces locked in together?

Start blender and delete the default cube.

Press Num Pad 7 for top view. Your scene should look like this:

Now press Shift+A and select Mesh ‣ Single Vert ‣ Add Single Vert

Now press Tab to enter edit mode. Press E then Y then 1 to extrude the vertex up on the "y" axis.

Now set Pivot Point to 3d Cursor.

Now press A until both your vertices are selected, then Alt+R to spin your mesh, and finally F6 to bring up the operator settings. Copy the values below (22 steps and 360 degree angle).

Now press A until until all vertices are selected, then go to Tool Shelf ‣ Tools ‣ Mesh Tools ‣ Remove: and click Remove Doubles.

Press Ctrl+Tab and select "Face"

Now select a face and press Y to separate.

Do that for all the faces and you are done.

I hope this helps you.


What is the key combination in 2.8 that brings up the cursor moving pie menu?

It's called the "Snap" menu, opened with Shift+S.


Texture Paint: Pixelated after texture paint

Generally, you should be aware of two things:

The resolution of the background image.
The level of detail of the paint texture.

In your case, I'm not sure how big you build the background image, but if it's 2048 x 2048 px, then, in the current zoom level, the stencil texture may probably covers about 10% of the whole area, which means 648 x 648 px around, far from enough, isn't it?

Besides, your stencil texture seems sort of a gravel texture, which means the detail unit is quite small. Obviously, you need enough pixels on the background image to at least cover the detail of the a unit gravel, in order to preserve the original detail as you want.

My suggestion is: try not to have the background image over zoomed in while painting.


Pipe joint addon: changing individual cylinder's geometry (radius, length)

The geometry of the objects added from the pipe joint addon is the same as any of the other items, whether from the primitives menus, or added by a user, and can be manipulated the same way. Portions of meshes which align neatly with one of the primary axes, in the case of the pipe joint "y", the base which aligns with the z axis are fairly easy. Make a couple of loop cuts, slide them up the cylinder to where you want them, scale them to zero in the appropriate direction (in the case of the base cylinder, this would be "z"), then lock the z axis and scale them to size on the x and y axes.

When the case of the arms of the y-joint, it is a bit more difficult for me, as I've not figured out a good way to move items along an axis which was not parallel to one of the principal axes. With to my current skillset, my procedure is illustrated by this image:

where I use "helper geometry" to get the alignment correct. Sharp eyes may note that in the illustration in step 10 I've not yet removed the helper geometry, but it's trivial to do, selecting the helper geometry edge in edge select mode, and removing the edge only.

Another option, is, of course, to rotate the whole mesh at the beginning so that the axis you want to change is aligned with the x, y, or z axis, and use the simpler procedure outlined above.

Finally a workflow comment: if you are using a lot of modified pipe joints, I'd keep the modifications in a separate blend file, as separate objects, and import them to your working file by appending them. Once you've got one modified y joint with an enlarged arm on one side, it's trivial to create a new instance of that joint, and change the size of the arm for a different location in your mesh.


This is my computer's OpenGL issue, according to people at blender's bug support.
Downloading this file and putting it at the same folder where blender.exe is will fix the issue.


Apply scale. Press Ctrl+A. Apply scale

Now select the empty and rotate


How do i unlink different parts of a 3d model?

You have successfully separated the objects, but they share a single material. This is indicated by the number of users next to the material name.

In order to create an individual copy of the material for the active object, click on the button with the number.


Project looks like it has doubled faces but doesnt

In your Properties pane, you have "Ambient Occlusion" turned on...uncheck that and it'll be fine:

Unless you want AO in that view, but be aware you'll see the artifacts.

If you want AO in your render, that's not where you should select it.  The AO setting for Renders is in the World pane:


How to fill a triangular shape with quads?

Credit to batFINGER (in the comments): "Related, What's the fastest way to turn a triangular face into three quads? in that once a triangle is 3 quads, each quad can be broken down into more. (still maintaining the 3 (edge) pole vert in the middle)"


How can I change the color of node names?

Thanks to Leon Cheung for this answer:

Theme -> Node Editor -> Theme Space Settings -> Text

Another alternative is:

Preferences -> Node Editor -> Node Backdrop


You could use a sin() function and a driver to animate e.g. the X scale. In Object Properties under Transform for one of the cylinders, click the number in Scale: X and type in something like:

#1.0 + 0.2 * sin(frame * 2.0 * pi / 30.0)

That'll vary scale every 30 frames between 0.8 and 1.2. For later cylinders you can offset the phase a little:

#1.0 + 0.2 * sin((frame + 5) * 2.0 * pi / 30.0)

That'll put that cylinder 5 frames ahead in the animation.


I'm doing something wrong while trying to PARENT an object together

Apply transformations to both the objects
Select the child object then the parent object, ctrl+p ("keep transform" - this maintains distance between objects)


Can you insert other objects, or is it only the plane that doesn't appear in your project? Also, as stated above you can always look for your plane in the Outliner (file browser in the upper right corner of the Default Blender view) for your imported plane. If it is in your outliner, select it and press "." to teleport to it. If it isn't, it may be a corrupted project file or plugin; in that case, simply start up a new project and see if you can import an image as a plane there instead.


There is a white phone that is not visible in viewport but active for render.


Why does sliding edge makes it slide being mirrored?

From my admittedly limited testing I believe it is a side effect of being in face selection mode.

By selecting the whole side face instead of only the desired edges you are unintentionally also edge-sliding the vertical edges perpendicular to the view plane. Somehow the tool's geometry calculation probably gets confused trying to slide both loops at the same time while sharing the same corner vertex.

You can see it behaves as expected when selecting two edges only, but behaves unexpectedly if the side face is selected instead.


is there have any way to use a Virtual numpad?

Enable the pie menus addon, one of the pie menus it adds is the view menu which is attached to Q.


How to combine two different textures into one

This can be done easily with some baking in Blender.
First, join your two object together with CTRL J.
Create UV map for your bake that include both objects.

Then create a new image for your texture bake, create a new material for it, and make sure it's selected.
Then go to the textures tab, create a new texture, and create (or link in) an image; for example, to create a new 4096² texture image for the output:

Then go to the Render tab of the Properties editor, and ensure that the Render Engine is set to Cycles (othwerise the Bake panel below will not be available):

In the Bake panel, set the Bake Mode to Textures, and press Bake.

You should get something like this. (of course it will be your textures instead of mine)

Then just save out the image, remove the other material slots and the first UV map, and you should be good!


How do I align the view to the local axis of an object?

Press Shift in combination with any of those number pad numbers to align to the local axes of the selected object.

Note that this will only work if you have rotated your object in object mode and haven't applied the rotation. If you have rotated in edit mode or applied the rotation then you can select a face (or vertices or edges) of the object and use Shift+1 (3,7,9 etc.) to align the view relative to the axis of the selected element.

If you use Ctrl+Shift in combination with the numpad numbers you will align to the opposite view of the object's axes, e.g. bottom, back instead of top, front.


How to get fragments of an exploded object to react more accurately to collisions with a plane?

You can make the explosion shards/particles rotate dynamically by enabling Rotation and Dynamic in the particle settings:

Result:

However, if you want realism I recommend you try the Cell fracture addon with rigid body physics. See this question for more info.


As Chebhou suggested in the comments, the 2D image stack can be achieved with dynamic painting an animated plane.

Add a plane, and animate it to pass through the main mesh
In the physics panel of the main mesh, enable Dynamic Paint and make it a brush
In the physics panel of the plane, enable Dynamic Paint and make it a canvas with these settings:

Format: Image Sequence
Dry time: 1
Dissolve time: 1

In the Dynamic Paint Output panel, click "Bake Image Sequence" to write out the plane/mesh intersection at each frame of the animation.


Smoke does not show in Post-render (neither Cycles nor Evee) (Blender 2.81)

The issue is that you haven't baked the simulation.

Save the .blend file.
Open the Physics Properties and click Bake in Smoke > Cache.


How to create a flickering light source using cycles?


Can't edit particle fluid or boid physics settings through python

Thanks for the clear question. I just added the bpy.types.Scene.update call and in Blender 2.79a it works.

import bpy

bpy.ops.mesh.primitive_plane_add()
emitter = bpy.context.object

mod = emitter.modifiers.new("ParticleSystem", type = 'PARTICLE_SYSTEM')
stngs = mod.particle_system.settings

stngs.physics_type = 'FLUID'
bpy.context.scene.update()
stngs.fluid.solver = 'CLASSICAL'    #This line results in the error
stngs.fluid.fluid_radius = 0.05     #So does this one if I skip the one above

Sleep

sleep will never work in Blender as blender will halt mostlyduring the running of a script. Blender will just wait until the script has finished completely and then run the internal variant of bpy.types.Scene.update.


How to do beveled curves with changing cross sectional shape along the curve?

You can simplify this by manipulating a straight object by hand and use a curve modifier. It is much easier to change this not bended object using your favourite technique like sculpting, lattice, skin or completely by hand in edit mode.

Let's start with a curve.

I will then create a linear extrude and give some variation in the cross section. In this case I will do it by hand  and provide a good enough resolution along the axis using loop cut.

Applying the curve modifier will deform the object along the curve. If the longitudinal resolution is not good enough, the deformed shape will not look continuous. Some tweaking or smoothing may be required.


Why can't objects in Edit Mode have their own name?

Blender uses a hierarchical structure to organize data.

Basically the confusion comes from the fact that you can Add a Mesh in Object Mode and Edit mode, but they are not the same.

So what is the difference?

When you add an mesh in Object Mode you are creating both, a mesh and an object. Objects created in object mode are independent of each other, meaning that they will be named with a unique name and will all have their own separate origin (or pivot point), and can be transformed independently.

As an example: Two objects created in object mode show as different objects in the outliner.

Meshes created in Edit Mode are part of the Active object, an already existing object that is being edited.

In this example, the monkey's mesh becomes part of the object called Cube and does not show in the outliner.

Objects can contain one or many meshes, connected or not.

All meshes within that object will share a common origin and will behave as what they are: a single object, meaning they will move, rotate and resize together when transformed in Object Mode.

To answer the question:

Objects must have unique names (blender will not allow the exact same name for different objects). Meshes within an object cannot have a name.

If you need to differentiate parts of an object, you can create vertex groups. Vertex groups can be named, but they will still be part of the same larger object that encloses them and cannot be selected directly in object mode.

To separate parts of a mesh and turn them into a new independent objects (with their own unique name and pivot point) you use the separate function (pressing P) and choosing if you want to separate by selection, unconnected parts or materials.


You have 'Face selection masking' turned on in the 3D view header (2.79):

The selection masking options in 2.8 are found here:

This means that only faces that are selected in edit mode will be able to be painted on when weight painting. It's useful to use as a mask in case you want certain parts of the mesh to be excluded from weight painting.

Either disable this button or select all the faces that you want to weight paint in edit mode before returning to weight paint mode.


Particle Hair Not Assuming Emitter Color

Having other maps such as normal map will cause all hair to show as black, I duplicate the material and disconnect every texture input other than base color, then assign it as the active material in the particle system to fix this.
I had a similar issue pop up which is unrelated. The hairs had desynchronized from the source mesh and were projecting the UV map in a really bad way. It was using the texture area for the characters mouth and tongue along a good stretch of the back, freaky!
If this happens, Click 'Disconnect Hair' near the top of the particle system setting panel, then after it has changed to 'Connect Hair' click the button again.
Another issue I've had is displaced or outright exploding hair caused by changes to the source mesh, this includes many modifiers and subdivision. Checking 'Use Modifier Stack' did not work for me here, strangely.


I'm just rewriting this whole answer i response to your edits, which reveal that the problem is with your node setup.

There are two (or more) ways to do one bump.  One is to use the displacement output with a material with bump displacement enabled.  The other is to use a bump map node to distort a normal and feed that into a shader.  Usually, not both (although there can be times for that as well.)

The easier, more typical way to do it is via displacement output.  Displacement expects a value.  Not a shader.  But you're plugging the output from a glossy BSDF into displacement.  That doesn't make any sense.

Here's proper node setup for bump mapping.  The image is 32 bit, which I recommend for bump textures, and I've just drawn manually, in UV edit paint mode, with brushes at default settings other than size.  Notice that to modulate the bump map, I've run it through a multiply (math) node, rather than using a bump node.  Although it can be a bad idea to run nodes from color to value, here it's fine, as it's just a grayscale image.


How to get rid of fireflies ?I had tried many solutions but it doesnt work

Go to the layer properties tab and tick the denoising box


Try re-baking your particle cache. You may need to click 'free bake' first before 'bake' will become available.


It looks like you did't add the Armature Modifier to the shoes. You need the armature to deform the shoes, using same vertex group names you used for feet.


While you can't really pause it, the best practice is actually to output the individual frames as single images. That way, if the process needs to be stopped, you can resume it from the last rendered frame.

To do that, go to the Output menu, in the Output Properties tab, and set the File Format to an image format of your liking. I'd recommend that you also create a dedicated temporary folder to house the raw frames, and instruct Blender to output the images there.

Once all the frames have been rendered, you can proceed to converting them to a video format. To do so, open a new instance of Blender and, in the Video Sequencer editor, click Add > Image/Sequence then select the previously rendered frames. Set the animation playback's start/end frames to match those of your image strip. If you want to, in the dropdown menu in the top bar, select Sequencer/Preview and check if the animation is in order.

Finally, in the Output Properties tab, select a video format, a suitable Output location and click Render Animation. Blender will then convert the image strip into a video.


Generate Curve from Motion Path of a Bone (to animate steering of a fork lift)

My good Buddy ClockMender has an excellent tutorial on this.
\


Yes.

Select an edge and press ⇧ ShiftG> Length. By default this will select all other edges with equal length to the active edge.
By adjusting the options in the redo panel (F6) or at the bottom of tool shelf (T), you can also select edges with greater or lesser lengths and compare lengths with a threshold to select edges that are not exactly the same length, but similar.

Once you have a partial selection on the billboards you want to select, you can select all geometry connected to the selection with ⎈ CtrlL. Or in the case of a plane, by switching to face select mode (⎈ Ctrl↹ Tab) while holding ⎈ Ctrl.


Creating a half tone like pattern with cylinders using Geometry Nodes

Blender 2.92.0. Let's start with a subdivided plane.

In edit mode select all faces then in top left corner click Face->Poke Faces

Then Face->Tris to Quads

I added a subdivided cube, because in my opinion it looked nicer than cylinders, and an empty to control the scale for animation purposes.

And I did this node setup.

From left:

Attribute Fill node sets scale on every instance (vertex) to 1.
Attribute Vector Math multiplies position of each instance by vector (1,0,0) and saves result to a custom positionX attribute, so positionX contains only (X,0,0) of each instance.
Attribute Vector Math calculates distance between positionX and (X,0,0) vector where X is X part of Empty location. Result of this operation is saved as custom attribute distanceX.
Attribute Vector Math divides scale of each instance (it's always set to 1 by Attribute Fill node above, but you can instead of it use Attribute Randomize to make initial scale of every instance a little different) by distanceX. This works fine for most cases, but when empty is really close to an instance we end up with extremely large scales (for example 1/0.001 = 1000)
Attribute Math is used to control how wide the "wave" of large instances there are. The larger the float value the smaller the "wave".
Attribute Color Ramp is placed to cut the scale so it never exceeds 1. It allows you also to control how small the far away instances should be. (just change color from black to dark gray)

And this is the final result.

You can animate the scales of the instanced objects by moving the empty so the animation is really easy.


How to bevel selected edges in non-destructive way?

You can set bevel weights on individual edges.

To enable this feature in the modifier, select Weight

Now go into edit mode and make sure you are in edge selection

Now select the edges you want to bevel (shift click for multi-select).

Now go to the Edge menu and select Edge Bevel Weight

Move the mouse to modify the value.

Once done you can use the panel as shown:

You can fine tune this after by hitting F9 to modify last operator.

Update

So while this works for most geometries, it seems that something odd has happened in your file.  I suspect that one of your addons has already been weighting your edges and combined with what we are trying to do here, makes for an unhappy mesh.

So I removed all you modifiers and created a vertex group with 4 vertices for the excision ( cut-out). Then, I recreated your bevel modifier with 40mm. The trick to getting this working correctly is adding an edge-loop in the center as shown.

Now you should have your rough cutout shape.  Here's the settings I used for this first modifier.

N.B. you must use Width Method: Width here:

So now it's time to setup the second bevel modifier weights as described above.

Make sure to pay attention to which edges have weight here:

And finally the settings I have used for this second bevel modifier are:

And the final geometry:


How do I hide these lines from automatic weight bones?


Creating a point at two intersecting lines

The easiest way will be to delete the free floating vertex, then subdivide the edges once (the only edges ones that will be left in the circles after you delete the vertices) and fill in the faces.


How to have an object lie on a specific face

In your case, this is pretty easy to do, since your mesh is already aligned to the axes.

Position the 3D cursor at the bottom vertex of the triangle you have selected. You can do this by selecting that vertex, then hitting SHIFT + S, Cursor to Selected.

Duplicate this vertex with SHIFT + D, and move it away along the x-axis.

Set the pivot point to 3D cursor. In your snap settings, Snap to Vertex, Snap with Active, and make sure Rotation is enabled. (https://i.imgur.com/RBV0Z5U.png)

Select one of the other two vertices of your target face, then with your cursor over the mesh, hit L to select the rest of the mesh while retaining your active vertex.

Press R to rotate, Y to constrain the rotation to the y axis, and snap to the vertex duplicated earlier.

These instructions work in this case as I say because your mesh is already aligned with the axes. If you need to align an object to lie on a face that has an arbitrary initial orientation, see the answer to this question: How do I orient a face so it lays flat?
It's a bit more technical and finicky, but it's really powerful once you figure it out.


custom color property in panel draw layout

The graphical representation is determined by the subtype field which is set in this example to 'COLOR'.

from bpy.props import FloatVectorProperty
...

object_color = FloatVectorProperty(
   name="object_color",
   subtype='COLOR',
   default=(1.0, 1.0, 1.0),
   min=0.0, max=1.0,
   description="color picker"
   )

Documentation on custom properties,
Nice tutorial on addons


What is this artifact and how to avoid it?

This is the sort of pattern that can arise in the transition between 'kite' quads and more regular quads under subdivision

If you can arrange for the transition to be inside a single-material region rather than at the boundary between materials, it doesn't show:

here, by I insetting the polar region

The Catmull-Clark subdivision algorithm drags newly-created edge-points away from the previous concentrations at one side of a face.. this shows the transition between Simple and Catmull-Clark subdivision:


Well, in the EXR image opened in Blender you can clearly see the lines in the top and bottom of the image, as well as in the viewport:

Just paint them away with Gimp, for example (which supports float EXR textures nowadays)


Why can't I snap curves vertices to vertices?

This is one of the cases where some Blender feature doesn't work properly until you Apply Scale.

Select the curves
Press CtrlA
Select Scale

The snapping should work fine then.


Does Cycles f-stop effect the brightness of the render

No the F stop has no effect in the overall brightness of a scene like it does in real life. It is meant to affect focus and the depth of field primarily.

In real life a opening the iris by one f stop would mean that twice the light would enter the camera making things brighter. 2 stops would be 4 times the amount of light, and so on in a square progression.

That does not happen in blender.

Here's an example:

F stop 0.5:

F stop 22:

Notice how the figure in the middle remains with no brightness change.
In the real world the first image would have been much brighter by several magnitudes.

Here's a simulated illustration of what you would get if by every stop the intensity of the light would change:

To control the overall exposure of a scene in cycles you have several options:

Using the Film->Eposure control.

Depending on what you are after you can also use Nodes on the compositor (Hue/saturation/Value, brightness/contrast/ gamma, or even tone mapping)

Or by messing with the color management's exposure control:


Is it possible to make randomly colored objects via the compositor in Blender Internal?

This is relatively simple to do, pick your add on: Animation Nodes or Sverchok, and per Object color is easily done via Color props of an Object. You can use AN Object Attribute Out or SV Object Set nodes to change Object Color.

Turn on Object Color in Material, and change give different color per Object, easily visualized and will render in BI.


Image with lots of reflections is split in half in the final render, but not in the render preview

I figured it out. The problem was caused by a glass pane which was hidden in the render preview but was present in the final image. The glass distorted the render.


Multiples animations in a single blend file

You can save multiple animations (called Actions in Blender) for a rig by using the Dope Sheet and changing its context to Action Editor (switched with a dropdown menu in the Dope Sheet's header). From the Action Editor, each animation can be stored as an Action datablock (the same way you can have multiple mesh or material datablocks).

Important: If you store multiple actions make sure you give each action a fake user by clicking the F button to the right of the Actions datablock in the Action Editor's header. Failure to do so will result in you losing animations after saving and closing Blender. This is because all datablocks without users (including Actions) are purged when a file is saved and reloaded. Giving the action a fake user prevents that from happening.


Align loopcuts (so it looks like one big face)

A series of narrow/thin faces like this will easily lead to such problem if the "big face" isn't as flat as they were coplanar. So the main problem here is about topology actually.

Try following steps to solve this issue:

Select all narraow/thin faces that form the "big face", then press F (or X > Dissolve Faces) to make it as a big Ngon face;
Press Spacebar and search for Split Non-Planar Faces (or access from Mesh > Clean up > Split Non-Planar Faces); F6 to adjust the max split angle until you get the expected result. (In your particular case, setting to 0° will triangulate it too, which means you can ignore step 3 below);
CtrlT to split Ngon faces into triangles. (optional)

Tip: For Step 2, You can also split it manually instead. Two nice ways are:

Press K to enable Knife tool, then cut line(s) on the big face;
Select two vertices, then J to connect them by adding a new edge on that face.

Either way above can help when doing retopology.

If you really don't want to change the topology too much, then a quick and dirty way at least would be:


In this case, the softbodies can be used to mold the geometry to a barrier. This uses a blender simulation to fit the geometry to a barrier.

Prepare the barrier by selecting, then, in object mode, using object>apply>scale, and using the toolbar, set origin > geometry center of mass. These two changes will make it easier to apply the barrier in later steps.
Add collision physics to the barrier.

Set the timeline to an end-frame of 25. This will reduce the time required to find the final shape.

At frame 25, add a keyframe with the scale set to 1.

At frame 1, add a keyframe with the scale set to 1.2. This makes the barrier larger then the geometry and as the simulation progresses, it will press on the geometry until it reaches its final shape.

If you animate this, the barrier should shrink into the geometry. This shrinking into the geometry is how it will be shaped.

Add collision physics to the barrier.

Fix the normals so they point towards the geometry. Go to edit mode, select all, then use Mesh>Faces>Flip Normals. The softbodies iteract with the faces that have normals towards them.

Add softbody physics to the geometry to mold. There should be no other modifiers on the geometry to mold. Follow the settings shown below. Set the gravity field weight to 0. Set the cache time to 25 (this will save a lot of time on calculations).

'Bake' the soft-body physics. At the physics panel>Soft Body>Soft Body Cache>Bake. Click on Bake.

The resulting animation presses the barrier against the geometry causing it to meet that form. The last frame of the animation has the desired shape.

Blend file here:


There's a big misunderstanding regarding tris. A lot of people say that you should never use tris, and they're somewhat right. But the main reason behind not using tris, is because they can be harder to work with, and they can cause issues with deformations. Although, before exporting/baking your model for use in games, it's advisable that it's triangulated anyway.

The thing is, people tend to go to overly extreme lengths to avoid tris, when in reality, adding a tri is a lot better than trying to work around having one.

One other thing to keep in mind, is that all faces are converted to triangles at rendertime anyway. You aren't speeding up rendertimes (If I'm not mistaken, some of the optimizations that are being added to blenders viewport are actually for quads only) but by using tris, but you are controlling how the faces are cut up (this is the big thing that effects shading).

Tris also cut off edge loops. So if you do something like this

and then you try to select one of the edges,

it will stop at the triangle. The same thing happens for both Tris, Poles, and N-Gons.

So, advantages to using tris

Can keep topology simpler in certain situations.
Much more effective at controlling shading on low poly models
Stops edge loops
Controls how the surface will be cut up, instead of allowing it to
be randomly done at render time.

Disadvantages of tris

Can be harder to work with at times
Can cause issues with deformations and subserf
Stops edge loops

In games however, There is a stage in the process where triangulation is often unavoidable and should be carefully embraced.

There is a point in the video game workflow where your game model should be completely triangulated, because most game engines will robotically do this for you if you don't, with often undesired results. Some concave surfaces will become convex and vise versa, while some unwanted/useless loops form from the resulting triangulation. You'll want to triangulate it before you export, and DEFINITELY before you bake normals. Here are two big things that can go wrong if you don't.

surface/color baking, especially normal baking, where you transfer details from Hi-res objects onto low res objects are very dependent on how a model has been triangulated. Rays cast from the high res surface to the low, virtually filling in low res gaps with information. So that if you export a model and it's map out to a different program, the triangles may be automatically cut differently to how they were in the other program, resulting in unwanted artifacts.

Surprising deformations/shape, The way that you animated/modeled the       object may appear different because of the engine's method of triangulation, 'what you see is what you get' should be the aim. (this may need a better explanation.)


Re-directing Help>Manual Menu to Local Drive

Two ways I can see to achieve this.

1 Manually edit the UI script

Either manually edit the space_topbar.py topbar UI file traditionally found at Blender_2.82\2.82\scripts\startup\bl_ui\space_topbar.py and type in an entry there to link to your local file.

You can optionally remove the online manual entry from there and replace it with an instance of wm.url_open operator pointing to your local file. Just copy one of the existing templates and modify it to your own use.

This is a quick and dirty solution, allows removing the existing entry, but is less maintainable, since it will likely not survive a software update nor is it easy to port to other installations.

2 Create a script or addon

Create a script that registers a new menu entry with a link to your own file. Easiest is probably to use wm.url_open operator pointing to your local file.

import bpy

def menu_func(self, context):
    self.layout.operator(
            "wm.url_open", text="Local Maual", icon='HELP',
        ).url = "Z:/Applications/Blender/Documentation/Blender_Manual.pdf"

def register():
    bpy.types.TOPBAR_MT_help.append(menu_func)

def unregister():
    bpy.types.TOPBAR_MT_help.remove(menu_func)

if __name__ == "__main__":
    register()

As far as I know this won't allow removing the existing entry, but you can have the addon under, several instances, and can easily be reinstalled after software updates.


I am not sure if this can be done from within blender while it's rendering. It would require rendering the screenshot while rendering the scene. Something like this could easily be done with a shell script outside of blender.

OSX example:

while true;
    do screencapture ~/Desktop/img$(date +"%Y-%m-%d-%H-%M-%S").jpg
    sleep 10
done

This would take a screenshot every 10 seconds, so needs some adjustments.
And then just cancel with 'Ctrl-C'.

If you only want the script to run for a specific period you could do something like:

end=$((SECONDS+360))

while [ $SECONDS -lt $end ];
    do screencapture ~/Desktop/img$(date +"%Y-%m-%d-%H-%M-%S").jpg
    sleep 10
done

This will automatically stop taking screenshots in 6 minutes.

I think Windows looks like this:

:loop
 For /f "tokens=2-4 delims=/ " %%a in ('date /t') do (set mydate=%%c-%%a-%%b)
 For /f "tokens=1-2 delims=/:" %%a in ('time /t') do (set mytime=%%a%%b)
 import -window root screen%mydate%-%mytime%.jpg
 timeout /t 10
 goto loop


How to make a file "non local-specific" for sheep-it render farm?

This just means that you need to make all file paths relative, instead of absolute. If you understand what that means, that's great. If not, I'll provide some explanation below (I don't intend to be insulting, if you already understand).

Relative and absolute paths are a bit beyond the scope of this site, but I can give a brief explanation.

If you have a Blender file that uses an image texture which is located at H:\Users\Node's Stuff\Blender Awesomeness\Sweet_Render\ReadyForSheepIt\Textures\FinalGroundTexture.png then Sheep-It won't know where to find it, because no such folder exists on their server.

That is called an "absolute path." No matter where you are on the machine, that path gives you everything you need to know in order to find FinalGroundTexture.png.

Alternatively, you can say "I don't care what hard drive you're on, and I don't care what higher folder you're in, just look in the folder next-door." This would be a relative path. If you had a Blender file in ReadyForSheepIt you could tell the Blender file that the texture is in \Textures\FinalGroundTexture.png. In this way, you tell Blender that it doesn't matter where the Blend file is located, it can find the texture by looking in whatever folder the Blend file is currently in, and finding a folder called Textures.

Regardless, there is a tool in Blender that will do a lot of the work for you.

From the Manual:

  If it is necessary to relocate a blend-file relative to its linked resources, use Blender’s File Save As function which has an option to Remap Relative file links.

You can just "Save As..." without changing the file name, and that'll give you the chance to "Remap Relative" to make sure you don't have any absolute paths.


Passes are accessible in the view layer tab:

Though there are not world/object position passes yet, you can make them by hand like explained on this other topic. It explains only for the world position, but you can deduce how to do for others.


Place the 3D cursor on one of the vertex on the opposite side of the mesh, press . to transform around the 3D cursor, and optionally press O to turn on Proportional Edit mode.

Select one of the top or two top edge loops (as prefered) and scale them with S


I solved it! I had to get hit apply on a mirror modifier and an armature modifier I added.


Finding domain/range of a specific shader node input/output, inside the Blender UI?

You can access this information for every IntProperty and FloatProperty through Python. It requires the access of RNA properties. The approach is the same for UI sliders as it is for node sockets, but as an easier introduction the first example uses a property of Eevee's render settings.

Example 1 - Regular UI Property

Let's start with finding the limits of Eevee's bloom threshold. The value that is currently set can be accessed through:

bpy.context.scene.eevee.bloom_threshold

This will only give us the current float value. If we want to get the property, we have to access the RNA. The following code gets the underlying FloatProperty.

bpy.context.scene.eevee.bl_rna.properties["bloom_threshold"]

There are four limits to the property soft_min, soft_max, hard_min and hard_max. The soft limits are used for the minimum and maximum value that can be reached through the slider, while the hard limits are the actual maximum and minimum values that can be entered manually.*

* This doesn't seem to apply to the nodes though, they allow to enter float values higher than the hard limits.

bloom_threshold = bpy.context.scene.eevee.bl_rna.properties["bloom_threshold"]
print(f"soft_min: {bloom_threshold.soft_min}")
print(f"soft_max: {bloom_threshold.soft_max}")
print(f"hard_min: {bloom_threshold.hard_min}")
print(f"hard_max: {bloom_threshold.hard_max}")

For the bloom threshold the values are:

soft_min:      0.0
soft_max:     10.0
hard_min:      0.0
hard_max: 100000.0

Example 2 - Node Socket

The following example assumes that the material with the node exists. Normally you would need to check for the existence of the keys first.

Assume that you have a material called Material which contains a node Noise Texture for which you would like to know the limits of the input Scale and the output Fac.

First the node has to be accessed (assuming that all these elements exist):

noise_texture = bpy.data.materials["Material"].node_tree.nodes["Noise Texture"]

For the limits of the Scale input we need to access the Property that is behind default_value of the socket that we're interested in. Scale is an input socket.

scale_property = noise_texture.inputs["Scale"].bl_rna.properties["default_value"]
print(f"soft_min: {scale_property.soft_min}")
print(f"soft_max: {scale_property.soft_max}")
print(f"hard_min: {scale_property.hard_min}")
print(f"hard_max: {scale_property.hard_max}")

The limits are:

soft_min: -10000.0
soft_max:  10000.0
hard_min:     -3.4028234663852886e+38
hard_max:      3.4028234663852886e+38

The same approach can be used to find the limits of an output socket, like Fac.

fac_property = noise_texture.outputs["Fac"].bl_rna.properties["default_value"]
print(f"soft_min: {fac_property.soft_min}")
print(f"soft_max: {fac_property.soft_max}")
print(f"hard_min: {fac_property.hard_min}")
print(f"hard_max: {fac_property.hard_max}")

The limits for this socket are:

soft_min: 0.0
soft_max: 1.0
hard_min: 0.0
hard_max: 1.0

There may be cases where the limits change dynamically, which isn't covered by this answer. It looks like a similar approach could possibly work for Vector sockets, where the limits likely apply for each dimension.


color strip or picture unfolding from one side to another in video editor

Step 1 - Transition
If you mean something like flipping cards transition - Video Sequencer doesn't have this kind of transitions. You would have to render this kind of transition as black and white animation (or image sequence) and use as a mask in video editor.
If you need to keep 3D effect of rotated parts of images you will have to create material for Front/Back side and in 3D editor.
... with Animation Nodes
To create transition like this you can try to use Animation Nodes add-on to create a node tree like here:

Node-tree for 2.92

Step by step tutorial is a bit outdated, but it is well explaned.
... with Constraints
Another option can be to use Object Constraints with a help of BlenderSushi script for Blender 2.79 to handle tedious tasks.

Add a Grid mesh like 6x4 segments
in Edit mode select all search for Split Edges
Add another Grid mesh, but with -1 segment on each axis (here 5x3 segments) and rename it to "Template"
Select first Grid and run script Alt+P from Script editor.
Script will generate Empty object for each face with Transformation Constraint - target to Template transforming location to rotation.
script should set also rotation Max 180°, that is not happening for me so just after script when all generated empties are selected go to Constraints tab and set value 180. WIth right click choose Copy to Selected.
Now you can add Displace Modifier to Template mesh and set any texture to control flipping. Cloud type for random animation, Blend type Linear or Diagonal for transition from side to side.

Step 2 - Video Sequencer
If you create some animation render this sequence in Black&White ...

Add this animation (or image sequence) as a strip into Video Sequencer (you can even hide this strip)
Add two images or colors strips you want to mix
Select top one and under Strip Properties N > Modifiers tab > add Mask modifier and set your B&W transition strip.

If you are interest to go by this way I can extend answer  how to create a BW mask for Video editor or use a Scene strip, but you are probably looking to easier solution. SO try to search for already done some BW transition or you would have to use other app for that.
Or closer specificities behaviour of transition so there can be other solution for you.


Mesh Deform Modifier Missing / not visible

DISCLAIMER: THIS IS NOT AN ANSWER! I am only taking this matter elsewhere since this may be a legit bug worth reporting. I think I will keep this up in case anyone else has anything to contribute; but for the time being, I will be taking this issue up with Blender Stack exchange.


python duplicate_move and snap_selected_to_cursor fails; context is incorrect

Figured it out - I needed to add
bpy.context.area.type = 'VIEW_3D'
to switch from the text editor to the 3dview, before snap_selected_to_cursor.


Is re-using materials on models faster than baking textures for each model?

Even if Blender did something non-efficient, like making new shader for each object, there still would be an obvious benefit which @maddin45 mentioned. The less textures you have (the more you combine them in big atlases), the better.

As for the models themselves, think of modularity - make LEGO-like pieces and duplicate them.
http://blog.timothyeustace.com/2012/04/gears-of-war-wireframes.html


Stencil image appearing extremely low resolution

Stencil has to be a power of 2 image, with dimensions of
8,16,32,64,128,256,512,1024px, etc in width or height (512x512, 1024x1024,
2048x2048 or 1024x512, 2048x1024 or 512x1024, 1024x2048, 1024x128, 128x4096 - and so on, as long as it can be doubled or halved by 2) that way Blender will display it correctly. It's a general rule for any 3D texture, actually.

I know it's an old question, but a lot of people asked me about this lately and they found no direct answers online. So I figured you can never be too late with an answer. :)


Error, region type missing in..? What is this?

The blender system is structured with Area's 1 and Regions 2.

Area

The application window is always a rectangle on your desktop. It is divided up into a number of re-sizable areas. An area contains the workspace for a particular type of editor, like a 3D View Editor, or an Outliner.

Region

An area is divided into regions (a sort of placeholders). For example:

Header
Main
Tool Shelf
Properties
etc

Scripts can use these regions to (for example) add custom panels to a region.

Now the Error

The message Error, region type missing in - name is send to the console when a script wants to access a region in a area for temporary windows.

This used to happen when users open a user-prefs or render window (those are temporary screen and). And then start using it as a regular window (split it, change space types... etc). This was solved in 2015, but could still be possible when scripting.


Whats wrong with my "snowglobe" object and/or lighting?

The viewport is in 'lookdev' mode. That means there is a hdri image as environment lighting. You don't have it while rendering. Lookdev is a builtin environment lighting for test purpose. Should set up an equivalent environment texture to render it. You can find some available hdri images in your installation directory in 'C:\Program Files\Blender Foundation\Blender\2.80\datafiles\studiolights\world'.

To setup that, you basically need to use this setting where 'forest.exr' is found in the directory indicated above:

But if you just render it, you'll see it in the rendering:

So you need to enhance the world node tree a bit (I've found no option to hide it automatically in Eevee).

This setting says: when a light ray is directly to the camera, then use the second 'background' node which is set with a transparent color.

So you can render this:

Here is the blend file (you may need to reopen/reload the hdri image to make it work in your environment):


How to tweak the radius scale of Sapling tree Gen add-on in blender v2.79?

2.79 has all 2.75 had and more. For this reason, some things got moved around/added and it can be more confusing. Allow me to help, then.
I think what you're looking for is this:


Switching the Codec to H.264 fixed the quality.


Can I relocate the manipulator in Blender 2.79?

The dot (normally in the centre of your primitive object is your origin point. (Picture 1 and picture 5)
The red and white crosshairs cursor in your viewport is your 3D cursor.
Individual vertices can be moved to the 3D cursor in edit mode OR the 3D cursor be snapped to a single vertex or median point between selected vertices or faces or edges using the shortcut Shift+S. There are various different options for interaction between mesh objects and the 3D cursor.
To place the 3D cursor to the centre of the viewport, press Shift+C. This will also centre your view.
The origin point can be changed in the Toolbar (T) where it says Origin. (Image 5)
The way a mesh translates or rotates or scales can be changed to use the origin point or the 3D cursor. The is very very useful. You can change these settings with the options at the bottom of your viewport. (Image 6)
If you would like your 3D cursor to sit on top of faces when you click on a mesh, you might find switching on Cursor Depth quite useful. This option can be found in the User preferences in the interface section. (Image 7)
the precise location of your 3D cursor can also be changed manually in the properties tab "N" if you scroll down. It's about halfway down or less.

Here is how the manipulator can be moved around in the viewport using the 3D cursor. The images go in order from left to right and top to bottom.

One other thing to note: When using proportional editing, scrolling the mouse wheel increases or decreases the area of influence. you'll see a circle getting bigger or smaller as you scroll up or down. Using shift and scrolling allows you to increase or decrease the influence much more accurately.
To place the 3D manipulator to the centre of 3D space, (0,0,0 in global coordinates), in Edit mode, press Shift+C to move the 3D cursor to the centre of 3D global space. Change the pivot point to be the 3D cursor (image 2 in the first diagram or the 3rd image in the second diagram).
The 3D manipulator will share the same place as the 3D cursor. If you want to make that permanent in Object mode, open the Tool Tab (Hotkey T) and click on the drop down menu which says "Origin". Set the "Origin to 3D cursor" in that menu. This menu also has a hotkey (Ctrl+Alt+Shift+C).
Perhaps this is what you were wanting to know. Let me know if this doesn't exactly answer your question.


How do I import a model which has .mat and texture files in separate folders?

.mat are only for 3ds Max only, it reads it to auto apply textures from the importer, in Blender you will need to setup textures manually.


Mirrored UV map is breaking up textures per-face

It's becouse faces in that place are "rotated". Let's i describe it in image:

your vertex number 1 is on position of vertex 3, n.2 on position of 1, n.3 on pos. 2.

so it look like all vertex on right place, but this places are wrong

Look at my another example. As you see all faces are in right place, but selected face is rotated at 90 degrees. Same thing in your model, but many of faces are rotated.

So if you have original model - try to transfer it UV map using Data Transfer modifier


How can I make a 3D mouse act the same as in other programs?

Just change navigation style of NDOF device to one which you like - orbit around selection or free. Trackball lets you bank the camera There isn't any other option I'm afraid there's no way to arbit around selected with ability to pan in 3d connexion mouse


Underlying tiny checkerboard on painted object

I figured out what was wrong: I needed to delete pre-existing textures in the texture tab.


Nodes: can't find material output or Diffuse BSDF

Maybe you're not in Cycles Render mode (top horizontal menu bar), or maybe you are, but in the Node editor you are not in Shader mode (bottom horizontal menu bar)?


Why does applying an objects matrix to a location fail?

When applying an objects transformation matrix to a vertex, you need to multiply:

Matrix * Vector

However your example does:

Vector * Matrix

This behavior matches numpy and other math libraries.


how to import a blender model and manipulate the imported model?

Look into bpy.ops.wm.link() and bpy.ops.wm.append(). This is how the GUI transfers objects across .blend files. (To find that out, I used the Python tooltips and hovered over the Link and Append buttons.)


Why does my lighting not work Blender v.28

The biggest issue is that the light you are using was only 10W. This is the default "power" of new lights added to the scene with the exception of a sun which starts at a value of 1. This is why all the new lights you added seemed to have no effect - they were way too dim. I upped it to 10000W and the light shines brightly. Also, however, you have the spot radius size set to 126 - I think something like 65 should be OK for what you're doing, unless you have some special need for it. Click the "show cone" box to make the light cone cast by the spotlight more visible so you can see where it's going. See below:


Different mirrored position when i need to join them

You have to select the head ( uncheck clipping) and rotate it by 180 degrees on the z axis. Then you just have to move it until it is on the same side as the body. For the actual joining part select both edge loops, press F, then click the right mouse button and select bridge faces.


Importing VSE project as sequence to another project

Many questions here, and plenty of complexity. Short answer is that the Blender doesn't support a form of EDLs so taking your project to Resolve or such will be difficult.

Your frame slippages are codec related. It is possible that one of the timestamp settings may help. If all else fails, render to frames and then set your strips to the frames.

The only way to conform shots is to dump them down to singular channels and render our reels of your cuts with black "slugs" to hold frame counts. If you collapse your final edit down to one or two tracks, they will hold sync because of the black slugs.


Create a configuration window for my add on

Add-ons can have their own user preferences.
https://docs.blender.org/api/current/bpy.types.AddonPreferences.html
This doesn't fill the entire window, but this is the intended way for your add-on to be configured.


It seems that bpy.context.evaluated_depsgraph_get() will return a Depsgraph() Python object.
bpy.context.evaluated_depsgraph_get().debug_relations_graphviz("/SomePath/SomeFile.gv") will then save the dependency graph in the Graphviz/DOT format, which can then be rendered out to an image using local or browser-based software:


How to do camera tracking for a video shot in portrait mode?

Portrait

Under Solve tab check Refine > Focal Length, Optical Center, Radial Distortion with those I got nice error only 0,10 px
Set Floor, Wall, Center, XY axis - with that I got camera correctly orientated

The only one thing that didn't match was camera Focal Length (and Shift).

If you select camera and go to Properties editor > Object Data > Camera > Sensor Fit and switch to Horizontal > Width 35 mm.

It does not fix the value itself, but empties and reconstructed scene match perfectly.

I still don't know why the given Focal Length is incorrect, but I'm not a tracking guru :) Alternatively you can adjust Focal Length and Shift manually according generated Empties.

Notes
How to determinate Lens Distortion
How to get better result ...


Answer my own question:
Just found out that you can achieve that effect by using offset node in Sverchok.