text:
Prevent Steering Actuator from over-shooting? BGE
It's a pretty simple question. How can I prevent the Steering Actuator from over-shooting the seeking target? The object must go extremely fast, therefore it over-shoots.
Any ideas?

could you post your blend with the problem or add more details? You can use a service such as blend exchange to upload your blend file.

I tried increasing the FPS to 240 and lowering your speed to 100 instead of 1000, and it works fine, perhaps the seek actuator is not the best approach. What do you need your object to do - just snap to a target object?

Yeah, basically snapping.

You can increase the number of frames per second your game calculates. The steering actuator works by calculating the needed rotation to reach the target for each logic tic. The faster an object is moving, the more moment per tic it has along its axis. Each tic, it moves the object along an axis and calculates the rotation needed to reach the target. When the moment is fast, it adds a lot of distance and calculates the new rotation. If that distance is long enough to move your object off it's target path, it will look like it is overshooting.

By increasing the frames per second that the game runs at, you will increase the logic tics per second. This helps because it calculates a new rotation faster, keeping it on the target path better.

For example, you could set it to 120 instead of 60. Your object should now recalculate it's rotation and trajectory along the path twice as fast. However - this will also drag down performance. The faster you set the FPS, the more work your computer needs to do. If you have a lot of logic, forcing it to run twice as fast should create a noticeable drain on performance.

Thanks for the advice, but it doesn't seem to be the answer I was looking. The Navmesh is basically a massive rectangle, and the target object is a small square inside it. When it tries to seek it, it shoots WAY pass it and then immediately over-shoot back again.

Do not increase FPS. Instead increase Logic Steps. Blender calculates that number of logic steps for every frame it draws. Drawing a frame is really expensive compared to logic calculations.
It's overshooting because it calculates where the object needs to point and then has to wait a whole tic before it can calculate again. Well, in that amount of time the object has traveled far beyond the target. Now, it calculates the new direction but has to wait a whole tic again before it can check again. Again, in that one tic, the object has traveled past the target.
Imagine driving a car, but you can only touch the steering wheel once every second. You might start a turn, but then you have to wait a whole second. You might be all the way past your turn before you are allowed to touch the steering wheel again. The solution is to give it more opportunities to adjust its heading. Give it enough logic tics every frame and it'll be able to change direction BEFORE it overshoots.
The other problem you're going to run into is what to do when it REACHES its target. Once it reaches its target, if it doesn't stop moving... of course it will overshoot it. Then it will start steering back to the target again. You might have the actor slow down as it gets closer, or you might just have it stop moving altogether if it's touching the target.

I suggest to enable "Self Terminated" to stop steering after reaching the target.
You could detect this situation with the actuator sensor (which evaluates if the referred actuator is active or not).
But, I do not know how the steering actuator performs the last step (e.g. if it is a full step or if it ends exactly at the target.


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What does the Freestyle Diffuse Color Modifier do?
I can't find any info on it. Anyone know what it does? Really curious.

As it says - it should mix the base color of your line with the diffuse color of the object the line is drawn on. Does it not?

I thought so as well, but I keep getting white lines, regardless of what color the material or freestyle lines are.

Huh, that's funny. I experimented a bit and found it only to work when "use nodes" is disabled in the material. Seems like a relic from good old Blender Internal-times?

Oh that's interesting. Thank you!

Alternatively, you should at least be able to set the line color as parameter in the material and mix this with your base color. AFAIK this only gives you one solid color per material, though, without texture.

source: Stack Exchange

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

sort: votes


text:
Is possible to render in Cycles with modifiers on the scene?
I'm a little bit newbie in Blender, I'm come from Maya and I'm still improving my skills on it hehe
I was making a tutorial about make tank tracks, but I have a problem. I made all the animation for the tank tracks, and it works fine, the problem is that I need to conserve the modifiers (Curve modifier and array) in order to keep the animation working, but I cannot render with modifiers without apply...
So, how can I render the model in cycles and don't loose this animation rigging? The tracks are linked to an empty cube, and rigged by using drivers.
Thanks for your help and consideration :)
Kind regards!

You should never have to remove or apply modifiers to render, unless you want to. Except for a few circumstances and specific uses, 3D applications are generally design to keep modifiers around as a non destructive workflow, for as long as possible.
What problems are you experiencing while rendering? What can't you render or what happens when you do? Post some screenshots or a Blend file. Some times render results differ from viewport preview because some modifiers have distinct settings for viewport and rendering, leading some times to unexpected results.

You probably accidentally disabled rendering with modifiers somewhere in the stack.

As explained in the manual here, each modifier has a few buttons that enable/disable it at certain times. The small camera button is used to for displaying the modified result when rendering, if this is off it will not be visible when rendering.

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


text:
Different start and end frame for each action
I have 2 actions, walk and idle.  The idle animation is much longer than the walk.  Each time I want to check my animations, I have to adjust the timeline ending frame, right now that's not too bad, as I only have 2 animations, but could be a pain when I want to go through more animations.
So the question is; Is there a way to set a start / end frame for each action?

I just adjusted my answer as I realised I forgot the best shortcut.

No you can't set a start/end frame for each action as the start and end frame is a setting that is global for the current scene.
Pressing Ctrl + End while your cursor is over the timeline will set the end frame to the current frame. A quick click at the last keyframe and a keystroke is easier than manually entering the end frame number. You can also press Ctrl + Home to set the start frame. This only works when the cursor is atop the timeline panel.
There is also a preview frame range setting, this allows you to adjust the start and end frames while animating without changing the frames that are used when rendering. This is useful when you only want to play a section of the animation that you are concentrating on.
The preview range leads to a shortcut that makes changing the frame range even easier while animating, press P and drag from the start to end frame to set the preview range. This works in any of the time based editors - timeline, dopesheet, graph editor, NLA editor, video sequencer.

Note that in blender 2.8 this was changed to Ctrl+Home and Ctrl+End

There is always a bunch of different ways to do stuff in Blender. One of which is to use NLA editor to make shorter animation repeat for all time needed like this:

As of blender 4.2, you can do this via script as such:
import bpy

def set_frame_range_for_action():
    # Check if there is an active action
    if bpy.context.object.animation_data and bpy.context.object.animation_data.action:
        action = bpy.context.object.animation_data.action

        # Set the scene frame range
        bpy.context.scene.frame_start = int(action.frame_range[0])
        bpy.context.scene.frame_end = int(action.frame_range[1])

# Run the function
set_frame_range_for_action()

Go to the scripting tab, paste the code and press the run button

If you don't want to do this repeatedly you can also create an addon, here's the script for that:
bl_info = {
    "name": "Auto Action Start End",
    "category": "Animation"
}

import bpy

# To keep track of the previously selected action name
prev_action_name = ""

def update_active_action(scene):
    global prev_action_name

    # Check if there is an object with animation data
    if (bpy.context.object and bpy.context.object.animation_data and bpy.context.object.animation_data.action):
        action = bpy.context.object.animation_data.action
        action_name = action.name

        # Print action name only if it's different from the previous one
        if action_name != prev_action_name:

            # Set frame start and frame end
            action = bpy.context.object.animation_data.action
            bpy.context.scene.frame_start = int(action.frame_range[0])
            bpy.context.scene.frame_end = int(action.frame_range[1])

            prev_action_name = action_name
    elif prev_action_name:
            prev_action_name = ""

def register():
    # Register the handler function
    bpy.app.handlers.depsgraph_update_post.append(update_active_action)

def unregister():
    # Unregister the handler function
    bpy.app.handlers.depsgraph_update_post.remove(update_active_action)

if __name__ == "__main__":
    register()

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

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


text:
How can I use a block size of 1m for different sized models using the remesh modifier?
I have models that are different sizes, and I am using the Remesh modifier with block mode selected.
How can I keep the block size at a very specific size (1m in my case), regardless of the size of the model?
So for example;  2 separate spheres, one that is scaled down.  Remesh applied separately to both with block mode enabled.  They now have different sized blocks.
One way I found was to join them and then add the remesh modifier to them.  But I want to make sure they are always 1m sized blocks, and not have to rely on joining lots of models each time.
So in this first image they are separate objects with the modifier added.  Even though the remesh settings are the same, the block size compared to each object is different.

In this image below, I join them together then add the modifier.  This keeps all the blocks the same for both objects, but not at the size I want (1m blocks).  Plus I would need to join all my models I guess?

I read that drivers might be able to do this, but I couldn't understand how to set it up.
Here is a link to the images I found, but I don't quite understand what I am looking at:  https://i.sstatic.net/QxLDs.jpg

If you want to make the driver in my answer more flexible, so it can be more conveniently copied between objects (which I got stuck with).. @batFINGER's answer here.. will help.

Oh nice.  After implementing your solution, I went searching how to copy the driver stuff to other objects and couldn't find anything (poor search terms on my part).  Thanks for your solution and the link.

You will probably wind up writing it into a driver_namespace function, but that's kind of a different answer..

Your illustrations are of a scripted expression driver, driving the 'Scale' property of a Remesh modifier with a function of the dimensions of the object to which it is assigned.
A complete description and examples of setting up drivers can be found here, but as a rough start:

Right-Click the 'Scale' field of your Remesh modifier, and select 'Add Driver' > 'Manually Create Later'
Make the object active, and open a Graph Editor window.
In its header, set the Graph Editor window to display 'Drivers'
You should see the 'Scale' driver in the left region; select it .. use N to open the property region on the right of the graph youmay have to fiddle with the graph region's width to get it to appear.

Now as a start, you could fill the panel as shown above. This is a tweak of the setup you illustrated, adjusted so the cubes will be 1 unit in width, whatever the size of your model, or octree depth.
Select 'Scripted Expression'. You may have to give it explicit permission to run in user prefs.. see here.
In this example,the model is called 'Suzanne'. (you can pick yours with the eyedropper). Here I've added 4 variables, using the driver UI: naming them dx,dy, and dz referring to the dimensions of the unmodified object, and od referring to the Octree Depth in the modifier, which I've named 'RM' in its own panel, to keep everything short.
In the modifier, the 'Scale' is (object size)/(modifier base cube size) where the object size is measured by its maximum dimension, and you can implicitly vary the base cube size. 'Octree Depth' is the number of times the base cube is subdivided to give your blocks. So this expression will yield blocks with one-unit sides: max(dx,dy,dz)/(2**od)
This is the result as Suzanne is scaled up: the blocks stay at 1 unit on the side, (the view is tracking back)


text:
How can I move an edge a precise distance from another edge?
In the image below, I have an edge loop selected.  I would like to move that edge loop to be exactly 0.30083 from the edge loop on the right.  How can I move it precisely?

Use the snap to edge tool while in edit mode found on the bottom toolbar of the Viewport. Snap the selected edge to the second one and then use the keys G + y + -0.30083 to move it left by the appropriate amount.


text:
Rigging voxel character; How to reduce deforming of mesh at joints
I've created a very basic character so that I can learn to do basic rigging and animation, but I'm struggling with areas of the mesh that will bend.
This will be easier to show.  In the first picture, you can see the leg is bent, however, I want the mesh to remain as boxy as possible.  I don't mind some deforming, but in the picture, it's way too much, but am unsure what to do next.  I tried adding more loop cuts around the joint (1 above, and 1 below), but I seemed to make it a lot worse.
Is this a case where I may have to have an upper and lower leg that are separate parts?

Related: http://blender.stackexchange.com/questions/46315/how-do-rigs-relate-to-weights

One way would be to make pseudo joint on the mesh, where you expect it to bend (like knee) by making 2 additional edge loops and merging them on one side like this:

A)
You could add a *_fix bone to the joint that is perpendicular to the parent of the one that is moving, and points in the direction of the joint bending (Track To constraint towards the pole target of the joint)
Then weight paint the problematic-vertex to it.
That way the vertex is being held in place by the parent of your joint amd turns with it.
But thats basically a dirty "preserve volume"-like hack.
B)
Another way is to add a shapekey that deforms the mesh to look right when fully bent.
That shapekey would be controlled by a driver that translates the rotation of the moving bone into 0-1 values for the shapekey, that tweaks the joint vertex to stay in place by using an f-curve you can manually tweak in the drivers section of the F-Curve editor.
If you can do that for that voxel-character you also learn how 'organic' deformation can be tweaked to look right on "realistic" characters.

Point B) is very helpful. You may use corrective shapekeys as shown in this tutorial: https://www.youtube.com/watch?v=f3JWNIkwBZ8

When I read this answer, most of it went right over my head, as I'm still a beginner with Blender, but after watching that video, it made it really clear, and I'll definitely be giving that a try.


text:
Cycles - Baking to image problem (looks like seams on the image, but not sure)
Am totally lost as to why this is happening.  I'm quite new to Blender, but have been trying to use nodes lately.  I'm trying to make some game assets, and am baking my material to an image, but I am getting what appears to be seams showing on the image.
I have no clue how I would UV unwrap my model (low poly rocks / mountains), so I use the Smart UV Project option, so am not sure if that is the cause or not.

Thanks

Your face is non-planar.
Go in Edit Mode (Tab), enter face selection mode (Ctrl+Tab, Face), select your face (RMB). Open the Mesh menu, Cleanup, Make Planar Faces.

This should fix it, but can make surrounding faces non-planar...

Thanks a ton, that actually solved a few other issues I had as well.

Another reason for this could be that with your current settings you are actually bake lighting into your texture. You might want to deselect "Direct" and "Indirect" in your Bake Type options and try only "Diffuse".

Oh wow, that makes a big difference and actually fixed a few other issues I had when baking.  Sorry I can't accept this as well, as it has helped greatly.  I didn't really know what those 2 settings did, so left them as default. Thanks a lot.

@JacketPotatoeFan - no prob. You could still upvote my answer, though...

Soon as I get 15 rep, I certainly will :)

It's probably due to the mesh topology. Try to join vertices on these face (with j) and check with w> remove doubles if some vertices aren't welded.

authors: Леонид Зоткин

authors: พิชัยยุทธ บุตรเรียง


text:
Particle effect to mesh - Strange issue
I am trying to convert a particle system using an object into a mesh, but am running into some issues.  When I hit convert under the modifiers tab, it adds the same object to all of the objects in the particle system.
It looks like I want it to with the parent and the objects coming from it before I hit convert, but when I do it adds the particle system to each object in the original system.
To make it more clear, I have a half UV sphere as the parent and a branch object that I made as the particle.  When I hit convert it adds branches to each branch particle.
Please help ):


text:
Why are my textures pink? (Duplicatee)
So, I was trying to make an image for an online game, (ROBLOX). I understand fully how to do it, as I have done it in the first place. However, whenever I try to actually upload the 3D image into blender, the texture file does not show up and my entire character turns pink ( https://gyazo.com/49266465a404cba245453d766d6629ce ). I tried to search for the missing files, but it said there was an error. I've tried uninstalling and reinstalling Blender, but everything that I've tried hasn't worked. Also, whenever I go on Blender, I have to change the RGB from pink to black EVERY TIME.
Please help!

If you could add a link to your blend file, we could help you more easily. There are quite a few reasons why this might happen. Also are you using cycles or blender render?

I'm not quite sure how to link the file, haha sorry I'm new to blender a bit. I'm using Blender Render.

authors: Михаил Семенов


text:
How texturing works
So i was wondering how actually texturing works. Cause i've seen some videos when people use materials on different part of the bodies, like hair, skin, eyes... and not texture.
I have a model he has some clothes on. A vest, body suit, gloves,... Should i use a particular material for each of them and set the color of the material i want for those objects, or should i use a general material for everything and texture them with a color i want?
And also, i'm not sure when to use vertex paint, and when to use texture paint.

Welcome to the site. Consider taking the tour, and checking out sections of the help center. As written, your question is not within the scope of this site as I understand it, as it is too broad; there is no single good to your question, because it depends too much on specific details of individual situations. Learning how to model different kinds of materials in different situations. Knowing when to use one method, and when to use a different one is a much more challenging part of using Blender.

A material defines basic properties to be applied to the entire surface of an object. A texture is used to add variety to the material.
For example a material defines a simple blue colour for the cube. The same colour is used over the entire surface, with variation due to lighting.

Adding a texture can then add some variety to the colour. In this example I use a cloud texture to add some green patches to the cube.

Textures can be used to alter almost any part of the material properties from diffuse and specular to transparency or normals (that provides the appearance of surface detail without the complex geometry). A single image texture can also be used to define the surface colour of the entire model.
The above example uses blender internal but the same applies to cycles, it is just less separated in cycles, with texture nodes being mixed in with simple diffuse nodes.
Where vertex painting assigns a colour to a single vertex that can be used to colour the model around that vertex, texture painting is used to paint onto an image of any resolution you choose, allowing you to specify much more detail to your texture.


text:
Volumetrics - Different results GPU vs CPU
Hey fellow Blendy people,
I'm running some benchmark comparisons between various render engines involving a lot of small, simple scenes.
Anyway, on my test scene for volumetrics, I'm noticing a large discrepancy between GPU and CPU rendering. All other settings in the scene are identical.
Any ideas? I've never come accross this before, though to be fair I rarely render on CPU.
As you can see from the picture below, it's as though the volumetric density is different.

Any thoughts on this would be greatly appreciated.
Bill

Does this answer your question? Why do volumetrics render noisier when using GPU then when using CPU in Cycles?

It looks like more of a discrepancy with density than a noise difference. In the GPU render the background is obscured by the fog, but the CPU render isn't behaving in the same way.

You're right, seems like it. Is that light a circular area light pointing at the camera or something like a point light or mesh light?

I wish this was mentioned somewhere in the Blender when switching between GPU and CPU rendering. Only yesterday I learned that GPU and CPU renders aren't always identical. (Arnold possibly being the one exception?)


text:
2 Objects have the same Particle system setup
So I made an object and realized that I majorly screwed up. So I manually selected vertices (sorry if I spelt that wrong) and seperated that, making a new object. Anyways, whenever I edit the particles of the 2nd object, it also changes the first one's particle system. If there is any way to make them different, please tell me. Thanks for reading! :D

You need to click the number button next to the particle selection.


text:
How can I edit a vertex's index order
I need to create a few meshes where vertex index order is important.  I am trying to write a script as such:
import bpy
import bmesh

mesh = bpy.context.object.data
print(mesh)

bm = bmesh.new()
bm.from_mesh(mesh)
bm.verts.ensure_lookup_table()

def switchIndices(i1, i2):
    v1 = bm.verts[i1]
    v2 = bm.verts[i2]

    bm.verts[i1] = v2
    bm.verts[i2] = v1

switchIndices(32, 4)

But when I try to write to bm.verts it says it cannot.  I can assign/swap the values of v1 and v2 but then I still need to edit edges and when I try to change the two vertices of an edge I get the same write problems.  I thought the whole point of the bmesh was to be able to edit it.  What am I doing wrong?

Related http://blender.stackexchange.com/questions/36577/how-are-vertex-indices-determined


text:
My lowest panel is changing from the editor window to the rendered view
ORIGINAL:
Have made several videos successfully but suddenly my [render] button does nothing but change my lowest panel from the editor to the result view

https://i.sstatic.net/KSN98.png
changes to

https://i.sstatic.net/lUEHN.png
I also noticed it does pop up "Sequence Render" for a very fast moment in place of the blender version above preview. I've never had this happen before and when I try to find previous mentions for help I get bogged down in threads about 3d rendering. I've not changed my settings except to increase the Sequence/Clip Editor Cache. I've checked my properties to make sure those are the same as before. Dimensions, fps, start and end frames, output folder is correct, encoding is the h264 preset, ac3 audio.

While interesting and I'm glad to know better now what this means it does not change anything other than a visual function. Still tho, thank you. I hated that it kept stealing that section of my  work.

Maybe related: http://blender.stackexchange.com/q/38098/2843

Ah, sorry. I'm used to reddit and a few others that use flair or edited titles.

It turns out the problem was that I had a combination of two issues.
Firstly, I have about 3 minutes of blank video so rather than showing black the preview window shows the gray background that is throughout Blender. This made me assume it wasn't working because it was not black, but really it was just transparent.
Secondly, I set it again, then left to make dinner. Turns out it takes a long time to start up (I guess). I've watching it right now and it is creating the video at about 2/3 speed of original footage in the preview. This is largest video in blender by about double in time and also my first 1080 rather than 720. I guess I was just too impatient.
The important thing is I learned some stuff today. :)

Since you don't have the alternative preview range enabled and your Properties Frame Range matches your timeline ones, it looks like your Sequencer isn't considered any more... Make sure, the Sequencer checkbox in Post Processing Panel from your Render Properties Tab is selected:

Though as you mention this quick popup that might already be the case.

You could as well try to use the OpenGL Render button.

http://i.imgur.com/HSjkBdw.png
It is selected. I also tried selecting the alternate start/end frame button which didn't make it work.
As for Samoth's suggestion I believe this is what I was already doing but I used the render button in the properties section instead. This seems to have the same icon as in the preview, so I don't think it would be different.


text:
Blender 2.76b Depth of Field doesn't work

Blender 2.76b Depth of Field doesn't work. Any idea why?

Do you have "Compositing" checked in the "Post Processing" panel in the Render Settings?

I have try it all, but it dosn't work.

Have you made or selected a Focus object in the 'Depth of Field' panel and set a distance value under the D.o.F. box?

Yes, I do. But it doesn't work.

Do you have "Use Nodes" checked in the Compositor? Also try increasing the "Focal Length" of the Camera.

It could be a bug?

Make sure the camera at the top of window containing the Depth of Field tab is actually set to your active camera. I had the exact same problem.


text:
AO, Bump, Normal, Albedo, Depth, Gloss, hi-gloss and roughness
I get a nice texture with AO, Bump, Normal, Albedo, Depth, Gloss, hi-gloss and roughness images texture. How i can put all images in cycles nodes for a realistic textures, i know the composition of nodes

Possible duplicate of: How do you apply a gloss and spec map on one cycles material? and How are texture maps imported into Blender?


text:
scale multiple textures
is there anyway to scale multiple texture nodes? for example the image below. Is there anyway to scale these three textures together?

If you are wanting to keep their scales relative you could use the math node and multiply each scale value by a factor. For example below, I am doubling the scale of each texture, where the first math node is my factor (highlighted in yellow), and each of the next math nodes are my scale of each texture. Just change the factor in the first math node to adjust all three.

Using a Value Input Node might make it clearer


text:
blender 2.8 Smoke color change?
new to blender 2.8. i never moved to 2.8 when it came out and now im hating myself for it.
my goal here is to change the color of the quick effects smoke in blender 2.8 in the cycles render engine. how would i do this? ive tried inserting keyframes for the colors of the smoke but they dont change. i think the reason this might be is because im using the HSV color picker instead of the RGB. If i select my smoke flow object then in the shader editor the only thing that pops up is the shader nodes for the material applied to the object itself. how do i edit the shader for the smoke color directly and not for the objects material?
thank you for the help!

When you use the quick effect Blender automatically creates a Principled Volume material for the domain. In the shader editor type in "color" for "Color Attribute". Don't use capital letter.

the shader editor shows the material for the domain yes. but would you know if there was a way to change the individual smoke flow color in the shader editor?

The color attribute is located in the inflow's smoke properties.


text:
change color ramp hue using nodes?
i was hoping someone could tell me how to change the color of a color ramp using other connected nodes.

the second image does it almost right but the color of the whites from the color ramp are only half as strong as they should be. what im trying to do is to change the hue of the white values of the color ramp to a selected color using other attached nodes. the desired effect would be similar to simply changing the white stop of the color ramp to a desired color. but i need the color to be accessible from a group node which is why i cant simply do that.

Connect the ColorRamp output to the Mix node's "Fac", and assign the two colors of the Mix node.

i feel so stupid lmao. thank you oh wise one for the knowledge now bestowed to me.


text:
Texture inside of texture?
is there anyway to texture over another texture? for example: lets say i add a musgrave texture to a sphere and use a color ramp to separate the blacks and whites. kinda like this:
is there anyway to have a noise texture in the black parts and a wave texture in the white parts? i guess what i mean is: is there anyway to use a texture as bounds for another texture?
forgive my overuse of ":" please. my comma key broke lol.
thank you for any help.

Sure.  The output of the color ramp can be interpreted as a factor, which can be used as input to a color Mix node to mix two textures, like so:

i feel stupid now. i cant believe i didnt think of that. thank you for the help!!


text:
Unknown option removing background In render
Background material just showing as blank (Plane background with image texture on it) If I put a working material onto it, it still shows as blank, Its all checked in the top right, cant see what I've done, was trying to get a toon shader on and changed something following a tutorial.
When I render the vehicle looks exactly as I want it but I cant for the life of me get a new plane to show an image (UVMAP used and tried Coordinates)

There are a couple of different problems with your scene that are causing black materials.

The ground for example is missing a shader. You have the image texture directly connected to the shader output, and there should be a shader in there, like a Diffuse, or Glossy or Toon.
The glass color is a bit dark, though that may be the look you are aiming for.
In the Light Path settings of the render panel you have all bounces set to zero, which will make most transparent or reflective materials return black

General tip, watch for the socket colors in the material node editor, under most circumstances connected socket colors should match (green with green, blue with blue, etc).


text:
Subdivide only adding vertices, wont subdivide faces
I am trying to use the subdivide tool, but when I do it only works on certain faces.  The next time I try to subdivide a face, it only adds vertices to the edge.

Can you share an image

It's most likely that the faces which you are trying to subdivide are Ngons (which have > 4 vertices). To subdivide cleanly try editing topology with joining adjacent vertices to return to quads.

I'm not sure but I think you may be referring to the Loop Cut tool.
You press Ctrl+R to use the Loop Cut tool.
To subdivide a certain face, select the face in Edit mode and press W and select Subdivide. Then in the Toolshelf in the lower left Last Operator panel on the screen you can change the number of subdivisions. The maximum is 10 but if you need more you will have to subdivide again or you can type value manually.

Note that Subdivide won't split face if the latter is Ngon; it will only split the edges.

There are probably faces in your model that contain more than 4 vertices. Because in that case it will subdivide the edges of that face only.


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How would you implement a lookat + up-vector / pole target in geometry nodes
I've seen a few implementations of a geometry nodes "lookat" setup, where your object is facing an empty. The easiest setup being like this:

However when both object (source object and lookat target) are moving around, there are always moments where the rotation is suddenly mixed up.
Does anyone know how to add an up-vector or some kind of pole target (like in IK-rigging) or is this a limitation of the geometry nodes itself / do we need to revert to python scripting / matrix manipulations for this?

First, GN is probably not the best way to do this specific problem.  An armature modifier (or object constraints, if you don't care about deformation vs transformation) is going to be faster and easier.
However, it is possible in GN.  I don't think Align Euler to Vector is going to work, because that only aligns object space basis vectors, and for what you want, we need serial rotations-- rotations that align already modified vectors to vectors, not basis vectors.
A track-to is basically two different rotations.  We first rotate in (object) Z to the target, as best we can; we then rotate in X to the target, at which point we reach the target.
We'll start with rotating in object Z to point at the target, so that we can then node group and re-use for our rotation in X:

Our constant -YVec is the vector we want to point at the target.  We get the vector to our target and discard the Z component, since we can't rotate that way.  We get the arccos of the normalized dot product to get the angle, and we rotate about cross product of our vectors (which creates a vector perpendicular to both vectors) to figure out our axis.  We rotate our individual vertices and write our new position.
We also perform this same rotation on the vector that represents our tracking vector, the -Y vector, so that we can use this as our new tracking vector for the next rotation.  Let's group it up and add another copy:

Now we can use our new vector-to-align as the input for a new copy.  We're not discarding any target XYZ components on this, making it equivalent to a damped track/swing, but because we've already rotated in Z to the target, that's the same thing as a locked track, same as rotation in only X.
Okay, so what about a pole angle?  A pole angle is similar, in that it is two sequential rotations: first we track the target, then we rotate about our modified tracking axis to a new target.  This is actually a little more complicated-- we could use some tricks before to do our earlier locked track, by just discarding vector components, that we can't do once we're no longer measuring object basis vectors:

So for our inputs, we have the relative location of two empties, we have a track-to vector, and we also have a pole vector-- the vector that should point to our pole.  We've slightly edited our node group so that in addition to outputting our modified track-to vector, it also outputs a modified extra vector-- in this case, our modified pole vector.
We need to measure the angle between our pole target and our modified pole vector, but the vec to pole target isn't necessarily going to be in the new XZ plane in which we want to rotate, so to get the target vector into the proper plane, we do a pair of cross-products.
We can use the arcos of the dot product of normalized vectors to get the angle between them (note that cross-products are not necessarily normalized vectors!)  This angle isn't directional however, so we need to look at which direction our rotation axis is pointing to decide whether to rotate by arccos(dot) or by negative arcos(dot).  I'm using a mixRGB as a simple switch here.  Finally, we'll rotate about our modified tracking vector as an axis.
Of course, you'll want to

I wouldn't be surprised if there were some optimizations to be found here.  This is merely me working out the problem, testing it, fixing bugs as I go.


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Beginner Rig Problem - Model spinning around root bone
I'm not quite sure what's changed, since I didn't have this problem a half an hour ago with the same bone. Except for my "root" bone, each of my bones deforms the surrounding model correctly according to its weight paint. The root bone, however, while painted, moves or rotates the entire model when posed.

That is the expected behaviour. The root bone is the parent of every bone in your armature, by moving the root bone you are also moving every bone in your armature.
Technically it isn't moving your entire model, it is moving every armature bone that in turn moves each corresponding part of the model. This is like moving the upper arm bone and having the lower arm and hand follow along.
Often the root bone is placed at the bottom of the armature and is only moved to position the entire model. You may want to add another bone to be the root and set it as the parent to your lower spine bone.


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QUALITY- how I can reduce or increase quality?
I have an actually simply question. Pleas tell me how I can reduce/increase generally the quality. So that I must not render so long or whatever- pls. name all possibilities:) (or the most important)
Thank you in front :D

This is a poorly structured question. There is  not enough detail. But, generally, quality is adjusted in the render settings of whatever renderer your using. But, render time is determined by a number of factors.

You can reduce the quality/render times several ways.
-In the Render Panel under “Dimensions” reduce the “Resolution”.
-If you are rendering with “Cycles” in the Render Panel under “Sampling” reduce the number of render samples.
-Keep the number of vertices in you scene as low as possible.
-More info here if you are using cycles
http://www.blenderguru.com/articles/4-easy-ways-to-speed-up-cycles/#.U8bQthbFPG5


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Select which GPUs to use for rendering
I was wondering whether you can choose a pair of gpus to render in a three gpu machine. Maybe a checkbox-like option in which you designate which graphics cards to use. All that Blender is allowing is either using all three cards or just one.

Strange, I never had a 3 card setup but I have 2 and in user pref. in the system tab I'm able to select which card or combination of the two to use (if you have a multi-cpu card like mine) . Are you sure you don't have them connect in SLI? In that case the system (not blender) see it as one

Yes, when you have more than 1 GPU blender options are all the GPUs at once and then each single individual GPU.
This feature is on the dev's todo list for longer than 2 years.
You can check it here: https://developer.blender.org/T37717
Dec 8 2013, Brecht wrote:

It's on my todo list to improve graphics card configuration for 2.70, to allow you to select individual cards and enable/disable them. This is not considered a bug at the moment however.


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Importing VRML/X3D objects with their original file name
I'd like to batch import multiple VRML 2.0 files using a script.
However, in contrast to other importers (i.e that for .obj files) the X3D importer add-on rename the imported objects as ShapeIndexedFaceSet.(increasing numbers).
I succesfully modified a script originally doing a batch import of .obj files but since the file names are not specified, this is completely unuseful for me!
Any help to give the object the name of the file from which it was imported will be greatly appreciated!
here is the script
import os
import bpy

# location to the directory where the wrml are located
# if you are using windows style backslashes, you need to cancel one with    another
path_to_obj_dir = os.path.join('C:\\', 'prova')

# get list of all files in directory
file_list = sorted(os.listdir(path_to_obj_dir))

# get a list of files ending in 'wrl'
obj_list = [item for item in file_list if item[-3:] == 'wrl']

# loop through the strings in obj_list and add the files to the scene
for item in obj_list:
    path_to_file = os.path.join(path_to_obj_dir, item)
    bpy.ops.import_scene.x3d(filepath = path_to_file)

Do you want to import each wrl into a new scene? or simply rename the newly imported objects in one scene?

To start added a little script to make accessing the folder easier, we can now set the folder from the UI, Scene properties Scene panel.
import bpy
from bpy.props import StringProperty

bpy.types.Scene.wrl_dir = StringProperty(name="X3D Dir", subtype='DIR_PATH')

def x3d_path_draw(self, context):
    self.layout.prop(context.scene, "wrl_dir")

bpy.types.SCENE_PT_scene.remove(x3d_path_draw)
bpy.types.SCENE_PT_scene.append(x3d_path_draw)

Ok with that done, I can use scene.wrl_dir rather than hard coding the folder.  Here I simply deselect all objects (equiv of bpy.ops.object.select_all(action='DESELECT')) before calling the import op,
then rename the selected objects to the file's name as the newly created objects are selected after the import.
import bpy
import os
context = bpy.context
scene = context.scene

# get list of all files in directory
file_list = sorted(os.listdir(scene.wrl_dir))

# get a list of files ending in 'wrl'
wrl_files = [f for f in file_list if f[-3:].lower() == 'wrl']

# loop through the strings in obj_list and add the files to the scene
for f in wrl_files:
    print("Processing %s" % f)
    # deselect all objs
    for o in context.selected_objects:
        o.select_set(False)
    path_to_file = os.path.join(scene.wrl_dir, f)
    bpy.ops.import_scene.x3d(filepath = path_to_file)
    # rename them to file name, change to basename for instance.
    for o in context.selected_objects:
        o.name = f

Other methods would be to add an empty for each file, name the empty after the file and parent to it.  Or import each to a new scene.

Fantastic!! Thank you very much, it works perfectly!!

In Blender 2.8 / 2.81
Line 17 above o.select = False needs to be changed to:
o.select_set(False)

Better to just edit the original selected answer, rather than cause people like me to have to run code, debug it, then realize the correct answer is sitting below. I've made the edit. Have a good day.


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Why after transforming an object with the matrix_world of another object the reference and target object have different transformation matrices?
I'm quite confused on how the matrix_world is applyed to an object.

Why the transformed object has a different transformation matrix of the reference one?
Why the parented objects do not apparently have a transformation matrix? (getting their transformation gives an error)

Here is more in detail my problem:
I'am reconstructing cerebral regions from multiple brains in a separate software (TrakEM2) and using blender (2.79) to manually align all brains togheter to a common reference space. For this I create a central plane between 3 reference points for each brain, parent all objects to that plane and align it to the reference space.
The problem is that I continually edit these brains in TrkEM2, adding details or new parts, and when importing new objects or edited ones, I need to transform them as the previoulsy imported object of the same brain. For this I use the matrix_world of one of the previously imported object as reference (anyone is good but I need to un-parent it).

the imported object goes to the right place (after an additional rotation) but the transformation matrix is different from the one I have applyed to that object. This is wierd to me, and partially a problem beacause I must remeber that these secondarily imported object should not be used as reference objects.
I tried to use the plane that I create when importing as reference, but for some reason the imported object are than shifted from where they should land (rotation ok..)

I attach a script that illustrate the firstissue, an .obj is imported, shifted and than re-imported using the first copy as a reference. As you can see, the origin and rotaion of the two copies are different, as is the printed transformation matrix.
Can anybody explain, give suggestions or send me to some documentation (for linear algebra ignorant?)
import bpy
import os

WORKING_DIR = "G:\Progetto QA\RR PSD Gephryn\Export\Obj\import"
file_name = "RRGEF1_An_LV-pi_1226.obj"
file_loc = os.path.join(WORKING_DIR, file_name)

#import object
imported_object = bpy.ops.import_scene.obj(filepath=file_loc)
obj_object = bpy.context.selected_objects[0]
bpy.context.scene.objects.active = obj_object

#Transform the object to correct default TrakEM2 orientation and scale
bpy.ops.transform.resize(value=(-0.001, 0.001, -0.001), constraint_axis=(False, False, False), constraint_orientation='GLOBAL', mirror=False, proportional='DISABLED', proportional_edit_falloff='SMOOTH', proportional_size=1)

#Translate the imported object
bpy.ops.transform.translate(value=(2.45409, 1.31843, 2.94766), constraint_axis=(False, False, False), constraint_orientation='GLOBAL', mirror=False, proportional='DISABLED', proportional_edit_falloff='SMOOTH', proportional_size=1)

#get the transformation matrix of the transformed object
M=bpy.context.object.matrix_world
print ("reference:",M)
bpy.ops.object.select_all(action='DESELECT')

#import object
imported_object = bpy.ops.import_scene.obj(filepath=file_loc)

#select imported object and apply the transformation matrix
obj_object2 = bpy.context.selected_objects[0]
bpy.context.scene.objects.active = obj_object2
me = obj_object2.data
me.transform(M)
me.update()

#Correct the transformation of the imported object
bpy.ops.transform.rotate(value=1.5708, axis=(-1, -0, -0), constraint_axis=(False, False, False), constraint_orientation='GLOBAL', mirror=False, proportional='DISABLED', proportional_edit_falloff='SMOOTH', proportional_size=1)

M2=bpy.context.object.matrix_world

print ("target:",M2)

Related https://blender.stackexchange.com/questions/102293/how-to-properly-use-exporthelpers-axis-conversion-method  A lot of importers have conversion arguments, to import into the different space.

Thank you very much! You defenetely point me in the right direction. I've found the option to convert the axes while importing, and mupltiplying the matrix_world of reference and target objects resolved the issue. Yet I don't understand why I still need to adjust the transformation after the matrix multiplication. I Attach the new code in case it could help somebody else.

Here the updated code after following batFINGER suggestions
import bpy
import os
from mathutils import Matrix,Euler

WORKING_DIR = "G:\Progetto QA\RR PSD Gephryn\Export\Obj"
file_name = "RRGEF1_An_LV-pi_1226.obj"
file_loc = os.path.join(WORKING_DIR, file_name)

#import object
imported_object = bpy.ops.import_scene.obj(filepath=file_loc,axis_forward='Z', axis_up='-Y')
obj_object = bpy.context.selected_objects[0]
bpy.context.scene.objects.active = obj_object

obj_object.scale=(0.001,0.001,0.001)

#Translate the imported object
bpy.ops.transform.translate(value=(2.45409, 1.31843, 2.94766), constraint_axis=(False, False, False), constraint_orientation='GLOBAL', mirror=False, proportional='DISABLED', proportional_edit_falloff='SMOOTH', proportional_size=1)

#get the transformation matrix of the transformed object
M=bpy.context.object.matrix_world

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

#re-import object
imported_object = bpy.ops.import_scene.obj(filepath=file_loc,axis_forward='Z', axis_up='-Y')

#Transform with matrix multiplication
obj_object2 = bpy.context.selected_objects[0]
obj_object2.matrix_world = M * obj_object2.matrix_world

# Adjust the transformation
obj_object2.rotation_euler=Euler((-1.5708,0,0),'XYZ')

M2=bpy.context.object.matrix_world

print ("reference:",M)
print ("target:",M2)


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Cell shaded effect
Is it possible to get a cell shaded effect on blender similar to the image below?
http://gamegrass.com/game_img/2013/02/01/754.jpg

What you're looking for is FREESTYLE RENDERING ENGINE in Blender (https://wiki.blender.org/index.php/Dev:Ref/Release_Notes/2.67/FreeStyle).


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Model still appearing pink after applying image.
So I just started learning how to texture paint and am following this tutorial (https://youtu.be/LcCQKuWPhXk)
I followed everything up to the point where you add the image texture node.
When I add it, the image remains pink instead of turning black. Is there anything that's normally expected when texture painting that I missed?

related http://blender.stackexchange.com/a/5372/19287

The Image Texture node's color output needs to be connected to the Diffuse node's color input.

Did that solve it?

Image Texture's node color output does not need to be connected to the Diffuse's node for texture painting, it's enough placing node in the node tree. It would be required if you try render that. It's quite strange that Blender didn't show that image, probably it would help reloading it

Possible duplicate of Why are all the textures in my file pink?

I found that you can unwrap the object in glsl texture mode then import the texture and attach it to a material by adding a material, applying it to the faces you want textured, selecting the material, going to the textures tab, new, material. you can then edit the uv map of the object how you like


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How to texture paint a mesh while it's transparent?
So I finished modelling my mesh for a spaceship and moved on to texture painting it. The problem is that I'm following the design of an image in the background and I cannot see it while painting as the mesh is black. Is there some way to make it transparent so I can see the image while painting or...?

Thats good question. I'm not sure if you can do that, but what you could do is take that background image into something like photoshop or gimp and paint onto that and adjust it to how you want, then just apply that texture to the model, otherwise you might have to simply paint it with the bg image as a reference...

If it's just about seeing a reference image, which you loaded in as a Background image to a view, you can set the display of it to 'Front'. It's the Button under the 'Opacity' slider, by default it is set to 'Back':

Texture Paint with Brush Mapping Stencil.
In texture paint mode open the texture panel, select stencil, and select a destination image.  Slot creation may take care of some of these steps.
Texture Paint allows the user to paint directly on the surface, flat or not.  The paint source is shown below on the left, the human figure with transparent background.  The destination image is on the right with UV Map edges.  The transparent, of some level, brush stencil is in the middle with the yellow arrow.  You may choose the level of transparency.  The leg portion was painted. Position was changed. Head portion painted.  The pixels were copied from the Stencil image.
The sphere shape has a UV Unwrap which appears in the UV Image Editor window.
Remember to save the destination image. Counterexample. I had to paint twice because I forget to save. Thus image below is different than the one above. Strive to paint on surfaces directly facing view. Avoid painting faces in silhouette.  Counter example.  The smudge below is when I painted the faces in silhouette.

Image above.  Render result and the target image.
For the final render in Blender Render the target image was specified as a texture.  Cycles also applies textures in a different easy manner.  That detail is a separate question.
Know that the slot interface in the texture paint allows you to choose diffuse color slot and create a new blank image for the destination image.  I encourage you to try this on examples first which can be discarded then your production work.
Please see this answer as well.
How to paint a texture on, based on the way it was mapped on with UV?

Sorry, I'm fairly new to Blender and don't really understand how to do that. is the stencil transparent by default?

Do you see the texture panel on my image on the left portion .... and the Blender texture paint window on your computer?  Open that texture panel and select your image.  Part of the approach is to get you progressing  in the correct direction and let you discover somethings.  As indicated above,  I can not do justice to the texture painting in a short answer the way a video tutorial would.  There are so many features.

Go to PropertiesEditor->Object->Display->Wire
This will let you see the wireframe of your mesh in texture paint mode.
Now all you need to do is change the color of your ship to anything but black.


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Where did my texture go after selecting Use Nodes?

I created a material for the Cube

Color map
Normal map

Unwrapped it
Enjoyed the view in the viewport with Internal and the Game Engine
Then I switched to Cycles and clicked on Use nodes and there is no more texture in the viewport of Internal and Game Engine

What happened? Can I undo that somehow? I read that Cycles's is not compatible with Internal.
Can I have materials set for Internal/GE and Cycles and switch between them (the rendering engines)?
I intend to export my creations to my own game engine and eventually to render still images for enjoyment but the former is what I need most.

Possible duplicate of: http://blender.stackexchange.com/questions/364/how-do-i-convert-materials-from-blender-internal-to-cycles

Materials created for Blender Internal are not compatible with Cycles. Blender Internal uses an entirely different nodes system, stemming from the fact that it is an entirely different rendering engine and rendering images via an entirely different method.
To use your texture in Cycles, you would need to recreate your texture in Cycles, or otherwise use a script to convert it to Cycles. See this answer for more information.

This is something I already understand. My question is that after I clicked Use Node and went back to Blender Render/GE the texture would not display. The material is there but there is no texture in the viewport to be seen. Why would adding nodes in Cycles break what I have setup in BR/GE?

By pressing add nodes you basically 'converted' the Blender Internal material to a Cycles one, possibly breaking it for both engines, since the conversion is not really complete or reliably. Choose one engine and stick with it, create materials from scratch for each and avoid switching back and forth, that will only lead to misfortune.


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How to correct shading when connecting faces?
On this image I selected four vertices and then I pressed F to create a face and I repeated until I connected the two parts of the object. Then I deleted the "internal faces". But the shading is still wrong. Recalculating the normal doesn't fix it. I deleted one of the faces and recreated it and the shading on it was correct.
What is causing this un-smooth shading and how can I correct it?

When you add faces using F to a mesh they default to Flat shading - even if the rest of the object is set to Smooth shading. To set all faces to Smooth shading in Object mode, simply click 'Smooth' shading in the toolshelf (T). Alternatively, in Edit mode, simply select those faces, press Control-F to bring up the Faces menu and select 'Shade Smooth' (or 'Shade Flat' to set individual faces back to Flat shading).

OMG! You are right! Thank you so much. I am pretty sure I quit Blender once just because of that as I am now recalling. I was expecting that shading is per scene/object. Why can an object have two shadings at the same time?


text:
I moved two vertices on the cube: once side is bent inwards and the other not
What I did is:

I selected the right vertex and moved it to the left.
I selected the left vertex and moved it to the right.

Please notice how on the right the geometry is somehow bent inwards and on the left it is not.
Why is that so? Is that a correct behavior?

To add to the other answer, it is possible to fix errors in the automatic triangulation of meshes.  Faces can be triangulated by pressing Ctrl+T and converted to quads by pressing Alt+J.
When you force triangulation you often find Blender evens out any inconsistencies, but you can manually rotate edges using the Edge menu if necessary.  When done convert back to quads and your mesh should look a lot a more even.

Yes, this is the correct behavior. In representing the appearance of an surface defined by more than 3 vertices, as each of the two sides of the cube are, 3D modeling programs (at lest the ones I know much about) use triangles to determine how to represent the surface. I copied your image, and added in the lines that determine the triangle in your cube.
[
In mathematical terms, the vertex you moved on the right is part of the hypotenuse; the vertex you moved on the left is opposite the hypotenuse.


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Why does Blender re-calculate lighting when you pan/zoom/rotate?
This isn't a urgent question, I'm just curious. Why does blender have to recalculate the lighting every time you pan/rotate/zoom in rendered view? The lighting itself is not changing, so why does it have to do that?

hmm, I guess that makes sense. Thanks for your response :)


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Video Editor Rendering - 7 hours to render 22 mins of video / audio
I've got what I think is a rendering issue and despite reading and watching many things on here and the internet in general, I can't fathom it out.
Firstly, I'm quite new to blender video editor and have only been using it for about 3 or 4 months now but am really enjoying using it.  I've rendered several videos on it all and from what I can remember, all seemed to go fine.
However, the last few videos I've edited and rendered (all circa 20 mins) have taken between 6 and 7 hours.  I have no idea if this is considered good or bad, but no mater what changes in blender I make, nothing changes regarding the render time and was wondering if the fine people on here could assist me please.
The last video I created in there was a combination of 2 video + audio files and 1 audio file.
Video 1 is a 22 min long game footage capture from my xbox one via an el gato HD60 capture device.  This video and audio is then soft cut into smaller sections in BVE with the audio being lowered on some of the cuts.
Video 2 is an 8 second long intro video + its audio with no adjustments.
Both of these videos are setup on the same strips while the 3rd file (audio only MP3) is setup on it's own strip.
The specs for each file and my hardware are as follows....
Video / audio 1:
22 mins long
.M4V
1920 x 1080
59.94 FPS
Stereo
48 kHz
Video / audio 2:
8 secs long
.MOV
1920 x 1080
59.94 FPS
Stereo
48 kHz
Audio file :
22 mins long
.MP3
Stereo
44.1 khz
Blender settings / output details:
Memory Cache Limit - 4gb on the laptop / 32gb on the PC
Interestingly, no mater what I set it to, BVE only seems to use half of it, however, again, no mater what I set it to in terms of size, it doesn't make any difference to the render time.
Dimensions:
1920 x 1080 (100% scaling)
59.94 FPS
Anti -Aliasing, Sampled Motion Blur, Shading:
All off
Performance:
Threads auto detect
Output:
H.264 RGB
Encoding:
MPEG4 H.264
Bitrate 6000
GOP size 30
Audio codec MP3
Bitrate 384
Hardware details:
PC -
Dell Precision T7400
Windows 10
56GB RAM
2.5ghz Xeon Quad Core CPU
AMD Radeon HD 6000 series (I think) (1gb)
Laptop -
Macbook Pro Early 2013
OSx 10.10.3
8GB RAM
2.4ghz i7
Geforce GT 650M 1gb
SSD
Something to note is that everything is being done from / to a WD Elements USB HDD (IE all blender and original video / audio files are on the drive + rendering to the drive), but this has always been the case, including on the earlier videos which seemed to render fine.
I've also tried rendering from the USB HDD to the PC SSD but there is no difference in time to render.
Hopefully there is enough info in here, but if anyone requires any more info, please just ask. :)
I Really want to keep using BVE for now as I've only been video editing for a short time and can't afford the bigger / more professional packages out there. :(

Related: http://blender.stackexchange.com/q/41717/2843, http://blender.stackexchange.com/q/38631/2843

You are converting 44.1k audio to 48k audio (render hit) and if there is any difference between source dimensions and project render dimensions, another render hit. Try to eliminate these discrepancies.

If you are rendering anything on the stock USB 2.0 ports, you should expect slow times.  You could get either a USB 3.0 or 3.1 card for your box or move all of your files to an internal media drive and work from there.


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Export a video to a .blend file
Yesterday I downloaded an intro template from Youtube and I have now edited it in Blender Video Editing, but I also want to edit the animation in the video. So how can I do this? Can I export the video to a .blend file and open it that way?

It's not clear what you want to do, as it currently stands, try adding more info to your question, like a screenshot of what you are trying to do, a link to the video, or the downloaded file. It seems you can't do what you are trying to achieve, you can do minor editing to a video in Blender using the Video Sequence Editor, but if you want to do heavy modification to the animated content you probably have to make your own 3D model and render it from scratch, instead of tweaking an existing one.

So what are you trying to achieve? I'm not much into video editing, but as far as I know you can do some minor adjustments in the video editor like color adjustments, fading and transition effects, overlaying text or other images but that is it. Any further editing requires you to do 3D modeling and rendering footage you can then overlay over your video.

Here is the video I downloaded from Youtube: https://www.dropbox.com/s/1f9vufbct62kqft/intro%20from%20yt.avi?dl=0  As you can see it says' Your Name "in the video, which I want to change. I'll be able to do that through  blender. But how can I open this video in Blender and change it?

The video is an .avi file, but what I know can you just open a .blend file in Blender, so how should I do now?

Here is a video with a guy that open a .blend file in Blender and edit the text: https://youtu.be/CfCIDbWdJtw?t=1m21s I want to do same thing with my video, but my video is an .avi file, so I must do it to a .blend file, how?

In that video the author downloaded a source Blend file, not an AVI video, to achieve that your need to get the source blender file with the 3D scene it was rendered from, not a final video.

AVI is a video container as in a final "presentation" file format, not really an editable or working project file format per-se. You can't just edit the AVI file and replace the text with your own like you would, say, a word document or a text file.
In this case Blender can read the AVI file, use it in the video editor as an external reference, and can overlay stuff over it, like overlaying a new string of text over "Your Name" but not in an automatic way.
You will have to do it manually and integrate it into the video, cut it, move it, and rotate it in a way that blends it in with the animation.
You might want to do that in a 3D scene with 3D objects and then render it, but it is not an easy "press one button" task

So I can't convert the file to a .blend file and edit the video then?

No, not immediately. What you need to do is to search for the source file or ask the author if the source Blender file is available somewhere, you can't easily edit that from an AVI file


text:
Strange horizontal stripe on a surface with a Cycles material applied
I am getting a strange horizontal stripe with rendering a curved surface with a wooden material applied by using the Cycles renderer. The picture below basically tells it all:

I've uploaded the Blender model here:
The Blender model for reproducing the problem
As far as I can tell, there's nothing wrong neither with normals nor with the geometry itself at the location where the stripe appears. Nor does it seem to be a texture mapping issue since if I switch to the "textured" display in the main editor pane, the stripe goes away and I can see the texture mapped exactly the way I want.
I've also played a bit with the node editor for the material to check to see if there are certain nodes that could contribute to this strange effect, but to no avail :(
Hopefully someone experienced from the community could give me a hint what's going on since I seem to be out of further ideas to try.
Thanks!

Your textures are not included in the file.  This will result in purple images as in the proposed answer below.  You should also show your material nodes and UV information in the question itself.

I suggest that you turn off your current [sun] lamp for rendering.
Add a new [plane] with emission material and use this as a light source.
The visibility settings of the new [plane] should have camera visibility off depending on the placement.
All these actions should take 3 minutes or less when you have practiced them.

Thanks, replacing the sun light source with an emission surface did the trick!


text:
bake strange black corners and black points
finally after all day trying and looking here, and youtube videos, i baked my first test object.
i managed to bake multimaterial object into a single baked texture.
but now i have this black corners and black points.
i am rendering with cycles.

of course without baking, the 3d is perfect
please. help me


text:
Dynamically change the bl_label for an operator
I have an operator, attached to a button. The button creates a tower of cubes depending on 3 input dimensions. What I would like to do is dynamically change the text on the button so that it tells me how many cubes you're about to create, before you create them.
When I run the script, it initialises the button to the correct number, but the number doesn't change when I change the input conditions. The only way to do that at the moment is to re-run the script. I would appreciate any help finding a better solution, here's a code snippet so you can understand what I mean a bit better:
# operator for pressing the button
class Button(Operator):

button_text = bpy.context.scene.my_tool.cube_number

bl_idname = "object.simple_operator"
bl_label = str(button_text)

please check this code:

'''
BEGIN GPL LICENSE BLOCK
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.    See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software Foundation,
Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
END GPL LICENCE BLOCK
'''

bl_info = {
 "name": "test properties",
 "author": "Diego Quevedo ( http://doshape.com/ )",
 "version": (1, 0),
 "blender": (2, 7 , 3),
 "location": "View3D > EditMode > ToolShelf",
 "description": "test properties ",
 "warning": "",
 "wiki_url": "",
 "tracker_url": "",
 "category": "Mesh"}

import bpy, sys, math
from bpy.props import (StringProperty,
                       BoolProperty,
                       IntProperty,
                       FloatProperty,
                       FloatVectorProperty,
                       EnumProperty,
                       PointerProperty,
                       )
from bpy.types import (Panel,
                       Operator,
                       AddonPreferences,
                       PropertyGroup,
                       )

class testOperador(bpy.types.Operator):

    bl_idname = 'ops.test'
    bl_label = 'test'
    bl_description  = ""
    bl_options = {'REGISTER', 'UNDO'}

    test1 = bpy.props.BoolProperty(
        name="test_properties after execution",
        default= False
    )

    def main(self, context):

        print("hello")

    @classmethod
    def poll(self, context):
        obj = context.active_object
        return all([obj is not None])

    def execute(self, context):

        self.main(context)
        return {'FINISHED'}

class MySettings(PropertyGroup):

    x_size = FloatProperty(
        name = "x size",
        description = "A float property",
        default = 23.7,
        min = 0.01,
        max = sys.float_info.max
        )

    test = bpy.props.BoolProperty(
        name="test",
        default= False
    )

    vertices = bpy.props.BoolProperty(
        name="vertices",
        default= True
    )

class UV_OT_my_panel(Panel):

    bl_space_type = "VIEW_3D"
    bl_region_type = "TOOLS"
    bl_label = "test"

    def draw(self, context):
        layout = self.layout
        scene = context.scene
        mytool = scene.my_tool

        split = layout.split()
        col = split.column()

        a= bpy.context.scene.my_tool.x_size

        layout.prop(mytool, "x_size", text="x-size")
        col.operator(testOperador.bl_idname, text=str(a), icon="COPYDOWN")

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

        split = layout.split()
        col = split.column()

        b = bpy.context.scene.my_tool.test

        row = col.row(align=True)
        row.prop(mytool, "test")

        if b:
            col.operator(testOperador.bl_idname, text="test1", icon="COPYDOWN")
        else:
            col.operator(testOperador.bl_idname, text="test2", icon="COPYDOWN")

def register():
    bpy.utils.register_module(__name__)
    bpy.types.Scene.my_tool = PointerProperty(type=MySettings)

def unregister():
    bpy.utils.unregister_module(__name__)
    del bpy.types.Scene.my_tool

if __name__ == "__main__":
    register()

The key point there is using text='xx' when adding the operator to the panel draw code.

Please add some explanation of the key parts of the code.

I tried to do it by assigning bl_label (within the operator) to a variable, but changing that variable didn't work. However, what does work is overriding that so bl_label isn't used at all. When you draw the button as part of the "Panel", adding an extra argument "text = str(variable_name)" fixes the problem, as that seems to refresh it when the variable changes. Hope that makes sense, and thank you yhoyo for the answer


text:
Change start and end frame of rigid physics simulation with python
I'm having a lot of difficulty trying to change the start and end frame of a rigid body physics simulation with python. Changing the settings in the UI shows the following in info view:
bpy.context.scene.frame_end = 850

However, running this will change the end frame of the timeline, which is not what I want. I saw the following post which solves this for cloth simulation, however this doesn't work, because the rigid body physics are not employed as a "Modifier". (Change the start frame and end frame of a bake in Blender using script)
Perhaps I have to change the context and then running the above code? I would appreciate any help implementing this, or any other way to achieve this effect.

Just figured this out, hopefully this helps someone else. If you access the point cache within the rigid body world (simply make at least one object in your scene a rigid body, otherwise no rigid body world will be created and the script will throw an error), this has a frame start and frame end which you can change with, for example:
import bpy

# Get the current scene
scene = bpy.context.scene

# Set Rigid Body World Cache Simulation Start and End Frames
scene.rigidbody_world.point_cache.frame_start = 1
scene.rigidbody_world.point_cache.frame_end = 1000

You can also set the rigid body world cache to match your scene timeline rendering / playback frame range like this:
import bpy

# Get the current scene
scene = bpy.context.scene

# Match the rigid body world's cache frames to scene start and end
scene.rigidbody_world.point_cache.frame_start = scene.frame_start
scene.rigidbody_world.point_cache.frame_end = scene.frame_end


text:
Share Object data between two scenes, but no materials
My scene is planned for a realtime application.
I want to setup my lighting and materials on cycles, then bake some elements to lowpoly objects. Here an example scene : http://www.pasteall.org/blend/42859
I bake Selected to Active (HP_Cube to LP_Plane) to the texture LP_PLane.
All i want in my 3d engine is LP_Plane with his texture applied to a standard material.
Problem : cycles material are not compatible and can't be exported to the engine.
So i want a new scene where i could keep the LP_Plane object, but switch to blender internal and assign a new standard material to my object.
Here i have made a new scene set to full copy http://www.pasteall.org/blend/42861 but of course if i modify LP_Plane in the first scene the mesh data is not echoed to LP_Plane.001
Is their a way to have duplicate linked objects between two scenes, each object having the same name but one with cycles material, the other with standard ?
(and sorry if my english is shitty)

Yes this can be done. First, you need to create the two scenes where the Object Data is linked, but the objects are not. After that, you can setup the materials in a way so they are different in both scenes.
Start off by creating the second scene using 'Link Object data'. This will copy the object, but link the mesh data. That means, when you edit a mesh in one scene, its shape updates in the other as well.

Blender allows you to choose if the materials are linked to your Object or the Object Data. By default it links to Data, that means that somewhere in the datablock where the mesh is stored, the information which face receives which material is stored as well. Since both scenes share the same mesh data, the materials would always be the same in both of them.

In your case, you will need to set the Link to Object instead, like in the screenshot here:

Now the information which face has which material is stored in the Object. Again, for the two scenes, the objects are different, only the data is shared.
Note that when you switch your material link from Data to Object, the material slot will be emptied. Click on this Icon to browse through a list of materials to link it back:

In your 'Blender Render' scene you can now assign completely different materials to the same mesh. However, keep in mind that if you delete a material slot, it will disappear in both scenes!

Great thank you ! On top of that it's not a complex workflow :)

I make a test scene with a few explanations if some people want to play with this workflow : https://www.nothing-is-3d.com/dl/cycles_for_baking_BI_for_export.7z

glad it helped!

authors: محمد نیستانی


text:
Why do i have so ugly creases on my render
don't know why but i have very ugly creases when i plug my normal map in.
I fixed my normal map and tryed to delete all creases but still have no result , model is very ugly , this is my 3rd character and for very first time i have so ugly results ;/
https://dropmefiles.com/M9ON9
with out normal map everything looks very good.

hello, could you please use another download platform? Also, don't forget to pack the image inside the file: https://blend-exchange.giantcowfilms.com/

Hi. Please use the built-in uploader when adding images. See: https://meta.stackexchange.com/questions/75491/how-to-upload-an-image-to-a-post . Thanks.

Set the Color Space to Non-Color on the normal map's node in the shader editor.

Your mesh looks like a low poly mesh with shade smooth enabled. Add a Subdivision Surface modifier?

ty guys for attantion, have not expected so fast answers , cant upload on blender exchange dunno why .https://drive.google.com/drive/u/0/folders/1iV-v_eb7VlqOP0orvktBDGxM5DeI-nFU mb this link is ok ? non color data is enabled .

or this https://drive.google.com/drive/folders/1iV-v_eb7VlqOP0orvktBDGxM5DeI-nFU?usp=sharing


text:
Why are my keyframes stacking through the animation instead of moving frame by frame? (2D animation)
This is my first time using blender and I’m working on a 2D animation but my computer was having difficulties and now all of my keyframes stay on screen and stack together, like for example I used an interpolation sequence and every breakdown is displayed on screen together rather than moving frame by frame. Is there some setting I could change to fix this?

What you are describing sounds like some kind of onion skinning feature. But I don't know Blender to have one. Someone please confirm if it does.

Blender does have an onion skin feature, which I had been using throughout the animation but now each keyframe stays on screen for almost the entire animation,  adding on top of one another (when I was originally animating I would use additive animation where I built on the previous frame and erased a few things, now it seems like everything I erased is staying on screen and stacking on top of one another). The problem started after I merged two layers and then my computer started glitching out.

What kind of layers? What version of Blender are you using?

Grease pencil, I’m using version 2.83


text:
How can I remove black backgrounds from fire stock images to use in material with transparency?
An easy way to get fire in your scene without simulating - no matter if it's for still images or animation - is using stock footage/photos of fire, often with a black background and just as JPG or PNG. And the background is okay, if you want to add it over a rendered image in the Compositor.
But for use in a material with the black background being transparent, a common way shown in tutorials is to mix the fire image plugged into an Emission shader with a Transparent BSDF, using the image as the mix factor either directly or plugged into a Color Ramp to have some control over the contrast etc. Adjusting the Strength on the Emission then helps brightening up the flames.
However, the result without boosting the strength looks quite flat compared to the original image and misses detail in the darker flame areas. Even with the help of a Color Ramp and increasing the Strength, it is not easy to bring back the darker parts without increasing the contrast and then maybe losing detail in the bright areas:

So the question is: Is there a better setup to maintain all the brightness information of the image without losing the detail?

Do you see something special about 'fire stock images' or will the same techniques apply to any other flickering image, as for example, human hair or tree branches?

In that case why would you try this in Blender, rather than somewhere like Photoshop?

Hi,  Gordon and @RobbieGoodwin .. this commentary seems to have got a little out of hand.. it's  become more about itself than the question or answer. I've taken the liberty of removing those parts. If you still have have  points to make on the central issues  that can be stated clearly, independently of other comments, please go ahead.

The problem with the above setup is, using the image as mix factor directly or with the help of a Color Ramp converts the colored image into a greyscale image which gives a combined brightness value of the overall color, although separating the image with a Separate Color or Separate XYZ node you can see, the RGB channels might be very different in brightness like shown in the following comparison:

As to be expected with yellow/orange flames, the red channel has the most bright pixels overall, the green is still quite bright while the blue channel is mostly dark.
So the secret to keeping the brightness and detail of the original image lies in separating the channels and using them for Emission shaders with different colors and adding them to a transparent material.
To achieve this, you first of all need three Add Shader nodes. Plug a Transparent BSDF into the first Add Shader. The Image Texture will be plugged into a Separate Color node (or Separate XYZ, it does not matter since the RGB channels are a 3-dimensional vector as well).
Now you need three Emission nodes: the first one set to pure red (RGB: 1/0/0), the second to green (RGB: 0/1/0) and the third to blue (RGB: 0/0/1). In the Strength inputs you plug the Separate Color outputs of the according color channels: Red into the red Emission shader, Green into the green one and Blue into Strength of the blue Emission node of course.
Now plug the red Emission into the Add Shader with the Transparent BSDF already plugged in, the output of the addition into the next Add Shader together with the green Emission and that output in the third Add Shader together with the blue Emission. The order does not matter though, since addition is commutative.
Now the result without improving anything like e.g. boosting the brightness already looks a lot better than the basic transparency setup in the question, the colors are more vivid and there is more detail in the flames:

For tweaking the look there are now different options, basically depending on what you want to do and which method you prefer. Just for a general increase of the emission strength overall like in the question you can use a Vector Math node set to Scale and plug it between the image and the Separate Color node:

But if you are maybe not happy with the color of the flames, let's say they are to yellow and you want them a little more red, and maybe going towards white in the bright areas - in this case, instead of scaling the channels uniformly, you can set the Vector Math node to Multiply and use different factors per channel. So for a little more red than yellow, multiply red/X with a slightly higher value than green/Y. For making the bright areas turning more white, multiply blue/Z with a higher value than red and green:

Another way to change the strength of the emission with also having control other the individual colors would be to not scale the image before separating the colors, but multiplying the separate channels after splitting them up with normal Math nodes set to Multiply after the Red, Green and Blue outputs.
If you want to increase the contrast you could either do this with a Bright/Contrast node plugged between image and Separate Color node or for each channel separately by using Math nodes set to Power. Plug the color channel into the Base input and set an Exponent. Exponents > 1 will increase contrast, values between 0 and 1 will decrease contrast.

In the above example I scaled the strength before separating colors, however you have to keep one thing in mind: Let's say you want to increase the strength by 5 and do this with a Scale node. Then you want to increase the contrast by an exponent of 2 maybe, but: it makes a big difference if you first scale by a factor of 5 and then use the Power node on separate channels or if you do not scale before separation, then use the Power node and afterwards a Multiply node with a factor of 5. In the first case your maximum strength suddenly jumps to 25, in the second case you keep the maximum strength at 5 as it was before changing the contrast.
The mathematical reason is simple, in the first case the strength per channel $y$ is calculated as
$$y=(5x)^2$$
and since $x\in[0,1]$ this results in $y\in[0,25]$, while the second case is calculated as
$$y=5x^2 =5\cdot x^2$$
and so for the strength you get the range $y\in[0,5]$.
Here you see the first case:

And this is the result of the second case:

Wow, we need more of these. Great answer, and the effect looks great too.

@DuarteFarrajotaRamos I can only agree! Gordon, keep it up, this is a great post! ...and shaders are apparently also more popular than Geometry Nodes :D


text:
Is it possible to tweak round corners of UI?
I haven't seen an option which allow to "rectangularize" some rounded corners of UI buttons. It is possible ?

Not yet,
but I dislike the rounded corners as well, I decided to fix this.
It's hardcoded, so I'm exposing a option that enables you to turn this on\off.
I've uploaded a patch here:
https://developer.blender.org/D2178
I have a example screenshot here showing it:

authors: Ирина Маленьких


text:
I can’t get rid of pink objects
I’m new to Nlender.
I think I’ve deleted my texture files by accident.
I’ve watched several videos on how to try to sort this but nothing is working.
I’ve tried uninstalling but I have a Mac and it’s not uninstalling everything.

Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking.

When I open up shading or texture paint, the object is pink. Which means missing texture files. I’ve tried to find them and report them. Nothing changes. My object remains pink.

You said you think you've probably deleted the files by accident. If they are deleted, there's no way Blender will find them and then it's normal that everything stays pink. The "Find Missing Files" function is to tell Blender where files are if you moved them from the original position. If they are completely gone this won't help - Blender is no recovery tool for deleted files.

Oh no, so I need to completely uninstall it from the MacBook then?   Because when I install it, it isn’t uninstalling it completely.  maybe if I restore my MacBook. I don’t know

Thank you. So much, I thought this was the problem. I can’t believe I did this.

...actually I don't understand what deleted texture files have to do with installing/uninstalling Blender.

How can I get the files again?
I can’t remember how I done it lol I am new to blender.

When you are talking about deleted files, you mean files that you removed from your computer? 1. look in the recycle bin of your computer, in Windows you can "undelete" them, I don't know if it's the same for Mac and 2. if this is about deleted files, this is not a Blender-specific problem.

I’ve Been all through my recycle bin. I thought it was an image when I deleted it. . It’s ok, I’m going to watch some lessons in learning blender, maybe il find the solution along the way. Thank you


text:
Why is my material changing in cycles?

On the robe it changes in cycles. why? its just a normal image texture. I Don't understand why it is different. I was having some issues with the displacement on the ground but i fixed it but the clothes are still a different color. What would cause this?
https://www.dropbox.com/s/kuzyaujep8ebd3c/Landscape_free_files.blend?dl=0

pls check this: https://blender.stackexchange.com/questions/123724/eevee-and-cycles-render-lighting-differences

Hello and welcome. Please don't post the same question more than once. If your previous question was put on hold, address raised the issues by editing it so it can be reopened rather than post a new one, otherwise see What should I do if no one answers my question?

Does this answer your question? Some parts of material appear darker than it should be


text:
How to delete parts of an object which are transparent in its image texture?
I want to delete the black parts of this head object. There is nothing there it is transparent.
I want it to look like it does in the texture paint mode so i can just put the face on the other head.
Here is a video
https://i.sstatic.net/aKXD9.jpg
https://drive.google.com/file/d/1Rrq6Wt_44W68tpk1aewl-IiEyokSF85g/view?usp=sharing

pls provide blend file, thx

heres the blend file https://drive.google.com/file/d/1Rrq6Wt_44W68tpk1aewl-IiEyokSF85g/view?usp=sharing

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

Hi. Please don't post essential information like links, file downloads or additional details in the comments section where it can be easily missed. Instead edit them into your original post with the [Edit] button above. Comments are transitory by nature, are hard to index or search for, and may be erased at any moment.

While files, images, and external videos or links may be helpful additions they should not be the only way to obtain information about your issue. Don't make understanding your question rely on downloading a file, watching a video or visiting an external site. Use the builtin tools to upload images or gifs, along with thoroughly explaining the problem in written form so it can be indexed and searched for thus helping future visitors with similar issues.

in your material, just plug in alpha to alpha like so:

and in your material change blend mode to "alpha blend".

Then you get (in rendered mode) this:


text:
How to render with same style as seen in solid viewport?
I'm new to Blender and I like very much the esthetics of the viewport. Is it possible to replicate those settings when rendering it?

I got this look when those settings are applied.

Bigger resolution image:

the Input > Ambient Occlusion (AO output) node and the Input > Geometry (Pointiness output) seem to be the closest thing to this cavity effect, but it looks like you can't render the exact same thing

Change the render engine from Cycles or Eevee to Workbench in the Render Properties tab and play with the configurations:

also, this video show in details how to use Workbench:
Introduction to Workbench Blender 2.8

If you want to render exactly what you see in the viewport, you can use : View Menu / Viewport Render Image.
Before doing that, it could be nice to deactivate some options in the Overlays and Gizmos settings. You can even uncheck the menu icons to disable them totally.


text:
Creating a Card Stack with Geomery Nodes
I'm trying to create something like a stack of cards using Geo Nodes. Following a tutorial on YouTube, I managed to arrange the cards along a curve using the Resample Curve node. Now, I want to give the cards a random rotation around the Z-axis to make the stack look more natural. I've attempted to use the Rotate Instances node, but it didn't work, and I'm not quite sure how to achieve what I have in mind.
The nodes I've used.

Card stack I'd like to create

noise texture (scaled up or down) + euler rotation (on Z) and plug that in the instance on point rotation, most likely

@lemon, thank you for your response! However, I'm still having trouble understanding how to constrain the rotation to the Z-axis. I attempted to incorporate those geonodes, but now it's rotating on all axes.

UPD: i've done rotation with combine XYZ node. Now I would like to break the curve into segments and rotate these segments relative to each other. Could you please advise on how to achieve this result?

make segments rouding for instance the curve point indexes, or the curve height (Z).

just an idea: you can also control the rotation using the curve tilt (+ what we said above)

Perhaps you could get a nice result with just one Noise Texture with the right settings, but I find it easier to reason about multiple separate noise textures:

First a noise texture giving a basic profile to the stack, low scale for smoothness (actually very low, because I use Index as coordinate, and indices tend to be bigger than position components) and no roughness/detail for the same reason; consider some minimal distortion for uneven profile.
Then noise with slightly bigger scale to add some more chaos with local shifts of the stack; plus some distortion, so the shifts vary in size.
Add them together:

Voronoi texture is good for sudden boundary changes, but you could achieve similar by posterizing (snapping) a normal noise texture. This simulates big shifts of the stack. If you want to instead simulate joining separate stacks together, you need to use the voronoi cell position as the base for the coordinates for all other noises!
A white noise can be added to slightly move all cards randomly, however another noise with much bigger scale and/or roughness works more realistically, because in reality cards will tend to line up.

The setup then becomes:

And the stacks (the 2nd with all offsets scaled down for a more subtle effect):

One non-realistic thing here (the continuity across voronoi boundaries could be considered another) is that all cards centers stick to $xy = 0$. You could use the same noise textures (or transform them e.g. using other noises) to also offset the cards slightly.

Thank you so much for the effort and the detailed explanation! It's an excellent solution and incredibly helpful; I truly appreciate it. I'm marking your response as the answer because it provides the most comprehensive solution.
I do have one remaining question: for some reason, in my Blender, the Voronoi Texture node has fewer input fields than shown in your screenshot. I only have Scale and Randomness, whereas in your screenshot, there's also Detail, Roughness, and Lacunarity. Could this be due to the Blender version? Or do I need a specific add-on? I'm using Blender 3.4.1.

I used Blender 4.0 for this answer, but you should have similar results with 3.4.1.

Basically, you need to rotate and translate the instances using a noise texture. I found that tweaking the pivot of the rotation helps. The result looked good, but was missing something.
In the reference, it seems that the cards tend to clump together; a group of them roughly rotate together by the same amount. To replicate that, I posterized the noise using a Color Ramp (because it seems that the posterize node only exists in the Compositor). I ended up mixing the original noise with the posterized version.
A clamped noise texture produces values between 0.0 and 1.0. Typically, we subtract 0.5 and multiply by 2.0 to move the values to the -1.0 to 1.0 range. Then, we can scale the values up or down according to our needs. I combined the latter two steps in my setup.
Note that the rotation should only be around the z-axis, so I multiplied the x and y components of the noise output by zero. On the other hand, the translation should be limited to the x-y plane. Multiplying the z-component by zero does the trick.
The rest is to tweak the values to get something that looks good.
A screenshot showing the final node setup and the result is attached below.

There is an issue with my setup. I shouldn't have used the Factor output from the noise as a vector. This will cause all components to be the same.

Thank you! I'll try to play around with these Color Ramp node and see what comes out of it.

You're welcome!

You can play with the Voronoi texture node to get different results. All you really need from my node tree is the Set Position, Combine XYZ and Voronoi Texture nodes.


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Can Blender model interaction of complex shapes
I have just read the basic background to Blender and am considering its use to study an engineering problem.  In constructing breakwaters different concrete armour shapes are used.  Their efficiency depends a lot on the ability to interlock with each other.  I am looking to build numerical models that simulate this and need to extract information from the constructed slopes.  Here is an example:

One way of checking how well units interlock is to apply a force normal to the slope to pull a single unit out of the slope.  The required force would typically be 2 to 4 times more than the weight of a unit.
My question is:  Can Blender model the process of slowly lowering these large concrete units with a crane.  As a unit is lowered it touches the rock underlayer and other units, rotates, slides and comes to rest.  Forces affecting this process is gravity, friction and unit dynamics (momentum).  Can Blender handle this with sufficient control over friction aspects?  Can one extract inter-unit friction and contact forces?
Here is a picture of a FEMDEM model specifically written for this problem.  Units are coloured based on inter-unit forces.  This was a major project so I suspect Blender does not have these capabilities?

Thanks in advance
Anton

Blender can, but  in  a large scale, our computers can't handle it!
Plus we don't need to really make anything. we can just fake things.  If you know what I mean ;)

You won't be able to accurately produce the interaction of Stone Tetra Pods with the beach area and water in Blender. I'd advise against using it as a tool for engeneering research. It is best used as a tool for visual representations which don't have to be physically accurate. (However, there have been plenty of other applications.)
However, Blender has the rigid body system which can be used to simulate rigid bodies.

Add a rigid body world.
Add the objects (related) and make them active rigid bodies (with correct friction values e.g.).
Cache the simulation.

In this example the resulting interlocking of the shapes can be seen.


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Objects not appearing in Blender in 3d viewport
The local view port has a can I made earlier, but when I come to global 3d view everything disappears please see the second 3d viewport its global perspective ,why is this happening as you can see in ouliner the objects are visible why is this happening ? I have attached image and file itself

https://imgur.com/QCO58G1
https://www.mediafire.com/?9crrwp8hv3do73d

You are on the wrong layer as your objects are in layer one, just press 1 with the mouse over the 3d view.

Easy mistake to fix you're on the wrong layer.  Just go ahead and click 1 while your cursor is in the 3D viewport to make everything appear.


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Why are my objects flattened or distorted when using the Shrinkwrap modifier?
Perhaps I'm using the wrong modifier, but I'm trying to conform a series of nuts to a curved plane. I first thought the shrinkwrap modifier would be the best way to go , but I'm confused by the results I get.
My results show the nuts either being flattened (project) or being distorted violently (other settings)
What am I not realizing here?
Many thanks
Sam

Your are using the wrong modifier, this is the expected behavior, Shrinkwrap modifier is designed to flatten things. Use a Curve modifier instead, or perhaps Duplifaces

The Shrinkwrap Modifier moves vertices against the target object. The effect you are seeing is the intended effect, as it has no notion of maintaining the volume of an object.
To move the whole object, while maintaining the shape of the object, you can use a Shrinkwrap Constraint, which will move the object as a whole to place its origin onto the target surface.

how can i apply the constraint

You apply the visual tranform.

Thanks! This explains why none of the instructions I tried to follow worked! :D