text:
How do I use the Freestyle SVG Exporter to reproduce the examples in the documentation?
If I understand correctly from the severely short documentation page, the Freestyle SVG exporter can export a model to a SVG file using different styles:
-a series of volumetric lines, as seen here:

-outlines where the hidden edges are rendered as dotted lines, as seen here:

However, the documentation doesn't bother expanding on how these results were achieved. There are no modifiers in the Modifiers Panel, or in the Freestyle Export Panels, that seem to correspond to these examples (I looked in both 2.79 and 2.80).
How does one render 3D models into SVG, while applying the styles of these examples?

An example for the dotted lines can be found in this answer. Note that you don't have to use edge marks if you want all edges to be drawn. The line styles are created by setting up FreeStyle Line Sets. The exporter just outputs the result as SVG file, it does not configure the appearance except for  stroke cap style and fill contours.

Thanks, I'm looking into it. I guess I've just spent 4 hours trying to understand what settings to select to get the results in the first image from the Freestyle Line Sets and nothing I try works. The documentation doesn't help. Just wasting my time trying to click all the buttons and getting infuriated. Are the strokes in the picture of Suzanne all actual edge loops?

No, the lines in the first image do not follow the edge loops, Suzannes topology is different. The creation was explained in this answer.

I found this video which is short and sweet and this video which explains how to export SVG including the fill and this video which talk about export animations in SVG.


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Why does the edge of my Emission object have dark pixels?
I am trying to render an object with a white Emission material in front of a transparent background, in Cycles and Blender 3.1.2.
When the object renders, the edge of the object has black or grey pixels:

And when I import it in After Effects for compositing, this is what it looks like:

I have looked for anti-aliasing solutions, but it seems things have changed in Blender 3.

source: Stack Exchange

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

sort: votes


text:
Modify the parameters of the Wave Modifier
I am working on this animation and losing my sanity.
I would like the waves to make ripples that die out in half a second.
But unfortunately no matter what I do, the ripples go on and bounce off the edge of the pool object. I've tried modifying the settings of the Wave modifier, and deleting/redoing the bake, nothing has worked.

after you delete your bake; on your "piscine" physics properties increase your damping to something between 0.15 and 0.3

@Ratt i think part of the problem is that there are parameters for Wave in both the modifier tab and in the Physics tab. They seem independent from each other

the settings in the modifier panel are for the standing wave (not the wet paint map) the settings in the physics panel are with regards to the interaction with the wetmap. The damping will affect the amplitude over time so once you have that set to die off in the proper frame count you can adjust the speed which will affect the wave propagation outward to a distance you desire.

Shader Method
You could use a mask that defines a gradient over your object and use a Math node set to Multiply to mix with a Wave Texture.

Then the timing comes down to how fast your Phase Offset value is animated, and the range of your gradient, which can be controlled with a Color Ramp.

Many ways to arrange this to get the control you want.

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


text:
Can this ripples effect be replicated in Blender 3?
I have been trying to replicate this great trick in a newer project.
It worked perfectly fine in earlier versions of Blender, but unfortunately doesn't seem to work anymore in 3.1.
Can this easy ripples effect be replicated, or is there another simple way of creating ripples?

Perhaps it uses some addon that is out of date.

It seems relatively to the native version of blender and only uses Wave modifier, Dynamic Paint and that's it. See if you can replicate it in 3.1 and how, I would be interested - thanks

Still seems to work you likely missed a step.

@Ratt as soon as I add the waves modifier the plane bounces up and down and looks like a sphere cut in half

It's working for me too, can you add a gif or a blender file with the problem to your question? .blend preferred.

@MicroMachine when you follow the tutorial Gleb zero's out the initial wave height. you only get the ripples from the dynamic paint after.

@Ratt At 1:10 into it "if you press play" his waves create many concentric ripples around the origin of the object. This is what you get  if you follow the same steps - new plane, subdivide, add modifier - in Blender 3.1

I think the plane in the video was scaled up and then had it's scale applied before the recording started.

I think it's too straightforward to actually write up, but the way I'd try to approach this is to have a plane for each drop with the procedural animation of ripples and some transparency, then render overlapping ripples as a bump information, and then use that animation to control the texture of water.

Settings for confirmation:
Objects:
1 plane ~100,000 faces
1 uv sphere
modifier stack on plane:

physics dynamic paint

sphere particle system

sphere dynamic paint


text:
Keyframing a UV texture on a mesh isn't working as expected
I used to be able to do this easily in 2.7x but now things seem to have changed.
I have a rectangular object with a seamless pattern applied to it (.png). I would like to keyframe the vertices in the UV Editor to make the pattern change position in relation to the object during the animation.
However, the I key doesn't allow me to do that anymore. The Keyframing menu doesn't pop up when I press I while hovering over the vertices in the UV Editor window and when I press I in my 3D Viewport, it seems to do something else (I noticed this message atop the 3D Viewport after pressing I).
I have been looking in the Preferences to find if a wrong key was mapped to the I key, but things seem normal (although I don't see the UV Editor as a list of panels where the shortcut can be used).
Is there something wrong with the mapping of my keys, and how can I add a Keyframe to the UV Editor without using a shortcut if all else fails?

At least as far back as 2.77, this wasn't directly possible.  At least, not without an addon.
It's possible to do indirectly, by copying UV from a different mesh, but it's more work than you'd probably like:

Duplicate your object.  Make your duplicate non-rendering.  Edit the UV of the duplicate.

Give the original a data transfer modifier, targeting the duplicate.  Set it to copy face-corner data, copying UVs, by topology.

At the frame you want to "keyframe" those UVs, instead keyframe the mix factor of the data transfer modifier (at 1.0 to copy those UVs, at 0.0 to not copy them.)  It will linearly interpolate your UV between your old UV and your duplicate's UV on the basis of the animated mix factor.

If there are multiple different UVs you'd like to keyframe, you need a fresh duplicate and data transfer modifier for each independent sets of UVs.
This is the broadest, most general purpose way of doing this.  A UV Warp modifier can be much simpler if it can do what you want.  Keyframing the values in a mapping node, in your materials, can also be much simpler.
Keymesh, recently released, may provide a different way to approach this-- I'm not sure, I haven't played with that feature much.  In the future, geometry nodes should provide a further way to animate UVs, but even in the 2.93 beta, they're not really there yet.


text:
Force specific model to be drawn in "texture" mode
I am using a 3D model that I mapped a texture onto as a reference image. (I find this workflow easier than using background images.) However, I cannot switch into wireframe mode and see the images at the same time, since the render mode is changed for all objects at once, meaning I will be constantly switching between wireframe and texture modes (with Z and alt+Z) to take a look at the reference image.

Long story short, I want an object to be rendered in texture mode, regardless of the current display mode for other objects. Is there a built-in way of doing that? I'm also open to solutions involving Python scripting.

You might want to try using an image empty instead

Thanks, that works. I would still like to have an actual mesh that behaves like that, though.

I often use a workaround: instead of changing the general view mode i leave it as "textured" and change into wireframe the object I'm working on. Hope it helps.

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


text:
Change the position of an Icon
I am creating an addon, but I needed a small help. This is the code
    row2.label("Text",icon = 'BLENDER')

Now, if I execute it, the Icon is placed before the Text.
Is there anyway to place the Icon after the text?

You could add two labels, one with the text only, and another with the icon only:
    row = layout.row()
    row.alignment = 'LEFT'
    row.label("Text")
    row.label(icon='BLENDER')

will not work for menus operator button tho

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


text:
How to run a piece of code when addon is just activated
Is there a way to run a block of code when the user activates the add-on?
I am creating my add-on, in which my add-on appends in a few node groups from other .blend file.
I would like my add-on to directly append the nodes rather than the user having to click some button to do that!
Thanks for help....

do you mean when you register the addon, or when blender start and the addon is enabled ( registered )?

Yes, just like that....

which one exactly?

blender start and addon is enabled

This is an example addon that will execute the function "load_fonts" when blender starts,  it use the handlers to run a function at blender start :
import os
import bpy
from bpy.app.handlers import persistent

@persistent
def load_fonts(scene):
    font_dir = bpy.context.user_preferences.filepaths.font_directory
    for file in os.listdir(font_dir):
        if file.endswith(".ttf"):
            bpy.data.fonts.load(font_dir+file)

def register():
    bpy.app.handlers.load_post.append(load_fonts)

def unregister():
    bpy.app.handlers.load_post.remove(load_fonts)

if __name__ == "__main__":
    register()

you can call the function  you want inside the register() function, but you can't get access to the scene :
def load_fonts(scene):
    print("addon activated ")

def register():
    load_fonts()

if __name__ == "__main__":
    register()

to overcome this problem you can use handlers to access the scene as @CoDEmanX shows in this thread :  example
import os
import bpy
from bpy.app.handlers import persistent

@persistent
def load_fonts(scene):
    bpy.app.handlers.scene_update_pre.remove(load_fonts)
    font_dir = bpy.context.user_preferences.filepaths.font_directory
    for file in os.listdir(font_dir):
        if file.endswith(".ttf"):
            bpy.data.fonts.load(font_dir+file)

def register():
    bpy.app.handlers.scene_update_pre.append(load_fonts)

def unregister():
    pass

if __name__ == "__main__":
    register()

This works when the addon is activated by default. I want it to work even if the user activates it after blender has loaded...

@Always4u try calling the function inside the register() function

I did not get that, can you please give an example.. :)

def  register():   load_fonts()  but I think you can't access the scene in the register function

my function needs at least 1 argument, and I don't know how to call it through the register() function!

load_fonts(None) ?

unregister_class(...):, missing bl_rna attribute from 'RNAMeta' instance (may not be registered)

sorry but this does not work at all, unregister fails miserably, and on register, the function is NEVER called (blender 2.9)

This might help explain the source of the problem. https://wiki.blender.org/index.php/Extensions:2.6/Py/API_Changes#Restricted_Context
I think we are left with checking every update cycle, so hundreds of times a second via scene_update_pre handler?! super ugly, super wasteful, something is very wrong with this convoluted situation. I, We or They probably need to rethink from some other examples something totally different here.
bpy.app.handlers.scene_update_pre.append(initsetup_operators_needing_scene_function)

Yeah, it does some wasteful. If I understand it correctly, it only happens when a value in the scene is changed though, not every program tick.


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Store which Image is being used
I am thinking how to store the image which is being used in an image texture node
 bpy.context.object.active_material.node_tree.nodes['Image Texture'].image

I want to store the image used, and then on clicking a button, that image stored will be applied to some other active object's image texture node
I tried using StringProperty but that stores only String type and not images!
I don't get know how to do that......

Use your StringProperty to save the image.name,
then load it by accessing the image through bpy.data.images:
imageNameStringProp = bpy.context.object.active_material.node_tree.nodes['Image Texture'].image.name

someOtherObject.active_material.node_tree.nodes['Image Texture'].image = bpy.data.images[ imageNameStringProp ]


text:
How to create a button in Custom panel to take you to the specified url
I am having trouble creating a button on a custom panel, which on clicking will open the browser and take the user to the specified url. Can anyone help me with the code!

see the docs for bpy.ops.wm.url_open
bpy.ops.wm.url_open(url="")
so a button would be
row.operator('wm.url_open', text='open url').url='http://www.blender.org'


text:
Display material preview in custom panel
I have created the material preview box in the custom panel by using the following code for the active material
layout.template_preview(bpy.context.object.active_material)
And the preview box was added, but now when I update the material using the custom panel, the preview does not update. Can Anyone help me!

IIRC it's tied in with the context.material of the material tab of the PROPERTIES panel & is more hassle than it's worth to get working otherwise.  You may find the following links useful. http://blenderartists.org/forum/showthread.php?261311-Does-anyone-know-how-to-display-the-BI-material-preview&p=2169931&viewfull=1#post2169931 and   http://blenderartists.org/forum/showthread.php?331963-moving-panels-possible-or-imposible


text:
Accepting Values in variables
I am creating an addon for blender 2.75. Is there a way to accept user's input by creating a Variable? There can be an input slot in the Tools panel, and the user can enter the value in it, which will be stored in a variable which can use later in my code. :)

possible duplicate of Creating a custom permanent property in Blender 2.70 python script to access in GUI Panel. Also see https://blender.stackexchange.com/questions/36587/how-to-define-customized-property-in-material


text:
How to check if the active object is using no material
Is there a way, to check if the current object is using no material for cycles engine, so that the code could take a logical decision based on that!

Get all the materials
materials = bpy.context.active_object.data.materials

Count the material slots
nMat = len(materials)

Check if a material slot is empty (in this case, the first slot)
isEmpty = not materials[0]


text:
Info Panel Missing
the Info Panel is Missing. I need it back.
The thing on the top marked with (1):

you can simply restore it by setting the "info" panel into one of the areas.  Then, you can reset file > "load factory settings" and then "save startup file".

Didn't realize it was simply a panel, thanks! No idea what your 2nd sentence is about though.

2nd sentence was just in case you found the same missing info panel at a new blender startup. In that case somehow you could have saved a "wrong layout" as default. So, as said, using  file > "load factory settings" and then "save startup file" you could reset blender interface at default "factory" settings.

I see... I run blender on three monitors. So If I close the windows in the wrong order everything gets screwed up when I reopen the file.

I never used more than one monitor but blender preferences must be explicitly saved (file menu) to survive a program restart, usually.


text:
Armature: Alternate Bone Parent between 2 bones
I'm working on weapon reload animations. The magazine bone is a Child of the rest of the gun (I'm using the bone constraint "Child of" in Pose Mode). When the hand removes the magazine from the shaft the magazine should be parented to the hand. How do I switch the Parent bone in the middle of the animation?
Sofar I had to frame-by-frame move the mag with the hand and of course it's never pixel accurate. I have to do like 30 reload animations so I would be glad if somebody could help.

This is what the problem looks like https://youtu.be/iMpLyJbTgt0 The mag doesn't stick to the hand. Fixing it takes a lot of time everytime you adjust the animation.

You do that exactly like here: https://blender.stackexchange.com/a/86451/7777, but watch for double parent transforms inside an armature.

I'll try that right now. Are you sure this will translate properly when I export it to Unity?


text:
How to UV Smart-Unwrap Properly?
I am lazy. I select my mesh, U -> Smart Unwrap -> Ok. And I would go on and texture it with SubstancePainter or Photoshop. I only create low Poly stuff and this has worked perfectly sofar. Everything is in correct angle and proportion:

More and more often I get resulst like these, even though I have "Correct Aspect" checked. This makes it impossible to work with:

Tweaking values doesn't fix anything. The Unwrapped Mesh is in inappropriate proportions and it stays this way. It's actually FASTER to redo the entire model and unwrap it again than to complicately mark seams and fiddle with the Mesh in the UV-Editor. Unless of course it comes out bugged again, but sofar that was never the case. The model is pretty much equal, the result is totally out of whack.
WHY???
What is happening here behind the curtains that I don't see/understand?

Chances are your objects have a non uniform scale. Try to apply scale (Ctrl+A->Scale).

Does disabling "Stretch to UV bounds" make any difference?

Neither solutions work.

Related The python code to the smart unwrap.

I have found a Solution. This is not really an answer as to why it is happening but it's too long to put into a comment and at least it fixes the problem.

Go into Edit Mode
Press P (for Seperate) and select By Loose Parts
Create a Cube somewhere in the scene
Select all the loose parts of your model and then the cube so the
cube is the active object and press Ctrl+J (for join)
Go back into Edit mode and delete the Cube, unwrap: done.

This is the same procedure by the way that I frequently use to set the rotation and scale of an object to 1.

It probably works because in the joining process the meshes take on a uniform scale (the scale of the cube). Have you tried applying scale as @Dimali suggested? It would be easier.

Yes. That did not work.

Interesting. I wonder if the unwrapping algorithm is using the cube mesh like a bounding box to set the scale, or something like that. Can you upload the .blend to Blend Exchange?

I will if I encounter the error again. Unfortunately I have no blend file right now with this problem.


text:
How do I use the tooltip to create keybinds?

The specific command I'm trying to set is bpy.ops.object.origin_set() which sets the origin of an object which is bound to default to Ctrl +Shift+Alt +C
This doesn't work:

What is your actual goal? Creating a shortcut for Origin to 3D cursor without getting the menu? Search for origin and see how that's done. Your test doesn't work because you have use the identifier of the desired operator not the function() call.

Nah I want the menu to pop up. How do I find the identifier?

Go to User Preferences > Input and type origin...

Yeah duh, in this case. What about Pivot center? Viewport shading? Interaction Mode? I'm coming from here: https://blender.stackexchange.com/questions/7878/how-do-i-find-the-technical-name-for-a-function-so-i-can-assign-a-hotkey-to-it

See my edit here. Also consider that you can always right-click the relevant button within the UI to change the shortcut and notice that all previously registered shortcuts listed in User Preferences > Input as mentioned before...


text:
Bezier Interpolation messes up Animation Loop
My Animation loops are never smooth when they loop. This is a bone from an animation (I've made a habit of saving the default position into keyframe 0 which is not used by the animation)
The green bar is the part that loops:

This image shows what happens when the animation starts Looping. The Green Bars mark the same bit as the top picture. The cyan circle shows the problem. What I used to do is double the animation and simply use what is within the Blue bar. I would go on and fix the keyframes in the middle manually.

Since I am doing A LOT of animations lately with A LOT of bones, I cannot go through this process everytime. How can I smooth the animation without complicating things too much?
And please don't tell me that dragging those THINGS is the only way.

and that graph cycles alright I assume?.  In image in link above you have 5 keyframes in your cycle.  If you copy  frame 4 and paste it as a keyframe to left of keyframe 1 the same amount it is left of  frame 5, and similarly with the other end. Your cycle will be keyframes 2 to 6, keyframe 1 and keyframe 7 are making sure "alpha" is the same.  Actually end your cycle one frame to left of keyframe 6.  Can be automated easily with a script.

.. or if you are open to using the  NLA Editor can influence the blend in blend out.

Thanks, there was a misunderstanding between "frame" and "keyframe" :-)


text:
Trouble Proportionally Scaling with Python
I'm working with a model of a man. Using imperial units, I want to set the model's height (his z-dimension) to 5' and have his x and y dimensions scale proportionally so he doesn't end up distorted.
I tried using the bpy.ops.transform.resize() operator, but I'm not sure how it works: I know you can set "proportional" to "ENABLED", but how can it remain proportional if you're defining scale factors for all three axes? I'm also fairly certain I've defeated the purpose of using the "proportional" parameter since I'm just passing the "value" parameter scale factors that I hand-calculated to be proportional anyway. (Which didn't work, for some reason.) Despite my efforts, the model still seems distorted.
Here's the code:
import bpy
from bpy import context
from math import sin, cos, radians

# For file manipulation
import os

# Establish context and scene
context = bpy.context
scene = context.scene

# Set units to feet
scene.unit_settings.system='IMPERIAL'

# test height (in feet)
height = 5 # 5'

# Load object
def model_loader(scene):

    # Establish path to model directory
    path_to_directory = os.path.join(
        '/', 'Users', 'jackburker', 'Documents',
        'Code', 'Blender', 'base_models')

    # Establish path to model file
    path_to_file = os.path.join(path_to_directory, "male_keyTest.obj")

    # Print paths for debug
    print(path_to_directory)
    print(path_to_file)

    # Import model
    bpy.ops.import_scene.obj(filepath=path_to_file)
    # Debug
    print("THING TO ASSIGN")
    print(bpy.context.selected_objects)

    # Select user model
    obj = bpy.data.objects['base_human_male_default']

    # Check that selected object is user model
    print("OBJ")
    print(obj)

    # Check current objects
    print("CURRENT OBJECTS")
    for o in bpy.data.objects:
        print(o)

    # Retrieve object dimensions
    obj_dimensions = obj.dimensions

    # Define dimensional ratios
    xz_ratio = obj.dimensions[0] / obj.dimensions[2]
    yz_ratio = obj.dimensions[1] / obj.dimensions[2]

    # Check dimensions and values!
    print("OBJ X, Y, Z")
    print(obj_dimensions)
    print("RATIOS (XZ, YZ)")
    print(xz_ratio)
    print(yz_ratio)

    # Determine vertical scale factor
    z_scale = height / obj.dimensions[2]

    # Print vertical scale factor
    print("VERTICAL SCALE")
    print(z_scale)

    # Define proportional scale factors
    obj_y = z_scale * yz_ratio
    obj_x = z_scale * xz_ratio
    obj_z = z_scale

    # Scale all dimensions proportionally
    bpy.ops.transform.resize(value=(obj_x, obj_y, obj_z), proportional='ENABLED')

    # Get and print post-scale dimensions
    obj_dimensions = obj.dimensions
    print("POST-SCALE OBJ (X, Y, Z):")
    print(obj_dimensions)

    return

if __name__ == "__main__":
    model_loader(scene)
    bpy.data.objects

I have included two screenshots:
one of the model pre-resize,

and one of it post-resize with the camera zoomed out.

(I don't have enough rep to post a third picture showing this, but it's much bigger.)
I know this is an incredibly noob question to ask, in that I'm just doing something (maybe multiple somethings) fundamentally wrong -- no ambiguity about it. But I just started with Blender and python about a week ago, so I've much to learn. Thanks!

Hi Jack,  check out http://blender.stackexchange.com/questions/48268/python-resize-imported-svg/48281#48281 proportionally set the scale vector by multiplying it by your scalar ratios.  obj.scale *= ratio

@batFINGER thanks! Can/should I multiply it by all three? Like, obj.scale *= (obj_x, obj_y, obj_z)?

No .. it is a scalar ratio r multiplied by a scale Vector((x, y, z)) after which scale will be Vector((sx, sy, sz))  Scalar multiplication https://en.wikipedia.org/wiki/Euclidean_vector#Scalar_multiplication is a fundamental Vector Mathematics.  Also v *= s is the same as v = s * v

Oh.... So by multiplying my scale vector by the scalar ratio calculated to give me the desired height, it will give me a proportional scale, right? That makes sense. @batFINGER

@batFINGER so I don't have my ratio correct, but the model scales proportionally! Thanks so much!

In the comments, @batFINGER pointed out that I could achieve what I was looking for by multiplying the object's "scale" parameter by the ratio required to give me the correct height: e.g., obj.scale *= ratio. This worked perfectly for me. See the comments for a slightly more in-depth discussion.


text:
Can I delete these past version folders in my user App data
I'm running out of space fast on my ssd and am looking for files I can safely delete. Are these folders in the image safe to get rid of for the past versions of blender?

Each of those folders is only required for that specific version of Blender.
You only need to keep the folders for any versions of Blender that you still use. So, for example, if you no longer use version 2.65, you can safely delete that folder, etc.


text:
Blender 2.76b wont install. Error Message pops up
I've been trying to install the latest build of blender on my PC but every time I try I get this error message
Does anyone know why this is happening and how I can fix it?  Thanks!

Move the file to a location like Desktop before running the Setup.

I did that. Still didn't work.

the error is really Windows/Explorer telling you "The cabinet file 'media1.cab' required for this installation is corrupt and cannot be used"  -- it's worth googling.

I just tried it on another computer and I ran into the same issue, so I think it's safe to assume it's a problem with the installer and not my machine.

Which operating systems?  The point i'd like to counter with is those installers are used by at least 500k people, using all kinds of versions of windows. The installer expects certain components to be present, if it doesn't find those or they are corrupt it will throw a warning message like this one.  Are you downloading the .exe to the desktop then double-clicking it or did you press Run in the downloaded files in the browser?

I managed to install the 32-bit version. For me, the problem was with the 64-bit version.

I also had this problem using chrome, trying all the available packages, downloading to various places including desktop, and running after saving.
I switched to Windows 10 Microsoft Edge browser and was unable to download the installer.  However I was able to download the zip file correctly and run blender from there.
Moral of story, keep trying different things until something works....

Go to http://download.blender.org/release/
Download the compressed zip file instead of the .msi. Then extract the folder. That seemed to work for me.

I had the same problem using chrome. I changed my browser and I successfully installed it. So I guess you should try another browser. I hope this helps.

Unless previous browser was downloading corrupted files every time (one should search really hard to find browser like that) this answer can't be related to the problem.


text:
Animation exported to Unity is always Default Take
I have a simple character with three actions: MeleeHit, Walk and Default (one frame on T-pose). I am importing to Unity using the .blend file, not exporting it as FBX. MeleeHit and Default appear as they should on Unity, but Walk is shown as DefaultTake.

I tried to change the name of Walk in Blender and it still was as Default Take in Unity. Even if I delete the animation and create it again with the name "Walk" it will be the Default Take.
I've been trying to figure this out for hours now, if someone could just point me at the right direction I would appreciate.
I think it's also worth mentioning that I'm not an artist (I'm a programmer) so I don't know much about blender.

To fix it I first created a pose called "0T-pose" (zero is the first character so it is at the top of the action list in Blender), selected it as the current pose and exported the file as FBX (Binary). Idk why it didn't work before. I hope this helps someone with the same problem I hade.
(followed instructions from this link)

When you import the model into Unity, a "Default Take" is included in the .FBX. It shouldn't matter if you're directly importing the .blend or .FBX, the default take is created. The default take would include all of the keyframes.
Basically, in Unity you then create additional animations clips (walk, melee), all of these are created based on this Default Take.
When you create additional animation clips in Unity, the source take is usually always the "Default Take", because this is the master source for all animations.
You should end up seeing something like this for the clips:

CLIP           RANGE       SOURCE TAKE
Default Take   0 to 100    Default Take (master take)
Walk           27 to 50    Default Take
MeleeHit       -1 to 26    Default Take


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Problem exporting blender model to substance painter, Marmoset and sketchfab
When i export this model in as an .obj and import them into the other software the meshes get all mest up. I recalculated the normals and made sure is facing out but nothing fixes it. Also i used other models i had to test and they all work fine so i don't know why this model in specific is giving me problems.

Weird thing is when i flip the normals (they look darker) and import it into SP it looks fine. So i guess the reason i'm having the problem might be the normals but i don't know. also in sketchfab the model becomes transparent.

Here's my blend file http://www.filedropper.com/spawnresurrectiongreatsword

It seems it was the mesh itself, there were some vertices that weren't connected, making the mesh act like that when exported to other software. So went back took a good look and connected some vertices and cleaned the mesh, that fixed the problem.

authors: Влада Петрова


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How to change the grid's length values?
I have a model of a gear that should be in the millimeters but when I scale it to that size it becomes so small that I can't zoom in to see it. Right now the grid is in metric and each grid is 1m x 1m x 1m. But I want to change the grid so each square in the grid is 10mm x 10mm x 10mm.

You have 3 options essentially.
Two of which are cosmetic, and involve changing the grid size - but will not affect actual scale or unit measurements of your file for 3D printing or other CAM methods.

By default, 1 blender unit (and 1 grid unit) equals 1 meter. If you want to 1 blender unit to equal 1mm, you can either:
Option 1 - scale the grid via the Properties Panel (N) --> Display --> Grid Floor Scale.
Option 2 - In the Properties Window --> Scene settings --> Units, 1st set to Metric, then set the scale to 0.001.
However, if you export or save your file, 1 blender unit will still equal 1mm for most external programs.
If you want to print your model, your safest bet will be to scale your model and regard your model's dimensions as if they are in millimeters. For instance, 155 blender units = 15.5cm.
Of course you can scale your model AND change the grid settings to make the grid nicer, no contradiction there.

Would it also be possible to set 1 blender unit to equal, say, 4mm? I am working with wood with a thickness of 4mm. The parts will be cut from this wood later on.

In Blender 4.0, the method 2 only affects how length units are handled.  Only method 1 will change the "floor grid" the intended way, which is now done as described here: https://blender.stackexchange.com/questions/129259/how-do-i-change-the-grid-floor


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See render progress in VSE
I have several scenes in strips in the VSE. When I use the VSE to render I get the results I want but I cannot see the frames as they are rendering the same way I do when I render directly from the scenes themselves (not the VSE scene where all the clips are brought together). They only appear after the frame is completely rendered.
Is there any way to render everything from the VSE and see the progress as it renders in the Image Viewer like you do in a single scene?
Hope this makes sense - thanks!

That just depends on what you set your Display to in your Render Properties:

Set it to Image Editor, Full Screen or New Window to see the result as it's being rendered.
Though you have to keep in mind that Frames that originate from a Movie Clip, Video Strip or Image Strip won't be rendered partially but as a whole image anyways. So you will only see real rendered images that originate from a 3D scene.


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Every time I touch an object a full-render starts
I don't know what setting I switched, or what happened, but for some reason now every time I move, scale or rotate an object in the 3d View - blender starts a render. I am not talking about the 3d View being in "Rendered" mode. I am talking about the same behavior as when you click the "Render" button (switch to image editor, begin full render). This is driving me crazy and I can't seem to figure out how to turn it off or what I did to start it. It happens whether I use the mouse or keys. If I open a new document the behavior goes away so it is probably a preference setting(?) If you can help, I will be eternally grateful.
Thanks in advance.

Hit Z twice.
This switches you out of Render Preview mode, into Wireframe, then back to Solid mode.

"I am not talking about the 3d View being in "Rendered" mode."

@Jerryno Good catch, I missed that. Cegaton's answer looks like the right one.


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Creating a textured Mesh for 3D printing
I need to create a textured object to be 3D printed. Is there a way I can import a texture and apply it to my mesh so that the mesh changes to become textured? thanks !

@Nora I can't understand if you wish a textured file that can be printed textured in 3D? If yes, knowing which printer or printing service you're going to use would help...


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Enemy AI Reacts To Player
I'm making a horror game using Blender, but there's just one code I struggle with.The code is how to make an enemy follow you, but stop when looked at by the player's camera. I'm pretty sure this action is done using Python scripting.

Without Python, you can have a steering - 'path following' logic brick to target your player.
A ray/near sensor from the players eyes that detects the enemy can then toggle a (boolean) property that sets the state of the enemy to follow or not.
Like the Weeping Angels from Dr. Who, your enemy would only move when they are not looked at.


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Play Game Texture
Whenever I apply texture to my game models in blender game, it won't display the texture and will either make it invisable or white. What should I do?

I suggest to post your question and your blend file on blenderartists.org. The information you currently provide is not sufficient to provide specific help. It might be better to post at least some screen shots (with some information about your setup).

Make sure you are in textured mode rather than solid mode.


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Animate changing textures with keyframes in cycles
In Blender internal render the Textures tab has checkboxes that can be keyframed. This means you can change textures by unchecking and checking. An example would be if you had 3 different textures with eyes (1 is open, 2 is half open, 3 is closed) and you key them to simulate the texture animation.
Is there a similar way to do that in Cycles Render, because those boxes don't appear.

Switch textures by MixRGB node, Fac slider from 0 to 1


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Fluid simulation pours into the cup in a box shape and won't spill
I was working with the fluid simulator in Blender, and I wanted to make an animation where water flows into a cup and spills out. When I bake the fluid it pours into the cup in a box shape, even if the bounds are the same shape of the cup. The other problem is that the fluid won't spill out when the cup is knocked over.
Is there a way to fix either of these problems?

The fluid domain object will be always treated as a box so don't edit it. Instead add Fluid modifier to cup and set it to Obstacle.Same for your second problem; fluid can't be anywhere except for the inside of domain.

Setting your cup to obstacle (as mentioned in the comment above) should fix the problem of the cup bounds being square. The main thing you would want to fix, though, would be the size of your fluid domain. It will not affect the fluid, but will simulate the bounds of where the fluid will go. A smaller domain will give the waters smaller boundaries. Also, if you are using a rigid body for the cup, it will not simulate well with the fluid.


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BGE Facing Plane
I'm creating a game in Blender. The enemies in the FPS are sprites on a flat plane. The only problem I have is making the flat plane to where it's constantly facing the player camera similar to Doom, because the enemies aren't in 3D. Is there a way to make the flat plane mesh constantly face the player camera using the Logic, or is there any Python coding involved?

If you enable Billboard in Materials Tab under Game Settings > Face Orientation, the planes local x-axis will always face the camera while the z-axis remains as it is (= the object rotates only on its z-axis).
https://docs.blender.org/manual/en/dev/game_engine/materials.html#face-orientation

Good one red @Momel .  My version hasn't got that.  Would have been handy!

Correction - I did find it, thanks to your post. :)

This is not a very good answer but it should get you there.  I've dug out the logic bricks of a game I made a long time ago when learning the BGE.  The pic pretty much says it all...

To bring the enemy sprites' logic up, select them in the 3D window.
The "Near" sensor detects when the player gets within the distance range you type in and sets off 3 actuators.  The one you're looking for is "Steering".  That will make the enemy face the player or whatever you nominate.  I see I'd set him to an almost zero velocity. (coward that I am)
The other two are broadcasting messages which other "Sensors" can pick up and act upon or ignore.
I imagine you'd need your enemy sprites to pick up a broadcast "message" and "Steer" them towards the camera or player.  Same with anything else that has to do the same.
Good luck with your game.  It was a lot of fun as I recall.


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Navigation Mesh
The game I'm working on involves the enemy following the player through rooms; however, when I add a Navigational Mesh for the enemy, the mesh doesn't pass through the rooms, so the enemy is stuck inside one room. Is there a way to make the Navigational Mesh large enough for the enemy to transition from one room to the other?
Example image

I guess this is the solution to your problem!
https://i.sstatic.net/4NYNS.png


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Music Looping BGE
I'm making music for my Blender game. After the song ends, I want it to start or loop from another portion of the song rather than the very beginning. I notice some games do that with music, but is it possible to do that with Blender?
Let's say the song starts off with a drum beat and then a melody later. When the song ends, I want it to start from the melody rather than the drum beat (the very beginning of the song).

It's possible, and you should use Python. Example blend file can be downloaded here, the code is fully commented.
Notes:

I've made this song especially for this answer. ;)
For moderators: The zip file is needed as I can't pack the music file on blend if I want to load it through Python. It's not possible to upload zip files on Blend-Exchange, so I posted the example file on my Google Drive. Sorry for the inconvenience.

import bge
import aud
from bge.logic import expandPath, globalDict

# Load music factory to memory at start, if not already
if not 'music' in globalDict.keys():

    # Self explanatory
    music_path = expandPath('//example_music.ogg')

    # Load at globalDict the buffered music factory
    # Buffering allows lower delay on playing a new loop
    globalDict['music'] = aud.Factory(music_path).buffer()

def main(cont):

    own = cont.owner

    # Sensors
    always = cont.sensors[0]

    # Other
    device = aud.device()

    # Constants
    START_POS = 0.0
    LOOP_POS = 8.0

    # If sensor activated and music factory is loaded in globalDict
    if always.positive and 'music' in globalDict.keys():

        # If playback handle is not present in current object
        # After handle is created, this block will not run anymore
        if not 'music' in own:

            # Create a property in current object with playback handle
            own['music'] = device.play(globalDict['music'])

            # Set starting position of first playback
            own['music'].position = START_POS

            # Warning message
            print('Song not playing, playing it from start', START_POS)

        # If playback handle is present in current object
        if 'music' in own:

            # If music stopped playing
            if own['music'].status == False:

                # Play and save a new handle in place of the older one
                own['music'] = device.play(globalDict['music'])

                # Set starting position of loop playback
                own['music'].position = LOOP_POS

                # Warning message
                print('Loop song at position', LOOP_POS)


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Difference in Emission Node
I am not sure if there is an answer to this, but what is the difference between plugging in a texture to the Emission in Principled BSDF and using a Mix Shader to apply it to an Emission shader? Is there anything different in the way things appear?

Option 1 shows the texture being applied to the Emission slot.
Option 2 shows the texture being applied to the Emission shader instead of the Principled.

The equivalent would be an Add Shader, not a Mix Shader. One difference is the order of alpha and emission; Principled does emission first. See what happens if you set Alpha=0.

I see now. Thank you for helping me understand.


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How to add faces to underside of a model

Hi. Attached is an image of just the bottom verts of a model that I have. I have hidden the top section so it can easily be seen.
I plan to print the model, so this is the open underside face, I need to create faces on this underside to effectively close the model, would anyone know an easy way of doing this?
Your help is really appreciated.
Thanks.Richard.

Does selecting the vertices, then pressing F to make a face work?

If you're going to print it the geometry will be triangulated which might not work as expected if filling an Ngon with F. You could try to convert this shape into a curve with Alt+C, then set the curve type to 2D and set Fill type to something other than None. I don't think there are any other easy ways.

Have you tried creating a circle, and then using mesh addons to bridge between all of the vertecies of the model and the circle, then just F with the circle created to make a face? If that works, let me know

Thank all. I managed to sort and print the model with copying the top part of the model, extruding then scaling global Z to scale 0. Much appreciate everyones comments. Thanks! again.

Thanks all. I managed to sort and print the model with copying the top part of the model, extruding then scaling global Z to scale 0. Much appreciate everyones comments. Thanks again.


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Missing model whilst viewing in active camera
Wonder if someone could help? Whilst viewing a simple pulley model in active camera view, I can only see the foremost part of the model. What am I doing wrong?
Much appreciate any help.

I attach a pic of the full model in 3D View.

The problem is the value of your camera clipping in the Properties Panel N. At the top of the Panel you should see a section called Clip. Increase the End value and this should fix your problem.

Changing the clipping End value from the properties panel, this for some reason never worked, however tried the properties of the camera (select camera first) which also has a clipping section under the 'Lens' properties. I adjusted that and gave me the full model. Updating the Lens End clipping properties does not update on the Properties Panel, it still shows a value of 1m. Should this not update?

I believe that these two are independent, similar like that you can control the subdivision surface levels for both the viewport and render independently.


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Controlling scalp hair for braid effects?
I'm trying to control hair particles to emulate scalp effects similar to French, Dutch or cornrow braids. The scalp patterning is important for several character designs.
Here's an example of the tight-to-scalp braiding I'm trying to achieve, sketched in grease pencil -- the two dutch braids on the sides of the head.

I figure I could attempt a lot of curve guides for individual locks, but would that be efficient?
Any ideas?


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How to make Hair without use of particles system?
I'm searching for technique to make realistic hairs in blender internal without using particle system.
I found this trick

But is there any way to do this in blender?
Any answer will be appreciated

This technique is called poly-hair.
There are a couple of different approaches but these are the basic steps:
1) Render/download a hair patch
Create and render out a hair patch created with the particle system.
Bake a normal map for extra detail in your render as well.
Make a couple of them so you get some variation.
2) The patches
Model a couple of hair patches and UV un-wrap them to match your rendered hair patches.
3) Placement
This step will take the most time if you want a realistic result.
Place and edit each strand individually. Layer them on top of each other, make them blend well, ...
This image might help this explanation.

Look on youtube and google for more detailed steps and info on the shading.


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How to fit the eyes in character?
I'm Currently working on a chacaracter. I want Eyes to fit into its head but I'm finding this task difficult.
I have found a another question on blender.stackexchange.com but it is not answered correctly.
(Only a simple tip will be helpful)

To make the eyes fit properly in your character's head there are a couple of things to keep in mind.

Eyeball size: If the eyes are incorrectly sized they will not fit right no matter what you do.
Eye position: Make sure the eyes are in the correct location on all axes. One thing to try is to move the eye just slightly above center on the z axis (so that the center of the eye socket opening is very slightly below the center of the eye sphere).
Eye socket geometry: If you look at references for eyes you can get an idea of how the eye socket is shaped and how the eyelid is around the eye. Many people often forget to include the tear duct at the inner corner of the eye, and that can cause a lot of issues.

The main thing to keep (which encompasses all of what I said above) is how eyes look in real life. Find some reference images of a character similar to what you are going for and keep them handy to refer to.


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Export/list out object information as text format
Is there an option in blender to export (or list out) certain properties of all (selected) objects?
My case is: I have modelled a furniture using real size, metric measurements. Now I want to hand a list of sheet sizes over (x-y-z dimensions of objects in blender) to the carpenter so he would be able to cut the correct sheets for me.
I am looking for an option to do all inside blender, if that isn't possible, an option of some kind of export would be acceptable.

You could get some help from this addon/script (never tried, though)
http://wiki.blender.org/index.php/Extensions:2.6/Py/Scripts/Neuro_tool/Measurement

It's pretty easy with if you know a little Python.
# import the necessary modules we need
# in our case, blender's python API and python's os module
import bpy, os

# get the current selection
selection = bpy.context.selected_objects

# initialize a blank result variable
result = ""

# iterate through the selected objects
for sel in selection:
    # get the current object's dimensions
    dims = sel.dimensions
    # write the selected object's name and dimensions to a string
    result += "%s - %.03fm x %.03fm x %.03fm\n" % (sel.name, dims.x, dims.y, dims.z)

# get path to render output (usually /tmp\)
tempFolder = os.path.abspath (bpy.context.scene.render.filepath)
# make a filename
filename = os.path.join (tempFolder, "newfile.txt")
# confirm path exists
os.makedirs(os.path.dirname(filename), exist_ok=True)
# open a file to write to
file = open(filename, "w")
# write the data to file
file.write(result)
# close the file
file.close()

Copy and paste the above into Blender's Text editor and press Run Script (Alt+P). It will save the data (object name and dimensions) into your tmp folder.

Thanks Keith, I have just tried to run the script and it says "Python script fail. Look in the console for now.."

great script, but may be unit scale is missing of the scene.

This did exactly what I wanted it to do, except I replaced selection = bpy.context.selected_objects with
selection = scene.data.objects and used a Find and Replace All function in my text editor on the output file to replace the punctuation with commas to make it valid CSV, and imported into Libreoffice Calc.

how about in inches? :)


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Normal bake randomly doesn't bake some faces
I'm having an issue with normal map baking from a hi poly to lo poly object where occasionally, and seemingly at random, certain faces of my object don't have anything rendered to the Normal image.
If I click the bake button again, without changing anything, it will rebake and a different face will be missing from the image. I have my normal map now just from pure luck clicking bake 10 or so times until it happened to bake each face.
Why is this happening? It seems weird that it's at random...

did you ever encounter any errors like this?

This is not necessarily a bug. Some faces of the object could be assigned a different material (see https://blenderartists.org/t/blender-is-only-baking-to-certain-parts-of-mesh/487863/2 ). Also, with Cycles Render in 2.79, I had to turn off "Selected to active," turn on "Use nodes" for the material, and assign the image to the object in the Cycles Material. However, with Blender Render, I had to turn "Selected to active" on, even if I assigned the image to a new texture in a non-cycles material on all faces--I'm not sure why.


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shadow not rendering
This is driving me insane !
I have been making a simple scene for a point&click game. Most of the models are 'done', and I now want to set up the lighting.
I am using Toon shaders for my models. I have added 1 hemi lamp, and 1 sun in my scene.
When I look through the camera, in the editor, I can see shadows in the sofa (left img). When I render the scene (Blender internal) there are no shadows (right img). And why is there such a difference in the way the scene looks ?
What settings could I inadvertently have changed ???
I have been trying to fix this for 2 days already ... I am getting desperate  :-)
Thanks for your help !

could you supply the .blend file?

I have found what is causing this, but I don't understand why ... My room has a ceiling ... I had both lamps inside the room, but apparently you cannot do that  ?! The moment I render without the ceiling, I have shadows. Render the roof as well, and the shadows are gone (even with both lamps inside the room)
So, how can I solve this ? Should I use point lights instead of a sun ???

Are you sure your lights and objects are on the same layer ?

Sun/hemi lights are always at infinity. Their location does not matter, only rotation. If you change them to a point light, do things work as expected?

Aleph : I don't think lights & objects have to be on the same layer, as long as you don't check 'this layer only' for the light ...
.
JtheNinja : yes ... that worked, but the lighting effect is not uniform that way. I'm now trying with area lights. That seems to be the way to go !

I know this is an old question, but --
are you sure you have shadows turned on in the render panel?
Under the render panel (the one with the little "camera" icon), scroll down to the "Shading" roll-out, and be sure you have "Shadows" checked.
Otherwise your shadows won't render.
Shadows are a two-step thing.  Once you've refined them in your lighting panel, be sure to turn them on in your render panel.


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black areas in ao map, but normal map looks ok?
I'm pretty new to baking maps for game assets, so I need some advice.
My settings are : Cycles, selected to active (with cage).
The normal map seems ok to me, but the ao map has really dark areas that I can't explain.
Am I doing something wrong during baking, or is it my mesh (cubes with bevel) ?

Ambient occlusion focuses darkness on the crevices of the model that's why you have those dark areas. If you didn't already know, the ambient occlusion map is usually used to isolate the edges of a model for wear/tear and (if i remember correctly) it is a linear type of map (black and white image)

More specifically, I was concerned about the black vertical blocks that seem harsh ... Also, I don't see similar structures in the normal map (light info).

I have done some more research and found this as well: Ambient occlusion shading is determined by the relationships objects and surfaces have to each other, the closer one object is to another, the darker the immediate area surround each due to the way in which their proximity occludes and/or attenuates ambient light. So it could be because of your mesh, and if that's the case:  1) separate objects and/or elements should be joined together into a single contiguous mesh. 2) elements should be positioned relative to final use.

Thanks for your help ! I've been trying some more, with cage, without, with baking plane in front/behind of the wall, flipping the baking plane (normals), ... I finally did get an ao bake that looks softer (still not 100% ok), but I have no idea why or how to repeat it. Might be Blender being sensitive (or me being dumb) ... =p


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Creating an Object Matrix in Blender 2.82
To create an array of object in C4D, I would select the object, select a modifier, and enter the number of objects needed in the X, Y, and Z directions. Is there a similar method in Blender? Using the Matrix Modifier works but is not that simple.

did you test the "mirror" or "array" modifiers?

To get something that looks like this;

You can use a modifier stack that looks like this;

An array only goes in one direction at a time.


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What Am I Doing Wrong?
Im trying to follow the CGgeek Steve Lund's Blender tutorial on the swinging balls animation at (Youtube.com/watch?v=Uq4OLSRgSQE). When I reach the section on duplicating the first swinging ball I can create and confirm the duplicate, but the duplicate disappears when I attempt to change its orientation and I end up changing the original's orientation instead.

Hi. Please make the title of the question specific to what you are asking and not just the general topic. Thanks.

Change the title and add .blend or screenshots of your problem?


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Satellite Terrain Mapping
I use a utlity called TERRALAND in Unity that will pull in a digital elevation map (DEM) of a selected area and overlay it with satellite imagery of that area.  I've used a similar utility in Cinema 4D called DEMearth. I have two questions: (1) Is there a similar addon for Blender 2.8x?  (2) How would I export the TERRALAND terrain object from Unity into Blender.  I've researched but found little information.

blendergis is an excellent free addon for adding terrain and satellite found on github. easy to use a little tricky to install

Why is it tricky?

well its not too tricky if i remember i had to add 2 dependencies. https://github.com/domlysz/BlenderGIS/wiki

You can discount my perceptions as a novice. I tried multiple times to install BLenderGIS by pointing to the BlenderGISmaster folder that had already been unpacked from the ZIP. Nothing happened and no new entry appeared in the addon listings  (I was trying to load it into the  "community" addons section.
It succeeded only when pointing to the original zip file
  I saw a reference somehwhere that Blender could install from a zip but nowhere have I seen a statement that the addon MUST  be in ZIP form in order for the install script to put it where ever it goes
I propose that the addon  install interface be labeled as "Install from ZIP only" because this appears to be an undocumented requirement,


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Blender Cheat Sheet
I'm retired and cannot afford C4D anymore, so I'm switching to Blender 2.8.  Is there a simple, one or two page file that list at least the most used shortcut keys?

2 pages for a often used shortcut in Blender? That's quite difficult, but there is bunch of pdf file over each forum with google search. Also, Blender can switch those keymap to Industry Standard to mimic those shortcut in other software (MAYA,3ds,C4D). You might try it if you don't want to learn new key.

There are two 2.8 cheat sheets that I'm aware of:

Blender Guru (Andrew Price)
Zacharias Reinhardt

However the former is 7 pages and the latter 12 pages long, so not quite as compact as you were expecting. Both require a registration to their newsletter in order to download the PDF (copies may be found elsewhere on the web).


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Where is "combine hsv" in Geometry Nodes
In Blender 2.93.2, I can find the "combine RGB" Geometry Node but I cannot find the "combine HSV" Geometry Node. Where is it hiding?

Related: Can't find the node! Which node is available in which Blender version?

EDIT: Gorgious correctly pointed out that I missed the Geometry in the question.  As they say in their comment on the question: there isn't (yet) a geometry Combine HSV node.
As to the Shader Combine HSV node: It's hiding in converters, where it always hides:

You can always enter HSV in the search bar to find it:

You can build your own, using math nodes... and ColorRamp:

I like the color-ramp to avoid the math .. :)


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How to separate wheels and body from and imported car model
I would like to use the RBC addon to animate a car model. To do this, I first must separate the wheels from the car body. I've tried several ideas to do this and also searched the net for a tutorial with no luck. Can someone point me to a tutorial on how to perform the separation?

It depends whether each wheel was originally modelled in seperate parts (tyre, wheel rim, etc.) as to how easy it will be to seperate them. Start by going into Edit mode and deselecting all by clicking away from the model Then select a vertex on one of the tyres and hit Ctrl-L. If you're lucky this should hilight the wheel and tyre in one go. Then hit 'P' (Seperate) Selection. Back in Object mode you'll now have a separate wheel object. Do this for the other 3 wheels. If the parts of the wheel were modelled separately you'll just have to seperate each part in turn and join them with Ctrl-J.

@JohnEason: i think this is an answer - not a comment ;)

@Chris That was written just as I was about to go to bed. I didn't have a model available to compose a full answer with images at the time! :^)


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Geometry Node Creation
Is there a tutorial that explains how to create an individual geometry node? I don't mean a node network, I mean the node itself.

If you meant using python:

Here is a topic with many example of custom node interface https://devtalk.blender.org/t/extra-nodes-for-geometrynodes/20942

If you meant using C++:

See this topic by Elie https://devtalk.blender.org/t/tutorial-about-writing-a-custom-geometry-node-for-blender/24561

If you meant using blender native functionality:

Use control+G to group a node, then in the N panel you are able to expose inputs/outputs

Amazing! Would it be possible to program a node with it (C++) without recompiling Blender completely and implement the node independently as an addon? ...or would that only work as an addon via Python? Or would it work at all to implement own nodes as addon?

although i have no idea - i cannot imagine that this works without recompiling...else there would be hundreds of GN add-ons...wouldn't it?

but the links are really great and already amazing stuff can be done...!!! WOW

@Chris no you need to recompile, the API is intentionally weak so you'll submit patches

That’s great! Would be even greater, if we could change geometry too…or…as in animation nodes - you can use script nodes and do whatever you want!


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Merge these two meshes and export as .obj
I'm attempting to merge these two meshes together. They are already right beside each other in the way that I want to merge them.

The top mesh, highlighted in orange, and the bottom mesh, which is a flattened cube that I've curved using a path (the black line on the right)
I'm trying to follow this question and answer to join the two meshes but I can't get past the first step of selecting both of them at one time - is this because of the curve?
Thanks,
P.S. Here's the .blend

When joining [⎈ CtrlJ] objects, the new object will have the modifier stack of the active object.
If you (e.g.) select the mesh with the modifier and then the mesh without, the last selected becomes the active object (in this case the mesh without the modifier). When joining them, the new object will have no modifier and the mesh part which needs the modifier will be wrong.
The solution is to apply the modifier first by selecting the mesh and pressing apply on the modifier.

(legoparrot beat me, still going to leave the answer since there are some more details)

I applied the modifier but still can't select the other model

I actually had to use the "Border Select" tool to select both before joining

@Katana24 I could select the object just fine in your file. Try temporarily reseting your settings to check if you have messed up some operation?

Apply the curve modifier. Then select both > control+J. Then go File > Export > Wavefront(.obj), and select the file location and click Export OBJ.


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Circular edges on a plane with example
How can I make the outer edges of my plane a circle like in image 2?

You can use LoopTools add-on, turn it on it the User Preferences:

After it select outer rim and press W > LoopTools > Circle.


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Why is the camera drifting when following a path and tracking an object?
Is it possible to put a camera on a path and maintain it at a 1:1 ratio? what I mean by this, is if you look at the image below, it sort of drifts when rotating around..
I have it tracking an empty in the middle of the bed frame.
An example of the drift I'm on about: compare the camera location in the view port on frame 1 compared to frame 70, u see how the camera kind of moves away from the nurbs?

Thanks


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Object fade out while going from point A to B in animation
I'm making an animation in Cycles and need an object to fade out from point A to B. I've already key framed the movement for it but I need to know how I can make it fade out?
The node setup for the my material is below.
I have seen this asked on here before but I'm not having success with their answers.

Add a Mix shader connected to

your material
a 100% white Transparent BSDF shader

Then keyframe the Mix factor ("Fac:"):

set it to 0.00 when you want the fading effect to start. Then, having your pointer over the value input, hit I (the box becomes yellow)
then move to the frame where you want the fading out effect to be completed. Set the value to 1.00 and hit I again.

If you want to make the "Fac:" dependent on the distance from another object (an Empty representing point "B"), you can use drivers as in the answer to this question: Cycles Node to tell Distance from an Empty

That done it, cheers.


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"File format is not supported" when trying to open a 2.72 .blend file
I was looking into Sun Rays done in Compositor, so I headed over to this link.
Neither of the two files hosted there (Windows.blend and Sky.blend) could be opened by my 2.78 version of Blender:

I have always been able to open older files, even much older files, so what is going on here and why can't I open these files?

Could not open any of the files either, but I didn't get any message like you did, it just failed silently, and ket the default scene open as if nothing happened. Not sure, might be a bug or corrupted files.

me too, both open normally on my 2.78a on w7x64

could they be incomplete/corrupted? windows.blend is 529.436 byte and sky.blend is 906.624 byte

I think you are saving the file from the links on the page you show. You need to open each page and then download the blend file from the second page.


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I "run out of application memory" when trying to render a scene
I spent a long time designing a scene which involves 5 particle systems (no more than 1000 particles in each), and now I would like to render it.
Unfortunately, I invariably get this error message when I start trying to render it:

This is a problem brought up in this discussion but this page doesn't give solutions I can apply.
There is no doubt for me that Blender is the culprit, since I tried to render the same scene on two different computers and got the same error messages on each one, even when Blender was the only program running.
Computer 1

Computer 2

Is there anything I can do to make sure I can render this scene without crashing the computer? I tried quitting all the other apps besides Blender, and rendering as a PNG instead as EXR, but it doesn't make a difference.
(I would share the file but it is around 50 megs, is there a way to do so?)

Particles use up a lot of memory. What I normally do, is to create different scenes (e.g.: 5 particle systems = 5 scenes)  - if that's possible of course -, then render one scene at the time making sure to leave the background transparent (alpha). When all the scenes have been rendered (use png or similar and not a video format), open the video editor and put each rendered series on top of each other in a different channel. Only one series can have the background activated but the shadows can be a little tricky. I hope this helps!

I wouldn't expect to have issues with 16GB of ram. Try clearing all bakes in the particle cache and then make a compressed copy of the blend to see how small you can get it. If you don't have hosting to upload to have a look here.


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What is this Fresnel node?
I was trying to reproduce defmaka's Node setup from this BA article seen here, and came across this Fresnel Node:

It looks like a Geometry Node, but is called a Fresnel Node.
Alternatively, I couldn't make the Edge Detection part of the setup or the material look anywhere near their result.
I've tried moving around several sets of values, but I can't understand what I'm doing wrong.
What is wrong with my setup?

It is Geometry Node with label changed to Fresnel name.

That's what I used but I couldn't get it to work

Real objects both reflect and adsorb light. How much reflection you see at each point of the object depends on the angle at which you look at it.  Think of a lake of clear water.  Up close, none of the water is reflected, so you see to the bottom. Farther away, the water reflects more, so you see less into the water and more of what is reflected by the water.
The fresnel node applies this effect.  There are several good tutorials on Physics Based Rendering (PBR) that talk about Fresnel effect and using the Fresnel node.  I recommend a two part tutorial by Blender Guru. Part 1 contains a pointer to part 2.


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Export Compositor image and rendered image as two layers in the same file
I am wondering if there is a way to output a single image file that contains two layers: one with the rendered image, and one with the composited image.
This would be useful when importing renders in Photoshop, or in order to have two options for each image when exporting an animation. It could also be cool to have the composited layer and the rendered image when importing the sequence into an editing program (one would then have two footage layers instead of one and can blend/fade between the two etc).
Here's a file I experimented with, I exported to .tif which I think supports layers, but in Photoshop there was just one image.

Multilayer OpenEXR will export that with data packed in lossless way (which might be desirable if compositing is expected to be done)


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Sort by Modification Time doesn't work
I just created a file in my computer "test-color.png" that I would like to Import as plane. On my Mac, the file is the last one modified in the folder "other-fabrice":

However, when I click on "Import > Image as Planes", the first files are not the last files modified:

Sort by Modification Time is enabled

I thought that maybe it was showing me reverse order (earliest modified first) so I went to the end of the list.
It's also not there:

How do I use "Sort by Modification Time" to find this file?

Works on my end.. Try switching Display mode for the file list option to Long List and looking what modification time does Blender see for those files. Maybe try updating Blender although I don't think this didn't work as of 2.78

Newest modified files are at the top of the list - after folders, you are showing the oldest files at the bottom of the list. You can turn off the folder filter to see only files.

An you explain further? So it's a time related filter but the type of files has priority over the time modified?


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Light emitted through a translucent plastic material
I often see hallway lights or street signs made from translucent plastic shapes inside of which is a light. The light doesn't spread through the thicker parts of the plastic, and some angles are materialized by being dimmer such as in these photos:

The darker areas help see the object's volume and its structure, and I am trying to reproduce the same thing in Blender.
I have tried to make a material that is a mix of translucent and transparent, and also transparent and volume absorption, but I cannot seem to get it right.

(Shared screenshot and version are shareable, dumbed-down versions of the current project).
Also, all the edges aren't outlined the same way, and it's hard to tweak their appearance.
Either the darker areas are too sharp, or the material looks like smoke more than plastic.
How could I make this effect in Blender?

Don't over complicate. Just use a simple Translucent shader, possibly mixed with a Glossy one if you want some reflections. Translucency will take care of the rest. Make sure your light emitting mesh is smaller than the translucent surface, to create interesting dark edges.

First, I seriously doubt that the bulbs inside the text sign are in the shape of the letters.  They are probably some kind of fluorescent bulb whether CFL's or standard T8 tubes.  I usually try to model as close to physically accurate as possible.  That said, the letters of that sign have a thickness.  So use a Solidify modifier and that will create the thickness in the corners that you're looking for.

I think this question has a solution for you.

Here's an interesting situation: the other question is indeed very similar, but the answers don't work in my case. Both solutions make it look like this.. I'd like light on the background wall and the darker edges like this, without exporting as EXF (because it's an animation).


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How to get precision when rotating / positioning textures?
I am modeling a coin where heads and tails are the same image, and imported an image for the heads/tails faces.
I created a new Emission material for the faces, then gave it an Image texture and assigned it.

However, my image is slightly rotated:

So in the UV/Image Editor window, I rotated the face to align it vertically (R), I also scaled it a bit:

However, now that I would like to apply the same rotation / scaling values to the other face of the coin, I cannot find the rotation values that I just created anywhere.
Do these values get applied automatically? Are they written in one of the panels? And what about the scaling info?
I couldn't find a similar question. This is the opposite of what I want to do, since I am rotating in the Image editor for visual comfort, not in a Mapping node (therefore, even if I add Mapping Nodes, rotating the texture in the Image editor doesn't change the Mapping Nodes value).

Edit1:
For conveniance I build a Group-Node that does the centering, and also allows to plug in Rot_Vectors.
This was done by combining the help from:
Cycles mapping node - rotation pivot
How to add a socket for mapping node?
Can I make a custom node from a group and have that available in other projects?
This is how the node is used:

This is the inside of the node, with the Translate and Rotate node from gandalf3:

And here an optional Driver Setup to controll your rotation with an gameobject in the scene. Maby you could build yourselfe a GameObject that Visualizes your Rotation in the Viewport if you want to go further.

Edit_0:
If there are no other reasons you dont want to use a mapping node i would recomend the material view for visual comfort.
The reason you dont get any rotation value in a panel as you get in Object-Mode is that there are no objects, just verts in the u-v-coordinate system those are represented as vector2 -> u and v. Its the same in Edit-Mode, there the vers are also just points as Vector3. Rotation can be done as an operation but to store those blender oughta be node-based and also produce temporary objects of specifiec groups of verts that had been rotated.
I would recomend you to unwrap you upper and lower face together so they are exacly ontop each other and "rotated" the same and use a mapping node in Material View.
maby an option: orthogonal upsidedown camera to your coin and "Project from View" as unrwaping so your uv is axis-aligned

Hmm but if I unwrap both coin sides and apply the Dollar Sign texture, won't the Dollar Sign sign be reverse on one end? It needs to be legible on both sides. Also what if I place Mapping Nodes for the textured faces and then rotate it in the UV view? Would that create the values I'm looking for in the Mapping node? Otherwise is there another node I can use for rotation that makes more sense than Mapping? (i.e. one that allows to rotate from center...)

Rotate with MappingNode from center: https://blender.stackexchange.com/a/71538/68710

No, when you rotate in UV-Editor there is no connection to mapping. Thats because you only rotate the selected verts there and not the hole thing as with the mapping node

Well, I think I don't rotate the verts, since they don't move in the 3D view, it rotates the image relatively to the verts (even though in the UV IMage Editor it's the verts that seem to move rather than the image... oddly enough). Your link is the one I refered to in the question, which is the one I say is I find very cumbersome...

Ah okay sry, found that one on my own :)

If i understand it correctly: in the UV-Editor you rotate the projection of the verts in the U-V Space, you just position them via the rotation to other individual coordinates between u:0-1, v:0-1, then in the mapping node you take the hole information as vector from the uv space and rotate that.

Yeah, I'm not sure I totally understand what gets transformed in the UV editor (vertices location in relation to the image?) and where this information is stored (it's definitely stored somewhere). There's mapping via the UV Image Editor window and then through the Nodes... this overlapping is weird. Maybe someone could make a node setup that makes placing image textures a little easier...?

check my updated answer at the top, its maby not the real easy placing texture solution but its one step less building the nodes, and via the driver option you got some kind of direct/visual controller in the 3D View.  had fun building it and already saved it in my node prests for further use, so thanks for the question :)


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Pin a Rigid Body Object
I am trying to find a way to make a Rigid Object object swing from a given point (an Empty or anything else) without being deformed.
For example:

In this example I want to make the Cone swing on the X axis without moving on the other axis.
I tried every Constraint and Rigid body options I could fin (Pivot, Clamp to, Tack to...), but haven't been able to find a simple solution. Alternatively, I would like the swinging animation to not slow down over time.

How can achieve this?

This is meant to be a comment, but I can't comment so I will put it as an answer. I managed to do this in my mesh because the chains (the things that I'm trying to pin down) are hooked together and if I hide the top one, then it will look like I have pinned it to one point.

A rigid body constraint always needs two rigid bodies. Add a passive rigid body above the cone: Cube.

Select the empty and make it a rigid body hinge constraint, with the new Cube and Cone as the objects.
Other tweaks:

The hinge constraint rotates around its Z axis. You will have to reorient it.
Move the origin of the cone to its geometric center.
Set the Cones shape to Cone.

I would just hand animate it in your place since you desire such a simple motion and you don't want it to slow down over time either so there is no need for any complex simulation.
Select the top verticie of the cone in Edit mode than Shift+S to set cursor to selected,go back to Object mode and press W or Right click (depending on if you use right or left click select respectively) and Set Origin to 3D Cursor.
Than just rotate it 90 degrees on th X axis, press I to insert key frame and select Rotation. Go a few frames forward on the timeline depending on how long you want you swing to last than rotate 180 degrees in the other direction and instert another rotation keyframe.
From than swithc your timeline to dope sheet, B for box select and select your 2 frames. Shift+D to duplicate and slide them across the time line, tha rinse and repeat until you have enough frames for your animation.
https://youtu.be/ZdRbRyzaCDo


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Where are the Settings for F-Curve Modifiers?
I tried to follow this, but I'm failing at seeing where the F-Curve modifier Settings are displayed. Once more, the Blender UI is failing me with its logic.
According to the Manual they should be in the Sidebar! No luck in either 2.79 or 2.80.
Blender 2.79
I Went to the Graph Editor and selected Key > Add F-Curve Modifier > Generator. The Cube in my scene disappeared and where in the Sidebar there should have been settings, there were none:

File for 2.79

Blender 2.80
Blender 2.80 is even more confusing since they redesigned the Sidebar but didn't update the Manual to match. I followed the same steps but didn't even know where to look for Settings.
File for 2.80

How does one edit an F-Curve modifier?

My problem was that I hadn't clicked on a keyframe yet. The modifier tab didn't open if I pressed A to select all, but it did pop up once I clicked on an individual keyframe.

They are talking about the Graph Editor right panel, displayed with N. You can click on the Modifiers tab, click on Add Modifier, choose Generator. Once created, as it has a Y coefficient of 1 by default, it moves your cube away, you can reduce this factor.

Thanks. So in the first link it is a duplicated cube that is offset?

It is not duplicated, it's the generator effect that pushes it away as ypu can see if you play with the modifier parameters

I am using Blender 2.82.

Select axis on the left side
press TAB or 'right-click' -> Toggle Channel Editability
press N

You'll see modifiers :)


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Export as .obj and .jpg
I was wondering if anyone could please help me figure out how to export my work from blender.
I made a snowman in blender render and want to export it. The issue is, I would like to be able to export it as a combination of a jpeg and Obj files rather than a .mtl and a .obj. Is this possible? Any help would be greatly appreciated! Thanks! (I also tried to use textures to give the snowman colors instead however wasn't sure how to bake them to allow me to export as a jpg and obj.

OBJ export is exclusively concerned with exporting geometry only, some and basic material properties are exported too, but in all honesty you shouldn't bother much with those. Actual materials should be remade in the destination application anyway. As for the textures they have nothing to do with OBJ exporting, either reuse the same image based textures you already used in Blender, or if you use procedural ones then bake them to a texture. You can then save the image in whatever format suits you best (be it JPGE, PNG, TGA or otherwise)

Also see related https://blender.stackexchange.com/questions/57531/fbx-export-why-there-are-no-materials-or-textures

When you want to export an obj file with jpeg textures, simply create jpg textures first.
*.mtl is no image format. A Obj file is made of two parts. The *.obj part contains the mesh data. The *.mtl part contains material settings for a primitive phong shader, including the texture paths. You should not leave the *.mtl part away, it is part of the obj file. And when you leave it away then the textures are not found.
So when you export an obj file with jpg textures, then you should end in three parts. The *.obj file, the *.mtl file, and the *.jpg file.
(As a side note, Jpg is the worst texture format you can choose. It uses a lossy compression. You loose quality. I prefer PNG)


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How do I reset the origin placement?
The origin (or the small orange dot, if that's even the origin but I'm going to call it that) use to be placed always in the center of the selected shape, when I pressed the comma key, the view would always center to the current selected part(s).
Now I must have hit some key by accident and the origin is now always at the center of the model (where the three axis cross), I looked it up and found out that you could press CTRL+SHIFT+ALT+C for a menu that lets you move the origin, but that set the origin for the whole object, not for the faces seperatly like it used to be. I also tried resetting the preferences and uninstalling(!!) blender which for some reason didn't work!
Is there some shotcut to undo that? Or at least some option file I can get rid of unaffected by the uninstall?

related https://blender.stackexchange.com/questions/24078/set-origin-to-geometry-center https://blender.stackexchange.com/questions/14294/how-to-recenter-an-objects-origin/14296#14296

It would help if you include screenshots of the objects which you have. Origin of the object can be set to some arbitrary faces only if you select those in Edit mode, snap 3d Cursor to them and choose in Object mode origin to cursor, Numpad period button will center on selection regardless of its origin.

That doesn't solve my actual problem, if it were only about getting the camera right I could simply turn the current view. My problem is that I can't quickly snap the camera to a selected part without these extra steps as the orange dot is now locked at the center of the object. Before the mishap it was always in the center of the current selected part by default.

Turns out it wasn't even the origin's fault but more like the 3D view center.
I must have accidently pressed Shift+Numpad period which permanently locks the 3D view center to the selected object (therefore Shift+F wouldn't work either) which can be unlocked either by removing the lock in the properties panel (shortcut N, in the View rollout) or by pressing Alt+Numpad period.
What I thought to be the origin must have been the face's center, which when selected, looks similar.

I suspect you've selected another pivot mode:


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Create spiral out of circle
I want to create a spiral that looks like this:

From green to purple is one "circle", but the green part is below the purple. This circle repeats below and so on
Actually it just a circle (pie chart) that is cut at a radius line and then "drawn down" so there results a spiral if you add multiple of these circles.
Does someone have an idea how to achieve this kind of model?

Maybe you can get some tips from here https://blender.stackexchange.com/questions/77233/simulate-a-split-washer-getting-tightened-down, screw modifier and simple deform taper could work.

Create a simple mesh composed of only one edge progressing along the X or Y axis.
Add a Screw modifier to it, adjust properties as desired, mainly the Steps for smoothness, Screw for height, and Iterations for number of turns.

To assign different colors to your mesh you will have to apply the modifier though, then create multiple Material Slots, assign them to the desired faces, then create your colors as desired.


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How to prevent meshes from passing through each other?
I'm trying two put a guitar in animated rigid body's hands with armature, but there's a problem - a guitar is just gone through rigid body. How to prevent this?

I expect you actually mean a rigged body as a rigid body is a type of physics simulation.

You need to animate the location of the guitar and hands so that they are in sync with each other. Start with a pose for the body, then place the guitar in front of it and place the hands to match. This could mean adding keyframes every frame to keep the hands and guitar together.
For your character, enable (or create) IK for the arms. This will allow you to place the hands and have them stay still as you move the body. Some child of constraints might help move the guitar and hands together while still allowing the hands to be moved independently. You may want to look at using the rigify addon to create a basic armature that you match to your character, then have it generate a more complex rig that has IK/FK switches etc. You can find some tutorials like this one that explain using rigify in more detail.
If your interests are in rigging then you could look into setting up a more complex rig that could make animating easier, if you only want to animate then focus on animating the two objects so they appear in sync with each other.


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Weird spots in my mesh
In the mesh on the picture of a rear wheel I have weird spots and I don't tear them off.
It's not a light trap and when I add texture it gets worse.
Does anyone know what to do?
I work with Blender 2.83

Can you post the blend file?  There are several possibilities.  If you're using smooth shading you may want to set the object data properties -> Normals -> Auto Smooth on.  You might also try recalculating the normals. (In edit mode select all and then SHIFT-N). Or you could have some bad geometry.  There are several things you could do in that case.

Super!
The Shift-N and the Auto Smooth were the trick, Thanks !


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Blender Fluids - Start Time
I'm having an issue getting fluids to calculate if i set the stat time anything other than 0. I have a situation where the calculations (base on an object track) need to start 4 seconds in and end 32 seconds later. I've tried a number of things all of which don't net the correct results.
1) Setting start-end frame ranges
 - Everything still simulates from frame 0 even if i set the frame ranges where i need them.
 - Have TIME on the domain set to 0 and 32. was assuming that it would use the start time based on the current frame range? Guessing not.
2) Setting the start time
 - Frame range is left to start at 0.
 - Domain is set to start of 4.0 and end of 36 (to include the offset of the 4 second start).
 - Upon doing this it never actually simulates. Just sits on a calculating to infinity.
So my first question is is it even possible to simulate MID portion of an animation or do i need to slide everything back to start where i want the action the begin?
And secondly, does the time offset for start work currently? I've read mixed results online.
Appreciate the help!

Not sure exactly what you want to do, but sure, it can be done.
Yes, things will start at frame 0 unless you change the Offset value in the Domain settings. You will want to set it to -(framerate times 4). So -96 or -100 I guess. By the way, the Offset value does not need being set before baking. You can change it anytime you want.
The Start value is something else. If you set it to 4, then the first 4 seconds won't show, so you won't see the beginning of the animation. It will still need to be calculated though, so there is no saving time. I don't know why it wouldn't bake at one time. I did some tests and experienced no problems.
In general, there is usually no need to change the Start value. Offset is what you need.

This should be noticed If you got a longer frame and inflow object is moving, the messing thing was happened that your offset also offset the inflow behavior to later frame.  This is expected, but I cannot believe Blender Team haven't found a good idea to slove this to save baking times.


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Finger stops moving while the bone keeps going
I've been trying to transfer over an XNALara model to SFM by using blender. So far I haven't really had too much of an issue but I'm struggling to figure out how to get the fingers to bend properly on the model. This model in particular has his fingers curled up to begin with so it's a little bit harder for me to really pinpoint what my problem is when most examples start with a straight finger.
I have a feeling my problem is mainly with the IK setup when it comes to the bones. The mesh doesn't seem to want to deform with it either even after weight painting but I think it would work out once I get the bone problem out of the way.

I'm fairly new to blender, really just started last week. Might be evident in the lack of hip bones on the model (Haven't figured that one out just yet)
Anyway the blend file is here: https://www.mediafire.com/?ohg221owj56c7b1
If anyone can give me input I'd be grateful. I've been looking at various tutorials but like I mentioned, it's just kind of difficult since I'm starting on a model that already has posed fingers.

The reason of the fingers issue is, that vertices of fingers are in Wrist (left and right accordingly) Vertex Groups with weight of 1 and in appropriate fingers Vertex Groups.
Remove them from Wrists Vertex Groups and they will start follow fingers accurately.

P.S. Consider removing doubles in the model, there are bunch of those.

Thank you! I went ahead and removed them from the wrist group and the fingers are moving a lot more smoothly after adjusting the rest of the overlapping vertexes. The mesh is still kind of stretching weird here and there but it's nothing major that can't be solved with a little bit of tweaking. I also went and removed the doubles, which is something I didn't even know about so an extra thanks for teaching me something additional there.


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How to get a rigid body to rotate?
I would like to get a cube to rotate in a scene as seen in this image. Is there any way to do this without animation?

Could you use animation nodes? Of course, unless procedural animation is your thing it might be more difficult than just animating it.

It's really very easy to do this, Just follow these steps:

In addition to this if you want to add a force in the forward axis, then add a linear velocity or force in that axis.

There isn't a way that I know of to do that without animation. But, that would be very simple to do. You can simply add your cube, press "i" and press lokrot scale, then chose another frame rotate it and do lokrot again.


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Automatically move the camera and incorrect context error
I understood that the problem of incorrect context is a pain, and overriding context is not always a good idea, because there are generally better solutions.
I need to import and render hundreds of meshes with different sizes, and I'm looking for a way to automatically place the camera.
For now I just need the three axis view, and I found two useful functions:
View -> Align View -> View Selected or bpy.ops.view3d.view_selected()
View -> Cameras -> Set Active Oject as Camera or bpt.ops.view3d.object_as_camera()
This is what I thought: I place the 3d view upon one of the three axis, pretty far from the origin; then I call bpy.ops.view3d.view_selected() to have the mesh just insede the 3d view, and finally call bpt.ops.view3d.object_as_camera() to place the camera in that point (I could then slightly move it a bit further).
This is the best way I found to center the mesh inside the camera; if you come up with new ideas they're more than welcomed.
The problem is that I cannot override the active context :/
import bpy

original_type = bpy.context.area.type
bpy.context.area.type = "VIEW_3D"
bpy.ops.view3d.view_selected()
bpy.context.area.type = original_type

Is view3D really overrideable?
Thank you very much

You can see how to override the view operator's context in this answer:
http://blender.stackexchange.com/questions/30643/how-to-toggle-to-camera-view-via-python

Related http://blender.stackexchange.com/questions/51563/how-to-automatically-fit-the-camera-to-objects-in-the-view?rq=1  If it's the ortho view you are after have a look at Object.camera_fit_coords  If you make your code into an operator, running it from the space bar in or from a button in the 3dview space will put it into context for you.

Further to above look at preview_render_do line 289 in https://github.com/Moguri/blender/blob/master/release/scripts/modules/bl_previews_utils/bl_previews_render.py

@batFINGER thank you, it was what I needed :)


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In Edit Mode, is it possible to invert selection?
I wish to select areas of a mesh, but it would be much simpler to just select the ones I don't want selected (because they are easier to access), and then inverse the selection.
Is this possible?