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How to fix Blender 3.0 animation flicker?
I'm new to Blender 3.0 animations and one of my test animations (a martian sunrise) has some unwanted brightness flicker, especially noticeable on the foreground landscape:
https://youtu.be/rPX2yrO9DJI
Any idea what's causing this? And how to fix it?
The sun and atmosphere is created by an addon called, "Physical Starlight and Atmosphere;" this is the first time I've seen it flicker.
Output settings:
bpy.context.scene.render.use_file_extension = True
bpy.context.scene.render.use_render_cache = False
bpy.context.scene.render.image_settings.file_format = 'PNG'
bpy.context.scene.render.image_settings.color_mode = 'RGB'
bpy.context.scene.render.image_settings.views_format = 'INDIVIDUAL'
bpy.context.scene.render.image_settings.compression = 15
bpy.context.scene.render.image_settings.quality = 90
bpy.context.scene.render.image_settings.jpeg2k_codec = 'JP2'
bpy.context.scene.render.image_settings.use_jpeg2k_cinema_preset = False
bpy.context.scene.render.image_settings.use_jpeg2k_cinema_48 = False
bpy.context.scene.render.image_settings.use_jpeg2k_ycc = False
bpy.context.scene.render.image_settings.use_cineon_log = False
bpy.context.scene.render.image_settings.color_depth = '8'
bpy.context.scene.render.image_settings.exr_codec = 'ZIP'
bpy.context.scene.render.image_settings.use_zbuffer = False
bpy.context.scene.render.image_settings.use_preview = False
bpy.context.scene.render.use_overwrite = True
bpy.context.scene.render.use_placeholder = False
bpy.context.scene.render.image_settings.tiff_codec = 'DEFLATE'
Blender 3.0, Windows 11

Sorry ... I don't see any flickering in provided video.

No flickering here under Windows 10.

Thank you for the replies. Uploading the video to YouTube appears to have diminished the flickering, but it's still present.


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How to add more objects to an animation group?
I'm new to animating in Blender. The issue is I've created a simple space ship object and animated it. Working great! I then used Random Flow mesh generator (great 3rd party addon!) to create additional layered objects from the simple space ship object. The issue is that those new layered objects, e.g., Front.001_RExtr, are outside the group Space Ship Animated, but they need to be included in that group.
Question: Is there way to add those new objects to the group Space Ship Animated?
Thanks. Blender 2.93.5 under Windows 10.

Space Ship Animated is the parent of an empty and several meshes such as Front and Rear.  You can also parent the circled meshes to it and they will move with it in the animation.  1) Deselect everything.  2) Select all of the circled meshes.  3) Select Space Ship Animated . 4) Type CTRL-P.  5) Select Object from the drop down.  The circled meshes will now move with Space Ship Animated in the animation.  Is that what you want?

Thank you Marty Fouts. That works! :)

source: Stack Exchange

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

sort: votes


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Is there a way to change a dimension of a mesh by a specific percent?
I'm working with imported terrain meshes and for some of these meshes I would like to change the vertical (Z) dimension by a specific percent. Is there a way to do this?
For example, I import a terrain into Blender that by default has a 4x vertical exaggeration. Once in Blender, I would like to change its scale so that Z=25% while X & Y remain at 100%. I could eyeball it, but entering numerical values would be faster. Thanks.
Blender 2.93.5 Windows 10

In Edit mode, select your mesh and press S+Z+0.25?

The scale command takes both an axis and a numerical argument.
For your example, SZ.25Enter would scale the selection to 25% of its size only on the Z axis.
The axis designation is optional.  If you use Shift before the axis letter it will scale on the other two axis.  I.E. ShiftZ will scale on X and Y but not Z.
If you leave the axis out it scales on all three axis.
If you don't specify a number it scales only on the selected axes, but using left-mouse drag.
If you scale in object mode, be sure to apply the scale.

Works great moonboots. Thanks! :)

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


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Resize object and materials change appearance
I've got a beautiful 3rd-party payware product by a competent artist. The issue is that when I resize the object for use in another project (it needs to be resized to match the dimensions of the other project), the materials change dramatically.
I realize this may be a RTFM moment, but I'm wondering if there is something basic that can be addressed to fix this issue? Thanks. Blender 2.93.5, Cycles, Windows 10

Is it maybe the case that the material works properly after resizing, but once you apply scale it breaks?

Markus von Broady, thank you for the response. One or more of the shaders have scale-specific values maybe? I don't know. Like everything else Blender, I'll probably figure it out eventually. :)

You didn't answer my question, but if it was supposed to be "yes", then the answer could be to multiply/divide each object coordinate used in the material.

Markus von Broady, thank you again for the response. No, I did not answer your question because I did not understand it. I think of resizing and scaling as the same thing via the Scale tool, but you're suggesting it might be two steps?

resize;
apply scale?

Screenshots of the material node setup and outliner would help to investigate the issue.

Good suggestion. I'd share, but since this is a product I purchased I'm reluctant post the artist's node setup. I recall several years ago when rescaling objects in Blender that bump map values would not scale proportionately, at least the way I was doing it. Scale an object down and the bump depths would become much more pronounced, so I suspect something along the same lines is happening here.


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UV editor - Mirror modifier not working on all faces of cube
I'm working with the UV mapping editor for the first time and there's something fundamental that I'm not understanding. I want to map an image texture to all faces of a cube so it reads correctly on all faces. I started with the front face, Unwrapped the texture, then used the mirror modifiers to fix the orientation. Works great. However, when I select the other faces, unwrap the texture, the mirror modifiers have no effect; mirror modifiers only seem to work on the front face. Any suggestions? Thanks. Blender 2.93.5 Windows 10

I figured it out. The difference between the faces was that for the top and sides I hadn't selected the image texture's corner points before applying the mirror transformations. Now all is working great!


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Does Blender have these simple UV mapping options?
I'm new to model building and UV mapping in Blender. I used to do my modeling/kit bashing in 3ds Max. 3ds Max has a simple way to 1) clear existing UV mapping from objects; 2) apply a UV mapping format to an entire object, e.g., Cylindrical, Spherical, etc. Does Blender have similar way to do this? Thanks. Blender 2.93.5 Windows 10

if you select all in Edit mode and press U you'll have the Cylinder Projection option

Yes, in general.  If you enter edit mode on a mesh, select all, and hit 'u' for the unwrap menu, you'll see a list of various ways to unwrap a mesh.  That includes project from view (presumably the same as Max's "Plane"), cube projection ("Box"), cylinder projection, and sphere projection.  All of these depend on the current view in the 3D viewport from which the unwrap is called.  For all of these, you should be using an orthogonal view, pointing in the object's +Y axis.  You can get this view, in default 2.93 with any startup interface options (I believe) with numpad 1.
"Cap" options presumably unwraps the cap of cylinders to separate islands projected from view; this has to be done manually in Blender, but is a simple  project from view with cap faces selected.  XYZ to UVW doesn't make sense in Blender with only 2D UV, but XY to UV is just a plane projection from the top view, assuming the XYZ under consideration is world XYZ position.
I'm not sure what face or shrink wrap options are.  Given demonstrations of how Max handles those options, I could probably tell you how to reproduce them.
Not confident that I can guess what Max is doing with dimension and tile options, but these are probably best handled with math in the material nodes (mapping and modulo on coordinates.)  Dimensions are probably just a simple scale of UV.  Modulo on coordinates in Blender is kinda not right-- doesn't handle texture filtering correctly when you do that-- but then, I don't know that Max handles that right either.
For many of these, it's also possible to do mapping in a material's image texture node, from generated coordinates to "box", "sphere", or "tube" (cylinder) map a texture without even bothering with UV.
It's also possible to have material node groups that do plane, cylinder, sphere, or box mapping on individual samples, without regard to UV.  The math for these can be intimidating, but once done it's reusable, and I'd bet somebody has shared the node groups to do this somewhere or other.

Thank you everybody for your responses. Much appreciated!

You can select your object, and then go to UV workspace on the top side. Usually it will automatically turn into edit mode, and select all vertices.
Then you can hit the U button or UV>unwrap,and then you can see some simple uv options.
You can follow my steps,then you can have quick UV.


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Blender Preferences > System > Memory & Limits = RAM or VRAM?
I'm trying to optimize my Blender 3.0 under Windows 11 and I occasionally get a render error stating that I've run out of "GPU Memory." Blender Preferences > System offers various memory settings, but they don't specify whether they're referring to system RAM (I have 64GB) or VRAM (8GB). I can't find info on what sort of memory these options address. RAM? VRAM? or both? Thanks.
Operating system: Windows-10-10.0.22000-SP0 64 Bits
Graphics card: NVIDIA GeForce RTX 3060 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 511.23

System RAM, not VRAM

"out of GPU memory" usually means that your scene does not fit onto your graphics card anymore and you'd have to find a way reducing memory usage. One easy way is to close everything else and try rendering from the command line. If that does not help, you'd have to optimize your scene (textures, polygons etc.) or render using your CPU (unfortunately).


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"File > External Data > Report missing files" reports dozens of "missing" .blend files?
I have a second Windows PC that I dedicate to rendering some of my Blender projects, so needless to say, managing dependencies (external textures, etc.) is an ongoing process. Here's something I'm trying to figure out:
File > External Data > Report missing files reports dozens, sometimes hundreds, of "missing" blend, files. All of these missing blend files are from other projects, and have nothing to do with the current blend file.
This isn't a showstopper, but it does clutter the reporting process, continually leads me to ask: Why?
Blender 3.0, Windows 11

In some way your blend file is referencing these external files.   If you use the Outliner, "Blender File" mode (drop down to the right of the Outliner symbol in the header).  You can try to search for a fragment of the file name reported, and see what is referring to such an external fil (Image node, etc). you can find this node, right-click and Delete.

Hi :). I guess it's to save you from checking each linked .blend individually if you have tens of linked assets

@james_t Oh my lord, why didn't i think of the search function last week! :)) So simple. Thanks.

@james_t Thank you for your response. Unfortunately, none of the referenced files show up by searching the Outliner.


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Rename add-ons as they appear in the N-Panel menu?
I have acquired a lot of add-ons that now clutter the N-Panel menu. Is there a way to rename some of these add-ons so, at the very least, they have shorter names? I'm comfortable editing Python scripts, if it can be safely done there?
I tried a great add-on called SIMPLE TABS by Chipp Walters that allows you to rename add-ons--and more--but the problem is that not all add-ons play nicely. For example, BlenderKit and ToOptimize Tools menus become distorted and even broken up by SIMPLE TABS, and EasyLight isn't even accessible from SIMPLE TABS.
Thankfully, some add-ons allow you to change the N-Panel menu, but that's the exception. Again, I'm tempted to edit the add-on Python scripts themselves, but I'm not sure I know enough to do it without adverse consequences. Any suggestions? Thanks. Blender 3.01, Windows 11.

To do this in python, you need to edit the file with the panel class for the addon and find the bl_category and bl_label fields and modify them appropriately.

@MartyFouts Thanks! I tried this on "ToOptimize Tools", changing the name to "ToOpt." (There were a bunch of *.py files so I used a multi-file search & replace tool; there was no "bl_label" entry to be found.) It seems to have worked. Much appreciated!


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Make the sun disk visible?
I'm working on an outer space scene with a HDRi star texture and while I'm happy with the sun settings (direction, intensity, angle), I'm trying to figure out if there is a way to make the sun disk itself visible.
A Google search results in a link to the Blender manual, but there's nothing in there regarding the sun disk itself. https://docs.blender.org/manual/en/latest/addons/lighting/sun_position.html
Can the sun disk be made visible? or is there a workaround? Thanks. Blender 3.01, Windows 11

no you can't, you need to use another object like a sphere or a circle, and give it an Emission node

@moonboots Thank you! Another question: Is there a quick way to align an object to the sun's position? Or is that a trial & error process?

if you want to put it at the same position, select the sun object, then Shift S > Cursor to Selected, select the sphere you've created and Shift S again > Selection to 3D Cursor, but actually the sun location doesn't count so I'm not sure what you mean

I guess what I mean is if I have a sun light object with a solar azimuth of 150 degrees and an elevation of 130 degrees relative to the scene's ground plane, is there a way to quickly place an object, a suitable distance away, at that position in the sky? Thanks again.

As I said, if you're talking about the sun object itself, contrary to, for example, a point light, its location doesn't count, only the rotation (and all the parameters you'll find in the Object Data panel of course). You can place the sun wherever you want in the scene, it's considered to be infinitely far away, and its rays are parallel

I'm having success by creating an emissive sphere to serve as the visible sun, placing it sufficiently far away from the center of the scene to be at near-infinity, and then using the directional indicator of the sun light object to align the position of the emissive sphere. Close enough for my purposes.

You could also make a sun part of the HDRI image, this way it will always look far away

You can't make a light visible as an object in render, you need to use another object like a sphere or a circle, and give it an Emission node.


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How to merge materials for joined objects?
I've recently starting joining similar objects in my projects, each using the same material. The issue is that each joined object retains its own material slot, even though each object uses the identical material. I figure there must be a way to merge/flatten those slots so that in the future if I want to apply a different material I don't have to apply it multiple times, but I can't figure out how to do it. Any suggestions? Thanks! Blender 3.0, Windows 11

If there is only one material in there you can safely delete them all but one and all the faces that pointed to ther other material slots will be redirected to the last remaining material

Gorgious, thank you for the response. Unfortunately, when I join the objects, each object ends up with its own material name. For example, the first object has the material "metal," the second is assigned "metal.001", the third, "metal.002," and so on. If I delete any of those materials, then that joined object is not redirected to a new material.

I can't find anything what can cause this in the Preferences, but did you try to reset it?

FFeller, reset the Preferences?


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Is there a way to force a project to reload *all* textures?
I work with a lot of materials that utilize external textures and frequently I want Blender to reload all of the external textures associated with the current project, but the only way I know to do this is to shut down the project and then re-open it. Is there a way I can to this with the project open?
I know that in the Shading or UV Editing tabs you can click on a node and hit "Alt+R" to reload the texture for the selected Texture node, but that's time-consuming. Any suggestions? Thanks! Blender 3.0, Windows 11

There is an add-on that I use that comes with Blender called TexTools. This has a ton of useful features! The one's I use most are reloading all textures (like what you're wanting), and "rectify" which will try it's best to layout a wonky looking UV map into a square. Perfect for pipes/cushions/etc.. Hope this helps!

I can't find this add-on anymore (Blender 3.5). Must've been removed from the built-in add-ons?

It may have, I don't have that version installed yet, but you can find the file here: https://github.com/SavMartin/TexTools-Blender/releases

Well, I need to clarify LWS SWL's answer. He has talked about functionality of Amaranth toolset add-on
You can enable it in user preferences, add-ons tab:

Then the add-on is enabled you can simply save and reload scene, that forces all libs and textures to be reloaded:

It is the easiest way to do this in one click

If you press shift-ctrl-w, that will save and reload the file (including textures).
It is also under file>save & reload.

Thank you everyone for your responses! Very helpful. The Amaranth toolset "Save & Reload" button is a dream. Thanks!


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Blender for Windows Best Practices: Blank spaces in asset names?
I'm working with Blender 3.0 in Windows 11 and I notice that in naming assets--object names, material names, file names, folder paths, et al--sometimes underscores (_) are used and sometimes blank spaces ( ). Is there a preferred practice?
I know that years ago when I worked with 3ds Max it was recommended that you never use blank spaces; is there a preference for Blender? Thanks!

I personally keep avoiding special letters, spaces, semicolon and dashes. I've had issues with python addons so I keep doing that. Even in my files.

This. If you think you might eventually work some day in the future with some kind of add-on or script or third-party software, avoid spaces. Otherwises, it's a matter of preferences. You should be aware that there are some ISO standards concerning asset management, so you might also try and see what's said in these documentations


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How to evenly distribute a group of objects?
I've imported groups of object files (OBJs) into a Blender project and the problem is that they're all sitting on the 3D cursor one inside the other, so I'm looking for a quick way to evenly spread them out/distribute them. I can do this manually, but that's time-consuming. Any suggestions?
I found a YouTube video that recommends a built-in Blender Addon called Oscurart Tools. Unfortunately, Oscurart Tools are no longer included in Blender 3.0. I found a link to the tools (https://github.com/oscurart/Blender-28-Addons) and while I was able to installed them, I can't find any way to access them from any Blender menu. Again, anybody have any ideas? Thanks! Blender 3.0, Windows 11

Thanks for the tip. I installed the tools, but unfortunately when I try to use Distribute Object, I get the message: "Needs at least two selected objects." I have multiple objects selected, but Oscurart seems to think I have only one selected. :(

If your question was solved, please be so kind and mark the answer that contributed to the solution as "Accepted Answer". This will make it easier for others to see which way leads to the solution, and the question will no longer appear as unsolved. Thank you! Here you can find more information: What should I do when someone answers my question?. If you still didn't get a solution to your question, please be kind enough to address it.

You can solve this with a simple and short piece of code (python).

Put all objects into one collection
Open the Text Editor in Blender (SHIFT + F11)
Enter the code below and fill in the name of the Collection and a value for the distance
Run the script (click on the play button)

import bpy

# Starting offset
offset = 0
# Distance between the objects
distance = 3
# Name of the collection containing the objects
collection = "Objects"

for obj in bpy.data.collections[collection].all_objects:
    offset = offset + distance
    obj.location.x = offset

Here's a script that works on whatever is selected, and distributes the object's locations equally between the two extremes; you just have to type the axis name at the top of the script. Follow the directions in @quellenform's answer for how to run it.
AXIS = "y"

import bpy
selected = bpy.context.selected_objects
min_v = min([getattr(obj.location, AXIS) for obj in selected])
max_v = max([getattr(obj.location, AXIS) for obj in selected])
selected.sort(key=lambda obj: getattr(obj.location, AXIS))
offset = (max_v - min_v) / (len(selected) - 1)
for i, obj in enumerate(selected):
    setattr(obj.location, AXIS, min_v + i * offset)

When you import Kenny game assets into Bender they are all on 0,0,0, so I needed a way to spread them out over a grid.
So after import, I selected all, cleared the parenting (AltP/clear parent) and executed this script:
import bpy
selected = bpy.context.selected_objects

d = 20

x = 0
y = 0

xoffset = -d/2
yoffset = -d/2

offset = 2

for i, obj in enumerate(selected):
    obj.location.x = xoffset
    obj.location.y = yoffset

    yoffset += offset

    if i % 20 == 0:
        yoffset = -d/2
        xoffset += offset

result:


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OpenEXR animations and Adobe Premiere Pro?
I'm experimenting with rendering my Blender animations as OpenEXR MultiLayer image sequences (this video piqued my interest: https://www.youtube.com/watch?v=-UjJqwwMJc8). The problem is that I do my video editing with Adobe Premiere Pro and Premiere imports the OpenEXR images as black frames; there's nothing I can do with them.
Meanwhile, I installed an addon called "Exr-IO" which allows Adobe Photoshop to read these OpenEXR files, and it does an excellent job, so I'm reasonably confident that the OpenEXR files Blender rendered are fine. Unfortunately, I cannot find an addon that will allow Premiere to do the same.
Anybody else have any luck with OpenEXR and Premiere Pro? or another video editor? Thanks. Blender 3.0, Premiere Pro 22.1.2, Windows 11

Try the free version of Blackmagic Da Vinci Resolve as shown in the video. I use it all the time, and personally, it's a lovely piece of software. It's like the Blender of Video Editing softwares. So good that it competes with paid softwares like Adobe, and yet, completely free!

@Hrishav Saha, thank you!


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How to rig objects to rotate around their long axes?
I thought I could find a tutorial for this, but so far no joy. What I want to do is rig/constrain these solar panels so I can manually rotate them around their long axes regardless of the orientation of the larger spacecraft model. Rigging 101? Can someone point me in the right direction? Thanks! Windows 10, Blender 3.0

One root parent bone establish the main rot of the whole objects. 4 child bones control the panels: if the bones are created in edit mode with their long axis lying on the panels long axis, animating their Y local coordinates will result in the rotation you need, regardless of the global rotation of the root bone.

Thank you for the response, Marty Fouts. I’ve got some homework. :)


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How do I adjust segments and rings on a UV Sphere?
I'm working with a UV Sphere and I need to adjust its segments and rings. When I first added it to the scene a menu called, "Add UV Sphere" appeared. Unfortunately, the menu then went away. How do I call it up again?
I found relevant video suggesting that pressing F6 will call up the menu again, but F6 does nothing on my system (I tried to find out what F6 is supposed to do, but searching for F6 in Preferences > Keymap > Key-Binding yields no results; in fact the search field doesn't appear to recognize function keys at all). Any suggestions? Thanks.

it should be F9, not F6, but as soon as you do anything else (like move, edit...) you won't be able to have access to the last action

Thank you moonboots. Looks like once I've created a mesh, any further subdividing is done this way: https://docs.blender.org/manual/en/2.81/modeling/meshes/editing/subdividing/subdivide.html

yes once you've created a primitive you can't change the initial settings anymore as soon as you move or edit etc... but of course you can still do whatever you want like subdivide etc


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Object Move arrows no longer aligned to grid?
I'm working on a project where I suddenly realized that the object Move arrows are no longer aligned to the grid, rather they're aligned to my viewing position in the 3D view. I must have done something to make this happen; how do I change the Move arrows back to be aligned to the grid? Thanks. Windows 10, Blender 3.0.0

You are currently using view transform orientation. Because of this, the gizmo will always be oriented toward your view.
From the manual on view transform orientation:

View
Align the transformation axes to the window of the 3D Viewport:

Y: Up/Down

X: Left/Right

Z: Towards/Away from the screen

You may change it back to global in the header as shown below.

Thank you so much, Timaroberts! :)


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Blender 3.0: Toggle visibility of all items in a collection?
Is there a way to make sure that all items in a collection, and its sub-collections, are visible for render and/or viewport editing? Currently the only way I know to do this is to expand the collection, and its subcollections, and visually inspect each item.
Unfortunately, it's not unusual for me to render a complicated scene only to realize that I'd forgotten to unhide one or more items that I'd hidden during the editing process. At the very least, it would be useful if I could right-click a collection and toggle the visibility of every associated item. Any such method? Thanks.

@MartyFouts Thank you! By the way, I want to mark your answer as the right answer, but I see no option here, just the up arrow. As I recall, on some occasions I've seen an option for marking a response as the right answer, but not this time? Thanks again.

Hold Shift while toggling the property on the outermost collection. That will recursively apply the change to all nested collections.


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Animate the Sun's true motion through the sky?
I'm experimenting with the Sun, skies and atmospheres in Blender and I'm looking for a way to accurately animate the Sun's motion through the sky from sunrise to sunset.
The Sun Position addon works great for setting the position of the Sun for a moment in time, but I see no way to animate its natural arc though the sky. Can this be done? Thanks. Blender 3.0, Windows 11

You can set keyframes for the time and day parameters of the Sun Position by right clicking on them:

You find these settings in the World tab of the properties editor. The manual entry has more details on how to coordinate the Sun with and HDR, et cetera.

Marty Fouts, very cool! Thanks!

@WilburPost  If that works, maybe click the arrow and accept the answer?

sure thing. I didn't realize that's how it works here. :)

This is only practical for one day, though. If I want a complete year, that does not work.


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How to undo Preview Node Output in Shader Editor?
I've discovered a useful shortcut for previewing a Shader node by Ctrl+Shift+LMB on the node. Nice! Problem: How do I undo the preview? The Blender manual doesn't explain how. I've seen other references that say Ctrl+Shift+LMB again on a blank area in the node editor will do it, but that doesn't work for me. Any suggestions? Thanks. Blender 3.6
https://docs.blender.org/manual/en/latest/addons/node/node_wrangler.html

Never mind. I figured it out: Ctrl+Shift+LMB on the Principled BSDF node will undo the preview.

CTRL + Z?

Ctrl+Z works, but that's assuming you haven't done other operations after enabling the preview.

I've seen other references that say Ctrl+Shift+LMB again on a blank area.

That is in the Geometry Nodes Editor.
You can click in a blank area to disable the Viewer Node. Just selecting the node once again or previewing another thing makes it active once again.
In the Shader Editor however, there is no viewer node. Ctrl+Shift+LMB connects the node output directly to the Active Output. So if you just want to preview the final node, you simply have to click Ctrl+Shift+LMB on the final node.


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Sometimes camera rotates with targeted empty, sometimes not. Why?
I have a blend file where the camera, constrained to an empty, rotates when I rotate the empty. This is what I want to happen. I have another blend file where the camera will not rotate when I rotate the empty. Why? Setups appear to be the same in both blend files. Any suggestions? Thanks. Blender 3.5, Windows 11
Camera rotates with empty
Camera does not rotate with empty

You need to enable the Target Z option:

Aha! Thank you! :)


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Shade Smooth creates gradient artifact that shows through materials
I've noticed that if I take a simple cylinder and choose Object Context Menu > Shade Smooth, it creates a gradient artifact that's obvious even when a material is applied to the cylinder. Is it possible to shade smooth without this artifact? Thanks.

it creates these artefacts because it tries to smooth between the perpendicular faces, try the Auto Smooth option (Properties panel > Object Data > Normals)

Oh yeah, the combination of Shade Smooth + Auto Smooth = a much better result. Thanks!

It creates these artefacts because it tries to smooth between the perpendicular faces, try the Auto Smooth option in the Properties panel > Object Data > Normals.


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Eevee issue: Foreground plane mysteriously eclipsed by plane behind it when rendered
I've run across a strange Eevee issue where a plane in the background appears in front of a foreground plane when rendered. Not an issue when rendered with Cycles. Any suggestions? Thanks. Blender 3.4.1, Windows 11

This is a known limitation of Alpha Blend mode with Eevee: Wrong Draw Order with Alpha Blend in Eevee - you can read there that the ordering of alpha blended objects depends on their origins.
In terms of solutions there's a few options.
If you can make the material's Blend Mode: Opaque, and that will resolve the issue:

Alternatively you can try changing the material to use a different Blend Mode like Alpha hashed.
Lastly, if that does not work, another workaround would be to separate out your meshes into separate objects, and then ensure their origin points are ordered nearest-to-furthest to ensure the alpha blend ordering is correct.


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Why is object origin stuck to 3D cursor? How to get it unstuck?
Why is the origin of this empty stuck on the 3D cursor? How do I get it unstuck?
Setting the origin to geometry doesn’t fix it. Thanks. Blender 3.2.2, Windows 11
Blend

Actually the origin isn't "stuck on the 3d cursor" in your case like this case.  I see the little orange dot (orange dot) is at the center of the empty and moves with it.
Instead your have your Transform Pivot Point set to 3d Cursor, instead of something like Individual [object] Origins  Or Active Element.

Indeed it is so easy to get disoriented and get blender "off kilter" with so many dials and settings!

That's it! Yes, it's always something with Blender. Thank you!

@WilburPost I attribute my loss of hair to frustrating moments with such a complex piece of software; not much better in 3ds Max.  We need the "read my mind" interface that's coming in 2035.

Wow.
30 second fix.
I was panicking for nothing! Thanks!


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Object linking weirdness: Why does unlinking this object make it disappear?
I have some third-party objects that display an odd linking behavior that I do not understand. If I right-click on the object in the ViewLayer pane and select Unlink, the object disappears entirely. Where did it go? There is no external linking I can see, so I am assuming that the object is linking to something within the Blend file, but to what?
I have attached a blend file containing a piece of one of these objects in the hopes that someone here can tell me what is going on. Thanks! Blender 3.5.0, Windows 11

blend file example

I've just given a test, it looks like it acts like that with any object, if you unlink an object from a collection, and if this object only exist in this collection, it will be the same as deleting this object

Do you mean a collection as in a Collection in the ViewLayer pane? Or something else? (there are no Collections that I am aware of).
Also, I am only familiar with linking to things in external Blend files, and not within a blend file; is that possible?

What you show is a pop-up panel that is relative to the Outliner, yes. In the Outliner, "linking" has another meaning than "linking" an object from a file to another file, it means that you can give the same object to several collections, and that it will stay in that collection unless you unlink it. If an object is not part from any collection anymore and you decide to unlink it, it's the same as deleting it

Another thing I have noticed is that this Blend file is 20 MB, and that seems really big for a single box object. I have purged all orphaned data, but somehow there still seems to be 20 MB of content lurking somewhere in the Blend file. Where is this hidden data? Is it accessible? Thanks again. I really appreciate your help.

It is part of the default collection of the Outliner, called Scene Collection. As for the size, its because you have tens of meshes that you've saved as Fake User, switch your Outliner to Orphan Data and you'll see them, disable the Fake User option and click on the Purge button

Of course, I had marked them as assets. I should have seen that. Thanks! :)

Oh ok this explains that   ;)

You're confusing a linked object (an object that can be imported from a file to another and stays linked to the first file) and an object that is linked in the Outliner, meaning that it is shared by several collections.
To put an object in several collections at the same time you just need to press ShiftM in the 3D view or in the Outliner, or select the object in the Outliner, press Ctrl and move it into the wanted collection, as you'll see the object will remain in its current collection but will also appear in the new one.
To remove an object from a collection, right click on it and Unlink. The object will remain in all the other collections where it already exists. If you unlink an object that is in one collection only, it will be the same as deleting it (yes, in that case unlinking makes no sense and should not be available). Note that Scene Collection is a collection (it's the root collection).


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What is making the colors on this object?
I've got a 3rd-party payware object that when imported into Blender contains colors that override the applied shader material. Where are these colors coming from? How do I make them go away?
I count at least three colors: white, gray and black, but I can't figure out why they are there. A plain white shader material has been applied to the entire object. Thanks. Blender 3.1.2, Windows 11

Blend file

It looks like a split normals problem (which happens with some .fbx imports), go into the Object Data panel > Geometry Data > Clear Custom Split Normals Data:

That works! Thank you!


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Turn off Temporary Viewer Node?
I've just discovered the Temporary Viewer Node in Blender by clicking Shift-Ctrl-LMB on a node. Very useful! Question: Is there a way to turn off the Temporary Viewer Node just as quickly without having to delete the Viewer Node and reconnect the BSDF to the Material Output? Thanks. Blender 3.1.2

You have your answer below, but that's actually one of the functions of the Node Wrangler addon which has many other useful functions. There's a quick YT tutorial here and you can find the full hotkey list for it if you open the dropdown description panel for the Node Wrangler addon on the Edit > Preferences > Addons tab.

Just click Shift>Ctrl>LMB on the principled BSDF. It will automatically remove the viewer node and connect the P BSDF.

Thank you for the responses. Much appreciated. I looked at the Blender 3 online manual, but it only explained how to add the viewer node, so that's why I pinged the brain trust here. Thanks again.

No problem! Just keep experimenting with stuff along the way !)

This doesn't work if you're inside of a group, because that still will keep the new route out of the group it created in the first place. So to fix it you would need to go out of all the groups and sub-groups and click the original group with shift ctrl lmb, which is far from being useful.


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View Layer versus Render Layer: What's the difference?
I'm learning how to separate renders into layers, which are then combined in the Compositor. However, in researching the literature I see references to View Layers and Render Layers. It seems they might be the same thing, but I'm not sure. Are they? If not, what's the difference? Thanks. Blender 3.1.2, Windows 11.

Is "View Layers" not the new name of the former "Render Layers" (of 2.7)? It looks like "Render Layers" are still used for the Compositor though

Hi :). Yes they are the same thing, although the naming isn't consistent in the UI :))

Thanks for the responses. I used to create UIs and write software documentation and using different names for the same thing is a big no-no, but Blender is an evolving product, so there you go. :)

@moonboots, you should make your comment a question so WilburPost can be solved on this.

View Layers are the new name of the former Render Layers of 2.7.
The way you use the Compositor is now different, you need to create several view layers, activate or deactivate the visibility of your collections in each view layer, render with Film > Transparency, and at last in the Compositor load your view layers in some Render Layers nodes and mix them with some Alpha Over nodes.

Here's the version 2.79 manual page for Render Layers. It says

Render layers allow you to render your scene in separate layers, usually with the intension of compositing them back together afterwards.

Here's the version 2.80 manual page for View Layers. It says

Renders can be separated into layers, to composite them back together afterwards.

One could simply say that View Layers are simply a renaming of Render Layers; but there is a bit more to it than that.  Render layers were part of a system that had an actual set of layers that one chose from to select what was included in the compositor:

That layer system was removed in 2.80;  Collections were introduced and the way to specify what was included in a particular render changed from selecting layers with the toggle switches to enabling layers in the new layer panel.
So not only the name changed, but the way of utilizing the layers changed.


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Invisible Area Light source is visible when reflected in glass material?
I've come across a Cycles issue where the disks of disk-shaped area lights are invisible in a rendered scene, but they are visible in a window with reflective glass material.
To put it another way, the light issuing from the disk-shaped area lights works fine, and the disks themselves are invisible when rendered--as they should be--with the exception that they are visible when reflected in a glass window. Why? Is there a way to fix this? Thanks. Blender 3.3.1, Windows 11

This is normal behavior.  The reason you can't see lights in the camera is because they are not a 'surface' themselves, but they are seen reflected on all surfaces.  Consider that if the light were not visible as diffuse or glossy reflections... what would they be doing in the scene?

You could go into Object panel > Visibility and disable the Glossy option:

I was looking in the wrong place. Thanks! :)

@WilburPost Just be aware that this means the area lights also have no effect on glossiness. Which means, glossy surfaces will no longer reflect the light onto other surfaces. In the image above this would mean, if the icosphere is in front of a mirror, and the backside would only be lit by light reflected from this mirror, than it would turn dark because the mirror doesn't reflect the area light anymore.


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Why does Blender say, "No more keyframes to jump to in this direction"?
Sometimes while editing keyframes I'll see this message when attempting hotkey to the next or previous keyframe: "No more keyframes to jump to in this direction." The timeline is full of keyframes, so why does Blender think otherwise? Thanks. Blender 3.3.0, Windows 11

It is showing all keyframes, but jumping only to the next one for the active object and when there are no more keyframes for it, it reports that.


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Can't see results in real time when painting on top of a material
I'm trying texture painting for the first time by painting on top of an existing texture (I want to add dust to parts of a car model). I'm following this video: https://www.youtube.com/watch?v=eS3bp8f3i2U
Problem: I can't see the results of my painting in real time in the Rendered 3D viewport. Sometimes switching to the UV Editor and back to the 3D Viewport will make the latest brush strokes visible, sometimes not. The only sure way to see painting results is as follows:
I see that my brush strokes are saved to an external PNG file, but the only time that file appears to be updated is when I Ctrl+Q to quit, whereupon I'll get a dialog that says, "Save changes before closing? Save 1 modified image(s)." When I reload the Blender file my brush strokes are now visible in the 3D Viewport, but again, why aren't the results visible in real time like the video tutorial? Thanks. Blender 3.3.1, Windows 11
blend file

Hello, I can't download the file with the current link, could you relink?

@moonboots Did you try right-clicking on the link and selecting "Save link as..." ?

oh ok it works  ;)

You don't precise in what mode you are, I don't think that you can paint in real time in Rendered Preview mode, switch to Material Preview mode, in the N panel > Texture Slots, choose the Material mode and in the Shader Editor select the Image Texture node you want to paint on, it seems to work as it is supposed to

That works! Knowing me, I figured I was missing something basic. Thank you!

You don't precise in what mode you are, I don't think that you can paint in real time in Rendered Preview mode, and in Solid mode you'll only see one of your image textures, so switch to Material Preview mode, in the N panel > Texture Slots, choose the Material mode and in the Shader Editor select the Image Texture node you want to paint on, it seems to work as it is supposed to.


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Animated object keeps moving past last keyframe; why?
I'm animating a flying drone quadcopter, moving the quadcopter around the scene, adding, editing and deleting keyframes in the process. The issue is that suddenly instead of coming to a stop at the last keyframe, the quadcopter stays in motion, moving at the same vector as the last keyframe, apparently sailing onward to infinity. Why?
I have a noise modifier applied to the X,Y,& Z axes to simulate mild instability; would this have anything to do with it? Thanks. Blender 3.2.2, Windows 11

yes it has. As you can see in the graph editor, if you add noise, Blender adds noise to "infinity".

But as you can see too, you can restrict the frame range there:

That's it. Thank you!

glad i could help


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How to track billboard background plane to camera?
I've got a billboard plane I'm using for a scene background and I have it aligned square to the active camera. I want the billboard to track to the motion of the camera so that when I move and rotate the camera the billboard moves and rotates maintaining its relative position to the camera at all times.
I've tried adding various tracking constraints to the billboard with the camera as target, but nothing is working thus far. Any suggestions? Thanks. Blender 3.2.0, Windows 11

Did you try using the child of constraint? Or did you try parenting?

Parent the billboard to the camera! So obvious I missed it. Thank you!

I posted it as an answer, consider accepting it in case it might help someone else searching ;)

Use a Child Of constraint or try Parenting the billboard to the camera.


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How do I stack tool icons vertically
Sometimes my tool bar icons end up in two columns, but I prefer them to be in a single column. How to I make the tools icons stack vertically? (I know this is a minor issue, but it annoys me.) Any suggestions? Thanks. Blender 3.10, Windows 11

You just need to grab the border and move to the left:


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HDRi backgrounds refuse to display on certain Blend files
I'm suddenly running into an issue where certain Blend files will not display an HDRi in the viewport or render. Objects behave as though they're receiving light from the HDRi, but the HDRi background itself is a no show. If there is a setting for this, I can't find it. Any suggestions? Thanks. Blender 3.3.0., Windows 11

blend

The fixed checker background is indicative of a transparent background display. This happens when you enable the transparency of your background.
You can undo this by unchecking the option in the Properties Editor > Render  tab > Film panel > Transparent option:


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How to mix imperfections bitmap with emissive color?
I'm trying to create an emissive store sign for Cycles that applies imperfections from a bitmap (I want the sign to appear weathered and distressed).
Working with a Principled BSDF, I know how to apply imperfections to the Base Color output by linking the imperfections bitmap to the BSDF's Roughness input, but this does not appear to affect the Emission output. Try as I may, I cannot figure out how to mix imperfections into the Emission color output (short of creating a color bitmap with imperfections already applied). Any suggestions? Thanks. Blender 3.3.0, Windows 11

Variability in roughness affects the surface in subtle ways. Since emission overlays color on top of the base, it makes the effect even more subtle. So what you want to do is either decrease the emission strength (and perhaps also plug the emission color to the the base color, to at least partially neutralize brightness decrease), or crank up things that make the roughness more prominent (changing to metallic or increasing specularity).
Or perhaps you just don't know that you can mix colors yourself, and so all you need is a Mix RGB node connected to the emission:


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AttributeError: 'Mesh' object has no attribute 'use_auto_smooth'
When I attempt to import an image as a decal, I get this Python error:
AttributeError: 'Mesh' object has no attribute 'use_auto_smooth'
Traceback (most recent call last):
File "C:\Users<redacted>\AppData\Roaming\Blender Foundation\Blender\4.1\scripts\addons\Import As Decal_init_.py", line 275, in execute
plane.data.use_auto_smooth=True
^^^^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: 'Mesh' object has no attribute 'use_auto_smooth'
I have no idea what it means. I work with image decals all the time, but this is new. Any suggestions? Thanks.
Blender 4.1, Windows 11

I assume "Import as Decal" is a third-party addon? If so, check with the author (Amandeep)? whether it's been updated for Blender 4.1!

use_auto_smooth has been removed in Blender 4.1. If the addon hasn't been updated, you can still use it by downgrading to Blender 4.0.

bpy.types.Mesh.use_auto_smooth was removed in Blender 4.1.
Find an updated version of the addon or use the addon in an older version of Blender and then import to the newer or try to fix it yourself.
import math
import bpy

def get_object_override(active_object, objects: list = None):

    if objects is None:
        objects = []
    else:
        objects = list(objects)

    if not active_object in objects:
        objects.append(active_object)

    assert all(isinstance(object, bpy.types.Object) for object in objects)

    return dict(
        selectable_objects = objects,
        selected_objects = objects,
        selected_editable_objects = objects,
        editable_objects = objects,
        visible_objects = objects,
        active_object = active_object,
        object = active_object,
    )

def has_smooth_by_angle(object: bpy.types.Object):
    for modifier in object.modifiers:

        if modifier.type != 'NODES':
            continue

        if modifier.node_group and 'Smooth by Angle' in modifier.node_group.name:
            return True

    return False

def do_auto_smooth(object: bpy.types.Object, angle = 30):

    try:
        object.data.use_auto_smooth=True
    except AttributeError:

        # may just use shade_smooth_by_angle but it modifies the mesh and goes against the new non-destructive auto-smooth idea

        if not hasattr(object, 'modifiers'):
            return

        if has_smooth_by_angle(object):
            return

        with bpy.context.temp_override(**get_object_override(object)):
            result = bpy.ops.object.modifier_add_node_group(asset_library_type='ESSENTIALS', asset_library_identifier="", relative_asset_identifier="geometry_nodes\\smooth_by_angle.blend\\NodeTree\\Smooth by Angle")
            if 'CANCELLED' in result:
                return

            modifier = object.modifiers[-1]
            modifier["Socket_1"] = True
            modifier["Input_1"] = math.radians(angle)
            object.update_tag()

do_auto_smooth(bpy.context.object)

Thank you everyone for your comments! I did not realize that this is a 3rd-party add-on. I'll follow up with the creator. Thanks again!

Well, what I really "adore" the blender development team for is the fact that every "......" patch they not only add something, but also remove something. and then you, dear user, sit and think how to live with it.
I just got back from 3d max, and I immediately remembered why I left.

to substitute
obj.data.use_auto_smooth = True
obj.data.auto_smooth_angle = 30*0.0174533

in Blender >4.1 you can do
bpy.ops.object.modifier_add_node_group(asset_library_type='ESSENTIALS', asset_library_identifier="", relative_asset_identifier="geometry_nodes/smooth_by_angle.blend/NodeTree/Smooth by Angle")

or using context override:
import bpy
obj=bpy.context.active_object

(lambda obj: (foo:=bpy.context.temp_override(active_object= obj),foo.__enter__(),bpy.ops.object.modifier_add_node_group(asset_library_type='ESSENTIALS', asset_library_identifier="", relative_asset_identifier="geometry_nodes/smooth_by_angle.blend/NodeTree/Smooth by Angle"),foo.__exit__()))(obj)

I also came up with a one liner for doing the same thing without ops (can probably be simplified, I just cant find any docs on how to do it "properly" so therefore I had to build the file path manually based on blender version number & executable file path):
import bpy
obj=bpy.context.active_object

node=obj.modifiers.new("Smooth by Angle", "NODES"); node.node_group=bpy.data.node_groups['Smooth by Angle'] if 'Smooth by Angle' in bpy.data.node_groups else (bpy.ops.wm.append(directory=bpy.app.binary_path.replace('\\','/')[0:bpy.app.binary_path.replace('\\','/').rfind('/')]+f"/{bpy.app.version_string[:bpy.app.version_string.rindex('.')]}/datafiles/assets/geometry_nodes/smooth_by_angle.blend/NodeTree/Smooth by Angle"),bpy.data.node_groups['Smooth by Angle'])[1];node["Input_1"]=30*0.0174533

Note that only the last example gives you a reference to the newly added modifier - and is therefore the only of these solutions that lets you set the angle to anything but its default.
I suppose one might also want to check if a modifier by the name "Smooth by Angle" exists on the object, and only add one if it doesnt - and then set the angle to whatever one desires on the newly added or existing "Smooth by Angle" modifier:
import bpy
obj=bpy.context.active_object

(lambda obj, angleDegrees=30: (obj.modifiers["Smooth by Angle"].__setitem__("Input_1",angleDegrees*0.0174533) if "Smooth by Angle" in obj.modifiers else (foo:=bpy.context.temp_override(active_object= obj),foo.__enter__(),bpy.ops.object.modifier_add_node_group(asset_library_type='ESSENTIALS', asset_library_identifier="", relative_asset_identifier="geometry_nodes/smooth_by_angle.blend/NodeTree/Smooth by Angle"),foo.__exit__(),obj.modifiers["Smooth by Angle"].__setitem__("Input_1",angleDegrees*0.0174533))))(obj,25)

authors: Человек похожий на меня


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Why does workspace keep changing modes?
I have customized workspace that keeps automatically changing from Object Mode to Sculpt Mode whenever I switch to it. I keep changing it back to Object Mode, but when I return to it, it's in Sculpt Mode again. I recall having this problem once before, but I don't recall the fix. Any suggestions? Thanks. Blender 4.2.0, Windows 11

Thank you very much! :)


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Why does Blender think local assets are still linked?
I've run into a problem I've never experienced before. I have a large project with many linked assets in the form of other Blend files.
PROBLEM: I created a new Blend file and appended some of the assets (objects) which themselves were linked to external assets. Everything looked good, but I realized that my file size had increased eight-fold--eight times larger than the source file I had appended from. That did not make sense.
I eventually discovered that the new Blend file had localized some of the linked assets, i.e., had incorporated them into the new file. However, the linked assets were still indicated as being linked in the new Blend file. The result was if I updated the linked assets, the updates were not reflected in the new Blend file, and there was no way to edit these assets in the new Blend file because Blender thought they were linked.
I thought maybe the new Blend file had packed these resources, but there's nothing to unpack. Appears my new Blend file had become corrupted. :(
Anybody know of a fix? Thanks.
Blender 4.2, Windows 11

Maybe https://blender.stackexchange.com/questions/195345/blender-how-do-i-unpack-a-linked-instance-to-make-changes-to-it?rq=1 ?

Thanks for the suggestion, John Eason. I think the file is just corrupt. I don't see corrupted files often in Blender, but this appears to be one of them. Fortunately, I have plenty of earlier versions backed up.


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How to change Image > View Center hotkey from "Numpad ." to something else?
In the past I've frequently used "Numpad ." to center the scene on the selected object in Layout view. However I'm am now using the numpad to emulate mouse buttons, so "Numpad ." no longer centers the scene. The problem is that when I change this keyboard mapping to another key (via Preferences > Keymap > Image > View Center), it doesn't work.
It doesn't matter what hotkey I change View Center to, or whether it includes Alt or Shift or Ctrl, the hotkey only works when it's set to the default "Numpad ."
I've set Preferences > Input > Keyboard to "Emulate Numpad," but that only relocates the numpad number keys.
Am I missing a step? Any suggestions? Thanks.
Blender 2.93.5
Windows 10 Home v2004 OS build 19043.1288 v21H1

Never could figure this out in Blender, but I've implemented a workaround: My keyboard (Logictech G910) allows me to assign macros to certain keys, so I programmed a single key press to do the following:
NumLock > Numpad . > NumLock
NumLock toggles the mouse button keypad emulation (a built-in Windows 10 feature). Works like a charm.


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Mix procedural displacement with a texture-based displacement for Cycles?
I want to mix procedural displacement with a texture-based displacement.
While I can combine two BSDF nodes using the Mix Shader node, the Displacement input of the Material Output node does not accept input from the Mix Shader. Is there a way to mix two displacement outputs? Thanks! Blender 3.6.2, Windows 11

Mix the 2 images into a Color Mix that you plug into the Displacement node?

That works! Thank you! :)

Mix the 2 textures in a Color > Mix Color node (in Multiply mode or whatever other mode), it should give something like that:


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Unlinking objects make them disappear entirely. Why?
I've used Blender for years, but one thing that continually baffles me is when objects are "linked." Frequently, when I "unlink" a group of objects, they disappear entirely from the project. How did that happen? What were they linked to? And where did they go? I didn't delete anything, only unlinked.
This usually happens when I import a 3rd-party product, and when I try to work with it linking weirdness happens. Can someone enlighten me? Thanks. Blender 3.4.1, Windows 11

Linking objects into a scene is a form of virtual import, where instead of copying elements from an external source into your scene, you only make a "link" that reads the content from the external source.
It's like in your file explorer when you make a shortcut to a file instead of copying it.
That's why, unlinking basically deletes whatever you unlinked from your scene. It doesn't delete the source of the link, it just removes its presence from your scene.
To know what is the source of a link, you can switch your Outliner's Display Mode to Blender File and look at the bottom of your file (or the Libraries category):

You can see either the absolute path of the source file, or its relative path from your current .blend.
It is good to know that it is possible to pack the source file of a link into the .blend file. So sometimes you will see a path to a .blend file that doesn't exist. To fix that, go to the menu File > External Data > Unpack Linked Libraries.

Thank you for the responses! I'm aware of linking to external files, and I do it all the time, but I frequently encounter situations where the "linked" file is not linked to an external resource, nevertheless it will disappear when "unlinked." This makes me think there's some sort of internal linking I'm not familiar with. Thanks again.


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Material name is grayed out in Shader editor; cannot rename it
This is an issue I have never encountered before:  I have a material where I cannot change its name, duplicate it, remove it, or make it a fake user. Otherwise, I can still edit it in the Node editor and the material renders fine. Why?
Other weird things: This material links to two bitmaps, but it would not let me edit the bitmap settings unless I made them unique by clicking on the number of users in the texture box; never had that happen before.
If I try to locate the source bitmap from the texture box, it does not seem to know where the texture is, despite my repeatedly reconnecting to it. What's going on? Any suggestions? Thanks. Blender 3.5.0, Windows 11

You have pinned the material. See the pin icon right next to the 2nd arrow in your screenshot. Just click it.

That's it! Thank you!!


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Blender Cycles render settings: How does Total Max Bounces work?
In Cycles Render Properties > Light Paths > Max Bounces there is the Total field. What does Total mean?
If Total is set to 12, does that mean if any the other values (Diffuse, Glossy, etc.) is greater than 12, then it's clamped to 12?
Or does Total mean the sum of the other values, i.e., if the sum of the other values is greater than 12, then the sum is clamped to 12?
Or does it mean something else? I can't find a definitive explanation. Any suggestions? Thanks. Blender 3.5.1, Windows 11

After a bit of brainstorming, I guess I could try to give you some guesses, just give me a bit of time to type my answer.

Indeed, the official documentation for it does not give a lot of explanation about how it works :

But after having thought about it for a while, I think I can try to give some sort of answer.
The word 'bounce' reffers to a ray that hits a surface (at least a second time) before reaching a light source. When a ray is cast from the camera, it's going to bounce around untill eventually reaching a light source. The total max bounces reffers to the number of bounces a ray can make before it is 'canceled'. The first hit is not considered a bounce for it's considered to be a direct hit (that's why when the number of bounces is set to 0, it results in direct only).
I put bounce in quotes because, it doesn't have to be a litteral bounce, the ray can be penetrating some transparent surface, or entering a volume etc... And that's where those values kick in :

Those values above, for instance, mean that a ray can bounce at most once on a diffuse surface, at most 4 times on a glossy one, go through a reffractive surface at most 8 times, enter a volume at most 2 times and traverse a transparent surface 8 times at most. At the moment the ray exeeds one of those numbers, the ray is going to be killed. Atop of that, the total numbers of the bounces it makes is not allowed to exeed 8 which means, after 8 bounces, the ray will be also be killed.
As an example, let's consider two rays R1, R2 and R3 cast from the camera and the bounces they make in order :
R1 : camera -> diffuse -> transparent -> glossy -> transparent -> glossy -> reffractive -> light source.
R2 : camera -> transparent -> glossy -> glossy -> transparent -> glossy -> diffuse -> light source.
R3 : camera -> transparent -> glossy -> diffuse -> glossy -> diffuse.
In this case, only R1 and R2 are going to make it to the light source as R3 already exeeded the allowed amount of diffuse bounces, even though it is still under the max 8 bounces so it gets terminated before it could make it to the light source.
You can think of it as 'quotas'. Each ray has 8 bounces that can be whatever type they are as long as each bounce type stays under its 'quota'. If, after the 8th bounce, the ray still haven't reached a light source, it will be terminated.
The keypoint in understanding it is that the number of bounces the ray makes is computed on-the-go and the ray is going to be killed as soon as it exeeds one of its bounce quota so there is no clamping going on. It's like using a credit card where the user is just not allowed to spend beyond the card's limit and if he reaches the limit, the card is immediatly disabled.
I don't know if I made it clear enough but that's how I understand how it works. Anyway you can just comment out if some point of the explanation are fuzzy or inacurate.
I hope I helped.

Thank you for your thoughtful response. Much appreciated! I think I understand the purpose of defining bounces/quotas for Diffuse, Glossy, etc., however, I still don't understand the role of Total and how its value influences the other values.

As I explained in the answer, it doesn't influence the other values, it influences the render. Max bounces means that every ray that exeeds that number of bounce before reaching a light source is killed.

Thank you again for your response. I'm afraid I still don't understand. If, for example, Total is 12 while all the other categories (Diffuse, Glossy, etc.) are 24, does that mean all those other categories get their 24 bounces? If yes, then what is the purpose of Total? If no and Total restricts those values to 12, then isn't that clamping?

As I told you before, it's not merely clamping. If total is 12 then the ray is killed after 12 bounces, that's all. Those 12 bounces may be all 12 diffuse,12 glossy or 6 diffuse and 6 glossy. Total bounces doesn't care about the type of bounce, it just kills the ray after 12 bounces.

If total is 12, no category is ever going to have 24 bounces as the ray is killed after 12 bounces.

Thank for your help! :)

Did you get it, though? If you still don't understand, we can talk about it in chat


text:
Models for 3D printing are sliced wrong, can't figure out optimal thickness
I have a 3D printer with 0.3mm and 0.8mm nozzles, and I am trying to figure out the optimal line widths for extruding some line art.
Workflow

I create the vector graphics in Illustrator, expand strokes and group everything as a Compound Path: Slice-test.svg
In Blender I import the SVG, go to Properties panel > Curves, extrude to approx. 2mm height, then convert to mesh: Slice-test.stl
I take the exported STL and slice it with Slic3r, 0.3mm nozzle diameter: Slice-test.gcode

Results
The first layer comes out wrong:

What's going on here. Is there something wrong with the model? I'm trying to figure out the best thickness and angle sharpness so that I can produce a bunch of extruded line art for making molds. I'm trying to avoid interrupted perimeters and fingernail-looking things at corners:

Also my workflow seems kinda slow for such a basic task. As a noob to Blender and total noob to Python scripting where can I learn about automating the part with the SVG import > Constant thickness extrude > Mesh > STL, so I can focus on the line art?

What printer are you trying to use? Does it support direct g-code upload?

Robox. Yes it does support transferring GCODE directly.

Have you tried Cura for slicing?

I opened your Slice-test.stl file in cura, and this is what I get:

The first layer appears correct to me.
Since you did not provide the line art for your flowers, I cannot verify that with cura.

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


text:
How to stop object from moving past last keyframe?
I have a simple animation showing a landing spacecraft. The problem is that after the object's last keyframe it still keeps moving--very slowly--like a breeze is pushing it across a layer of ice. How do I make it come to complete stop on all axes?
I think the issue came from my tweaking the Bezier curves in the graph editor, but no further tweaking stops the motion. Adding more keyframes downstream makes no difference. Ideally I'm looking for a command that will stop all motion (at frame 1100 in the example).  Any suggestions? Thanks. Blender 3.6, Windows 11

try to change the last keyframe's interpolation to vector

You could also duplicate those keyframes and drag them to the end of your animation.

Thank you for your suggestions. Duplicating the final keyframes and moving them to the end of the animation makes no difference (first thing I tried). Per your suggestion, I changed the Handle Type to Vector (Handle Type is the only place I found the Vector option) and that stopped the sliding on the X-Y axes, the only problem now is that the spacecraft is still moving very slowly on the Z axis. I think it's because the Z axis line on the graph editor is not exactly horizontal, i.e., it has just a tiny slope; is there a way I can zero out this slope?

@WilburPost Select the last keyframe on the Z axis (with handles) then press Z Y 0 Return to scale vertically to 0, that should  probably help. Although if there is no more keyframe past that one, it should not slope down, even if you move the handle down a lot...

Thank you Gordon Brinkmann. Applying Z-Y-0  to the Z axis fixed it. I then noticed that the spacecraft was rocking gently along the X axis. Applying Z-Y-0  to that fixed the rocking, so now the spacecraft is showing zero movement.

Regarding slope, I find that I can select the last keyframe and use the handles in the Graph Editor to slope the line up or down way past (to infinity?) the last keyframe, so maybe I misunderstand. Thanks again! :)


text:
How do I edit the data for these named Shader UV attributes?
I am working with a third-party Blender model and the creator is using what appears to be named attributes for the UV Map node: "meatball," "feather" "UVMap". What I cannot figure out is how to edit this data. Can I edit it? If yes, then how? Where is it? Thanks. Blender 3.6, Windows 11

What exactly do you mean by editing the data? Like you can (probably) just use it like any other coordinate system. Like using a mapping node after that UV output is also called editing. Please be a bit more specific.

I changed the source images for the Texture nodes which have a different ratio (1:1 instead of 1:2), but the UV Map node is imposing the old ratio (1:2) onto the Texture nodes. How do I edit these UV Map nodes to make them 1:1?

If I understood what you said, then use a mapping node and just scale by 2 on the necessary axis.

Edit your question and add these details as well. If possible add the images of the changed ratios as well. You are an old member, kinda expected you to be precise enough.

I'm not sure how I can be any more precise. I like the current placement and scale of these textures, so all I want to do is edit the current image ratio values. Maybe I'm wrong, but I presuming that somewhere the UV data for "meatball," "feather" and "UVMap" are stored in the Blender file, but where? I'm thinking that if I can find those, then I can edit them directly without too much fuss.

Ok so those are UV mps right? So selecting the one (in the obj data properties panel)you need to edit and opening the UV editor will give you access to that UV Map. You can change the map however you want.

Via the UV Editor then. There's a gaping hole in my knowledge when it comes to UVs. Thanks! :)


text:
Why can't I copy and paste all selected key frames on the same timeline?
I'm trying to edit my existing keyframes and I have an issue where I am unable to copy and paste all the selected keyframes; only some of the selected key frames can be pasted. Why?
In the attached example, I have a moving camera and I want it to pause between frames 680 to 700. Usually, all I need do is copy and paste key frames to do this, (e.g., copy key frames at 680 and paste them to 700), but sometimes, like in this example, only some of the selected key frames will paste with the result that the camera keeps moving, influenced by the key frames downstream. Any suggestions? Thanks. Blender 3.3.1, Windows 11

I seem to remember sometimes having this problem in the timeline editor, but not in the Graph Editor (Animation workspace).  Until you/we get an expert answer, try using that editor instead (or the Dope Sheet editor as well).

@james_t Yep, it works from the Graph Editor. That's a workaround. Thanks!


text:
Fading and animating objects without materials
I have a scene where I have a lot of particles (> 5000) which are essentially spheres, that I would like to animate in a particular fashion. Basically, the thousands of particles can be categorized into a few types, with each type having its own material.
I am working on animating the behavior of a "periodic" box where, as particles cross a plane, they appear out the other side. Similar to a game of snake where the snake goes through one wall and appears out the other. However, I have come across the following limitation(s):

When I keyframe the animation, unless the frames are literally 1 apart, the particles will travel backwards then start moving forwards again. If the frames are 1 apart, the particle will disappear and reappear at the back. This is undesirable as I would like to have a smooth animation.

As a solution to this, I thought of fading out the object, move it, then fade it back in at the start. However this brings up another issue:

I am using cycles. Short of having 5000+ materials, one for each objects, I don't know how to control the opacity/transparency of an object independently. Also, if I have that many materials, I lose the ability to change the attributes (color/texture/etc...) of an entire group collectively.

If anyone has any thoughts on how to deal with this issue, whether in terms of fading out an object independently of its material, or any neat approaches to what I am trying to do, it would be greatly appreciated. Just for sake of completeness, I am writing a blender python module to do this, since all the position data for the particles are in a file generated by a simulation, and this is the remaining issue I have.
Thanks!

Maybe I've not well understood the situation, but what would the benefit be in terms of simplicity by not using materials? This "vanishing" property must be controlled per object too,..or not? Changing the attributes of an entire group can be done by using materials node groups. Do you have an example video to show? It would be helpful to better understand the situation

So you are saying I create independent materials for each particle, but have all the similar particles in one node group? I did not think of that. If I do that, how can I change the materials of all of the nodes collectively? Will it override the individual material properties of each one? This may be what I'm looking for, but if you could clarify that would be great.

No, I was just asking for clarifications. What I was suggesting that with material nodes group you can give a base shader, one per type, and than add a node setup to controle the transparency, that would work per object, so you'll still have 5000 material but based on few groups. The challenge is to avoid to control 5000 transparency keyframes

Ok so I figured out a solution thanks to @Carlo's comment. Hopefully this will help anyone else who's trying to do something similar.
I create one node group per object type that has a default color, and accepts one input: transparency. The node group itself is basically a mixer between Diffuse bsdf and transparent bsdf shaders.
Each object of that type has it's own material which basically links the node group with the material output. I can then keyframe the opacity on each material independently, but still maintain the ability to change the color collectively for the type by changing the node group color.
Since I am scripting this, I am not worried about having to keyframe 5000+ objects. I came up with the following functions:
# create_node_group - Creates a node group
# for a particle type with a default color.
def create_node_group(name, color):
    group = bpy.data.node_groups.new(name, 'ShaderNodeTree')

    # Create node group input.
    inputs = group.nodes.new('NodeGroupInput')
    inputs.location = (-300, 0)

    # Create diffuse shader.
    diffuse = group.nodes.new('ShaderNodeBsdfDiffuse')
    diffuse.location = (0, -200)
    diffuse.inputs[0].default_value = (color[0], color[1], color[2], 1)

    # Create transparent shader.
    transparent = group.nodes.new('ShaderNodeBsdfTransparent')
    transparent.location = (0, -400)

    # Create shader mixer.
    mixer = group.nodes.new('ShaderNodeMixShader')
    mixer.location = (200, 0)

    # Create node group output.
    outputs = group.nodes.new('NodeGroupOutput')
    outputs.location = (350, 0)

    # Create input and output sockets.
    group.inputs.new('NodeSocketFloat', 'Transparency')
    group.outputs.new('NodeSocketShader', 'Shader')

    # Link everything together.
    group.links.new(inputs.outputs[0], mixer.inputs[0])
    group.links.new(diffuse.outputs[0], mixer.inputs[1])
    group.links.new(transparent.outputs[0], mixer.inputs[2])
    group.links.new(mixer.outputs[0], outputs.inputs[0])

    return group

The above function creates the node group and returns a reference to it. I then use the function below to create a material for each object in my scene, which calls the function above.
# create_material - Creates a material with a color
# for the group (if not created already). Name and
# group name should typically be the same.
def create_material(name, group_name, color):
    group = bpy.data.node_groups.get(group_name)
    if group is None:
        group = create_node_group(group_name, color)

    mat = bpy.data.materials.new(name)
    mat.use_nodes = True

    for node in mat.node_tree.nodes:
        mat.node_tree.nodes.remove(node)

    mgroup = mat.node_tree.nodes.new('ShaderNodeGroup')
    mgroup.node_tree = group

    outmat = mat.node_tree.nodes.new('ShaderNodeOutputMaterial')
    outmat.location = (200, 0)

    mat.node_tree.links.new(mgroup.outputs[0], outmat.inputs[0])
    return mat

Finally, if I want to change the opacity of an object, I simply call this small function:
# set_transparency - Set the transparency of an object.
def set_transparency(ob, val):
    mat = ob.data.materials[0]
    mat.node_tree.nodes["Group"].inputs[0].default_value = val

This may not be the best solution, but it works for me, and hopefully it will help others in a similar situation.
Thanks!

Just to clarify. Do you call the create_material() method 5k times once for each sphere? Or just a few times, once for each sphere type?

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


text:
Is there a more accurate way of knowing which vertice are affected by proportional editing?
The proportional editing tool use a white circle as an indicator to which vertice are affected but that works in 2D world well and not 3D.(for example if you design a flat paper page in blender and view it from top it works 100% accurately)

As you see in the image above some vertice are within the circle but they aren't affected.Is there a more accurate way to know which are affected?

View it from the top and you'll find they are within the circle.  Consider the guide as a "sphere" around the vert (or median point of verts) when first selected.

@batFINGER In complex meshes this won't work :/

can you explain?, mentioned view from top in context to your screenshot as you have translated in what appears to be a global z direction.

Consider using quad view or multiple views to see more.  Consider circle select.  Consider Hide Vertices to prevent movement.  Even though Hide Vertices has limitations.

This script / addon may help. It simply selects the vertices impacted by the proportional editing, starting from the current selection.
Once visualized, you can Ctrl+Z to come back to your current selection.

bl_info = {
    "name": "Select proportional editing impact",
    "author": "lemon acidjuice",
    "version": (1, 0),
    "blender": (2, 77, 1),
    "location": "View3D > Select > Edit mesh > Select proportional editing",
    "description": "Selects vertices influenced by proportional editing",
    "warning": "",
    "wiki_url": "",
    "category": "3D View",
    }

import bpy
from bpy.types import Operator

def Influenced( u, selected, size2 ):
    for s in selected:
        if (s.co - u.co).length_squared <= size2:
            return True
    return False

class EDIT_MESH_select_proportional(Operator):
    """Select proportional editing impact"""
    bl_idname = "editmesh.select_proportional"
    bl_label = "Select vertices influenced by proportional editing"
    bl_options = {'REGISTER', 'UNDO'}

    def execute(self, context):
        scene = context.scene
        obj = context.active_object

        size = scene.tool_settings.proportional_size
        size2 = size * size

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

        selected = [v for v in obj.data.vertices if v.select]
        unselected = [v for v in obj.data.vertices if not v.select]

        for u in unselected:
            u.select = Influenced( u, selected, size2 )

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

        bpy.context.scene.update()

        return {'FINISHED'}

# Registration

def add_select_menu(self, context):
    return self.layout.operator( EDIT_MESH_select_proportional.bl_idname )

def register():
    bpy.types.VIEW3D_MT_select_edit_mesh.prepend(add_select_menu)
    bpy.utils.register_class(EDIT_MESH_select_proportional)

def unregister():
    bpy.types.VIEW3D_MT_select_edit_mesh.remove(add_select_menu)
    bpy.utils.unregister_class(EDIT_MESH_select_proportional)

if __name__ == "__main__":
    register()

Is there a possibility to display the impacted vertices with weight colors while doing proportional editing?


text:
How to add an origin point without adding anything else?
How to add an origin point without adding anything else?
For example this could be done if you add a cube, go to edit mode , delete all vertice and you are left with an origin point but is there a faster way?

why do would want an origin point without vertices? Functionally in some cases, this would be an empty, so this might be an easier way.

This function is already delivered with Blender, just not enabled. Go to File > User Preferences > Add-ons > Add Mesh and enable Add Mesh: Extra Objects. Now if you press ShiftA in 3D View and go to Mesh > Single Vert you'll have an option called Object Origin Only. This will add an object origin in edit mode and you can start editing.


text:
how to move some vertices of the same object to a desired x,y,z location?
so the question is:how to move selected vertices all in the same coordinate.
for example how to move 30 selected vertices in x:3.1 and y:1.5 and in the z axis not to move them.
I can't make this questions simplier i can't descibe it better D:.Please comment if u doesn't understand me.
Note:This can be done easily by selecting individual vertices and entering the desired coordinates, but it will take ages if you have many :/, so is there a better way?

Select vertices
Collapse XY coordinates: with "Median point" pivot selected, scale to zero on all but Z axis by pressing S, than Shift+Z, than set the amount to 0
Move vertices to desiderd XY coordinates (you can use the Transform coordinates in the Properties panel to set precise coordinates)

Another way is to place the 3D cursor manually via the location input fields in n-panel, 3D Cursor tab. Then select your vertices, hit Shift + S (or Mesh -> Snap from the menu), and then "Selection to Cursor".

You can also use the flatten command (Space then type "flatten"). In the option panel (F6), you can choose the axis you want to flatten on. The only downside of this tool is that it makes the face an n-gon, which may not be useful.


text:
How to use sharp edges?
Well sorry if this one is a duplicate but i couldn't find it. Can someone please list the uses of sharp edges ?
I know the very basic uses like :

They can be used in edge split modifier.

But I can't think of more is there anything else that I miss?

AFAIK the only use for "Mark Sharp" is the edge split modifier.
Technically "Mark Sharp" simply sets the mark where the modifier later has to do its job. If you don't apply the modifier, you can still add geometry with "snap onto itself" and "Automatically merge vertices" activated without having to manually edge-split the sharp edges later again.

AutoSmooth option also uses those marks. Just make sure to raise angle a bit higher.

@MrZak - right, totally forgot about that.


text:
Operator.report not showing up in header
class my_operator(bpy.types.Operator)
    bl_idname = "op.my_custom_operator"
    bl_label = "my_custom_operator"

    @classmethod
    def poll(cls,context):
        return True

    def execute(self,context):
        return self.invoke(context,None)

    def invoke(self,context,event):
       ... do some code here...
       self.report({'INFO'},"MESSAGE OF SOME SORT")

The above is a representation of what my code looks like - it executes fine, the only problem seems to be that whatever I use self.report with, the resulting message never appears in blender's header, as it should according to the documentation and every topic I've found on the subject ( I have looked around and found nothing that helps me ). Instead, the output refuses to go anywhere but the console window.
Does anyone know a way to get information to Blender's header?

the reason I'm doing it like that is because I'm using this operator as a handler for a post save event, through a separate method. I could try and put the code under execute and leave out invoke entirely, and see if that works. functionally there's not really a reason for me to do have it, other than that the only example I've found using an operator as a handler used it that way.


text:
Locking translation axis for multiple objects
Selecting multiple objects and pushing lock button in properties panel "transformation" locks the axis only for one object in the selection of objects.

Select all your objects, lock the channel, then right click on one of the lock icons and "copy to selected" to copy the locked status to the other objects.

Thats it! So easy knowing how to do it. Thank you!

You can apply the same "lock" to multiple objects by copying contraints from one object to others, but you have to "lock" your reference object with constraints (look the constraints tab in the selected object panels- right side of the default view) as in the image below.
Since the last selected object is the "active" object, you can get what you wish in this way: apply desired locks to one of the objects. Then select all the others, and as last also the locked one.
Then use the "copy constraint to selected objects" (use the space bar to find the command, or look under the menu "object > constraints").

Unfortunatly the copy of constraints has no effect on the selected objects. Also locking a parent object does not lock the children.

well, works here... are you sure to follow exactly the selection order?
can you post the .blend?

Sorry you said about transform panel but I meant "constraint" so I rephrase my answer. Contraints will work, transform panel will not.

Constraints are a powerfool tool for complex tasks. Thanks for the advice.


text:
Is there a way to know which vertice are affected by proportional editing?
Is there an option that will make the vertice that are being affected by proportional editing change colour ?


text:
the opposite of subdivide

So i was wandering is there a way to transform object 2 into object 1, without going into edit mode and deleting all extra vertice from object 2
i tried the un-subdivide option but it did something else :/ help please.

This is called 'Limited Dissolve'. You'll find it in the Clean up menu.

i'm pretty sure this has been asked before, but can't find the exact duplicate

not a bad question @xlxs, just it seem this has been asked already -- unless you can edit your question to make it some how unique

Thanks to zeffi's comment i was able to figure out a better way that decimate modifier, with almost none shape changes.
1)select mesh
2) go to edit mode
3) select all vertice
4)press delete and click limited dissolve
this will maintain the geometry but will get rid of non used vectice

The decimate modifier can do this, though it doesn't always work quite like you want it to.
Blender Reference Manual, Decimate Modifier

The Decimate modifier allows you to reduce the vertex/face count of a mesh with minimal shape changes....The Decimate modifier is a quick and easy way of reducing the polygon count of a mesh non-destructively. This modifier demonstrates the advantages of a mesh modifier system because it shows how an operation which is normally permanent and destroys original mesh data, can be done interactively and safely using a modifier.


text:
performance question
I have build a huge tower of blocks and floors with the array modifier about 20.000 blocks.However i need to separate them.When i separate them from loose parts the pc does ages and i think that it will never stop separating (i let it all night open, and nothink happened).
Is there an other way that will make me able to separate my cubes?
Please help i want to finish my physics simulation D:

Does the blocks and floors have any modifiers?

no they dont (they had but i applyed them)

did they have a Sub Surf Modifier?

no they dont.The only modifiers they used to have was 3 arrays that have been applyed before i tryed to seperate the blocks

i have 8 gb ram but swap memory is about 60 gb so ram may not be the problem :/ also when i had task manager on , blender didn't used more that 2 gb ram


text:
Is there a way to control master volume in vse?
I know that you can change the volume of selected sound track but its annoying if you have many of those.Is there a way to change master volume or are there any sound mixer options available?All answers are welcomed :).

There's a setting under scene data properties, here:

In v3.6.0:

If affects the current scene. So if you use multiple scenes to render things and a different scene to do the video editing, change the value in that video editing scene.

Awesome! Thank you so much! God bless you, you just saved me adjusting the volume of a ton of audio strips


text:
What's the difference between refraction and glass shader?
I have been experimenting with refraction shader and glass shader (using cycles render) and i noticed that a sphere with refraction shader looks almost the same compared to a sphere that has glass shader.
1)The only difference i noticed with the refraction shader compared to the glass shader is that when a light ray enters the material (that has refraction shader applied), the light ray ,that enters the material, changes once direction because of the ior (but cant bounce back) and when the ray exits the material it can't bounce back ,inside the material, but it can still change direction(because of ior) when it comes out.
Can someone help me spot out the difference?
Is 1) correct?

Firstly I'd like to point out that shaders are called BSDFs in cycles, and raytracing in general.
The difference is that the glass BSDF is essentially a mix of a refraction BSDF and a glossy BSDF - it reflects light as well as refracting it. The glass BSDF is designed to make glass and similar materials easier to simulate - otherwise you would manually need to mix a refraction BSDF and a glossy BSDF.
Some quick example renders (the darker is refraction):

You can see the similarities in that the Glass shader is the refraction shader with some more bits added. Note the weird black artefacts in the Refraction BSDF, whereas the Glass BSDF has the rays bounce off the interior more realistically. For an even more realistic shader, you would want to mix a Refraction with Glossy BSDF - the Glass BSDF is just intended to be easy to use and do what the name says, AFAIK. (Edit: a glass BSDF is extremely similar, or possibly identical, to a refraction BSDF mixed with a glossy BSDF with the factor set to a fresnel node. The fresnel node returns values based on the angle of the surface to the camera. If you want to simulate glass and have more control over these kinds of things, this might be a better setup, although if you're just beginning to use Cycles then glass should do for now.)
Here's a picture showing two cubes with those two different materials applied, but with the same final result (one is a Refraction BSDF mixed with a Glossy with a Fresnel node as the factor, the other is a Glass BSDF):

If I had set up the scene better and put another object next to the cube you would see it reflecting off the glass BSDF but not off the refraction.
I can't offer an explanation for the black bits in the Refraction BSDF, but I suspect it has something to do with the way the renderer processes internal light bounces. Edit: I believe that the refraction BSDF is casting a shadow on itself.
TL;DR (for those of you with really small screens): A glass BSDF is a refraction BSDF plus reflection.

Black parts are likely because the number of bounces in the render settings is set too low.

@Sazerac I tried cranking up the bounces to 400... nothing. As I have said in my answer I believe it is internal shadows.

The black spots are a result of internal total reflection. The Glass Shader has no light escape from below there either. What you see in those spots is pure reflection, no light from refraction. The Glass shader ought to behave exactly like a Glossy and Refraction shader mixed together with a Fresnel node of the same IOR. The Refraction shader just doesn't show any reflection at all, and so it's black where that's the only contribution.


text:
Is it possible to displace a mesh based on Light Path node?
At the image below I expected the cube to be displaced by plus 1 unit in x,y,z axis. However it is staying as it is (notice the yellow outline).

Try plug Invert node between Light Pass and Vector Displacement.

From the light path node. Only 0 is outputted. So invert just converts that to 1. So it doesn't work. Thanks for the suggestion though.


text:
How to read scene(s) data without loading content
I need to extract scene data without loading a blend file completely as some files might be in the upwards of 3GB and more.
Here is an example of the data I have managed to extract by loading everything in the blend via a python script.
{
    "scenes": [
        {
            "scene.cycles.samples": 250,
            "scene.frame_end": 250,
            "scene.frame_start": 1,
            "scene.frame_step": 1,
            "scene.name": "Scene",
            "scene.render.engine": "CYCLES",
            "scene.render.image_settings.file_format": "PNG",
            "scene.render.pixel_aspect_x": 1.0,
            "scene.render.pixel_aspect_y": 1.0,
            "scene.render.resolution_percentage": 100,
            "scene.render.resolution_x": 1920,
            "scene.render.resolution_y": 1080
        },
        {
            "scene.cycles.samples": 1111,
            "scene.frame_end": 250,
            "scene.frame_start": 1,
            "scene.frame_step": 1,
            "scene.name": "Scene.001",
            "scene.render.engine": "CYCLES",
            "scene.render.image_settings.file_format": "PNG",
            "scene.render.pixel_aspect_x": 1.0,
            "scene.render.pixel_aspect_y": 1.0,
            "scene.render.resolution_percentage": 100,
            "scene.render.resolution_x": 256,
            "scene.render.resolution_y": 256
        }
    ]
}

Note this is a very low level of access, not intended for general use.
So you could read this answer "no", unless you're willing to get into Blender's format internals.

This is possible but not trivial, especially for cycles settings which are stored in a generic IDProperty structure.

Blender comes with blendfile.py
This module can be used to load blend files and extract content without having to open them from Blender.
While we don't have docs for this, there is some example use.
It shouldn't take long to extract resolution, engine for e.g.
Cycles settings will be more work, if you have gotten this far you should be able to do it though.

This will work with files from both 2.7x and 2.8x
Edit: see this answer for a start on how to use blendfile.py.


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Fit a narrow image on a strip
I have a very narrow image (e.g. 100px * 10000px), and I would like to fold it into an infinity symbol as a strip.
I found this model: http://www.turbosquid.com/3d-models/3ds-mobius-strip/396686 It seems like all I have to do is put the image on each face. Is this something that can be done with Blender?
I also found the following model: http://www.turbosquid.com/3d-models/3ds-mobius-strip/574060 Can I expect more/less trouble in doing this with this model than with the other one?
Extra question: would it be hard to create my own model to do this?

related: http://blender.stackexchange.com/a/14824/3710

The second mesh isn't going to be any easier than the first to model since it is the same which has been given a shell. Start with creating the "simple'"Moebius and if you want you can add a 'solidify' modifier on it. For the texture you want either to unwrap your mesh or use the generated mapping, then you can apply your picture on it. Honestly I have tried to get the result you posted by playing around with curves but failed, I am not an expert in modelling and didn't put much time on it though, but you are attacking something quite difficult.Good luck mate.

If you follow the link that Poor posted and study Leon Cheung's answer you can get the shape you want. So save your money on that turbosquid model and try it yourself. After that the UV mapping is a bit tricky, but I had success with ripping the verts and UV unwrapping with "Follow Active Quads" using "Even" mode. This is a simplified how-to. I may or may not have time to give a detailed answer, but first wanted to let you know it's definitely possible.


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What is the difference between Visual Keyframes and Baking Animations
Recently I have been trying to animate some certain things for a game I'm writing. However, my game engine(Not the blender game engine) only takes rigged animation (without any bone constraints). So to import in the animations I have to use the Bake Action function, but every time I bake an action It would make another action and then I would have to rename everything.
But then I discovered what Visual Keying is and now I am wondering if I can just use visual keyframes instead of normal keyframes so that I don't have to Bake the action later.


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Layer specification for bpy.ops.mesh.primitive_torus_add
From this API documentation, it appears, unlike all the other mesh primitives, there is no provision for specifying the layer on which one would like the torus placed.
Would the best way of doing this be to create it, and then assign the layer, or is there an undocumented feature which I can use?

That's possibly a bug worth reporting, but i've shown a work around as requested

https://developer.blender.org/T46220

Yes, that's one primitive which doesn't seem to inherit the layers attribute. You can however in the meantime use code like this to set layers.
obj.layers = [(i in [0,3,5]) for i in range(20)]

the object will appear on layer 0, 3 and 5.


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when working in the viewing mode "editing materials" instead of material everything is black
Windows 7. Video Card - GtxForce 9500 GT (OpnGl 3.3) .blender version 2.81
when working in the mode of viewing materials instead of material, solid black .
but in mod rendered all ok .
I use diffuse BSDF

but in this mode it works . maybe something with the settings

Hello, could you add a screenshot of your interface ?

Your graphics card is below the minimum requirements.

specifications and compliments
I have 1gb video memory
openGl 3.3. 4 ram

@Gorgious all added photo

The Nvidia GeForce 9500 GT is from the GeForce 9 series which predates the Nvidia GeForce 400 series. Nvidia GeForce 400 or newer is required for Blender >2.8x.

authors: Cергей Зайченко


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How do I achieve the desired effect with the mirror modifier?
I'm trying to use the Mirror modifier to create a shape as shown below the cur Torus in the guide image floating below it,  but for the life of me, I cant get it to work

When I try to mirror it on the Y axis, the new mesh just overlaps with the existing one like so:

The object gets mirrored relative to it's Origin point (the little orange dot in the middle). To make the shape you want, you have to move the object in Edit Mode (this moves the object relative to its origin - in object mode the origin moves with the object when you move it). In your case, enter edit mode, select the whole mesh, and "drag it away" on the Y axis. Make sure to enable "merge" and "clipping" in the modifier panel

Thanks so much! Will try this right away.

This worked, Thank you!

I'm happy I could help ;)