text:
Wind has a weird stop in smoke simulation
I created a smoke explode;  and added wind (30 lvl).
In frame 32 of the animation there is a weird stop, and smoke changes color. But only in frame 32. How can it be fixed?
https://youtu.be/3ZiuBbAhqQE
Blender version 3.0

This was resolved by changing the cache path; effectively deleting the cache.

Ah yes, unfortunately caches in blender have a problem of being rather sticky and not clearing with changes.  I sometimes find the cache folder and delete, or change some sim parameter that I know will reliably reset the cache.  Sigh.


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Is there a way to convert a Mesh into a Lattice?
I want to do this to control the flow of another mesh. The problem is that it is very difficult to model a lattice. I wish we had a way to extrude the points.

Does the mesh deform modifier work for your case, or do you need a lattice specifically?

What I would like to do is to use the mesh as a path to guide another mesh. Think of it as a fluid simulation.

@Brenticus I am trying to find a workaround for this issue I am having: https://blender.stackexchange.com/questions/173208/how-to-make-mesh-grow-to-create-form
So that is why maybe a lattice approach could fix it, But it is so difficult to modify/shape a lattice.

source: Stack Exchange

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

sort: votes


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Why wont my bones respond to the shortcut keys?
So, I'm using rigify to rig my character, but the problem is, none of the bones will rotate or scale using the S and R shortcut keys. I can move most of them using the arrows and g shortcut, but unless I specifically go to the transform tab (shown below) and use one of the x, y and z values to rotate or scale it, it won't repond.

Can you please upload a screenshot, for better understanding ?

there you go...

Thanks, sorry, but its not showing here clear, can you please add the toolbar, full view of blender please

i updated my question

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


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Can you make particles affect a rigid body?
I am trying to crumble a block like in the gif below. Is there a way to have particles act like bullets and crumble the block? - Here I have just animated some spheres to try and do the same thing.

I have only been able to make the particles bounce off surfaces but the actual rigid body object's are never affected. i.e they stay put.

I am using cell fracture and bullet constraints for the block in the top image.
If it's not possible then is there a way to have a block 'crumble' away using forces rather than particles?
Thanks

Is your block really fractured? It doesn't look like it in the picture. Also increase the particle velocity and mass. And maybe your block is fixed?

No, Particle System is not working with Rigid Bodies. You'll need to change/convert your particles to animations, give them Rigid Bodies properties and then play animation. Here are links: https://blender.stackexchange.com/questions/4956/convert-particle-system-to-animated-meshes and script: https://blenderartists.org/forum/showthread.php?279329-Copy-Particles-to-Rigid-Bodies

Normally, no - particles do not impart any force on a Rigid Body. However, I'm currently working on a patch to Blender to do just this. It's only experimental at the moment but I've made some good progress. Also trying to get interaction with Soft Body and Cloth and looking to improve the collision between Rigid Body and Soft Body/Cloth as that's also currently lacking. I'll add more when I've anything to add but for now here's a little teaser :

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

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


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How would you make a 'long exposure' effect like this reference?
https://www.youtube.com/watch?v=rZfg0G1yTWk
I'm trying to make an echo effect and then feathering the edges of the object so it becomes a frozen smear.

I know how this ref was made (bullet time rig) but wondering how to get the same in blender, on a mesh.

Hi :). What have you tried so far and where exactly are you stuck?

At a quick glance it looks mostly like superimposed multiple exposures.  Probably the same bit of video offset a few frames.  The trick seems to be to age out the older frames by making them more transparent.  Toss in some motion blur and use a lot of camera movement to fool the eye.

This is as far as I have got: https://we.tl/t-pyOAQZ7hMc
Any ideas on how to make it more wispy, streaky?

The effect appears to be caused by having many cameras at slight offsets from each other, taking an exposure of objects in motion set against stable background objects.   The exposures are then played in sequence (each a frame) to give the camera-motion sensation.
If I wanted to accomplish this as stated, there are two tasks that I would undertake in my solution.
The first is to model the motionless and in-motion objects.   You'll only be taking a shot at one frame with multiple cameras, but I'd set up Motion Blur in the Renderer settings.  I'd use a single camera to test to iterate on the MB settings until I have sufficient and desired motion blur.

So a single image of the motion blurred rendering (here a single red cube amongst others that aren't in motion):

If the objects were complex (example: people dancing), I might cheat by Importing a "Picture as Plane", and animate the planes in motion.  These could also use an alpha channel in the rendering node to create some transparency.
To have the "array of cameras", I would use a python script to slowly move a single camera by some incremental position, and render and store that image into a series of files (basename with some incrementing value).  I'd use a constraint to have the camera always looking at (Track To) some empty (that can also be animated to pan somewhat, and the Influence can be adjusted (but not animated)).

The script would be something like:
import bpy

filepathFmt="C:\\tmp\\render\\art {0:04d}.jpg"
nFrames=90 # total number of camera positions and rendered frames
camera = bpy.data.objects['Camera']
xOffset=0.1
yOffset=0.05
zOffset=0.0
fp=''
fp = filepathFmt.format( 1 )
print("rendering " + fp )

## render nFrames shots while moving the camera
for frameIdx in range(1, nFrames, 1):

    ### render and save:
    try:
        fp = filepathFmt.format( frameIdx )
        print("rendering " + fp )
        bpy.context.scene.render.filepath = fp
        bpy.ops.render.render( write_still=True )
    except:
        print("exception: render")

    print("rendered " + fp )

    # move the camera for the next frame
    print( camera.location )
    camera.location[0] += xOffset
    camera.location[1] += yOffset
    camera.location[2] += zOffset

So you'll see something like:

And I bet you want this approach handed you to on the proverbial silver platter!
If you appreciate this please mark this as "Solution"

James....THANK YOU!


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Noob question x 2: toroidal channel & toroidal insert
Hello (blender) world...
Please go easy on me on this first post. I'm new to Blender (and 3D in general, but otherwise software literate) and ready for Total Immersion in all the usual tutorial channels etc. But it would be great if someone could start me off on the right foot for what I need to achieve...
I'm trying to model a circular concrete channel, roughly square section. Inside sits a metal ring, again square section but with a band around the inner surface, of a different material. A bit like an o-ring in a square ring, all inside a square channel, everything concentric...
I'm happy to put in the learning for materials etc but... but... what's the best way to make the square torus (with additional band), and the square toroidal channel?
Obvs I have read about cut lines to reshape the torus but should I use extrude instead? I had a go with that but the extrusion had only vertices, no faces... similarly starting off with a U-shaped plane then using rotate.
So, if an expert could tell me which learning path to follow, I'd be eternally grateful. Eternity being what it will take otherwise...

Please post some reference images.


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Viewport view to Camera view
There are many related topics in this fora, but I could not find a question/answer to my specific problem. Sorry upfront if I missed an answer to this.
I think the perspective given by the 3D Viewport is the best, it's much less distorted than the one offered by the Camera view. I am struggling to find a solution to render my image with the same perspective as in the 3D Viewport. This may be by design for various good reasons. Not debating that, just trying to find my way here.
What I'm looking for is this in my final render, a more relaxed perspective (this is the 3D Viewport view):

What I would like to avoid is this, a distorted view in my final render (this is the Camera view):

If anyone has an idea on how to achieve this it would be very helpful and thank you for your time.
UPDATE: Here's a render of my project, focal length 80mm in both viewport and camera:

Hi :). Simply match the camera's focal length to your viewport camera. They work the same.

@JachymMichal - that worked very well, thank you! In addition I also repositioned the camera by using the Camera to view option (and checking it off when finished).

I'm glad you made it work, good luck with your project :)

Thanks @JachymMichal I posted an image from the project :)

Very nice! Love the sense of scale in that scene. Can i check more of your work somewhere? Insta? Behance? :)

@JachymMichal - sure I have a portfolio over at Artstation: https://www.artstation.com/tegnemaskin and also on Insta: https://www.instagram.com/tegnemaskin/ . I have one on Behance as well but it is the same as on Artstation more or less.


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How can I change A-pose to T-pose without destroying the actions?
Is it possible without retargeting?
I have mocap actions already mapped to a rig I inherited, but the rest pose is in A-pose and it is rotated in a weird way.
How can I change to a proper T-pose (I need it to be a T-pose further down the pipeline) and keep all actions from being messed up in the process?
Thanks, and will appreciate any pointers
Using Blender 4.0.2

It is not possible without retargting, but it is the simplest retargeting job imaginable.  If only upper arm rotation changes, then only upper arm needs to be retargeted.  You can simply copy rotation, world->world, onto T-pose upper arms and bake the action (visual keying, pose, selected bones) onto those two bones; remove copy rotation constraints when done.

@nathan Thanks! I went on retargeting the whole thing. Too many various and complex actions. Figured out a way that fits my workflow. Involves Expy and Rokoko btw. Cheers!


text:
Trigging a driver on certain actions
I have searched for a few hours and tried things, but to no avail. At loss atm.
Background:
I'm working on rigged characters imported from Character Creater 4:

A driver that is attached to jaw-root bone drives a shape key on a face mesh.
This driver seems to be added when exporting the character from CC4 to Blender
as fbx, but only on certain rigged characters.
Without the driver the jaw bone won't move during the lip-sync action.
I have multiple lip-sync actions and armature actions on the same character.
I push all the actions to the NLA (shape key actions and armature
actions).
I export the character and it’s NLA tracks to .glb (naming the tracks that will play together with the same name (as said in the gltf add-on docs))

Problem:

In the gltf viewer this driver runs from start and not only when
lipsync actions are run.
It even runs when the character is idle and not supposed to say
anything.
The jaw bone should move on certain actions only, and not on all actions.

Questions:

What causes the jaw bone to move when the action itself doesn't
transform the jaw bone at all?
How can this driver instead be triggered on selected actions (when
the character is supposed to move its lips and jaw) and not on
other actions e.g. when idle?

NOTE: Characters that doesn't have this driver works as expected.
Files (simplified blend and glb):
https://www.dropbox.com/scl/fo/lrxwwcmzltkmsencb4tk9/AC_D1AQZOmUrcpOeWKMH1Yw?rlkey=8xvx6818einregdz284bdyq0t&dl=0
You can study the NLA and the Driver (on the CC_Base_JawRoot bone) in the blend file, and you'll spot the problem with the glb in the Donmccurdy's gltf previewer
Appreciate any pointers, and thanks for your time.
Using Blender 4.2.1

Did you try not pushing the jaw shape key action to NLA? It should be triggered by the dirver, not by an action. If this doesn't solve, please upload a (maybe simplified) version of your blend file.

Thanks @joshsanfelici, I have pushed down the vertex animations, named the track accordingly, so it plays along with the armature action with the same name. I have updated the post with link to the files.

I received a reply from Victor Soupday [the author of the CC/iC Blender Tools add-on] at the Reallusion forum. He kindly provided an explanation and a solution. I'm adding this as an answer to this thread just in case others would stumble into the same issue.
BTW I realize my questions and assumptions were a tad off, but I'm learning :)
"The drivers aren't exported from CC4 or Blender, they are set up as part of the add-on [CC/iC Blender tools]. It sounds like they are overriding the jaw bone movements when Blender is exporting the animations.
The reason I had to do it like this is because iClone controls the jaw and the eyes from the facial expressions, but also, all the face capture tools (for Blender and iClone) record only the expression blend shapes and ignore face bones, even for eye movements. So people were getting confused why the Jaw or the eyes weren't moving...
But it's optional and you can disable this behaviour:

Go to CC/iC Pipeline Tab > Character Build Settings panel
Expand the Build Settings foldout
Uncheck all the driver options.

This will stop the shape key drivers getting set up when importing new characters.
Then press the Remove Drivers button to remove them from any existing characters."

The solution is not straightforward, but point is that in your file there's a shapekey which is animated, and this animation drives the jaw bone, while it should be the opposite for a correct glb export: the bone should be animated, and that animation should trigger the shape key.
As many shape keys are animated, depending of the project, the workflow, and the number of animation involved, you could try to fix this animation only, inverting the driver direction (bake the animation to an empty using Copy transform constraint, then using the empty to bake the animation to the bone, then deleting the old driver and setting a new one from bone to shape key), or investing time in building the rig so that every shape key has a bone that drives its value.
Hope it can help!

Josh, thank you very much for looking into this! The first part of your answer is totally understandable. I don’t know why IC8/CC4 chose to do it this way. The second part I think I understand. Will look into it. Rebuilding the rig is a no go for various reasons. I’ll post a comment when I hit a snag trying to follow your solution. I will mark it as accepted. Thanks again!

Josh, I posted an answer that explained and solved the issue. I received a reply from the author of the add-on I use for the import. Thanks for your efforts -  I really appreciate it!

Perfect, thank you.


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get Vertex Group to survive Geometry Nodes
I have an object with a bunch of Vertex Groups. I need to use those Vertex Groups "after" an elaborate nest of Geometry Nodes. In general, how is this done?
As for what I've tried, sadly my typical approach of "do a bunch of work and watch Blender kindly overlook what I technically asked for and instead provide what I meant" is not going well. I see in the manual that Geometry Nodes genericizes all attributes (why?!). True enough, I see populated columns in Spreadsheet→Evaluated→Mesh→Vertex with the same names as my Vertex Groups. But I can't figure out how to then access them. I started down the road of tossing Capture/Store Named Attributes all over my GN trees, but only seemed to encounter additional problems—I'll write a separate question if that's the right road.

Here's a sample file created in v4.1, in which a Join Geometry node causes the above effect on two copies of incoming geometry. An Icosphere with a Vertex Group has two modifiers added; Geometry Nodes to pass through the original, plus create and move a duplicate icosphere, and a subsequent Mask modifier to hide part of the original Icosphere mesh by Vertex Group.

Unticking the ✓Join box in Icosphere→Modifiers→JoinerGN only gives the Join Geometry node one copy (translated and no-op joined, yet VG-intact?), and lets the lower Mask modifier work as intended, revealing the green "Go" object. How could the setup be altered such that, for example, the Mask modifier can affect the all of the Geometry Nodes-manipulated geometry?

I can confirm that Geometry Nodes tend to destroy vertex groups when adding geometry. It would help if you could emphasize in your question what you are trying to achieve exactly. So that we can find a workaround.

I have follow-up Questions to post if this goes anywhere, sourced from my actual project. That's a sufficiently awful mess I tried for a Minimal Reproducible Example sample file instead, hoping to get at the concept itself, and correct workflow. I'm desperately itching to expand it, but for this question as written, getting a Mask modifier to operate upon prior GN-duplicated geometry would ✓Solve it.

After constructive modification, the vgroup disappears, but does survive as an attribute,  which can be used by modifiers accepting attributes as parameters further down the stack.. (edge_bevel_weight survives..) I'll bow to superior knowledge.. but this looks to me  like a stage in the evolution of Blender, which will eventually see the end of vgroups altogether?

After playing with applying the "joining" GN, I am afraid a workaround is to develop your own GN mimicking the Mask modifier, but reading the cutaway attribute, as the vertex group is lost.

For any future readers, do not do this. As noted in the question's comments and indeed in the manual, Geometry Nodes make everything generic. Vector Groups will not survive as VGs, but as a float field. Plan your VGs and UVs and Modifiers and workflow accordingly.
I "solved" this problem in line with StefLAncien's suggestion—I've recreated my entire Modifiers stack in Geometry Nodes. Most Modifiers went without too much fuss. The Mask mod in the question, for example, was even improved when replaced with a Set Material node pulling a transparent material; letting renders omit the mesh and its shadow, but the geometry still be present.


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Add > Path with custom geometry using Python
I am writing a Python script and in part of it I want to do an Add > Curve > Path operation, but instead of the default 5-vert straight path, I want one at the object origin (which I have pre-defined with coordinates orig_x orig_y orig_z), and then another at some other location (let's say coords end_x end_y end_z).
Instead of the default primitive NURBS path, I want the script to add my own, which is just 2 vertices.
Here's that line of my script as it is currently:
bpy.ops.curve.primitive_nurbs_path_add(radius=1, enter_editmode=False, align='CURSOR', location=(orig_x, orig_y, orig_z), scale=(1, 1, 1))
I can't figure out if I should start by deleting all the vertices, then re-adding two, OR if I should try to select just the second [1] and fourth [3] indices and Dissolve Vertices... I've tried both approaches without success. I'm doing something wrong when trying to target those verts.
Can someone please point me in the right direction?

Does this help ? https://blender.stackexchange.com/q/61266/86891

@Gorgious Thanks for the clue. It helps a little, but also raises new questions about how that person removed the existing verts. I'm still studying it.

Well the idea is not to use the operator but rather instantiate an empty curve and add the relevant points rather than working backwards from a primitive curve added with an operator. I personnaly have trouble with both so I won't be of much more help but still, food for thought

Thanks, batFINGER! By following links from your link, I found this question that when I put the answers together, appears to be the sort of example I needed.

Good one.  Expanded https://blender.stackexchange.com/questions/180148/create-curve-from-numpy-array-using-python to have a 2 point nurbs option.   Can prob close this down as a dupe then?

@batFINGER Yes, I think so. I appreciate the nudge in the right direction.

NP Often see don't use operators in comments, my rule of thumb in particular is avoid edit mode toggling and edit mode operators..


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GN: How to pass an instancer's localized texture color to its instances?
How can Geometry Nodes be used to generate instances that inherit the texture color of their emitter/instancer?
Reference image of desired result:

(Above: screenshot by quellenform)
There is already a solution using particle systems in Cycles. Now I am looking for a way to do it using Geometry Nodes (that will be compatible with Eevee as well).
Because the "From Instancer" checkbox on the Texture Coordinate node is only for Cycles, and because particles and GN instances are fundamentally different, a new approach is needed.
(I have found an answer that uses the material index to assign multiple materials, but using multiple materials is something else altogether, and would only work for images with a handful of colors.)

Note to contributors: Thank you all for the 3 (as of this writing) helpful answers! I did not anticipate such a swift response. While I have upvoted each of them, I am having trouble determining which should be the "accepted" answer. Since I want to be fair, I will take some time to try out the different methods. If one stands out as most optimal, I will accept it. If I don't accept any, consider it a tie. Reminder to the community: Please upvote any answer that helped you.

Expect the unexpected, here on blender.stackexchange.com and take the time you need ;-)

Overview: quellenform's technique maps the texture to the object bounds. Since it doesn't rely on a UV map, the instances and the emitter plane can be joined as one object and still retain their texture mapping. TheJeran's technique and possibly ferret's technique are similar in that they both pull in a UV map through the modifier, allowing complex textured objects to be manipulated (not only planes). They differ in that the former returns a color, while the latter returns the UV (which allows for further manipulation of the vector within the material).

For people looking into controlling color on unrealized instances: it still seems impossible and all 3 answers here realize instances.

@MarkusvonBroady True - all three answers realize instances. I didn't specify any criteria about this in the question, as my total poly count will probably not be high enough for that to be a constraint. Also, I don't know if it's possible to work around that limitation. Each instance would need to receive some kind of unique data that could then be decoded into UV or color data within the material. Maybe there is some trickery that can be done, and I'd be curious to see an answer like that.

@Mentalist if you can derive instance position from sampled point position in shader, then you can, otherwise you can't (yet): Is where a way to pass data to material without realizing instances?

This variant is different because you do not need a UV map nor an existing ground plane. This is the case, for example, if you even want to create the grid on which you distribute the points in Geometry Nodes.

This is how I would solve it (no external attributes required, all in one place controlled by Geometry Nodes and independently displayable from the ground plane):

Use the node Bounding Box to capture the dimensions of the grid on which you want to instantiate the cubes.

Map these dimensions to a vector from $0,0,0$ to $1,1,1$ so that you can feed the node Image Texture correctly (You can of course directly feed in an external attribute, like your UV map, if you already have one).

Then distribute the points with the node Distribute Points on Faces on your grid and instantiate your objects there.

The nodes Random and Set Position will help you to distribute them randomly on the Z-axis in a certain area.

Finally you only have to capture the color from the node Image Texture with the node Capture Attribute per instance and pass it to the Group Output, as well as define the materials.

In the shader, you can then retrieve and process the color transferred to the instances with the Attribute node (in this example I also used another color for the sides of the cubes):

Update

...and here is an example and the reason why I prefer this variant: It is just super flexible and everything can be realized procedurally without UV mapping in Geometry Nodes:

Here's a short video, since it doesn't look good in the GIF (Rendered with EEVEE).
And this is the node group that generates that:

Nice animation you added to your answer! It does a good job of illustrating what's possible. I'm playing with your node setup and I have a question: If one were to want to project the instances out from face normals (instances rotated according to faces) on a non-planar mesh (Suzanne, Torus, etc) and use the UV map to assign the texture, what would need to change?

@Mentalist Interesting idea! But I think that would almost be worth a separate question again, especially because the answer here would have to go into a bit of detail, don't you think?

Never mind. I achieved the result I wanted. Will share my .blend file. (Made with Blender 3.1.2) The instance rotation method is from here. I borrowed and modified your animation technique. The coloring method is the same as in TheJeran's answer. There is the limitation of the instancer not being able to retain UV data if combined with the instances in a single object... so I simply used two separate objects.

all you need to do is capture the UV attribute to the instances

Hello ! Thanks for the answer :) Could you also post the shader node tree for completeness ?

it's in the blend file that you can download.

The process is a bit tedious but it's quite simple.
First load in the texture you wanna use (I recommend Images as planes)
I have this image of africa so I'm gonna use that.

Next create your geometry node setup and distribute some points and instances.

Next we need to bring in the UV data. So click the Group tab and then create a new input.

Change it to Vector type. Then make the input an attribute and select UVMap

Now load your image texture into Geonodes and set-it up like I have here. You will need to create a new material to put in the set material node.

Give your new color output a name.

Lastly connect that attribute to the color in your shader.

VIOLA!

Hmm, and what would you do if you wanted to distribute the points on an object that you also created with Geometry Nodes?

You'd have to use your bounding box method as far as I know.

....yes exactly, something like that, or exactly what I gave as an answer ;-)


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Proportional editing not effecting some faces
I have a flat watchband that I want to curve.
I have selected a few vertices on the further end, activated proportional edit and moved these vertices. The majority of the band then flexes as expected but there are some faces that are acting very strangely and it seems they aren't really affected by the proportional edit as desired.
See red arrows in the attached images pointing to these areas.

I then tried achieving the bend using the simple deform modifier and it also resulted in a strange outer surface while the inner surface of the band is more or less correct.

The below image is what happends when i bend it a full 360 degrees.

Probably the topology is bad. You can't bend long faces, you have to break them by adding new verts and edges.


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Smoke is not appearing in the "render" viewport, version 2.82
I am in need of help. I was trying to complete a smoke tutorial, but I needed to update Blender. After I had updated to 2.82, I had put in all of the desired values into their designated slots. I pressed Bake, and afterwards I tried to look at the results through all four Viewport Shading displays (Wireframe, Solid, Material Preview, and Rendered). At first I could see the smoke in Wireframe and Solid, but only if I don't place a Principled BSDF node. If I do, it is invisible no matter what.
If anyone has any suggestions, please let me know. Below is the screenshot. The emitter is in the red circle, a small plane.

Edit: I searched some more on the internet for answers. It appears that I have a Graphics Card that is incompatible with Blender, a Radeon Pro Vega 64 16 GB. The only graphics cards that are supported are from NVIDIA, Intel, AMD, and Macs with software with an IOS version of 10.12 or older. That is most likely why it shows up with the message "No compatible GPUs found for path tracing" when I try to render the smoke with CUDA or OpenCL. The CPU works fine, so that is why only Cycles works. However, even if I switched to Cycles and CPU processing, the "Render" Viewport Shading Display just fills up with blocky black and red pixels, instead of a single cloud.
Edit 2: I believe I found the solution! I now was able to see both modular and replay in WINDOWS rather than Apple, but now I found out that it renders the same image over and over again when I wanted to hit Render Animation. I created a new question that is more related to that rendering issue, rather than this Viewport issue.

I'm sorry if this is a dumb answer...but is your inflow (the plane) inside the confines of the domain? If it is even with the borders, or slightly outside the domain of the domain i don't think it will work. I think it needs to be totally inside.

Slorry not "outside the domain of the domain", I meant outside the borders of the domain.

Please edit your answer rather than comment it. Thank you

I've tried that, but the smoke is still invisible.

Go to cache settings of the domain and change the type from modular to replay

I have found a solution that is not related to selecting those two options, but thank you for the suggestion though!

do you mind sharing how you fixed it then?


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Weird grooves in mesh visible
I was trying to create a golden statue of an eagle in flight, but for some reason even after making multiple loop cuts and using the subdivision modifier, I could not make these weird grooves disappear. Should I use smooth in sculpting mode? If you have any suggestions, please let me know.

Edit: I apologize for not doing this before, please let me know if this image helps. The grooves only appear when the beak is opened in Pose Mode or when looking at the new pose in Object Mode. I am not sure how to see the altered pose in Edit Mode. Also if you wish to make a comparison between the rendered eagle and the topology of the eagle, I am not sure how to include more than one image on a post.

Please post a picture in edit mode showing the topology.


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Is there a way to have fewer polygons in the viewport temporarily or maybe only in viewport but after render it remains the same?
Just like, in the viewport there would be a lot fewer polygons but when you go in render it would show the original way the polygons of the model were just to save up your computer resources so you face less lag.

STEP 1
select your mesh , go to properties tab and to the modifiers properties(the wrench).

STEP 2
click add modifier and in the drop down select decimate.

STEP 3
Go to unsubdivide option and increase the iterations and as expected it will unsuubdivide your mesh.

STEP 4
to disable it in your renders select the camera so that an 'X' mark appears in the middle.

and now your mesh should be unsubdivided temporarily in your viewport but not in the render


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Rigify - arm twist troubles (pose/rest - IK> FK)
I have problem with arm tweaks. I noticed this problem when creating animation and try snap IK to FK. After snapping I have this. Then I was advised to change A or T pose, but this did not solve the problem.
I started to understand the topic and found these basic rigs:

Quadruped Meta-Rig
Human Meta-Rig

With Bird and Cat; Meta-Rig all ok, twist is good. But with Horse and Wolf I have the same problem as above.
I don't know if this is a bug or something else. Maybe I'm doing something wrong, but I need help with that :)

Click on the red IK control for the hand. Press N, to get the property panel on ITEM tab. Scroll to "Toggle Pole", set it to 1. Align this new orientation control.
Your problem is a point-to-target issue with the controlled direction from this Toggle Pole control.
To match IK - FK slides, you can use the MAGNETO ICON that says Fk-Ik to match it so to that position from FK to IK (FK are the green controllers, IK are the red controls)


text:
Problem with rotaton driver after a 180° rotation
I'm new to blender but not to 3d modeling,
and I'm trying to rig a 7 cylinder radial engine, everything is set: crankshaft, piston, counterweight, planetary gear made with the extra mesh add-on(it could be important cause those gears are working perfectly) and rigged with a rotation driver for an output of 1/6 ratio. I'm know trying to rig a hand modeled piece (the cam ring ) which spin at the same speed as the ring gear with the same driver: -(var*1/6) of the sun gear.
but a rotation of 180° on the X axis of the sun gear cause a sudden jump back of 30° on the x axis of the cam ring
I tried to delete the driver on the cam ring and parent it to the ring gear directly but still doing the same.
Could anyone help?

wow, sounds pretty complicated ;) can you somehow break it down to something like "i parent my rig and then this happens" and then provide your blend file? and maybe add some screenshots with annotations so we know what you are talking about?

Possibly related https://blender.stackexchange.com/questions/164765/rotation-driver-skipping-backwards-after-90-degrees

https://blender.stackexchange.com/questions/214576/drivers-breaking-down-after-model-transformation

There are two different kinds of ways you could be driving this.  One would be to drive it from a transform channel/rotation.  The other would be to drive it from a single property, like "rotation_euler".  The first will not work for you.  The second should.
I don't know which method you're using. A file would make it clear.
Driving rotation from a transform channel gives you the rotation after it has been converted into a matrix and had all constraints applied to it.  Matrix transformations do not represent rotations outside the -180, 180 degrees range, which is sufficient to represent all orientations of a specific object.  But when you go from 120 degrees to 180 degrees to, say, 240 degrees, your driver is seeing this as going from 120 to 180 to -120 degrees-- and a sixth of that is 20, 30, -20, which creates a discontinuity.
If you instead drive rotation from a single property, you get the actual amount of rotation specified directly by the f-curve, before any constraints, before it's been converted into a form that destroys this information about "extra" rotations.  In this case, in the example above, you would see a smooth 20, 30, 40, just like you'd expect.

thank you nathan , i think you understand where my problem come from even if don' t understand what you're answering me about matrix (i'm new to blender). i haven't created animation channel yet still rigging for now but i figured out something if i clear parents from the root bone created for the crank shaft i can rotate it whithout issues. I WISH I COULD HAVE NEO WITH ME.

@Oliver Don't worry too much about understanding everything-- we grown-ups aren't so different from babies, we still learn when hearing things that don't make any sense to us yet, it only takes repetition and time.  Just try using a different kind of driver and see if that fixes your problems.

@nathan thanks for your answer. I get the "gimble" lock principle, though I don't know how to drive it from a single property? Any recommendations on how to do that?

@CromeX It doesn't have anything to do with gimbal lock.  You drive from a single property by selecting the variable type for the driver in the driver editor viewport, in sidebar/driver.


text:
assigning existing bones to vertex groups
I have one model and it was separated by foot, head, hands, so on.. they had their own armature, I want to unite them under one armature, so I parented them under one armature and removed their own, the vertex groups are still there but bones are red, as you can see in the picture, looks like they are not connected to meshes, How can I fix this?

you need to make sure that the vertex groups of your mesh have the same name as the bones so that the bones will be able to control them


text:
How to change the color of an object using the timeline?
I’m trying to assign specific colors to a certain moment on the timeline.
For example:

From 0-50 I want Red,
From 50-75 pink,
From 75-85 orange,
From 85-95 gold,
From 95-100 purple.

Probably easiest to follow the first part of this YT video but using ColorRamps set to your colours instead of Image Texture nodes, then keyframe the Value node to your requirements.

Assuming you mean the color of a specific material, the easiest way to do it might be to use the RGB Input node in a material and set it.  Here's a very trivial material:

For your example, go to frame 0 and set the RGB Node to a nice red color.  Then hover over the color input of the RGB node and type I to insert a keyframe:

Set the frame to 49 and do it again.
Set the frame to 50, pick your pink, and type I to insert a keyframe.
Set the frame to 74 and do it again.
Doe the same for gold using 85 and 94, and purple using 95-100.
If you want the colors to fade from one to the other, then don't add the keyframes at 49, 74, 84, or 94.


text:
Why is my vertex painting sometimes working and sometimes not working?
I'm vertex painting another texture onto my mesh plane, sometimes it works sometimes it doesn't.

There are solid black lines in the background, the vertex painting works as expected. However, in some areas, when I paint, it creates this jagged random pattern instead of a solid black line. And this is the result, instead of the texture, it just leaves the black instead. Compare the areas in which there is a solid black line, compared to this jagged pattern area. You'll notice that the texture is applied in the solid black line area, but not the messed up area:

How do I fix this? Or, what causes this problem? Thanks in advance.

Vertex Paint gives color to your vertex, so it completely depends on your topology, are you sure that your topology is not completely messed up on these parts? Please share your file: https://pasteall.org/blend/

@moonboots it's a little raised there but I don't think the topology is messed up. only where it's a little higher it starts doing this for some reason. also I couldn't upload it to that site because 24mb was the maximum file size

could you at least share this particular part?

@moonboots how do I do that?

just save your file as a new file, delete all the objects except your ground, in Edit mode delete a large part of your ground and only keep the part with the problem, then share

@moonboots Sorry, took so long had to delete some terrain too, here it is now: https://pasteall.org/blend/4b1d63283649446d85b8307a689f82c1

Your object's scale is very stretched, apply it in Object mode (CtrlA), it will probably help to correctly vertex paint:

thank you so much, I can't believe I didn't do that, it works now


text:
Hair particle color in particle edit mode

I know that in particle edit mode the hair marks appear black.
But my particles appear light blue. It makes my eyes tired and I don't know exactly where I've chosen.
It looks simple, but I am unable to solve it due to lack of information.
Is there anything in the settings I need to touch?

The selected theme defines the colors. You can change them in the Preferences.
Select Edit > Preferences... from the main menu.
In the popup dialog, select Themes, then expand the 3D Viewport section.

here you will find the Vertex Selected color which is the color for selected hair particles. It's orange in Blender's dark default theme.
the Wire color defines the color for unselected hair particles. It's black in the dark default theme.

Thank you. I think I need to look around the basics a bit more.


text:
Python Keyframe Soft Landing Issue
So I am writing a script to animate a neutron hitting on a grid & changing trajectory to next spot using 2-3 key frames; one at the origin, one at the landing point, and/or one at the final point the projectile may bounce to. My problem is when using the key frame functionality, these points are animated with a soft landing which does not match the more aggressive "hitting" style of the projectile (neutron).
#create neutron at origin
bpy.ops.mesh.primitive_uv_sphere_add(radius=.15, location=(0, 0, 0))
testNeutron = bpy.context.object

#update location
#animate first landing of projectile aka (hit)
testNeutron.location = (x,y,z)
testNeutron.keyframe_insert(data_path = "location", frame = timeofimpact1st)

#update location
#animate second landing of projectile aka (hit)
testNeutron.location = (x2,y2,z2)
testNeutron.keyframe_insert(data_path = "location", frame = timeofimpact2nd)

#bpy.ops.action.interpolation_type(type='LINEAR')
keyframe1 = bpy.data.objects['Neutron'].animation_data.action.fcurves[0].keyframe_points[0]
keyframe1.interpolation = 'LINEAR'

keyframe2 = bpy.data.objects['Neutron'].animation_data.action.fcurves[0].keyframe_points[1]
keyframe2.interpolation = 'LINEAR'

I have tried something like this, but it does not resemble a hitting and quick change of direction to the next location. It resembles a soft landing at one location and a relaxing move to the next (followed by another soft landing)
Any help is appreciated. Thanks

Your problem seems to be that you've animated a sphere that will be called 'Sphere' because that's the default name you get from the mesh add call; but you're trying to modify the interpolation of an object called 'Neutron'.  You either need to add a name change, or use 'Sphere' in the bpy.data.objects references.
Your example is hard to follow because you don't include the location settings (x, y, z), (x2, y2, z2) or the frame numbers and you've completely left out your rebound keyframe.  I would need all of that to understand why your animation wasn't working.

Hey, thanks for the response. In the script, the neutron name is actually 'Sphere', I just put neutron in an effort to make it more readable. (x,y,z) = (6.834/100, -7.567/100, 677.3/100) & timeofimpact1st = 62.33. (x2,y2,z2)=(78.24/100, -47.31/100, 1109.0/100) & timeofimpact2nd = 101.6. This is for a script to read data, so depending on the dataset the variable values (location, timeofimpact) will change. I also have not put anything for the rebound keyframe I am unaware of the term in whole. Thanks again. Any help is much appreciated


text:
Keybinding for a python script
I want to delete object hierarchy from 3DView but I can not find any keybindings for this.
In outliner is this possible but not in 3DView so I wrote a simple script and wanted to execute it when pressing for example the delete key.
How can I do this?
Here the script (maybe somebody have an idea?)
import bpy

objs = bpy.context.selected_objects
delobj = bpy.ops.object.select_grouped(type='CHILDREN_RECURSIVE')
bpy.ops.object.delete({"selected_objects": objs})
bpy.ops.object.delete({"selected_objects": delobj})

Thanks!
UPDATE: This part was added as an answer. I've moved it to the question so that people without sufficient privilege to see deleted answers can respond:
I get a menu but it does nothing also the key binding is not visible in the preferences. I'm very new to blender programming so it would be great when you could check my code.
Thanks!
import bpy

class DeleteHierarchy(bpy.types.Operator):
    """Delete objects with children"""
    bl_idname = "view3d.delete_hier"
    bl_label = "Delete"

    def delete_hierarchy(self):
        parent = bpy.context.selected_objects
        child = bpy.ops.object.select_grouped(type='CHILDREN_RECURSIVE')
        bpy.ops.object.delete({"selected_objects": parent})
        bpy.ops.object.delete({"selected_objects": child})

        key_config = bpy.context.window_manager.keyconfigs.addon
        if key_config:
            key_map = key_config.kexmaps.new(name='3D View', space_type='VIEW_3D')
            key_entry = key_map.keymap_items.new(DeleteHierarchy.bl_idname, type='X', value='PRESS', ctrl=True)

    # delete_hierarchy(self)

def menu_func(self, context):
    self.layout.operator(DeleteHierarchy.bl_idname, text="Delete")

def register():
    bpy.utils.register_class(DeleteHierarchy)
    bpy.types.VIEW3D_MT_view.append(menu_func)

def unregister():
    bpy.utils.unregister_class(DeleteHierarchy)
    bpy.types.VIEW3D_MT_view.remove(menu_func)

if __name__ == "__main__":
    register()
```

https://blender.stackexchange.com/questions/282685/blender-python-im-unable-to-assign-a-hotkey-to-my-plugin/282786#282786

To add a shortcut to your code, you must first make your code into an operator by making it the execute function of a class derived from bpy.types.Operator.
Then you need to find or create the appropriate keymap and add an entry to the map.  Here's some sample code you can use for a template:
key_config = bpy.context.window_manager.keyconfigs.addon
if key_config:
    key_map = key_config.keymaps.new(name='3D View', space_type='VIEW_3D')
    key_entry = key_map.keymap_items.new(SKELETON_OT_Message.bl_idname,
                                         type='W',
                                         value='PRESS',
                                         ctrl=True,
)

This example makes Ctrl–W the shortcut for an operator in the class SKELETON_OT_Message.  Replace the class name with your class name and the type and ctrl fields with to set the shortcut you want.


text:
Is the w-coordinate of the UV coordinate system supported by Volumetric materials?
I want to calculate the density of a volumetric Emission material using the distance inward from the mesh surface. I've been able to do this with a cube and several coordinate systems: generated, object, I can display the u,v-coordinates as colors on the surface of a uv-mapped mesh. I can use the Mapping Node to rotate these coordinates around the X- or Y-axis and see the w-coordinate in shades of blue.
Within the Blender manual pages for Input Nodes, the description of the Texture Coordinate Node makes no mention of unsupported coordinate systems for volume materials. But the description of the Geometry Node states "For volume shaders, only the position and incoming vector are available."
Is the w-coordinate of the UV coordinate system supported for volume materials? I fear that the w-coordinate cannot be defined within a mesh of arbitrary shape because each interior point can be projected back to the mesh along many normal vectors. But I'm not sure I understand the w-coordinate well.

If by UV you mean unwrapped coordinates then no, volumetrics can not use UV coordinates.  This is for the exact reason you stated in your question, by unwrapping a mesh you are only assigning coordinates to the surface of your mesh, not the volume.

Here are the texture coordinates that work for volumetrics (i.e. not calculated based on the surface of the mesh).
Texture coordinate node:

Generated:  Generated coordinates are based on the bounding box of the object.  The left, bottom, front corner is (0, 0, 0) and the right, top, back corner is (1, 1, 1); the volume of the bounding box is interpolated linearly between these.  By default all procedural textures use generated coordinates.
Object: The coordinates in local-space of the specified object on the texture coordinate node.

Camera: The position in camera-space.

Other nodes:

Position (geometry node): The position in world-space.
Location (object info node): The object's position in world-space.  Note: Unlike object, camera, and position this is the position of the origin of the object possessing the material, not the point within the object.  (This one probably isn't that useful for your purposes.)

For more on texture coordinates see my explanation of texture coordinates here.

I think the OP was asking about the UV coordinate system in particular, but I guess this doesn't have a W axis?

@gandalf3  Ahh, I didn't think of it that way, coming from Max I am not used to UV only referring to unwrapped.  Technically unwrapped coordinates do have a W coordinate, but it is always 0.  But the reason they don't work for volumentrics is that they are only defined for the surface of a mesh, the the volume.

@PGmath, thanks for the effort to provide descriptions of the coordinates supported by volumes.


text:
Why would a plane displaced with Geometry Nodes not appear displaced in Cycles Rendered View but does in EEVEE?
I'm experimenting with Geometry Nodes after following the Entagma "Alien Orb" tutorial on YouTube. I'd like to develop a general method for creating complex procedural cavities on arbitrary shapes. I'm starting with a simple case - cones in a plane.
I'm getting a funny issue that the displacement is visible in the Solid viewport shading and the Material Preview viewport shading and in EEVEE Rendered View. But the plane is entirely flat in Cycles Rendered view. Unfortunately, I plan to use Cycles so this is a problem. I've spent the day trying to figure out what is happening and I have come up empty-handed. I suspect it is something basic. I'd like to understand so I can keep the problem from happening in the future.
Here is the appearance of the displaced plane in Material Preview. Surface color is mapped to z of the Object Coordinates, so the shader is aware of the vertical displacement I've created.

Here is the appearance of the displaced plane in Cycles Rendered View. The shader hasn't changed, so it thinks the plane is not displaced (z = 0 = red everywhere). The outline of the displaced plane is visible in Rendered View.

Entagma. Good choice. :) I'm sorry to say,  I can't reproduce this, in Blender 3.0a, 2021-06-24, on Linux, Nvidia. Does it work at lower subdiv. levels? Check graphics drivers? Maybe wait to see if others can reproduce.. if this is reportable, you want to make the report as useful as possible.

I get the same error as OP on Blender 2.93 (reproduceable). Also interesting to note that the displacement is still seen correctly in Solid View too!

Maybe fixed in 3.0a, then.

Thanks for the quick replies. I've been thinking of moving to 3.0a. This seems to clinch it.

I just went back to my original follow-through of the Alien Orb. When I worked through the tutorial step-by-step I did not have the problem with the Cycle's Render View. The displaced icosphere reacted to light and the surface rendered as expected.

Based on Robin's feedback, I opened my blend file in Blender 3.0a. The Rendered View works correctly. Seems to be a bug in 2.93.


text:
Using Proximity from Curve to control Volume Shader in Cube
I'm experimenting with the Geometry Proximity node in Geo Nodes, using Blender version 3.2.1. The effect I want to achieve is a volumetric shader within a cube domain that is controlled by the distance from a Curve.
I can achieve the effect I'm looking for on the surface of the cube (see figure below). You can see the Bezier curve poking out of the left face and the front face of the cube. Small distances to the curve are colored blue on the faces of the cube with larger distances colored green and red. This test case of a surface shader appears to work fine.

However, when I plug the Emission Shader into the Volume socket on the Material Output node the volume is colored a uniform blue inside the cube.
Any ideas why this setup works for a surface shader but not a volume shader? Maybe this use case isn't supported yet by Geometry Proximity? Or perhaps a setting or setup I'm not using correctly?
Blend file attached below. Any help is greatly appreciated!

I found a way!
its a bit of a workaround, but it does work.
So basically, you use the new-ish Volume Cube node, this allows you to plug a field into the density value. You can plug your proximity node into that and transform it a little bit with map ranges. Then, you can go into the shader editor and use the volume info node, that density value is the equivalent to your proximity, meaning you can use it however you'd like.
I've added a picture showing how it works, if my explanation wasnt clear. (I added a glowing material for the curve so you can see where it is)
I hope this helps anyone, even though im a little bit late.

Short answer: There is no geometry (no points, no edges, no faces) inside the cube, so there is nothing for the Geometry Proximity node to reference when calculating Distance values from the points on the Bezier curve.
I've experimented with creating a 3d grid of points positioned inside the cube, but so far no luck.
I'm still interested in solutions or suggestions!

have you find a way to solve this?


text:
How would I go about converting a 3d model to a .vox file
So I really want to convert a 3d model into a .vox file for use in Minecraft, there's a service out there that can convert .vox files to Minecraft .schematic files but my problem is I need a .vox file in the first place. I've tested the service and it works with .vox files with color data so yeah that's fine.
The issue comes with conversion, there seem to be a few options. The first is to convert OBJ to .vox and also literally just a .schematic with the service but the issue is I think what I need is a .obj file and a single image texture to go along with it that contains all the textures but when I export as OBJ in blender I get a .mtl which is definitely not an image file because it's a text file. I know you can do some fancy baking magic but I don't think I want to do that because some of the other solutions seem more fun to do because I'm doing this all for fun, it's for Minecraft. If there's an add-on to do this, that would be cool to know about but I don't want to spend ages trying to bake it and in the end have it not work because I'm using a pretty quirky 3d model that was originally made in a different language for a video game and was shakily converted to Blender so yeah IDK.
If everything fails I have MagicaVoxel which I can import OBJs into and have it be voxelly but I'd have to paint it which would be weird. I could do that however it would just be kinda lengthy to do. There are other options like Qubicle but that's payed and then there's an article on a thing called poly2vox which seems like it could work but the software seems very old and I'm not 100% sure it does what I want, also it's run in your command line which seems a bit too techy for me.
Essentially what I'm asking is if you know any plugins that can do something like this or export an obj as a .obj and one texture file. I'd also like to know if there are any other known ways of converting any 3d model type to a .vox without losing color data. Ok cool I'm gonna go be sad now.
The service: https://drububu.com/miscellaneous/voxelizer/?out=obj
By the way, most "OBJ to Minecraft" tutorials are years old and use outdated programs and things that just don't work anymore.
I hoped this was clear enough in the first version but I guess not, I'd like a way of doing this without losing colors because if I wanted I could just use magicavoxel or the service if I didn't care about colors but I want a way to get colors that works and doesn't require manual input because I can't paint in the slightest.

If you need any to make any mesh in blender look "minecraft-like", use a Remesh Modifier set to Blocks. You can then export this to a variety of formats, including .obj. If you need a .vox file, however, you will need a special addon. One of the best I can find to suit your purpose is here, but I can not vouch for its efficacy.
Addon to export to .vox is here:

https://github.com/Spyduck/voxwriter

As the other answer already linked, you can use this plugin to export to .vox, and then use the tool you mentioned to convert it to a schematic.
To get colors to work, you need one material per color. Use a principled BSDF and set the base color to the color you want.

you can convert obj to vox color using the new voxconvert. i made a tutorial on this https://youtu.be/Erstqc5uSxU


text:
Blender 2.91.2 Transparency Effect no longer works with emission
I use emissions to create flat renders, and I used this node layout in Eevee for images with alpha channels.

The above was provided to me by another user.
I've recently updated 2.91.2 and now I can no longer use this lay out. In the current image I'm using, I'm trying to render a checkerboard tile where the white spaces are transparent.

The original texture is png with alpha channel
But when I apply the same node layout I get a weird interpretation that isn't even transparent.

It instead creates a weird grid like wireframe effect. Why is this? Did they change how this works or am I doing something visibly wrong.
EDIT: I also went back to an older file, and the effect still works, UNTIL I apply it to a new mesh. By that I mean, copy and paste. Same image, same nodes, no alpha channel. HOWEVER if I use material copy via CTRL+L it does work. I am completely at a loss
Cheers!

check when you press n in the material editor > options, if blend mode is set to alpha blend or alpha hashed.

I just looked at the image and your blend mode is set to opaque, which will render alpha to black.

Yeah I think that solved it.

if you solved it, in order for people to find this answer when they search for it, answer your question and tag it as the correct answer.

Answer from a helpful person
"check when you press n in the material editor > options, if blend mode is set to alpha blend or alpha hashed. – Alex bries"


text:
Multiresolution Modifier - Lost of details
Blender Version 2.79
Problem:

With a multiresolution on, when switching between Sculpt and Object
Mode, the vertices displayed are different.
When the Multiresolution is applied, the object is not
subdivided in Edit mode neither is Object mode. Therefore, the
lack of vertices in Object mode resulting in the lost of fine
details such as pores and wrinkles on a character.

Additional Info:

No other active modifier is on.
Suspecting some settings are tweaked accidentally, as it works when appending the same mesh to a newly create blendfile.
Ensured the Level of Sculpt, Preview and Render is at the same level.
Below attached a sample of sundivided cube with same problem, please feel free to take a look.

https://jp410-my.sharepoint.com/:u:/g/personal/mac281_office2016_club/EdbYYnvCs-xEqiE7ZZzgOrcBUnIgrn0w7t6wvaT_A4qRXQ?e=AkVeWv [98mb]

No I don't have.


text:
Is there a way to properly mirror an animation?
I've already searched and searched and none of the answers to this question have helped me. I have an animation of a character moving right, and I need to flip it so that he's moving left. I've tried copying and pasting flipped both in the action editor and the 3D view and neither works right. My bone names are all correct with .L and .R for left and right respectively.
Any help would be greatly appreciated.
Here's the .blend file.

One hack I can think of is duplicating the armature, mirroring it and then using constraints on the original armature bones to snap to the mirrored counterparts (copy location, IK etc depends on the rig). Then you just bake it to flat animation that you can export. Takes a while to setup but would work on all your animations at once. Sorry no time to make this an actual answer and maybe there's a better way.

Add an Empty and place it in the same position where the origin point of your armature is. In Object Mode select your rig, then an Empty and press Ctrl+P.

Now select the Empty and scale it by -1 (S,X,-1).
Note that this may not be the proper way to do it. I think you should find the root bone (which controls all the other bones location) and rotate it by 180 degrees.

Thanks for taking a look, but this is being exported to Unity, so I need the real thing. :\

Pose mirroring through copy / mirrored pasting (CtrlC and CtrlShiftV ) works using the bone's axes.
If you haven't build your rig properly with the right symmetrization, then the bones axes won't be good and the mirroring will not work correctly.
To fix this, you have to change the bones rolls in edit mode, then remake the meshes's Armature Deform Modifier.
You can see a way to do this here. You can also use the Recalculate Roll menu (CtrlN in edit mode).


text:
Object surface be cracked when move too far grid center
I have a problem but i dont know how to describe it.
I have one object. It is look good if I put it in (0,0,0) xyz axis or about +- 100 unit location. But when i moved it to (1000,0,0) it became weird with some cracked on surface and it worse than that.
I applied locrotsccale already, just subsur modifier (but it not better when I removed modifier)
Some one help me how to fix it. Thank you
Here is my screenshot:

Update:
Here is my file to check FILE

Don't use clipping values for the viewport camera ranging from 0.1 up to 3000, decrease the difference at least 3 times. See https://blender.stackexchange.com/questions/4946/where-can-the-viewport-clipping-parameters-be-changed

I tried to change chip value but it's not affect tho, by the way it only show up when I turn to rendered view, It look fine when solid view.

Does this help? https://blender.stackexchange.com/questions/26558/mesh-lines-appear-in-quick-rendering/26560#26560

@Ray Mairlot sorry but it doesn't help, I had checked many times my object that look good, clear geometry without material. This problem present although I tried to change ortho nor pers view. it also prensent when rendered. About clipping value, I let it default but didn't work too

Looks like creasing due to the subsurf modifier and some non-subsurf-friendly topology. Would it be possible to see a wireframe or (better yet) the .blend?

@gandalf3♦ I have just add my blend file, thank for your time

@baophan Huh, I've never seen anything like this! It seems to be a numerical precision problem in cycles. As far as we're concerned from a user perspective, I'm not sure there really is a fix besides keeping the object closer to the origin.. Depending on what you're trying to do, perhaps we can come up with a workaround?

@gandalf3♦ I had created a big environment (a city)  and put my character to animated it. But when I move my char too far from center it became weird like that. Additional, I put char on a car and the car follow a long path so I can't control it.

@baophan I see. One possibly solution would be to separate the area the character stays in into a separate scene, moving it closer to the origin, then rendering both it and the far scene and compositing the two together. That would no doubt be a bit complicated to set up and might run into trouble if your animation is supposed to traverse a large distance without any cuts.

@baophan If that's the case, you might try animating the city moving long the path, keeping the camera close to the origin. That could prove rather annoying to manage, though it may be possible to have an addon take a normal animation apply the inverse as appropriate

Or poke the devs and see if they can make an up to date patch (I see there is a patch, but it apparently doesn't work with the latest version)

@gandalf3♦ thank you so much, I put my question into another forum and the answer is a bug of cycle, I will try to separate my scene and waiting for a patch too

This seems to be due to an old bug. The cause has been identified:

The issue is actually coming from the way how ray bounce is happening: it is using ray_offset() in order to avoid self-intersection. This function will push ray along the face normal by a small value. This small value is different for different axis and actually depends on magnitude of the original coordinate. In this case ray is getting pushed a bit more along Y axis than along X and Z axis. This makes ray to be moved into the surface itself, causing light artifacts.

But it's apparently difficult to solve. There is a patch you can try if you are familiar with building software, but you'll likely have to apply it to an older version of blender (and it doesn't fix everything).


text:
I want an arrayed object to be upright throughout a tapered spiral

I want all of the objects to stay upright and un-distorted throughout the whole structure.
Also if you notice anything fucky with what I'm doing and have suggestions I'm all ears. I am new to this and need to learn the proper workflow the first time as to not spend a lot of time unlearning bad habits.
Thanks!

I have followed what you said and now I'm getting 180 degree rotation on the y axis.
Also there is only one object at the very top that has a random amount of rotation.

I don't think you're doing anything funky..
The simplest way I can think of to persuade Blender to  respect the Normal, but ignore the Tangents of your curve is as follows:

In its Data tab > Shape panel, set the curve's Twist Method to 'Z Up'
Just as you have already, make a planar object, and give it array and curve modifiers:

As before, it tilts, but we're going to use it as a particle emitter, so it won't matter
Give this placeholder/emitter a Particle System with settings as follows:

All particles are emitted on frame 1
The same number of particles as the array count, evenly distributed, 1 per face.

And: ( my rendered object is called 'Mount')...

... emitting instances of your actual object, aligned to the emitter's Normal (but not its tangent axes)
The emitter planes are not shown in the final render... In my build, the viewport display sometimes needs kicking to refresh.. moving the current frame off 1 and back again does the trick.

This picture of the result also shows the working orientation of the green rendered mesh, with respect to its own object's local axes.. (adjust in Edit Mode)

To be fair, 'funky' wasn't the chosem adjective

Hey your post has been pretty helpful. but i have run into further issues. I dont know how to put images in the comments so i just put them in the parent post.
Thanks!

Also is it possible to make the particles into a real object that can be used for physics simulations? I eventually want to have fluid interact with them.

@hghfhgghg    To make particles real, apply the particle system modifier .. How did you construct your spiral?

I made the spiral by using a spiral generator addon called "extra shapes"


text:
Does blender video editor have a histogram? How to appear it
My question is how i can appear the histogram in blender video editor?
example i am looking for something like this

i added an image, i am looking for something like that in order to fix the color see the over/underexposed etc.
i know blender have got something like this for images but what about for videos??

If you set the a Video Sequence Editor window to 'Preview', a 'Display Mode' dropdown becomes available in its header.

On the right, the illustration shows a split into several VSE windows, with their Display Modes set to the options, and their headers hidden.
Now, if someone can tell me how to get rid of the little pan and zoom navigation icons, when there's no 'Gizmo' menu....

I followed what you said and it worked!
Thank you!!


text:
Is that a bug? Circular dependency on images
Im trying to bake textures, and i get this circular dependency even if i got 2 materials and its pretty straight forward plug 1 map in its socket. And this causes map that im baking to ignore that texture. But what makes me think that it is a bug of some sort is that if i replace this texture(delete and plug same one) it works just fine

So here is an example with 2 materials, some basic stuff
And here is what happens when i hit bake :/

maybe give some screenshots or even share your file (with the images packed witihn): https://blend-exchange.giantcowfilms.com/

added screenshots. i should mention this only occurs if i bake on copies of blendfiles that contain packed images. but its not for every image/material this happens, only some. Also as you might imagine it modifies both of those(no surprise here im guessing)

hard to understand with only screenshots, when you bake you need to select the Image Texture node with the image that is supposed to receive the bake picture, also there might be a refresh problem, so try to unplug and replug the Image Texture into the socket?

yes, that workes if you unplug it(well i deleted and plugin from new one it but same thing). Guess it is just a refresh problem , not a bug , ty


text:
Blender viewport frozen(can't perform operations)
I was working and probably hit some shortcut and it froze my viewport, i can not select anything other than what is selected nor i can delete stuff. What could that be ? here is a quick gif

Even the gif is not working! Maybe your computer has a ghost.

it did in chrome , probably cache lol, reuploaded it

Concerning my question : shortcut hid collection , but it was visible in local view


text:
Experimental sub surface modifier making the mesh look layered, seemingly not due to ngons?
I'm new to this 3D animating so I need a bit of help when there's troubleshooting in the air! I have an issue when I apply experimental subsurface modifier, where the mesh seems to be doubled or scaled inside out if that makes sense. I did some troubleshooting myself, and my own thoughts were that it could be flipped normals. Although there were 1 or 2 flipped normals, fixing this didn't solve the actual problem. Then I looked for ngons, which I know is the case for some of the mesh, but for the rest of it I'm not sure what causes the weird effect.
picture #1: Picture of the entire model in rendered view, the black areas are not intended either, some of this could be ngons as I haven't fixed them yet
picture #2: this is a cube inside the full model, it's literally just a cube where I moved the vertices and used the mirror modifier on the y-axis
picture #3: Same as 2nd picture but this is with x-ray on

Right I've forced myself to sit down and fix the ngons now and there are way more than I originally thought. The mesh looking strange on the 2 last pictures actually doesn't appear when I move from rendered edit mode to rendered object mode. I apologize if I have wasted anyone's time!


text:
Get access to the device type GPU and CPU activation
I would like to store and load the activation of CPU and GPU in the device types.
In the python console could I find this path:
bpy.context.preferences.addons['cycles'].preferences.compute_device_type

This shows the device type but I can't find the access to the active GPU or CPU.
Any idea?

@Robert Gützkow - I'm thinking you might be able to assist with this, based on your answer here - https://blender.stackexchange.com/questions/154510/how-to-select-all-non-cpu-cuda-or-non-cpu-opencl-devices-for-cycles-rendering-c. My knowledge of .bpy in this manner is rather limited, I'm afraid.

Does this answer your question? Selecting GPU with Python script

This information is in the cycles addon preferences.  As you know, access to the preferences for that addon can be found using bpy.context.preferences.addons["cycles"].preferences.
The cycles preference has a method get_devices that returns a list of tuples of CyclesDeviceSettings.  The information you want is in the tuples in the individual entries.  Here's some code that prints that information:
This, of course, is an undocumented API and may change from release to release.  This works for 2.93.6
import bpy

deviceList = bpy.context.preferences.addons["cycles"].preferences.get_devices()
for deviceTuple in deviceList:
    print("Devices:")
    for device in deviceTuple:
        print(f"\t{device.name} ({device.type}) {device.use}")

It is left as an exercise for the reader to determine how the tuples are used.  On my machine in 2.93.6 The output from that script is
Devices:
    GeForce GTX 1070 (CUDA) True
    Intel Core i7-7700HQ CPU @ 2.80GHz (CPU) False
Devices:
    Intel Core i7-7700HQ CPU @ 2.80GHz (CPU) False

The relevant source can be found, with developer extras enabled, by right clicking on the fields with the red arrows and selecting "edit source" from the menu. It is, um, enlightening.


text:
What maps should be baked in a high poly model to use in low poly?
Which of the following maps should I draw in High Poly, bake and transfer to Low Poly, and which ones should I draw directly on Low Poly?
When modeling a human character. Roughness map, Ambient Occlusion map, Diffuse map, Displacement map.

There's no right or wrong answer for that, it depends on what you need.
Usually to transfer model details from high poly to low poly you'll need to bake the normal map and/or displacement ("height") map. If all you're trying to bake is the geometry detail, that's all you need.
If you already textured the high poly model, you'll want to bake the diffuse to transfer the color map to the low poly. If your high poly already has roughness maps you'll want to bake them too, and the same goes for metallic, specular, etcetera.
Ambient Occlusion map I think is necessary only for game assets (and even so, not always necessary). As I said, everything depends on what your needs are.


text:
What does the MixRGB or Mix Shader node factor do exactly?
So on both the mixRGB and the mix shader nodes there is a factor input.
But what exactly does the node do? I know that in the case of mix RGB it has something to do with the probability light rays hit either material and that in the case of mix shader the node performs some kind of linear interpolation between the base layer image and the resulting image.
But is that really all there is to it?
Thanks!

The Factor input on its own is a linearly interpolated blend between the two inputs - the Factor can also be used as a socket for a black and white mask texture that will define the blend areas based on its parameters (light and dark areas).

The MixRGB node has two color inputs and a drop down menu, as well as the Factor input.
Each entry in the drop down menu selects a function that is applied to the two inputs to produce the output.  In some cases, the Factor input is used in the equation to control how much of the affect is applied.  In other cases it is ignored.
Here are some examples, using $a$ for the top color, $b$ for the bottom color, and $fac$ for factor

Mix: $a + (b - a) * fac$; Most useful for using a mask as the factor to select between an image versus a background color;
Darken: $min(a, b)$;
Multiply: $a * b$ [ie, $a_r * b_r$, $a_g * b_g$, $a_b * b_b$];
Color Burn: $1 - ( (1 - a) / b)$; can be used as to do things like setting the width of mortar.  Set $a$ to a gradient (IE, the X coordinate, Set $b$ to 0.  Then color burn effectively goes black from 0 to factor and then is a gradient from factor to 1. NOTE: always clamps to [0..1]
Lighten: $max(a, b)$;
Color Dodge: $a / (1-b)$; the opposite of color burn Does not clamp the negative [-inf..1]
Add: $a + b$; useful for layering displacement maps.
Linear Light: $(a + 2*b) - 1$;  Factor is important to this; but the big thing is that you can use it to add noise and control the noise.  Put the noise in b.  The basic shape of a doesn't change but factor acts to attenuate the noise. It's a good way to add noise to coordinates.
Difference: $abs(a - b)$

The Mix Shader node has two color inputs but no drop down.  It uses the same equation as the Mix mode of the MixRGB node.

Source code for reference. Usually the factor lerps between a and f(a,b), where f is the named function eg. a*b for Multiply.

Thanks @scurest

I like a+(b−a)∗fac as opposed to a∗(1-fac) + b∗fac  Worth a note the Factor is still used in every mode, where b becomes the result of the formula.

Well I'm aware that usually the fac input results in a lerp operation, but is that always the case, since it is also sometimes part of the color blénding functions?

@tempdevnova that's correct, as witness the way the Mix or difference operators are implemented.

@MartyFouts Hi! Could you please update full functions of the blend modes with Factor applied to each of them? Please check out my post for more details: https://blender.stackexchange.com/questions/302085/what-are-the-exact-functions-of-blend-modes


text:
how to attach a script to a button
I have a panel with 3 buttons and a script that they should execute. But the problem is that I can not connect the desired script with the button.

The script appends the desired character to the scene.

The second script should perform the render settings I need for my work. And I would like to stuff them into buttons

file_path = 'D:/11.blend'
inner_path = 'Object'
object_name = 'Suzanne'
bpy.ops.wm.append( filepath=os.path.join(file_path, inner_path, object_name), directory=os.path.join(file_path, inner_path), filename=object_name )

Perhaps if you pasted the text of your Python code into your question I could give you specific instructions, but the general answer is that you need an Operator. It is a class that, among other things, has an execute function.  You would put the code to set your render settings or run your script into the execute function.  The manual has this simple example:
class HelloWorldOperator(bpy.types.Operator):
    bl_idname = "wm.hello_world"
    bl_label = "Minimal Operator"

    def execute(self, context):
        print("Hello World")
        return {'FINISHED'}

The manual example shows using a menu to invoke the operator, but you could also do it from your Panel.  The technique for that is to assign the operator to an operator layout function.  The Panel manual entry also has an example of that.
Here's an example that puts that altogether.  It uses your commands from your comments; so it's not very general.  Usually one would make the input file and object setable, rather than hard code them.  All you need to do here is add your code for rendering where the comment is now.
import bpy
import os
from bpy.types import Operator
from bpy.types import Panel

# https://blender.stackexchange.com/questions/260863/how-to-attach-a-script-to-a-button

file_path = 'D:/11.blend'
inner_path = 'Object'
object_name = 'Suzanne'

class TLA_OT_addmonkey(Operator):
    """ Add an object called Suzanne from a specific file """
    bl_idname = "tla.addmonkey"
    bl_label = "add Suzanne"
    bl_options = {"REGISTER", "UNDO"}

    @classmethod
    def poll(cls, context):
        return context.mode == "OBJECT"

    def execute(self, context):
        bpy.ops.wm.append(
                filepath=os.path.join(file_path, inner_path, object_name),
                directory=os.path.join(file_path, inner_path),
                filename=object_name
            )

        return {'FINISHED'}

class TLA_OT_setrender(Operator):
    """ Set the render properties """
    bl_idname = "tla.setrender"
    bl_label = "set render properties"
    bl_options = {"REGISTER", "UNDO"}

    @classmethod
    def poll(cls, context):
        return context.mode == "OBJECT"

    def execute(self, context):
        # Put your render property code here
        return {'FINISHED'}

class TLA_PT_sidebar(Panel):
    """Sidebar"""
    bl_label = "Things to Do"
    bl_space_type = "VIEW_3D"
    bl_region_type = "UI"
    bl_category = "TLA"

    def draw(self, context):
        col = self.layout.column(align=True)
        col.operator("tla.addmonkey")
        col.operator("tla.setrender")

classes = [
    TLA_OT_addmonkey,
    TLA_OT_setrender,
    TLA_PT_sidebar,
]

def register():
    for c in classes:
        bpy.utils.register_class(c)

def unregister():
    for c in classes:
        bpy.utils.unregister_class(c)

if __name__ == '__main__':
    register()

I need append
import bpy
import os
file_path = 'D:/11.blend'
inner_path = 'Object'
object_name = 'Suzanne'
bpy.ops.wm.append(
filepath=os.path.join(file_path, inner_path, object_name),
directory=os.path.join(file_path, inner_path),
filename=object_name
)

@Welet put that script in your question rather than in a comment on my answer.  But basically you want to put that code, except the import statement in your Python where the print statement is above.  Perhaps you could benefit from watching the Scripting for Artist tutorials on YouTube?

I rarely write anything. On python, I need help with specific process automation
I will be glad if you can give me the code for my task

@Welet StackExchange really isn't a forum for finding other people to do work for you. It's meant for asking specific questions when you you get stuck trying to solve a problem.  The script I added at the end already does 90+% of the work you've described.  All that's left is for you to figure out what render settings you want and stuff code to do that where the comment is in the code I gave you.

Thanks for the help^_^ and I will keep in mind while improving my python knowledge. I had everything ready except understanding how to fasten the script to the button. So thank you more

@Welet you're welcome.  Good luck with your script.

Hi, could you help me again? https://blender.stackexchange.com/questions/261075/how-to-use-relative-paths-instead-of-absolute-ones


text:
How do I create a script to delete all objects sharing the same texture/material in all collections?
The project I'm working on in Blender has objects that aren't desired from the mesh rips I've pulled from PPSSPP using a tool called NinjaRipper. I'm looking to put together a script that targets meshes with a specific texture(and any iterations like "Texture.png.01") and have the objects deleted from all collections it is linked to. I have been looking at the python api documentation and found bpy.ops.object.delete(use_global=False, confirm=True) which seems to be the end goal of the script but I'm unsure how to go about targeting objects sharing the same material/texture and their iterations, selecting them, and deleting them.

iterate over bpy.data.materials searching the node trees for image textures.  Each time you find an image texture check the image. If it's one you want to delete, add the material to a list.  Then iterate over bpy.data.objects searching the material slots of each object.  If any of the material slots have any of the materials you found in the first search, delete the object.

You need to create a list of the relevant textures, something like this:
texture_names = [
    "texture1.jpg",
    "texture2.jpg",
    "Metal007_1K_Color.jpg"
]

replacing my three sample strings with whatever textures you want.  Once you've don that, this code will

First find all of the materials that use any of the textures in your list and
Then remove any object that uses any of the named materials.

import bpy

texture_names = [
    "texture1.jpg",
    "texture2.jpg",
    "Metal007_1K_Color.jpg"
]

wanted = []

for material in bpy.data.materials:
    node_tree = material.node_tree
    if node_tree:
        for node in node_tree.nodes:
            if node.type == "TEX_IMAGE" and node.image.name in texture_names:
                wanted.append(material)

for object in bpy.data.objects:
    for slot in object.material_slots:
        if slot.material in wanted:
            print(object.name, slot.material.name)
            bpy.data.objects.remove(object)

To do this from the known materials,  use a slightly different setup
import bpy
material_names = [
    #Fill this with strings of material names
]

for object in bpy.data.objects:
    for slot in object.material_slots:
        if slot.material.name in material_names:
            print(object.name, slot.material.name)
            bpy.data.objects.remove(object)
```


text:
How to align a volumetric texture along curve?
I need a Cycles volumetric material that appears to flow along a curved path. Specifically, I would like to stretch a texture along the direction of motion to mimic streamlines in fluid flow. I seem to keep running into the same problem: texture coordinates don't bend.
I originally wanted to model the flow with a particle system affected by a Force Field. While the particles (and their Object Instances) can be made to rotate to point in the direction of motion, the Object Texture coordinates remain constant for the lifetime of the particles.
I also tried mimicking the appearance with a beveled Curve and ticking the "Use UV for mapping" option, but UV coordinates do not support volumetric textures. That is, all coordinates are zero for all locations along and within the Curve shape.
I'm willing to try any method at this point, but utilizing the Compositor could be a problem given the complexity of the scene.
Two potential solutions come to mind but I don't know how to implement them:

Perhaps I'm missing a setting that allows Instances to retain their rotated coordinates?
Generating the UV coordinates of a Curve and using Drivers or some other method (Python? OSL?) to apply them to the volumetric texture to stretch it along the tangent of the Curve.

Any other methods that could work? Even methods restricted to 2 dimensions are welcome.
A couple of reference images:

Io's volcanic plumes The plume is made of multiple curves, each erupted from the volcano in a different direction.
NASA illustration of streamers This effect is likely created with Photoshop or GIMP. Focus your attention on the way the texture bends along each "streamer".

Here is an OpenGL render I did with a stretched cube using a Particle Instance modifier. The particles bend along a path controlled by a Force Field.
The effect I'm hoping to achieve would have the texture stretched along the long axes of these thin objects.

Could you post some example images of what you want to achieve, or perhaps an illustration of a similar effect? Would this be anywhere close to what you want to accomplish? https://plus.google.com/u/0/+DuarteFarrajotaRamos/posts/cJM1c6NyM5b (see the "white lines" flowing inside the colored shapes part)

@Duarte, I've added several examples after a lot of searching. I found that many potential examples did not include the level of detail I'm hoping to achieve. Their "streams" are basic halo-like blobs without any effect to indicate real motion.
I hope my references get the idea across. The curves to guide the texture stretching are not so complex as the example you provided. My curves will be simple arcs or, at most, S-shaped.
As you might tell from my references, I'm hoping to use this curved-texture effect in astronomical animations.

I couldn't think of any solution to your problem so far, the most obvious one of using UV mapping doesn't seem to work for volumes as you already mentioned, and guessing by the amount of answers bellow there doesn't seem to be any other obvious solution. So my suggestion to you would be to drop volumetric shaders as a means to represent the streaks and model them with actual geometry.

Thanks for the feedback, Duarte. I notice Particle Systems have a setting for Trail Count. But this does not seem to be active for Cycles. Do you know if this is true? Is there a way to mimic that effect with Cycles? I've thought of trying it using a frame offset, but I don't know how to implement that idea. Perhaps I should submit a new question?

Yes, maybe try asking a new more broad or open ended question like "how can I achieve particle trail effect" or something along those lines. Maybe someone else has as a way to do that using other methods not involving volumetric textures or even particles. From your image you might be able to do that in the compositor with motion blur quite easily, but I am not a compositor master, maybe someone else can help.

You can create your own rotation node that will allows non uniform rotation. You can then either use a vertex color data or surface normal data to specify the rotation to apply on each point. I'm doing a similar thing here: link


text:
Create light rays in Cycles
I am trying to create something like volumetrics with a falloff: beams of light that shine visibly into the air from an emissive object, becoming gradually less visible as they get farther from the object.

This strikes me as involving some sort of volumetrics, which Cycles supports (yay!), but extruding the actual geometry out and giving it an emission volume shader either produces extreme blocks of light or none at all (and it doesn't have that cool flame appearance).
Plain text on a plane would be perfect!

related: http://blender.stackexchange.com/questions/13802/using-volumetrics-in-2-71-i-have-to-have-the-light-strength-super-high

Related: http://blender.stackexchange.com/q/31562/599

Using a Gradient texture you can fade the volumetric emission off however you want:

In this case, since it should fade out spherically from the center of  the ring I used a spherical gradient:

The vector input of the gradient node defines the position and size of the resulting gradient.
Since in this case we want the center of the gradient to be in the center of the ring, the Object Coordinates (0,0,0 at the object's origin) are what we want. The multiply node scales the coordinate system, which lets us control the size of the gradient.
In the image above the rays are made up of an extruded text object:

For linear gradients, you might not even need the gradient node. For example, the Generated coordinate system has 0,0,0 at one corner of the object's bounding box and 1,1,1 at the opposite corner. Using this, you could fade an object out along it's length by using one of the axis as the gradient:

@gandalf3 Why has your multiply node color inputs and output? I only have one with value. Is that the same ? I googeled but only found examples with value.

@theoretisch You'll want to use a mixRGB node (in the "color" section)


text:
How to play a video strip backward in blender 2.8?
If I select a specific strip from a clip in video sequencer and in strip tab under video -> playback direction -> backward, something funny happens. Can someone tell me whether there is some other way to play the video strip backward.I

Check out your FPS readout in the Preview pane and the cache indicator in the Sequence view.
If your FPS is flashing red numbers that are lower rates than the source video, your machine's struggling to keep up.

Play in reverse Shift-Ctrl-Spacebar usually lags for me until the clip is mostly cached. You'll see the clip cache build as an orange bar below the tracks in Sequence.

Look into cache allocation via Blender's Preferences ... System ... Sequencer Cache Limit and into Proxies. These and other tips will help you squeeze more performance from your machine.


text:
applying multiple textures on the same face
I would like to apply two different textures on the same face. I a window textures over which I would like to put a letter texture. I watched many tutorials but many are old. Moreover trying to apply a different texture on the same face after UV unwrapping seems to be impossible.
To add clarity I am adding images.

ok, all I want is those purple bars to disappear as shown in the image. I tried everything I simply couldn't achieve it.

[Note to moderator: I checked for this over the stack overflow many are just old and difficult to understand I would like the answer for blender versions 2.8+]

The setup in shading nodes is just the same as it was in 2.7x versions. Only editor is called Shader editor now. It could be a bit different for different render engine. Related https://blender.stackexchange.com/questions/2100/different-image-textures-for-one-material-cycles

If what you want is to get rid of the red "letters" on the sections it does not belong, make 2 different materials, one with the letters and one without, and assign the one without to every face on the plane except where you want the logo to be. For the section where you want the letters, use the "letter" material. OR, if you just want one single image for the whole plane, check your UV maps to make sure there are no overlaps, or stretching beyond 1001 space.

thx for the comment, Can you pls elaborate. I want the logo Qatar over windows texture

There are a lot of factors that determine where an image gets placed on a model, including the faces that it is applied to, the scale of the image, and most importantly, the UV maps. It looks like from your picture, for example, that you have 2 different UV maps contributing to your image. Without seeing your file, it is very hard to tell where the issue is. I don't know what UV maps you have applied to your model, nor what they look like. The only thing I can suggest is to look at/play with your UV maps - anything else would be just guessing on my part.

ok just added .blend file

Hey, I got your file, but it doesn't have pictures and I need them, see the edit I made to my answer below.

A common setup for attaching 2 textures to one face is to mix them in the shader graph. The setup below shows a very basic setup for 2 diffuse textures mixed together to form one. If your "superimposed" image (the letter in your case) has an alpha, you can connect it as a mask for the mix factor to place one image cleanly on the other. However, if it does not have an alpha mask, a general purpose (b&w) mask can usually be created pretty easily by converting the color map to b&w and using that. If you end up needing instructions for how to do this, I will be happy to add them.
See image below:

EDIT - Hey, I checked out your .blend file, but unfortuately, it didn't come wuth any images. Often it doesn't matter, but in this case, where the positioning of the one image is important, I need to see that image. To pack all the resources into the .blend file, go File > External Data > Pack All Into .blend. If you send me the file with the images, I should be able to help.
See below:

EDIT 2 - Hey. The problem was rather simple, you have UV islands in a place where they are getting info from the letter logo. See the image below.

I'll also upload the .blend file, but i'm not sure it will work becaus I had trouble packing the textures. At least you can see where I placed the islands.
File is here -
Hope this helps

thx for the answer, I have added an edit can u pls look into it

Yeah, I added a comment to your question. Look up there ^

Ok, I updated my answer (EDIT 2)

thank you very much :)


text:
My mesh is a black wireframe but only on layout mode

My mesh is black and transparent, only on layout mode and I do not know how to change it.

The donut is in wireframe view, so to make it the default "grey" again, select the sphere in the top right corner of the interface that resembles a filled circle. This will set the object to a "solid" view.

You are in wireframe shading. Switch to solid shading to get it solid grey:


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Drivers disable lights
I wanted to use drivers to finely control the output of my scene lamps. But attaching a driver to the "Power" field causes the lamp to not render at all, even though the number I want is still appearing in the field. This is happening in both eevee and cycles.
The driver is controlled by the Z-location of another object, which is animated using the "follow path" constraint. The expression gives me the value I'm expecting, but that value doesn't seem to be actually used by the lamp as long as the driver is active.
Here is an example of the problem.

Works fine for me. Perhaps you could [edit] in an example file? https://pasteall.org/blend/

The power is set to mW, you want to at least multiply the driver expression by 10 or 100 to see the effect. Or scale your path up in object world

So basically I had to increase the number. Kind of sad that I didn't think of that, but I didn't notice the unit change.