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Having a material reveal itself along the object's path? -- For Lightning

Hello. I'm attempting lightning in Blender using Eevee. Referencing a video on Youtube, I created the material shader for the lightning bolt. In it, I am supposed to be able to create the "strike" of the lightning via texture coordinate magic. This KIND OF works. If it's just top to bottom or vice versa, straight up and down vertically, it works. But if I have the bolt mesh curve back around to go up again (as seen in pic), it's clear that the material reveal is doing a uniform top to bottom. If the beginning and end of the bolt are near each other at the top, they both come into view at the same time, and meet at the bend at the bottom. I can't for the life of me figure out a way to tell it to reveal from what I consider the beginning of the bolt, to the end of the bolt. Tried plugging all of the different little purple slots in the texture coordinate node in, and nothing fixes the issue.
I also tried looking into growing the bolt from one spot to another. Using bevel on a curve works great for this. Problem is, apparently I can't do displacement modifiers on a curve (which is needed for animating the bolt's movements). So I can either animate the bolt as mesh and its unable to grow along curve, or I can have it grow along curve and its not able to be animated via displacement modifiers.
Only workaround I can see is to just have the bolt physically pushed along a pre - placed curve. This sort of gives it the illusion that it's starting in one place, and ending at its target. However, I need to hide the bolts being active the entire render in some black object until they're needed. Which is a big hassle. There's gotta be a way to reveal this emission material along the bolt. Maybe there's a "start at this vertex, end at this vertex" sort of thing? I don't know.
If anyone has an idea of how to either A) make the material reveal itself from beginning to end custom, or B) I can make it grow from a point like a curve, I would be very grateful.

It looks like you're using a curve object.  Use UV coordinates instead.

@Nathan This doesn't work. If I use UV instead of object, I can go between 0 and .999 and the material is off. As soon as it hits 1.0 , its completely on now. Not gradually like I desire. Thank you for the comment though :)

See the answer for a bit more detail.

If you're using a curve to create this, curves in Blender have the pleasant property that they create a follow-active-quads style UV map.  We can take a look at how this UV map looks by converting a curve to a mesh and inspecting the UV map that is created:

This is a polar map: the Y axis represents angle from the center, from -180 to 180 degrees mapped to 0,1, while the X axis represents the length along the curve.
This makes it extremely easy to animate a curve growing simply by checking whether the UV.x is greater than some particular value.  Here, I'm just checking to see if the UV is greater than 0.5, and emitting white if it is, black if it is not, but there is no end to what can be done here; a simple modification would be to mix with transparency on the basis of UV.x.  Of course, the comparison value (for the greater than) can be animated, or driven from a #frame driver.
However, I'm not certain exactly how your exact shape is being created; the modifiers look quite a bit more complicated than I would expect.  You have several curves shown in your outliner, so I'm not sure if one of them represents your actual lightning bolt.

I feel I may be biting off more than I can chew haha. I've gotten bolts (mesh version) to do almost anything I need them to except having the grow from one point to another. (Or at least revealing it's texture giving the same illusion). Your answer is more complex than I am used to, specifically with all the UV info. I feel that communicating via this answer thread will not yield great results. Is there a place ( and are you willing?) where we can talk about this in detail? Like streamed to you via discord? Don't want to take up your time if you don't want, but it would make the process easier

Yeah, BSE isn't great for conversation.  I don't like real time stuff myself, but I'm always happy to help people out on blenderartists.org, where it's a bit easier to have a conversation (and there are other people happy to help there as well.)

Okay. I am not familiar with this BA, as I'm new to blender in general. But I can try to hop over there. Thanks for the suggestion!

i am not sure why you want to make it complicated, but you can easily animate a flash/curve with GN like this:

result:

Note: animating the End value from 0-1 animates as you see it.
Animating the other direchtion: animate the Start value from 1 to 0.

Hello! Thanks for the response. After some testing, this kinda helps / kinda hurts what my goal is. By using your method, I am able to animate the reveal like the video you have. I am also able to add my displace modifier AFTERWARDS to give it the wiggle effect like the lightning ought to have. However, when I go into edit mode on this spiral I've created, there are no anchor points do adjust the shape of the curve, nor vertices to edit like a mesh. This is important to other aspects of the bolt I need to animate. Converting to mesh eliminates everything done so far, so that's a no - go too.


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Imported .Obj has problem with texture export
The problem is that when i have to export it, and later I import it the textures are gone, the model appears black (like in the image) and the game that  I want to export it to does not recognize the textures and they appear missing any solution (?)

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

It looks like you switched from Cycles render to Blender Internal render at some point (or maybe the other way around). When you import an OBJ, blender will automatically generate and assign materials to the models you imported, but the materials are generated only for whatever render engine you have selected when you import.
It looks like you imported the model with Cycles render enabled, then later switched to Blender Internal. Try just switching your render engine, then trying again, or redo the import/export process, making sure to keep your render engine the same.
I recognized this error because in one of your images, your material looks like some sort of sky texure-like thing, which is what happens when you switch engines and leave your materials the same.

source: Stack Exchange

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

sort: votes


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Making a wall made from glass bricks
I need to make a frosted glass brick wall (see the example) for archvis picture. What is the best approach for it? Using just a cube with a texture of framing grout and glass shader for bricks will not make those clearly visible internal dividers on brick edges. Modelling the whole brick and making a wall from it will be time consuming and may probably lead to heavy geometry.
In both cases, a simple glass shader will absorb too much light for such a thick object, so what it is the better way for it?

I don't think you can avoid the geometry cost...

you can create your object and link-duplicate it, and add some water droplets to bring some variations, and about the shader maybe mix a Glass (with high Roughness and low IOS) with a Transparent shader, maybe try shaders like translucent, or Volume Scatter in the Volume input of the Material Output? Maybe also give it a bit of noise bump...

It reminds me of this beautiful building in Amsterdam : https://www.dezeen.com/2016/04/20/crystal-houses-amsterdam-chanel-store-mvrdv-glass-facade-technology/

Geometry should not be an issue here, glass shaders are noisy by nature and will probably have a bigger impact in your scene. If you use this technique and take advantage of instancing feature the memory consumption benefits should help mitigate the number of objects.
Make a simple box mesh with the desired dimensions of your brick, make sure you apply the scale.
Add three material slots with the following order: Clear Glass, Mortar, Frosted Glass.

Create materials accordingly as desired and assign clear glass to both front and back faces, and mortar to the remaining four rim faces around them. Two simple glass shader with different roughness values should suffice for both glass materials.
Now add two modifiers. One Solidify with the desired thickness; adjust the material offset to $2$, so the inner layer becomes all frosted glass.
Now add a Bevel modifier, to add some roundness; adjust radius as desired.

Now array the bricks with whichever method you like.

Either use an Array modifier: Quick and simple, no optimization and higher memory use.
Manually duplicate the object around: Instancing gives memory benefits, but ads lots of individual objects which may slow down the viewport and pollute your scene, making it harder to manage.
Use a particle system/Duplifaces. Array a simple plane and use either particles or duplifaces to distribute bricks along the faces. Harder to setup, memory benefits, and less individual objects to manage in the scene, but may still slow down the viewport.

Distributing the bricks using duplifaces is a very smart idea!

More memory for an array? I thought they were instances, just with a bit of organisation.. I'm surprised..

Array has no instancing optimizations, it just generates one big mesh, since you can't guarantee all items are exactly the same. With the Merge options it can even result in a single mesh with no separate parts.

you can model a brick and then bake it to a displacement or normal map and use that on a lower poly brick and then use 2 array modifiers on different axis to create the wall

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


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Need help aligning model in pose mode
I'm trying to animate a model with an armature and get it to bend its knees. When I try to do this along the Y-axis, it'll have the model be skewed way to the side when I switch the camera facing the X-axis. I probably have my alignment wrong somewhere, but i'm not sure how to fix it? Here's some pictures of the problem.

I want my model to be perfectly aligned along the X-axis stead of skewed like that. Any help would be much appreciated, thanks!

I figured it out! Make sure all your bones in your armature are set to this transform.

A few of my bones had -0.00 and for some reason that was throwing my alignment off.


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How to un-mirror object?
So I currently have my mesh mirrored to where if you edit one part of the object, it will edit that other side exactly the same way. I want to turn this off since I want to edit my left arm and not the right arm. How would I do this? I already tried turning off X-Mirror under Mesh Options but that didn't work.
Here is a picture of my object

If you are using a mirror modifier, simply apply it under the modifiers tab

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

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


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Freestyle Cell Shading flickering problem
I’ve made freestyle Black/White outline and for an unknown reason, some of the outlines flicker. Often I can freestyle rendering lines even if it’s behind other mesh which seems to work pretty randomly.
Does anyone know any fixes?
I’ve tried searching on google but nothing seemed to work.
I’ve tried Blender discord, nobody seems to know the fix.
I have had this problem since December 2021 and it kinda stopped this project for me after half of the year of work.
Here is a video showing this problem:
https://youtu.be/ouWvcSiaeyg


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Freestyle flickering problem
https://www.youtube.com/watch?v=ouWvcSiaeyg&ab_channel=Stesiek1235
I’ve made a freestyle Black/White outline and for an unknown reason, some of the outlines flickers. I have many scenes but only in this one, I’m having this problem.
Does anyone know any fix?
I tried searching on google but nothing seemed to work
I tried soo many things in freestyle options for several hours now.

Hello ! Hard to say but try to make sure you don't have any duplicate hidden object where the flickering happens

Inside of the mesh you mean?

Sometimes when modelling you duplicate your objects and hide them, but it does not hide them from rendering. So the renderer sees duplicate geometry on the exact same place and has to randomly decide which polygons to render. The concept is a bit complicated and it may not be the culprit in your case, if you're interested in looking it up, it's called Z-fighting

Doesn't seem like it. I unhide everything, moved a few models, tried to work with a single cube instead of a building, deleted all the lights near the building, deleted this wireframed fence between the buildings, tried to duplicate a scene, messed around with freestyle options, but the same thing happens.


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How to create an animation of a rotating shape?
I am very new to blender. I would like to animate this SVG file

Below is the SVG file, and below is a screenshot of it:

<?xml version="1.0" encoding="UTF-8"?>
<svg id="SVGRoot" width="151.2mm" height="143.79mm" version="1.1" viewBox="0 0 151.2 143.79" xmlns="http://www.w3.org/2000/svg" xmlns:cc="http://creativecommons.org/ns#" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
 <defs>
  <marker id="TriangleStart" overflow="visible" markerHeight="20.027746" markerWidth="17.323999" orient="auto-start-reverse" preserveAspectRatio="xMidYMid" viewBox="0 0 5.3244081 6.15538509">
   <path transform="scale(.5)" d="m5.77 0-8.65 5v-10z" fill="context-stroke" fill-rule="evenodd" stroke="context-stroke" stroke-width="1pt"/>
  </marker>
 </defs>
 <metadata>
  <rdf:RDF>
   <cc:Work rdf:about="">
    <dc:format>image/svg+xml</dc:format>
    <dc:type rdf:resource="http://purl.org/dc/dcmitype/StillImage"/>
   </cc:Work>
  </rdf:RDF>
 </metadata>
 <g transform="translate(-74.503 -36.09)" stroke="#000">
  <path d="m197.88 107.95a53.047 53.047 0 0 1-53.047 53.047 53.047 53.047 0 0 1-53.047-53.047 53.047 53.047 0 0 1 53.047-53.047 53.047 53.047 0 0 1 53.047 53.047z" fill="none" stroke-width=".26458"/>
  <rect x="137.8" y="48.706" width="16.757" height="12.347" fill="#0f0" fill-opacity=".99314" stroke-width=".26458"/>
  <path d="m141.84 107.94h6m-3-3v6" fill="none" stroke-width=".5"/>
  <path d="m131.55 80.351a13.633 12.828 0 0 1 11.149-7.0024 13.633 12.828 0 0 1 12.131 5.3647" fill="none" marker-start="url(#TriangleStart)" stroke-width=".27962"/>
 </g>
</svg>

I need to rotate the rectangle in a circular path (following the circle).
Could someone please guide me on how to proceed?

Hello and welcome. Please don't post the same question more than once. If you feel your previous question was incorrectly marked as duplicate, or the linked posts don't adequately address your issue, go back to your previous question and edit by pressing the Edit button below, including information of what you have tried, why it failed and how the duplicates don't address your issue. Once edited the question is automatically queued up for review so it can be reopened.

I'm not sure about animating the SVG file itself, but if what you need is an animation that does what you're asking, you could certainly use the SVG as a template to create yourself a cube and a circular path object to get started.
As mentioned, start by making sure your scene has both of those objects.
Select your cube, go to the object constraints tab and choose Follow Path. It should look like this:

Note: If you click the Follow Curve option, the cube will rotate as it moves along the path like a train on tracks. If you don't, it'll just move without rotating.
Now all you need to do is hit that Animate Path button and you're good. Adjust the size of your cube as required. Note that the Animate Path button will create an animation at a predetermined speed, so if you want to manually animate it, you can do so by using keyframes to adjust the Offset value.
To do that, don't click Animate Path (or Undo if you have), and follow these instructions:
At frame 1, hover your mouse over the Offset value.
Press the I key (this is the keyboard shortcut for adding a keyframe)
Move to another frame further along.
Set the Offset to 100 (this represents one full 360º turn).
With your mouse hovering over the value, press the I key again.
Go back to frame 1 and hit play. It should animate around the path nicely. Look in your timeline and you'll see the keyframes represented by little diamond shapes. Move the second keyframe around to adjust the speed.
Now to set up the frame and shoot the animation!
Move your camera upwards and point it down. With your camera still selected, go into the Camera settings tab and change the Type from Perspective to Orthographic. This will eliminate perspective warp and give you a flat box when viewed from the top. Like so:

To recreate the shapes in your SVG, we're going to shoot a bird's eye view of your scene. Look up a basic guide if you need help setting up your frame range, materials and render engine/settings.

Hi! Thank you very much for your answer. Unfortunately, I need to animate the SVG because usually it contains shapes that I can't reproduce on Blender.

@OK-Validation I see! In that case you may need to use something like After Effects. Blender, to my knowledge, does not have vector animation capabilities like this, but I could be wrong. It does have a 2D animation toolset, though, so it may be possible.


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How to line up armature and mesh after deleting the armature modifier?
So I accidentally deleted the armature modifier and when I go to make another one, my object warps. When I try un-checking vertex groups, the armature will line up with the object again but I cant use it for animation. So how do I line up the armature and mesh with keeping vertex groups checked?
Before adding armature modifier

After adding armature modifier

Could you upload your blend files here https://blend-exchange.giantcowfilms.com/ so I can try to help you?

Here's a link to it

To fix this follow the below steps:

Select your mesh
Hit ctrl+A and choose apply Scale
Do same step 2 and apply location and rotation
Select your armature
Switch to Pose mode
Hit Space Bar and choose "Apply Pose as Rest Pose"
Select Mesh then select armature and hit ctrl+P
Parent with automatic weighting

It will be working fine as shown below:

So when I did step 6, there was no option to apply Scale. The only option was Play Recorded Animation.

@Bionicman30 Sorry, I made a typo mistake in step 6. Answer updated.


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How do I make a pattern of holes going through a mesh ? I'm working on a chair and I'm new to Blender
A pattern of hollow holes on the surface of the chair going through it
Bottom of the chair
Reference photo

https://blender.stackexchange.com/questions/65395/repetitive-carvings-holes-around-a-sphere https://blender.stackexchange.com/questions/210786/modeling-hexagon-pinhole-lens-for-3d-printing/ https://blender.stackexchange.com/questions/58811/how-to-create-a-circular-shaped-grid-similar-to-a-manhole-cover https://blender.stackexchange.com/questions/28103/creating-a-truck-exhaust-mesh

create a plane, subdivide once, delete the inner vertex, extrude and scale inwards, right click > LoopTools > Circle, extrude down to give thickness, delete the side faces, array on X and Y, enable the Merge option of the arrays, give it a Subdivision Surface modifier


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How can I prevent accidentally dragging just one child of a parent?
I have imported a variety of tree models from Artstation into blender. When I drag some of these models, the entire object moves together. For other objects, it's like the children are unlinked or something - dragging them with the mouse results in e.g. just the leaves or branches moving. If I select the parent object under the Scene Collection menu, then I can move it as a whole unit.
See the attached picture, the ones moving as a unit (Beech_forest) show triangles in the Scene Collection menu and the ones which seem 'unlinked' (Black Alder1/2) show what appear to be 3D axes.

What's going on here? How can I combine the Black Alder imported objects into one item which moves as a unit when I drag it without selecting it in the Scene Collection?

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

"Beech_forest_12Xfo.006" and "Beech_young_8Xfo" are mesh objects (that's what the orange triangle means). "Black_Alder1" and "Black_Alder2" are empties which have 12 / 11 mesh objects parented to them, that's why there is an orange triangle with a 12 on the first and a triangle with a 11 on the second.
If you move them in the outliner by just dragging them, you only move the selected objects, i.e. in case of the empties just those, not the objects parented to them. Parent and child object can be associated to different collections, which means the children will not be moved automatically with the parent object in the outliner.
To move a parent with all its children to a different collection, right-click on the empty, choose Select Hierarchy from the context menu and then drag them where you want them.
If you want all children in a single object instead of separate objects parented to an empty, you could select all objects that belong to an empty and in the viewport press Ctrl+J to join them all into one object (therefore one of the mesh objects must be active i.e. have a brighter outline, not the empty) however without knowing the models I cannot recommend this because if they have different modifiers etc. on them they could all be reduced to whatever is set on the active object, which can change the appearance of the models in an unwanted way.


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Subdivision surface modifier & topology
I created this component see screenshot, but after applying subdivision surface modifier the whole surface was distorted. In previous projects, the edge split modifier helped me solve this, but in this particular case it doesn't work quite right. Is this a topology issue?
Thank you very much for all the comments :-)

Yes it is a topology problem, subdivision surface doesn't work well with n-gons and edge-split won't help you around this since it only splits the edges at a given angle threshold.

Big topology problems. please upload the blend file so that we can show you the right topology.

Also, edge split should be placed after the subsurf generally.

Thanks for the quick coments! Here is the link to the file: [link] (https://drive.google.com/file/d/1iFLNKE5lyT5rMgREcMm-J1wP5-rVB47c/view?usp=sharing)  @BarbodM

Honestly, I think the easiest way to fix your problem is to rebuild your mesh from scratch by following moonboots' method because it has really terrible geometry and you will not be able to work with this mesh in the future when you are texturing it, UV mapping it or adding modifiers etc. It's going to take a long time to clean up your mesh so instead, I think it`s best to start from the beginning...that is if you want to.

Sure, I understand, thank you for all the suggestions!

Maybe try this topology instead?

Create an angle, bevel it:

Extrude faces along normals:

Extrude this part:

Bevel:

Bevel the edges in order to sharpen:

Thank you, @moonboots ,  it's clearer now. So am I correct that for good topology, it is better, if it is a curve or a bevel for example, to have the same number of vertex on both sides?

sorry I'm not sure what you mean by "the same number on vertices on both sides"

I apologize for the bad wording, @moonboots. Basically, I mean more of a balancing of the overall topology, or better a vertex linking, where the preferred shape is a quad.

it's generally better to have quads (it easier to work with and create less artefacts) but here for example I have a ngon and it's ok as long as it doesn't create artefacts


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How to get rid of seams on model?

So, here you can see what I'm stuck with. Im trying to make character with different parts, and because they all are separated, you can see "disconnected seams" I want to smooth these seams, but idk how. Help please.

Most likely, you will have to merge the separate meshes. If this a sculpt, you can remesh it.

Hi, congrats on your first question here!  If my answer below doesn't answer your question then a few more details could be helpful, such as if these are different objects or a single non-continuous object, if you've checked that all the normals are facing out, or a screenshot showing the topology of the mesh/es.  Also, it's often a good idea to post your blend file, or a truncated version of it that has the problem.  The Blender StackExchange has its own service to share blend files:  https://blend-exchange.com/help

If you're trying to make character with different parts, it seems very hard to avoid that effect, why do you want to keep different parts?

If by “they all are separated” you mean that they're different objects, then you can't, it's not possible without joining them into a single object.

In the above screenshot the Suzanne on the left (subdivision applied) is a single object.  The Suzanne on the right is a copy of it with some parts separated into different objects.  Nothing else was done, the topologies are still otherwise identical, but the different objects of the Suzanne on the right can be clearly seen.


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How to automatically readjust "Final frame of the playback range"?
How to automatically readjust "Final frame of the playback range" to frame of last yellow dot in the Action Editor?

could you please elaborate a bit more what you want to have? maybe a small example or a sketch with annotations?

https://imgur.com/a/QqAdmyu
You can see that yellow dots are not at the end.
How I can readjust final frame to last yellow dot without manually typing it to the field?

I don't know whether it is possible what you want, but you can check your "Set end frame" settings in your preferences -> keymap.

Then the end frame will be set at that position, where the cursor is, if you press that button - combination:


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Am I assigning materials wrong? (Material will not display on object in any mode)
Blender version 3.0
OS: Windows 10
GPU: AMD Radeon HD 7900 (software version 21.5.2)
CPU: Intel i7-7700k
Hello, I have encountered a problem regarding assigning materials to my object that I cannot seem to fix on my own. What happens is that when I go to the material properties tab and add a new material, it does not show up on my object in object mode or edit mode using the material preview in the layout. My object turns into a grey silhouette.

I have gone into the node editor and tried assigning the principle BSDF and material output by placing the nodes in myself instead of using material properties to see if this fixes it. It does not. The material does not show up.
I have noticed that using no nodes allows the material to show up, but I want to use material nodes for this model. Assigning a base material in texture paint also works fine and displays properly.
Important note:
I do have a previous project that does show materials that are assigned to it, whether it is an image texture of just the settings of the principled BSDF but this previous project seems to be the only one that can display materials from the shader editor.
I have tried testing adding materials to the default cube in a new file to see if it is just this project that is the problem, and they will not apply, I get the same grey silhouette.
It seems like I am missing an important step in this that i have forgotten since my previous project, and all tutorials I have seen that concern assigning a material seem to just click "new material" in material properties and the principled BSDF assigns to their model with no issue. I do not think it is a gpu driver issue, since if it were, probably the materials of my previous project would not show at all.

It's your GPU drivers most likely. Try enabling "High Quality Normals" under Render Properties > Performance.

That fixed it! Thank you so much.


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How do I scale and rotate bones without stretching the mesh?
Ok, in short I have scaled the bones of a mesh to make a character look like a "dwarf" or "chibi" version of itself. However this seems to have applied as a pose and not a change to the armature. If I delete the pose, the mesh returns to its original state (as if I'd done nothing).
The problem is that I did this scaling with the character in T-Pose and trying to actually pose the character now causes parts to stretch and warp like they're Mr. Fantastic.
For example, if I rotate the shin bone to bend the knee, the shin and foot now elongate weirdly and out of proportion. How can I prevent this from happening?
My goal is to have the character remain posable in their new "dwarf" form as if that were the new normal. I'm not terribly well-versed in Blender for this sort of thing, so I may need a "for dummies" explanation.
Thanks in advance,

try to duplicate the Armature modifier, and apply the copy, it should apply the new limb proportions

A picture is worth a thousand words, please ... you lost me.

I recommend you apply the armature modifier on the mesh, then go into pose mode on the armature, select all, and “apply as rest pose.“ Then, relink the mesh to the armature with a new armature modifier.


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Double interaction with cell fracture
what is driving me crazy right now is that I want to animate a vase that is pushed off a pedestal and when it hits the ground it breaks into pieces. To break the vase into fragments I used the cell fracture add on, the problem is that the vase must not break as soon as it undergoes the first impact (i.e. when pushed by the pedestal) but that it breaks at the moment of its second interaction (i.e. with the ground). Do you have any ideas on what I can do? Thanks in advance

My first thought is several stiff constraints on a central empty, but that may not work. My second thought is that you animate a whole vase falling, and then replace it with the fractured vase later in animation.

This was written for those with reasonable experience...
The Blend file will be posted up if asked for but it won't help a lot because everything ends up baked & keyframed.

Vases don't actually bounce all that well so you don't really need physics in this case.  Once at the floor, the solid vase is switched over to the cell fractured version, and that's adjusted to do more of a collapse-shatter than allow it free reign and it's bits to fly apart, explosion style.
What was done here was to animate the initial tip-over, bounce, rolling action, and final fall.
(use physics if you wish but you'll need to bake that action to ensure nothing changes later)
.
At the impact frame the unbroken version of the vase is swapped for the cell fractured model.
The timeline is held at that frame and the fractured model aligned precisely to the unbroken one by

Setting the cursor to the unbroken vase's origin point.
(select it and with SH-S, set the cursor there)
Set the fractured model to the cursor position, again with SH-S.
Align the fractured model with the unbroken one.
('Object menu --> Transform --> Align to Selected' .
(Note - this works when 'Transformation Orientation' is set to
'Normal', not Global)

-=============-
For the inexperienced...

Switch the Transformation Orientation from Global to 'NORMAL'.
Select firstly the fractured version, and with SHIFT held, select the solid one.
Open the 'Object' menu in the window's header --> Transform --> Align to Transformation Orientation.

Both models should then be exactly aligned.
-============-
Still at that frame, swap them over - visually.  The solid to be invisible, the fractured, visible.
Later - NOT NOW, reverse that order at frame 1.  (Visibility and Render icons in the Outliner)
Note -  it helps enormously to link the fractured cells to one of their number so you only have to animate Dynamic physics etc in one, not them all individually.
.
Still at the change-over (impact) frame, switch the cell fracture physics on by ticking the 'Dynamic' box and keyframing that.
It's now safe to go to frame 1.  Untick the Dynamics and keyframe that also.
While you're at frame 1, reverse the visual switching for the two models.
(solid to visible, fracture to invisible)
When played, the solid vase will be seen to hit the floor, collapse and shatter.


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Too much noise on high samples
Why I still have too much noise on my 10,000 samples and 0.01 Noise Threshold (Denoiser blured this noise) I rendered at 1920x1080 (100%) on CPU (Ryzen 5 3600) because my GPU is slower (GTX 1050 Ti).

it'd be great if you share your .blend file so we can understand the problem better.
The big cube that cover whole scene is a volumetric right? If so, volumetrics are tend to increase noise in the scene, so your scene needs further optimization. I would analyze it better if you share your .blend file.


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Lines and dots on UV Editor

There are some weird dots and lines on the faces I select to resize the texture. I'm not sure how this has happened, and I think it's happened to me before as well. Any thoughts?

The texture is stretched, because the triangle dimensions in the UV map don't match the dimensions in geometry.

What do you mean by dots and lines? Do you mean this rectangular with white dots at the corners and one dot with line at the top of the rectangle?

The white lines and dots are handles for the Transform tool you have selected (Spacebar, T) in the UV Editor. The orange line is the UV island for the selected face that somehow got flattened and rotated. I'd suggest unwrapping the face again (U, U in Edit Mode in 3D Viewport) to get correct UVs.
Here's an example of two faces with the same texture applied. The UVs for the one on the right have been flattened and rotated:


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How do I add a texture to one specific face?
I'm really struggling with this part. I select a face, and then I drag the texture into the shader and click 'Assign', but the texture still appears across the whole model.

This is default behaviour because you only have one material. The first material will always be applied to the whole mesh.
Create a second material, give it another color and click assign -> this works.


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Return active FCurve with python ( blender 3.4.1 )
I would like to get the selected channel in python.
But I Don't find the right function to do it. or maybe it's the way I select the channel with the mouse in the graph editor ?
I tried based on this post but that don't work. I don't know why. Maybe the API have changed since then ? I'm using blender 3.4.1
Do you know how to do it ? Thanks !
import bpy

# Get the selected fcurves
selected_fcurves = bpy.context.selected_editable_fcurves

# Check if any fcurve is selected
if selected_fcurves:
    # Print the name of each selected channel
    for fcurve in selected_fcurves:
        print("Selected Channel:", fcurve.data_path)
else:
    print("No fcurves selected.")

You are running your code in the text editor. But it should run in the graph editor. Therefore you have to override your context with this:
bpy.context.temp_override

More info here: https://docs.blender.org/api/current/bpy.types.Context.html#bpy.types.Context.temp_override
Make sure that your graph editor is open, an object is selected and that this object has selected fcurves, else the code won't work.
import bpy

area = [area for area in bpy.context.screen.areas if area.type == "GRAPH_EDITOR"][0]
print("area is", area)

with bpy.context.temp_override(area=area):
    # Get the selected fcurves
    selected_fcurves = bpy.context.selected_editable_fcurves

    # Check if any fcurve is selected
    if selected_fcurves:
        # Print the name of each selected channel
        for fcurve in selected_fcurves:
            print("Selected Channel:", fcurve.data_path)
    else:
        print("No fcurves selected.")

Thanks for the fast response ! It works.


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How do you apply scale within geometry nodes, so that each instance has the same scale for procedural textures?
I have the following geometry nodes setup for a succulent plant.

I want to create a material for it to add details like dust, and other imperfections, but the textures are scaled down along with each instance, which is predictable behavior, but is there a way to bypass this behavior so that the mesh as a whole has the same scale for shading?

did you try to use realize instances?

This is exactly what I was looking for, thank you!

glad i could help

Figured it out, what I was looking for was the "Realize Instances" node. Thanks Chris!


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Geometry node, face normal directions
I want to place planes facing all the same direction on a tube/cylinder which positioned horizontally using the Geometry Nodes. I could do this if I didn't apply rotation after turning 90 degree. However, it flips half of them in opposite direction if I applied the rotation.
Does anybody know why this happen and how to fix it?
I'm just worried if "not applying rotation" cause problems when exported to Unity etc...?

As far as I know you cannot import the Geometry Nodes into Unity, so have to make a mesh of those planes... and in a regular mesh the normals can be flipped so if everything else fails you could do it manually.

Thank you very much! I'll make sure to convert to mesh when I export for other programs.

Note what the documentation for the Distribute Points on Faces Node says about the Rotation output:

An XYZ Euler rotation built from the normal attribute for convenience. Such a value can also be built from the normal with the Rotate Euler Node. Keep in mind that the Z axis of the result rotation will be arbitrary, since the mesh normal used to create the rotation does not have enough information to set all three rotation axes.

Emphasis mine. The rotation of your planes is not fully-determined by the surface normal of your cylinder, and it cannot be, since there is no way to know what direction “up” should be for each plane (only what direction “out” should be).
If you need to guarantee the planes will always be placed facing the same direction, you’ll need to use the normal in combination with some other vector to compute an unambiguous rotation. For example, you could choose to make the planes always face “upwards” according to the object’s local Z axis:

This results in the following when the object is rotated:

However, this is probably not what you want, since you presumably want the “up” direction for the planes to all point towards one end of the cylinder. Unfortunately, there isn’t really any consistent way to get that information—the concept doesn’t make terribly much sense for an arbitrary mesh. However, you could in theory compute it based on the relative positions of the top and bottom ends of the cylinder, like this:

This requires creating two vertex groups, one that contains the cylinder’s top vertices and another that contains the bottom ones, and passing those groups as the appropriate inputs. This results in the behavior I suspect you want:

However, this is a bit of a silly thing to do, and just not applying the rotation is probably a better choice.

Wow... Thank you very much for the informations and examples! That is amazing!!

I think you can get the rotations from normals.

Default rotations work not so well because the target axis is Z. But in Align Euler to vector you can set up the target axis manually.

This doesn’t really work—the other axis is unconstrained, so you sometimes get weird results. (See my answer for why, as well as a workaround.)

Thank you both very much for answering my question so quickly. It really helped me understand how some nodes works.


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KeyError: 'bpy_prop_collection[key]: error
I tried to fix my error with the error message "KeyError: 'bpy_prop_collection[key]: key "Sun" not found' ". The "Sun" is the object that I set up in the blender and the error pointed to this  Sunobj = bpy.data.objects['Sun'] So is there any way to that I fix this error?

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

Are you sure your Sun is named "Sun" and not something like "Sun.001" ? Are you sure there is a sun in your scene? You can also access objects by their index instead of their name. For example, if your sun is the fourth object in the scene, you may be able to access it with Sunobj = bpy.data.objects[3]


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What is the setup difference between the Blender free human meshes?
I'm trying to understand the difference between the set-up/nautre of the Blender free body meshes.
When I drag some into the viewport and remove the instance (figure on the left) I get an editable/rigable figure. However, there are others that I can't control the same way (figure on the right).
Thank you for any clarification you can offer!
Michael


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Can a figure made in skin modifier be parented to a rig?
Working in Blender 3.6. I have been experimenting with simple figures created with the skin modifier. Not satisfied with the automatic rig that is generated in the skin modifier, I tried to parent it to a standard bone rig. Parenting did not work. Just wanting to double check that rather than doing something wrong in the parenting process, one can't parent a modifier to a bone. Correct? Thanks!

There's a complete tutorial from Joey Carlino here which includes using the skin modifier armature, but I guess the best way would be to apply the modifier when you're happy with your model and then rig the resulting mesh in the normal way.

Hi, thank you so much for the help! I actually have watched that video several times (slowed down and following every step). Like many well mad Blender videos there are significant gaps in the procedures that can lead to lots of frustration. But your suggestion to apply modifier at end of process makes sense and one I hadn't thought of. Again, so grateful to you and the community here for the support you provide. Many thanks!


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In modelling is there a way to avoid a triangle where limbs meet torso?
in teaching myself how to build a human figure from a cube (following the guidance of several YouTube videos) I've noticed they end up with areas where arms and legs meet the torso at a triangular point. I realize this isn't quite the same as "tri's" but would a model like this have rigging issues?
Thanks!
Michael

It's not clear what kind of problem you are thinking about, that said, whatever your topology is, you need to consider what you want to do afterwards, how you want to animate this mesh, will it deform and bend correctly, etc. If you want to avoid these "triangles" for some reason, on the groin area you can create a gap with this topology, as for the armpits, it's generally better to have a T pose like this:

Thank you so much for your answer! My objective is to build very low poly figures with fairly realistic proportions that I can then rig and animate. I've tried the "extrude a cube" method as well as skin modifiers but the method as depicted in the image you shared seems to avoid the pitfalls of e-poles/tris/n-gons. Thank you again for taking the time to help me out!


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Problem with parenting mesh to rig
I have Blender 3.6 on Mac Big Sur.
After many read-throughs, searches, YouTube and multiple attempts, no success at the following:
I open the basic human metarig. I generate a rigify rig. I try to parent the mesh to the rig (to be clear, I choose the mesh first and then the rig) but not allowed to parent with automatic weights.
I know I am missing something so simple but I am driving myself nuts going in circles.
Thank you for your help.
Michael

Where is the mesh? Your screenshot shows a metarig and the generated rig. It looks like you are trying to parent the metarig to the rig. This does not work. They are 2 armatures so you cannot parent them with automatic weights. You need a mesh object.

Once you've generated the rig you can hide the actual armature by unchecking the eye icon against the metarig in the outliner. Now select the mesh and shift-click the rigify controls. Now use Ctrl-P > Parent > Object > With Automatic Weights and you should be good to go. There's a basic tutorial here. It's for Blender 3 but still applies with the latest versions. - As @Blunder says you do need a character mesh though...

Oh my gosh, yes, that makes complete sense. Thank you so much for the speedy response, I so appreciate it.


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Can a mesh block grease pencil strokes?
I need advice on how to achieve the effect in this video at 1:25. Basically, the artist was able to take a mesh that had grease pencil strokes "attached" and then by creating a shader holdout on the mesh and adding a solidify modifier, create a "drawing" that turns in space.
I followed her instructions to the T, multiple, multiple times and I still end up with the attached, in that you can still see through the mesh holdout to the lines on the other side.
The order of operations, as in video are:

In 2D workspace(3d workspace I tried as well) add UV Sphere.

Add stroke with Stroke Placement set to Surface and Offset to 0.

In Shader, add Holdout to Material of Sphere.

Back in 2d workspace, Select All Transforms.

Add Solidify Modifier, change offset to 1 and deselect Camera icon.

After doing that, I don't get the effect shown in vidoe
Thank you so much for helping me not lose more sleep.
https://www.youtube.com/watch?v=YY0gjIttZRw

So all those explanations can be distilled to: the sphere is not blocking the grease pencil strokes, do I read that correctly?

Hi Gorodn, Thank you so much for your help! Yes, you absolutely got what my issue was. And yes it worked when I checked the Z data pass. I do have a follow up just want to make sure if I should ask here or edit my original question. Thanks!

It is preferred to deal with one topic per post. If the original issue is solved it is always better to post a new question with another problem.

I totally get it. But if what if it's a follow up to the previous question/issue? Thanks!

This site is full of follow up questions. Either it is similar so that it is rather an addition to the original question and you might edit it into this one... but then you risk that people who already saw this question will not take a second look and it moves further down in the list of questions. Or it is somehow connected to this but can stand on its own as question, then it will also be on top of the list when posted new. But I forgot my crystal ball, I have no idea what you want to ask next and how I would categorize it.

Thanks again for the helpful advice! I think I'll try a few more things on my own before asking again. Again, I'm very grateful for your time and expertise.


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Is it possible in blender dope sheet?

I want to increase or decrease the proportion while keeping the keyframes at regular intervals, but is this function possible on the blender?

Hello and welcome. Please use a title that reflects the content of the question. It should be succinct, unique and identifying, and summarize what the issue is so that users can at a glance broadly understand what your post is about before opening it. Use the [edit] link below your post and avoid any emojis salutations or extraneous text not essential to the question. Remember, your title is the first thing potential visitors will see, and will weight heavily on their decision to open your question, which will directly affect the number of answers you might get.

I think there's some discussion, along with some possible (although not ideal) solutions here - https://blenderartists.org/t/scaling-keyframes-in-the-dope-sheet-unexpected-result/609082

Just select the keyframes you want and press S to scale:


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Modify instance parameter before the instance on points node, based on the position
I'm trying to make a grass field, and make flowers bloom when a 'sun' approaches the ground.
I have already solved the problem of making the grass taller and increasing the flower size, but I would like to add the blooming animation of the flower. Right now I have a node group that given an input between 0 and 1 creates a flower, closed with 0 and fully open with 1.
The problem is that when I try to instanciate flowers on top of the grass I just get the same flower repeated over and over, based on the distance between the 'sun' and the original position of the flower.
Basically I would need to know the distance between the flower and the sun before instancing the flower.
Does someone have a nice workaround for this issue?

Did you 'Realize Instances'?

Yes I've already tried that, but no success. I would need to give every flower a different input, like I do for the scale and rotation


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Blender stops responding when importing object
Whenever I import an object file larger than a GB or so blender stops responding and will eventually just close. I've tried leaving it on for hours on end and it still crashes. The file I want to import is roughly 3GB or so. It's a part of my minecraft server and probably has millions of triangles or something. Is there a way to get it to work or should I try to find a way to reduce the file further? It gives no error logs when it crashes. Closest thing I got was something similar to not enough memory. Sorry if it's a dumb question or has been asked before. I could'nt find anything on the topic.

Nevermind. 16GB is just not enough. I got it down to an 800mb file and my computer is just on fire trying to keep up with it all.


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Mapping a 3-D numpy array to a cube and visualize cross-sections
I am trying to find the simplest way to load and render a 3-D array (currently in a numpy ndarray) as texture in Blender.
Essentially, what I am trying to do is like these:
https://twitter.com/j6m8/status/1483968956138508291
https://twitter.com/j6m8/status/1484276015006375943
I've contacted the author of this tweet, the way this was done is by using node-editor and converting a 3D array into a filmstrip and map the z-axis of the object into offset in the filmstrip.
I am trying to see if there is way to program this in bpy from a numpy array without needing to convert to an image and node-editor. Or directly use any Blender object that can support visualization of 3D array data? My goal is to integrate this into a Blender based addon we recently published
https://twitter.com/FangQ/status/1483122446467223553
Appreciated if you have any suggestions.

I don't have any useful info, but I did want to congratulate you on an excellent visualization tool.  Look forward to seeing what you accomplish with it.

thank you Marty for your encouragement!

This might ? be possible with OSL, have you explored that ? In regular node editor I think the preferred solution would be the one you described


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how to create object 1 sliced by object 2?
In blender, if I create two intersecting objects A and B, I know how to obtain their intersections (A ⋂ B) or unions (A U B), or diff (A-B or B-A) using boolean modifiers.
However, I am wondering if there is a way for me to obtain A sliced by B (i.e. (A-B) U (A ⋂ B)), or likewise, B sliced by A, as a single output object? the result should contain both interior and exterior surfaces and should include multiple surface compartments.
thanks

this geo nodes setup should work in your case. All I did was to make both boolean operations and join the results. Hope that helps


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Rasterizing multiple shapes into integer-labeled 3D numpy arrays for a python based addon
I would like to convert multiple blender mesh objects into label-based python/numpy arrays.
For example, I have two intersecting shapes - 1) a cylinder "C", 2) a sphere "S", see attached image. In a Python addon I am working on, I want to rasterize this scene into a 3D integer numpy array, where each enclosed region is uniquely labeled, for example,

the region enclosed by C excluding S (C-S),is labeled as 1
the region enclosed by S excluding C (S-C),is labeled as 2
the region enclosed by "C and S" (C&S)),is labeled as 3

I don't know if there is such a function to rasterize shapes in blender. the closest I could find in Blender is the Remesh modifier with the "Block" option. Choosing this option converts the shapes, including intersecting surfaces, into voxel-like squared patches. By looping these patches, I can potentially rasterize the surface into a shell of boundary voxels, then with some floodfill algorithms, I may be able to fill the enclosed voxels into unique labels.
However, I found that the remesh modifier does not respect the "water-tight" nature of the surfaces. From the above screenshot, you can see there are small gaps between the voxelated cylinder and sphere surfaces. I don't know how to remove those.
I am open to any suggestion how to achieve this goal using Blender or Python (via bpy). I assume this can be done via geometry node programs?

Computing all possible intersections for arbitrary shapes (or even arbitrary manifolds) will be very difficult, I think, but if the shapes are somewhat simple (e.g. convex or not too non-convex), you can probably use something like BHVTree.ray_cast (https://docs.blender.org/api/current/mathutils.bvhtree.html#module-mathutils.bvhtree) in a few dozen directions to get reasonable detection of what objects have a boundary close to a given point, and to determine whether you're inside/outside the interior of each object, then build your indexing assignment logic using this as a subroutine

I am not sure if your comment "computing all possible intersection" was to address the gaps that I found in the remeshed surfaces, but blender was perfectly capable of handling intersections of complex objects and we have been successfully able to use it for our mesh-based model (see our paper: https://doi.org/10.1117/1.JBO.27.8.083014). However, the non-watertight issue is only a problem when using the remesh modifier. Again, I am not limit myself to the remesh modifier, but open to any other approaches to rasterize multiple intersecting objects.

No, it wasn't about water-tightness; the problem you described wanting to solve (assigning a unique label to each distinct enclosed space) doesn't seem to me to require voxelization. I think it can be achieved by using raycasts to classify appropriately chosen points as inside/outside each original (non-voxelized) 3D object. What I meant about difficulty is that more sample points and larger numbers of raycasts will be needed the more important it is to capture portions of an object with very high curvature.

So, for example, I imagine you could do this: 1. determine a bounding box that contains all your objects 2. for every pair of points in a 3D grid, check if a raycast from A to B crosses 0 surfaces; if so, these two points lie in the same enclosed space. And that's the entire thing, I suppose; there is extra information you can extract from the raycasts, and lots of ways you can make it more efficient (e.g., a first pass should raycast from each point by itself to identify and remove from use grid points that never intersect any of the objects), but this is the basic idea

And my comment about difficulty, in this approach, translates to needing the number of grid points to be something like proportional to the reciprocal of the largest rate of change you want to be detectable in the objects' surface---i.e., if there is a very small 'bump' of an object just barely intersecting another object, the grid has to be chosen to be fine enough to capture this detail, if it matters. (I don't think this needs a large number of raycast directions, though, contrary to what I wrote originally; use of a 3D grid of sample points removes the need for that)

I haven't thought about it deeply, but you may be able to iterate over the vertices of all objects and use something like the smallest distance between two vertices for all objects in a particular region of space to adaptively choose the number of sample points in that part of the space. Some form of this idea could remove the need for pre-specifying a grid that is sufficiently precise, by instead defining the sample points so that there are more of them exactly in those regions where some of the objects' surfaces change very quickly

@NeverConvex, my goal is not to simply assign shape regions by unique numbers, but doing so in a voxelated array. I can already solve this by calling bpy->oct2py->Octave/MATLAB and call my matlab based surface razterization function surf2vol.m. But it is somewhat slow. There are a few other ways this can be solved in MATLAB/Octave. However, I want to use Blender's rich features and solve this more efficiently. The methods you described seems to be even more computationally expensive & less robust than my existing MATLAB solutions.

Hm--maybe. I haven't read your paper, so not sure what your algorithm's run-time is like. I think you could make the approach I described above pretty efficient by limiting the raycasts to sample points that are near vertices of the objects; there's no reason to use sample points that are far from all objects' surfaces, now that I think about it.
Anyway, that may be all the help I can give; the only other option in Blender that occurs to me is to use binary operators to find intersections/unions of objects, but I expect this would be error-prone, and am not sure if it would be efficient.


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Remesh modifier converts intersecting surfaces to cavities and breaks water-tightness
This is an issue I found when I look for a solution for converting intersecting mesh objects to a single voxelated labeled array.
when applying the "remesh" modifier to intersecting surfaces, the intersection regions become cavities, and the exterior (joint) surface is no longer a single water-tight surface, showing holes that connect to the cavity.
In the below screenshot, I show two results using the remesh modifier to two intersecting spheres. On the bottom right, I first joined the two spheres and apply remesh, this gives me consistent voxelation (i.e. the spacing on the two objects is uniform) on the surface, but the intersecting region becomes a cavity - you can see the outer surface is also broken with holes.

On the bottom left, I applied remesh to two spheres separately. This way, the outer-surface is still water-tight (i.e. no holes, no cavities), but the voxelated surface is not consistent across two objects - the voxel of one object does not align with the voxel on the other.
I am wondering if

is there a way to voxelize both exterior and intersecting surfaces of a joint multi-object mesh without having holes and cavities? or
is there a way to voxelize multiple separate objects but with consistent voxel alignment?

It shouldn't be difficult with Geometry Nodes. You can use a Mesh Boolean to join both objects, then delete the intersection, merge by distances to clean up a little and, finally, use Instances on Point with a cube (you can align the rotation here)

Or separate the spheres into 2 objects and use the Boolean modifier on one of them to merge them. Then add the Remesh modifier to voxelize it.

thank you both for your comments! @Vagabonk, can you let me know what do you mean by "mesh boolean"? were your referring to the boolean modifier? Blunder, I would like to know how to "separate the sphere into 2 objects" - they are already two separate objects - are you saying unjoin them?

I was talking about this:

With Geometry Nodes, you have better control over everything, and you can align the rotation as you see fit. My example is poor and just shows the possibilities. I used the modifier on a cube and then dragged and dropped the two overlapping spheres. However, you can also select one of the spheres and apply the modifier to it, and then drag and drop the other one.

thanks, one thing I notice that your voxel size is not uniform, another issue is that your voxelated surfaces of the two spheres are not aligned on the same voxel grid - you see some of the voxels are half-way from the voxels of the other object. can both of these be resolved with geometry nodes?

Well, as I said, my example was very lazy. I think that this is exactly what you want: https://www.youtube.com/watch?v=QYmiY0B42c0 (a 3d GRID). You just need to join the objects with a boolean modifier set as "union" and use that instead of the TEXT.


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How to blender two materials on the same object together
Hey so im working with multiple materials on the same mesh. The materials have normals that don't really line up. (I'm using some textures I got from a CC3 export, and the normals don't seamlessly align.
I want to try to get some kind of gradient to blend the materials together so it looks more seamless.

If anyone can help that would be great

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

You can blend any two textures using a gradient.
And also distort the transition using a Noise texture
I'd use this basic setup to blend Normal maps.


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2k 5k even 13k same results in render Quality of my material?

Link to .blend file
https://drive.google.com/file/d/1SVpp9TP0znxXCh4schhPmfdOI7aP2n9_/view?usp=sharing
My diffuse baking comes out the same way no matter what i do ( yes I did apply all scales , i did try even with 13k to render ). I tried cycles and the other one PBR or whatever is called baking same results.
I dont know what I am missing or doing wrong maybe the shader settings is wrong ?
I want to render a HQ image that when u get close doesnt look like bunch of pixels and is the same on 2 k 4k or 13k (13k was random cause i got mad when at 8k was the same and wanted to do bigger number to see wtf is going on)

You're mistaken.  Your baking did not come out the same way.  The 9k has more resolution than the 5k.  While I didn't check the 13k (it's kind of painful to get a good test view at the range you need to be able to see the difference) I figure if the 9 is different than the 5, that's enough.  There are other differences between your material, like roughnesses and bump.

1st tanks for the reply. Now on the subject i did play around with the matterial to see if I can get it working. As for the result I am going for I would like when u get close to the oboject to be able to see a good quality not big pixels and i dont know what to do.


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How to move object to right infront of the viewport camera
I have an Object and I rotate it -90 degrees and it flies away. I tried setting to local coordinates rotation and nothing helped I tried every single rotation option. So now I just want to move the object to the camera. Not camera like in an object camera but where I am right now. I just want the object to teleport into view. But not move me to the object!.
Iv'e tried looking online for any help on this issue and no one seems to know. Iv'e also tried every single combination of the shift+s options. I just want the object to move to me. Its gone somewhere and I want it back.

hello, you say that you rotate it -90 degrees and it flies away, could you please give more details or show a screenshot because it is not very clear what you are trying to do. You can't automatically move an object in front of the view, you can bring it back to the center of the scene with alt G though

Have to agree with @moonboots here, it is not clear what you are doing and what you want to do. For the object "flying off" I can only speculate (now I want speculoo) that it's not the coordinates that make the problem - global and and local coordinates might only be different on what axes the object rotates - but the Transform Pivot Point or the object's origin. For example, if the pivot point is set to 3D Cursor and the object is way off center. Or with the default Median Point, but the mesh and origin are way apart from each other.

I also suspect the origin to be far from the mesh, in that case right click in Object mode > Set Origin > Origin to Geometry


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Geometry nodes. How to connect points with certain pattern?
Could you please help me to understand on how could I possibly connect the points with each other based on the following pattern: each red icosphere should be connected via thin line (low diameter cylinder) to 4 nearby yellow icospheres? At the same time each yellow icosphere should be connected to 2 nearby red icospheres.

Here is the simple geometry nodes setup that I currently have:

Thank you for your help!

i think that's the time for shifting to sverchok or animation nodes. I am pretty sure that GN cannot do this. But maybe Robin has another genius idea... ;)

Your question is too complex. That is why I will feel wrong if I will give you full answer. Because i do not want to do your jobe instead of you.
But i dislike that many people underestimate geonodes, even now when geonodes are very close to become more powerfull then old blender addons like sverchock or sorcar. In fact, geonodes have already surpassed sverchok and sorcar in several tasks. And they will become even more powerfull soon, because they have better blender integration and better support.
That's why i want to show that it is absolutely possible to do something like that in geonodes.
Here is solution for connecting 1 yellow ball to 1 closest red ball. And to connectig 1 red ball to 1 closest yellow ball. Also my node setup avoid situations when red line and yellow line have identical position and shape. In this case my node setup add a bend to booth lines, and create some kind of double bonds, like in molecule ball and stick models.
The key for this solution is comparing of positions of points between two point clouds. For this I use transfer atribute for target point cloud, and capture atribute for acting point cloud.
All setup:

Inside Ball_Gen group:

Inside Line_Gen group:

Inside Line_Cleanup group:

Larger result view:

i think you mean me with your "underestimate geonodes" comment - and shame on me, you are right - although i didn't give up my hope (that's why i commented this about Robin) and you just did it.  I can only bow to you and just admire your knowledge here. That's simply amazing. But maybe you saw some other comments of me about geonodes and hopefully you could see there, that i am a big fan of GN. And i can totally understand your "starter comment".

@Chris I mean a lot of people, not personaly you. For example, please, look at this: https://www.youtube.com/watch?v=o7Wbl8xp_w0 He got 630 likes under his video.

yes...but honestly...what are 630 likes? look at Blender guru's likes... ;) There will always be people who dislike the greatest things. And maybe he is a sverchok developer ;) and maybe you are a geometry nodes developer!? ;)

@Chris oh no no no. i am not blender developer :) i am just an ordinary blender user. I play with geonodes only for a three weeks. And if we talk about your "positive" comments, here is one more: https://blender.stackexchange.com/questions/247566/geometry-nodes-generating-geometry-per-instance/250452#250452 ;) Please stop telling people that things are impossible.

well...at least if wrote "AFAIK" ...and until now i didn't know better. But no, i have to disagree - you are NOT an ordinary user but a damn intelligent and smart one. Which is...äh....rare. ;) may i ask what background you have...? studied math? professor in vector graph? ;)

@Chris i think that we already at the edge of offtopic. And we should stop now. My background is philosophy studies in some very so so university. I learned a lot about Aristotle, Immanuel Kant, Martin Heidegger and other smartest and coolest nerd guys of all times. I am grateful for my education as it made me a better man. But it don't help me with blender at all. Math is my weak point. For example I face a luck of my math knowledge every time when I try to do python scripting.

Thank you very much for your help. It is simply awesome what you have provided in this answer. It will help me a lot and let me learn a lot too.


text:
I do not see camera and light icons in blender
I lost my camera and light icons in mode. I have them in scene collection and they are visible. Howerer they are not visible in modes with my object. Light is still being produced and after using CTRL ALT NUMBER PAD 0 I am in camera mode. I just do not have light and camera icons to grab or use "by hand" in blender. They turned invisible. This is what I see in Blender.

Just tap that icon:

.. to see them again.
The pyramid of the camera (its frustum) is its 'Extras' Viewport overlay. The rectangle is the result of 'Outline Selected'.

Thank you man. That was it


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How to bring back the tools menu under editor type?
so this might be a stupid question but as I am a complete beginner I will need some help with this - I have no idea how to bring back the toolbar under the Editor type - I am not even sure of the correct name for it so I am attaching a screenshot.
I am using Blender 3.0 on mac

If you should ever encounter this problem again, if I understand the question correctly you were looking for these "tools":

These are the Properties Tabs, they belong to the Properties Editor. In your screenshot it shows you have switched both editor windows in the right column to the Outliner. To get the Properties back, click on the dropdown menu in the top left corner of the editor window you want to change. There you choose Properties.


text:
How to intensify and edit glass caustics?
I am having trouble with my caustics - using 3.2 and they work fine. However they do not do the trick just right - I need the shadow of the glass to have much more of the light streaks, following the shape of object. Does anyone know how to intensify caustics? Add new light streaks onto the shadow?
I am attaching a picture of my result and of reference of how I need it to look like.
Thank you in advance for help


text:
How to control distance parameter in distribute points on faces with the object proximity in geometry nodes?
I am pretty new to the creation of geometry nodes setup by myself, and I came across a question - how would I control the distance factor in the distribute points on faces, with my proximity object?

Meaning that I want the distance between my instances to become smaller with further away my proximity object is, just as the scale of instanced objects is already set to decrease. Any help would be greatly appreciated, and in advance sorry if this has a straightforward answer.

the simply answer is: you can't because it is a circular input which means: this takes only one input value (not a field as the diamond shape reveals) - but of course you could solve it via a different way. So maybe you wanna change your question to "how can i...?" because you might get the answer you want ;)

@Chris hi and thank you for your fast reply! sure, then my question is how can i do that - i also wondered about the different shapes of the input sockets in the nodes, thank you for explaining it!


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Shape Keys Continuous Animation
I have researched it online, but found no answer - can I animate one mesh with Shape Keys, continuously? What I mean: I need the Key 3 to pick up shape of Key 2, change the shape of mesh, and further on. For some reason it does not work, the shape jumps back either to Key 1's or to the Basic's. I am guessing it has to do with the Relative setting in each Key- automatically it is set to Basic, and changing it to Key 2 does not work.
Please if anyone knows the answer, let me know, and in advance sorry if it is a basic question with an easy answer.

When you move to frame 1 and set the key value, you should lick on the small white dot to the right to add a key (it will turn into a white diamond and value yellow highlight), then move to another frame, value will be green and you can set and click on the open-diamond to set the next key-frame.  Etc at each frame to want changed.   Between keyed frames, the value will slowly change (interpreted values between frames).  You can go into the Amimation Graph Editor to change the Interpolation mode in the keyframe area of the panel (near the timeline cursor).

https://brandonsdrawings.com/blender-shape-keys/

@james_t hi and thank you for your prompt response; I guess I did not clearly state what I need, I know how the shape keys animation works; I need to know if it is possible to animate one shape with around 20 shape keys, when each of the keys takes shape of the previous, and not of the base key. I tried paying around with the settings of Relative, but any next key after Key 2 takes the start shape from the very beginning, and not the previous Shape Key. I will try and take some screenshots to attach, if the question is still not clear.

So I think you're asking...?... if you have Key3 Relative To Key2, how can you see the Key2 edits when working on Key3, and be able to move/edit vertices for Key3 while seeing the Key2 results?    Set Key2 value to 1 in Object Mode, then select Key3, go to EDIT mode, make Key3 Relative To Key2, click on the Apply Shake Key in Edit mode button (four cornered square on the Relative check box area, to the right on the pin button.  Ah, now I cannot edit!   Is that your problem to solve?


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2 or more cloth simulations on one object
I tried researching but seems no one else asked this question before me- correct me if I am wrong.
I have a plate of noodles modelled and simulated in Blender, and I need to find a way to apply new cloth simulations to my noodles model (which is multiple thin cylinders in one mesh)
Right now the only way I found around this is that I make a copy of my blend file and at the end of simulation #1 make a new one with the needed changes. Very time-consuming.
If anyone has a solution to this would appreciate greatly!

Can you explain further, what is whole purpose of this? Why do you need to continue with separate simulation. What is the purpose to duplicate file?

@vklidu sorry for taking a long time to reply and thank you for your question, the purpose is to keyframe the internal springs for my cloth object. The internal springs are not keyframe-able, and I needed it to decrease with time. The only way to do that I found was to duplicate the cloth sim object and enter a lesser internal springs value starting at the end of the first simulation. That was basically the question - is there an easier way to this ? And in advance sorry, I am not an expert in Blender

More than one sim is not possible (if you try to ad another Cloth sim modifier, bottom row is warning you). What exactly do you want to decrease? Some values like Tension, Compression can be animated.

Thank you for your reply! That is true, about the tension, compression, yes. What i needed animated was the internal springs of the cloth object as i am doing an animation of noodles falling down into a bowl - the internal springs add that bounciness & tension to the object when it falls. I needed it to start decreasing when the noodles settle into the bowl collision object - and that was the reason I "split" the simulation to start the second one off from where the first sim left off, but with the lesser internal springs value, so that the noodles settle into the bowl looking natural-like.

Sorry it seems to me we are walking in a circle ... I tried to summarised into an answer.

More than one sim is not possible
(if you try to add another Cloth sim modifier, bottom row is warning you).

The Internal Springs is bunch of parameters. If you say "I can't animate Internal Springs", what parametr do you mean exactly?
Internal Springs (whole panel) has only check box, that can't be lowered, it can be only switched on/off.
If you want to affect sim by less IS just animate Tension / Compression from something to zero value. Here in 150 frame animation goes at frame 80 from 30 to 0 at frame 120 ... so IS fully affects object up to frame 80 and at frame 120 has no effect at object.

The only two values can't be animated and that is for a reason - sim would be explosive if you would change number of springs in a process of sim.


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How to transfer Material Assignment data onto another mesh with same UV map and vertices
I'm trying to transfer the Material assignment of a material set from the original mesh to a new rigged mesh that has the same UV map and vertices count, but the problem is when I make-link for materials, the material assignment doesn't follow and when I tried to make link for Object data, due to those 2 rigs have different size and causes the object that gets data being messed up.

I have serched the way longtime. (I gave up it though) then requested it.
Would not You request it in blender right-click-select?
https://blender.community/c/rightclickselect/rm5k/
I made script, it seems work now for me... I hope blender add same function as default
import bpy
tmode = bpy.context.active_object.mode
objs = bpy.context.selected_objects
so = bpy.context.active_object
to = None

if objs[0] == so:
    to = objs[1]
else:
    to = objs[0]

sms = so.material_slots

bpy.ops.object.mode_set(mode='OBJECT')
bpy.context.view_layer.objects.active = to

while len(to.material_slots) != 0:
    bpy.ops.object.material_slot_remove()

while len(to.material_slots) != len(so.material_slots):
    bpy.ops.object.material_slot_add()

i = 0
while i < len(to.material_slots):
    to.material_slots[i].material = sms[i].material
    i += 1

tplgs = to.data.polygons
splgs = so.data.polygons

j = 0
while j < len(tplgs):
    tplgs[j].material_index = splgs[j].material_index
    j +=1

I changed script as add on. so you can transfer material slot assignment, materials, with UV (it auto transfer UV and activate  render UV) by one click.
just download and unzip, then install wifmatconvert_temp.py  as same as other add-on. ("Material", "Testing" group)
https://drive.google.com/file/d/1-0crLNntxFJOjNh3BTf4INxF21tx_f7q/view?usp=sharing
Usage

Select Source
Select Target (activate)
In Material property > Material link type > Click "Transfer Material".

you may need not use other functions. (Change object/data etc)

This add on auto generate and re-assign material-slots for target polygons as same as source , then transfer source materials , with transfer UV.
if you activate "Duplicate with suffix", it duplicate source materials and rename by your input suffix,  then add it for target / or simply link source material. (about both case, source material never change)
if someone test, edit, customize ,please use it as you need. I only test with 3.2
Of course until transfer mat-slots, you may better to duplicate your target mesh obj and keep it. (so you can easy return as dafault = transfer again)


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Make instances rotate outwards according to proximity using geometry nodes
I have instanced some grass on a plane, and i want an empty (or mesh, or whatever works) to go trough it, while folding, or rotating grass away so it makes a path. Ive been trying to do this with geometry nodes and geometry proximity but no luck, any help?

We can align their rotation to the vector from the empty controller to their position, and modulate this alignment by the distance from the empty controller:

Notice the instancing Suzanne in the background; her origin is located at her bottom.  This is important because the rotation will be about that origin.  (I also edited her a bit to stretch her out, so I could make sure I could see what I was doing.)
The map range is simply to tune the fall-off, and this should be done to eye.  Here, anything more than 1.2 units from the empty will be unaffected.

i tried your setup with 3.0 and i got: [1]: https://i.sstatic.net/lqAFN.gif but i don't think it is your fault, it think it is the Blender version - although it seems to be the same - might be different ones. On 3.1 it is weird too. Or i made a dumb mistake  - but i double checked.


text:
some object was not drawn in rendered photo
I'm new in blender. blender version is 3.0
I donwloaded model from sketch fab(https://skfb.ly/6QWNH)
but I have some struggled in render model.

(this is layout view and texture paint view)
It is okay in layout and sculpting, texture paint view and other views, except shader and render view.
below is shade view

it was crashed. I think shade view show back side becuase of triangle winding order. this is one of just my opinion.
I removed all shader input.
but it was still wrong.

I tried remove all inputs

below is result of what I remove all shader inputs.

could you tell me how to resolve it.

Click on any object in your scene. Go to Material properties at the right side of your window. Go down and open Viewport display.
You will notice that this option is checked on every single object:

Uncheck it on every object and try it again. It will work as supposed to:


text:
How to apply geonodes while retaining UV mapped geometry materials?
I've seen similar questions but this one is probably the most edge case.
I have geometry with UV mapped textures:

But when I toggle realize instances:

Moreover I'm instancing meshes with dual slots for its materials:

Is it simply not possible? I'm trying to export this to unreal engine 5 using Datasmith format. Would highly appreciate any help!

Is there a particular reason why you use the Realize Instances node?

One more try: You obviously only use instances and existing geometry here, which you transform, and don't create any geometry with Geometry Nodes. Then why do you use the node Realize Instances at the end?

@quellenform sorry for the late response. Applying geometry without realize makes the geometry disappear upon application...

The only possible solution for this problem: Use Blender 3.2+.

Previous versions unfortunately discarded the UVMaps of the instantiated objects as soon as the node Realize Instances was applied.

Wait a sec... Am I supposed to have the same materials as instances on the source geometry for GN or having it just on instance source objects suffice? From your screenshot it seems you have the cube materials in your plane geo as well. And also, is having UV map node as texture vector important (in shader editor) for geonodes to correctly apply?

In this case you would have to apply the material to the original objects, or assign it via Set Material. The material on the object containing the geometry nodes is irrelevant.

I see... Thanks a lot for your help. I'll see if I can get it to work..


text:
issues with UV unwraping
When I'm trying to unwrap the mug, it becomes a circle, and not a rectangular map

You need to add at least one vertical Seam to let blender unwrapp that part as rectangle.

When unwrapping a mesh, we need to cut the mesh up, so that we could lay it out flat, with minimal stretching. However, Blender needs to be told where to make the cuts. These are called seems. Currently, you don't have any seams, so the mug just get crushed into the circle, with lots of stretching, as shown here.

To fix this, I would add a seam down one edge, as well as another one separating the bottom of the mug from the sides. This will result in a more rectangular UV map, like you want. (seams can be added, by selecting an edge, pressing "CTRL+E" then select 'Mark-Seam'. These are then marked as a red line.)

Depending on how you want to texture the mug, you may want to reshape the UV map into a perfect rectangle, either manually, or using an addon like
UV squares
I hope that this has been helpful


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HSV Hue value is inconsistent. Why?
Can someone explain how Blender HSV works since it doesn't work as normal HSV should. Hue value 0-1 should be 360 deg so 1/4 value should be 90 deg. but somehow it's less? Then again 1/2 is 180 deg, as it should. But once again with 270deg in Blender it's 0.7 when it actually should be 0.75 This makes no sense. I'm lost. Any idea?
I also checked Blender manual. Blender manual says this: "Hue: Specifies the hue rotation of the image. 360° are mapped to (0 to 1)." This is from "Hue Saturation Value Node", but it was the only manual page what defined Hue mapping in Blender. It should follow the same logic in any HSV mapping.
Currently in Blender:
0.300 is 90 deg
0.500 is 180 deg
0.700 is 270 deg
1.000 is 360 deg
When logic says:
0.250 is 90 deg
0.500 is 180 deg
0.750 is 270 deg
1.000 is 360 deg
What? Why?

What version are you using? Might be worth reporting it as a bug.

Newest Blender 3.0.1 that had bunch of bug fixes @Onyx

Not absolutely sure, so not an answer, but what makes sense to me is:   the system is based on RGB, the translation from HSV to RGB is non-linear, and so getting the angles to be geometrically  correct would involve changing the entire  color-disk. That would be a more intrusive inconsistency than allowing the angles to be out.

Looks like a deliberate choice to make certain reagions wider and easier to pick from
Adobe's Color wheel has a similar inconsistency
"It's not a bug, it's a feature!"


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BlenderPythonAPI Save Image from console
What I want to do:
Have a script, which opens a glb file, reduce all textures with sizes greater than 512x512 to 512x512 and export to a glb again.
I've tested in blender:

import a .glb
open python console
type: bpy.data.images[0].scale(512,512)
type: bpy.data.images[0].save()
export as glb
which works fine.

Then I wrote a script:
# Import glb, which is working fine...
for image in bpy.data.images:
    if (image.size[0] > 512 or image.size[1] > 512):
        scalingfactor = 512.01 / max(image.size[0], image.size[1])
        nx = math.floor(scalingfactor * image.size[0])
        ny = math.floor(scalingfactor * image.size[1])
        print("scaling image", image.size[0], image.size[1], "to", nx, ny)
        image.scale( nx, ny )
        print("new size is:", image.size[0], image.size[1])
        image.save()
        print("image saved")
# Export .glb

The last valid output I get is: "new size is: 512 512"
and then
Error: Unable to pack file, source path 'C:\Users\MYNAME\AppData\Local\Temp\gltfimg-k4yrdaga\Image_1.png' not found
ERROR: Image "C:\Users\MYNAME\AppData\Local\Temp\gltfimg-k4yrdaga\Image_1.png" not available. Keeping packed image fp

If I remove image.save() then saving the glb does not work (not even in blender itself):
This causes the following error message:
TypeError: expected sequence size is 16777216, got 1048576
@ "gltf2_blender_image.py", line 254, in make_temp_image_copy
tmp_image.pixels.foreach_setting(tmp_buf)

The file, which I used, is a standard sample from Khronos Group: https://github.com/KhronosGroup/glTF-Sample-Models/tree/master/2.0/Corset/glTF-Binary
( But this happens across all files I tested )

What happens if you call image.pack() instead of image.save() there?

That did the trick! Thank you very much!

After modifying the image, the result becomes a temporary thing that's different from the original stored image.  To solve this, call:
image.pack()

This makes the resized image a more permanent object in the Blender project, and helps it export correctly.


text:
Translate objects along curve instances
I have a set of start positions and a set of end positions and I eventually want to connect the two by bezier curve. And then use this bezier curve as a path for a selection of objects. I can get a single curve to work like this:

But when I try to make multiple curves the nodes no longer work.

The curves get connected like I want it to (picture 3), but the "sample curve node" does not output a field of each curve fac position value, instead it outputs the same vector for each instance. This is probably intended, but I would still like to get a fac position value for each independent curve. So I can animate objects moving along their own paths.

The input of Sample Curve is not a Field, which is why you always get only one position.
But in your concrete case you don't need any curves to reach the desired position.
You already have all three necessary values at hand:

start points
end points
factor

Therefore you would only have to take the vector between the two points and scale it with your desired factor.

UPDATE:
If you don't use straight lines, but arbitrary curves (e.g. Quadratic Bezier), then you would have to approach the matter differently:
If you use the node Trim Curve instead of Sample Curve, you can determine the point in the same way with a factor and then, as soon as you reduce the curve to a point, you get exactly the position you are looking for.

Here is the Blend file:

Yes, while this works for straight lines I would eventually like to replace the "curve line" with a 4 point bezier. So simple vector math does not work for me.

@jstkiko Ah, I see, if you don't have straight lines, then of course this method won't work. An update will follow shortly.


text:
How to outset faces in geometry nodes
So essentially I need to scale edges so that the offset after transformation is constant distance away from original geometry (something like the opposite of inset). I need it to be procedural, so it has to be done using a combination of modifiers and geo-nodes. Is it possible?
If i just use the scale elements node i get:

What I want:

Try this addon https://www.youtube.com/watch?v=9vu0MRcq61I https://blenderartists.org/t/offset-edges/584283/397

New method:

Explanation:
(A) – For each vertex, get two edges that are boundaries (they are the ones relevant for calculating the offset), then remember the index of these two edges, and also get the index of the opposite vertex for the edge.
(B) – To resolve uncertainties in (C) step, it is important to obtain an unambiguous definition of the "outward" direction.
Use the Faces normal to define the direction for edge, and then use the direction from the center of the edge to face to ensure the direction of the edge is "out."
(C) – For each vertex, obtain the average direction from its two edges.
There are two problems with this:
1. The average direction is always between a short angle, which can be directed "inward" of the surface. To fix this, reflect the direction using the additional information from (B).
2. The edges of a vertex can be parallel. For each vertex for which this is true, use the "out" direction from (B) instead of the mean direction.
Now for each vertex there is a correct direction to offset.
(D) – To be able to offset on non-planar faces, you need to get the angle information between the faces for the vertex for the (E) step.
Using the vertex edge index, read the face normal through it, then dot product. If the normals are parallel and pointing in opposite directions, force rewrite to one.
There is a problem with this if the normals have different directions
(see gif 1).
To fix this, use the average position of the two faces to reverse the sign for cases where the normals are point in different directions.
(E) – Using cosine of angle (dot product) between edges for a vertex, calculate the "factor" of distance the vertex must travel for the offset to be "uniform".
There is one problem with this: for non-planar faces, the angle between the edges for the vertex will not correspond to reality (see gif 2).
To fix this, multiply the distance factor by the similarly adjusted cosine of (D).
Now for each vertex there is a correct distance for offset.
(F) – Vertices "inside" the surface were processed as is. Since they are not relevant for the offset, just ignore them, and move all other vertices on the final offset.
gif 1:

gif 2:

When editing this answer, please make sure that either the image links work or you remove them completely from the answer. Like this they are no use. The other thing is: the answer was accepted last year, there might be a new method now but I would add them to the old accepted method. Otherwise it might be that the new method has some flaws (maybe not this time, but generally speaking) and people might be wondering why this answer was accepted.


text:
Assign ID to all vertexes of the same instance (geometry nodes)
Essentially I want to distribute instances on points using geometry nodes, then realize instances and transform each one according to their index. Example (all instances with index 1 are tranformed by face extrude node, all instances with index 2 get "shrink wraped" using raycast nodes...)
Idealy I would want to make a grid from objects from 2 selections and "shrink wrap" each object from selection 1 with a predetermined object from selection 2.
But I am also interested, if the functionality of indexing the instances after "realize instance" node is supported. I feel like I could use it a lot in other projects.

all instances with index 1 are tranformed

Well, obviously, once you use Realize Instances, they're not gonna be instances anymore, so they won't have instance indices, but you could perhaps employ the Island Index from the Mesh Island node:

As they're not instances, you are actually somewhat freer with your transformations, since you can manipulate one's geometry without affecting the others, if you like. In the screenshot, you can see that every third island (Modulo 3) is separated into a different group and colored white, but I am also extruding half of all units regardless of their coloring.
If you wanted to turn some of them back to instances, you could use the Separate Geometry node and feed the selection into a Geometry to Instance, then perhaps distributing them on points of mesh island positions etc...

Looks promising will see if i can implement it this way.


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Vine growth around mesh with GeoNodes
I was wondering if there is a way to procedurally simulate a vine growth in Blender using GeoNode, like this guy did with Houdini (link down below). if anyone has a clue that would be really appreciated !
https://www.youtube.com/watch?v=HY5SjX3f-JA

You can wrap a curve around your mesh, manually or using a proximity node, and animate a Trim Curve node to simulate growth.

This is the basic idea, adding branches and leaves can be daunting, but it can be done.

Unless your request explicitly requires this be done with GeoNodes, I'd like to suggest having a look at IvyGen if you haven't already.
It's shipped with Blender like some other addons, but is disabled by default. Go to User Preferences > Addons and search for it. After enabling it, it appears in the Create tab of the sidebar and (if memory serves) in the shift-A (Add) menu of the 3D Viewport.
EDIT: More info here: https://docs.blender.org/manual/en/latest/addons/add_curve/ivy_gen.html


text:
exploding particles
trying desperately to prepare a short animation of the inside of a cell.   I want to show little proteins bouncing around inside the membrane.  I have 3 problems, I will post all 3 separately because it seems those are the rules.  I've also uploaded the blender session below.
problem #1:  I have my particles contained within a box constructed from 6 planes(front and back walls are transparent so I can see inside).  Walls and proteins have 1.0 bounciness.  I used solidify on all the walls.  When I run the animation EVERYTHING EXPLODES and flies through the walls out of the box.  Any suggestions appreciated.

https://www.mediafire.com/file/upw5904htbfry0s/Phospholipids_and_brownian_motion.blend/file

some ideas: could enable 'Split Impulse' in Rigid Body World to avoid the 'explosion' but making them smaller as Chris said should be enough here; you could use the Lock on Y for each object if you want a 2D simulation and delete 2 walls but lay objects on a plane first; reduce friction to zero; maybe add some turbulence for a few frames or set initial velocity to some objects via keyframes

For (physics) simulations you should always apply your scale. -> CTRL-A -> scale

You shouldn't ever use negative scales.
If you use "Sphere" as shape object, Blender uses your object as exact that sphere.

So your "spheres" are overlapping as you can see and this isn't possible in the "real" world so either they have to deform or something else bad will happen...which you can see as your "explosion".
So either you make them all smaller so they don't overlap or move them.
result after making them smaller:

this helped.  thank you so much.

Please check the checkmark left of my answer, if it helped. Thank you.


text:
physics: monkey heads contained in a box
trying to create something similar to a "molecular dynamics" simulation.  Basically a bunch of little objects bumping into each other to simulate what the inside of a biological cell looks like.   Any advice will help.
I did a test with a bunch of monkey heads inside of a box (planes).  I set the gravity to zero and built a box.   I turned on passive rigid body physics for the walls of the box.  I put on active physics for the heads.   Then I run the animation and EVERYTHING EXPLODES.   Well the heads go flying out of the box.  How can I contain the heads within an area?  The walls are useless.
Also, any idea how to get transparent shader to work with eevee?   I cant see through a transparent plane!
thanks

There are a dozen ways this could be going wrong. Are the monkey collision systems set to convex hull, or mesh? Are you sure the box pieces are oriented the right way? Is the box “overstuffed” as it were?

Keep it to one question! That last bit is not only totally unrelated, it is a very common problem. Look up “EEVEE alpha blending” for more of an explanation, but you need to change the alpha blend method in the material’s settings in the Properties editor.

@Chris done!   Thanks again!

To make material transparent in EEVEE, set mode to alpha blend:

Set the box rigid body -> shape -> to "mesh".

result (but with gravity):

Note: convex hull is just as you would wrap a paper tight around an object. So it is good for very easy cases like spheres or boxes if you use it at collision from outside of it. For everything else - more complex objects or objects with hole, you should use "mesh" because it really uses the geometry and not a simplified version for a better performance.
And you shouldn't write things like "the walls are useless" - could be considered as rude. You should write: what am i doing wrong that it doesn't work?
Note: another import aspect for running simulations: you should have applied scale and rotation for every object you use.
Watching beginner tutorials about rigid bodies on yt is also a big help as a beginner.

thank you!   did not mean to be rude.  Just frustrated with my knowledge.  heh.   Yes I have been digging through YT.  Hard for Blender 3 though.
That helped and I am making progress.  I have one more issue maybe you can help with please.  I followed tutorial in link below.  I have a membrane bilayer. I have "wave" modifier on.I want to have spheres floating inside the cell.  However I cant get the cell membrane to act like a static body to reflect back the bounces.  things just go right through.   any help <3
https://www.youtube.com/watch?v=LEmQoIxtbcQ&ab_channel=CGFigures

please open up a new question so everybody can answer it and everybody can learn from it. If i answer in comments nobody will find it. Thank you.