Tips for optimizing skinned/boned characters?

Questions
1

The only thing that seems to affect my frame rate is the number of characters on screen. (Well, that and portals). Everything else I throw at it - massively complex scenes, physics, shadows and so on it just shrugs off.

The characters are all GLTF, low-poly (couple thousand per character) and about 20 bones. I see significant frame rate drop after about a dozen characters on screen. I’ve run all the animations through the GLTF resampler.

Any general tips / suggestions on improving performance for character models?

2

Set visible to false for all bones.

mesh.traverse(function(child){


if(child.isBone){ child.visible=false; }


var children=child.children;


if(children.length>0){
child.updateMatrixWorld=function(){
this.updateMatrix();
this.matrixWorld.multiplyMatrices(this.parent.matrixWorld,this.matrix);
for(var i=0,l=children.length;i<l;i++){
children[i].updateMatrixWorld();
}
};
}
else{
child.updateMatrixWorld=function(){
this.updateMatrix();
this.matrixWorld.multiplyMatrices(this.parent.matrixWorld,this.matrix);
}
}


});


}
3

So, I tried setting bones to visible=false. This didn’t appear to have any effect on framerate. Also, it introduced a bug: the way I have characters wielding weapons is to set the weapon as a child of the weapon bone, when the bone is not visible the weapon does not appear. Oh well.

4

Are the characters all duplicates of the same thing or variants?

5

Here’s a test scene which might make the answer clearer:

bestiary
bestiary1920×1302 246 KB

There are 5 unique models in this shot, each model has been cloned using SkinningUtils, and then the materials on the clone replaced to provide for color schemes for each actor.

6

Is this all accurate?

  • about 10–20 SkinnedMesh instances
  • about 20 bones per SkinnedMesh
  • < 100,000 total vertices

If that’s all true and the performance is cratering, do you think you could create a demo for debugging? I don’t know why this would be slow, but it seems reasonable to consider it a performance bug we should fix.

Some users have set up GPU instancing to support different colors per-character, which can definitely get you a lot more characters on screen, but that much effort shouldn’t be necessary to render 10-20 characters…

7

I’ll put it on my todo list, but it may be a while. I can give you a private link to the game deployed on vercel, but if you need to look at the uncompiled source, or a minimal-code repro example, that will take somewhat longer. (I’m in the middle of a massive migration, 70k LoC :confused: )

8

So it turns out that the primary slowdown was due to physics - doing shapecasts to determine whether the character was standing on a solid surface. There are some minor slowdowns due to rendering skinned characters, but not nearly to the extent that I first believed. I started to create a free-standing demo of animated skinned characters, but with no physics it runs at 120fps with 25 characters.

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