This scene has two instanced animated objects (plus the original mesh) loaded from a gltf file with BABYLON.SceneLoader.LoadAssetContainer and container.instantiateModelsToScene. At first glance I thought this was caused by the bone animation, but it turns out this is not the case.
The problem is reproduced here: https://www.babylonjs-playground.com/#4ZVNJJ#3 Moving the meshes (by setting their position and direction) makes the fps fall to around 30 to 40fps. If they are static the performance is back to 60fps. There’s a flag animate to control this behavior (note that the objects are not visible with animate = true, they’re off screen).
What is going on? What can be done to improve this?
When you animate the root meshes, you are updating their world matrix and then all their children and the children of their children need to rebuild their world matrix
So this will trigger the rebuild of the entire hierarchy of world matrix per frame
Don’t the children inherit the world matrix from the parent with something like a glPushMatrix/PopMatrix?
Is there a way to collapse the hierarchy in BJS? Merge the geometry?
It’s not the most optimal object in the world, I know It’s an object I downloaded from a repository and I had no control over its creation. But the bone animation is not a problem, BJS handles it pretty well.
I’d expect this to be a big problem anyway, but if the objects are animated but not translated there’s no performance hit and the demo runs at 60fps. I originally imagined it was the bone animation that was making things slow, and was surprised that the first PG I built didn’t reproduce the issue.
Okay, but what could be done other than editing the model on a 3D modeler? Is it possible to collapse the nodes? Merge the geometry? Freeze the submeshes so the matrices are cached other than one parent transformnode multiplication?
So is the root node or the root mesh that I should animate?
I understand that instantiateModelsToScene returns a list of root nodes which may or may not be meshes. Is that correct? Is there an automatic way to find the root [mesh|node] (whichever is correct) automatically? I assumed whatever was returned in the .rootNodes was actually the root and not something in the hierarchy, so I’m kind of lost here.
I thought it had an issue with RTT if I used the original object, but apparently not, I misunderstood it. But it turns out that container.meshes have completely different objects than mantas. So what exactly instantiateModelsToScene returns? Can use the original mesh and the instances together on an array and treat them just alike, or are there any restrictions?
The one with the smallest hierarchy (hence the root mesh FOR the bones). You need to get the skeleton attached to your mesh, get the first bone (root bone) and then get the bone.transformNode to get the root node to animate
No restriction
It returns all the meshes created by the function. Mantas are more transformNode and not really meshes in your case
It’s an object I downloaded from a repository and I had no control over its creation. But the bone animation is not a problem, BJS handles it pretty well.
