InstancedBufferGeometry not updated properly between render calls

When you use InstancedBufferGeometry without using InstancedMesh, your geometry attributes are not updated properly. Here’s the culprit:

https://github.com/mrdoob/three.js/blob/0d7fb8d74f3c4d4e465b5a92ada65e1c789708e1/src/renderers/webgl/WebGLBindingStates.js#L50

Part of the fix would be to check the geometry and not the object. That is if the geometry.isInstancedBufferGeometry instead of checking for InstancedMesh specifically.

Frankly, looking in the binding states implementation - I’m puzzled by the fact that version of the attribute is never checked against the cache, it basically says “oh, look, it’s the same object reference, no update needed”. Or I’m missing something.

[Mugen87]

Since InstancedGeometryBuffer is updated as expected I think it’s okay to close the issue.

[Usnul]

I’m afraid that’s not true. WebGLShadowMap does use WebGLObjects. WebGLObjects also does not increase the frame counter. This is done in WebGLRenderer.render():

You’re absolutely right, I guess I’m the first person to have a use-case to modify geometry while assembling a single frame.

For the case of shadow map in three.js - geometry is assumed to remain the same, which is a perfectly valid assumption.

In case anyone’s interested, the reason why it matters for me - is because of the virtual geometry, that is, depending on the view geometry might be drastically simplified, so shadowmaps and the main view may render drastically different number of triangles for the same mesh, depending on the shadowmap resolution, size of the object in the view and a few other factors.