I’m working with Three.js’s latest TSL to create a custom vertex shader for an InstancedMesh . However, I’m struggling to access the instanceMatrix values in the shader. It seems TSL doesn’t yet support the built-in instanceMatrix property directly in the shader’s scope. Is there any solution? …

In r169 I used this construction to get access to instanceMatrix: const instMat = buffer( this.instanceMatrix.array, 'mat4', this.count ).element( instanceIndex ).toMat4().toVar(); Warning: I haven’t tested it with the latter revisions. The example of the using:

[image] prisoner849: const instMat = buffer( this.instanceMatrix.array, 'mat4', this.count ).element( instanceIndex ).toMat4().toVar(); EDIT: Did not work for me in r174 const buffy = buffer(instancedMesh.instanceMatrix.array, 'mat4', instancedMesh.count); const positionAlter = Fn(() => …

Here’s what worked for me in r174. Update March 25 2025 It is afaik impossible I think mostly due to under-the hood magic not exposed. Your best bet is to roll your own attributes. These attributes can then be accessed and updated from both custom CPU-side logic like render loop updates AND inside …

I’ve used my above solution in 177, 178, there are additional footguns I’ve encountered with instancedMesh but the approach for this specifically should work. Can’t remember if I tested in 176 but I assume it does? There was also a bug fixed in 177 for instancedMesh where now positionLocal.xyz work…

Title: How to Access instanceMatrix in Custom Vertex Shader with Three.js TSL (InstancedMesh)?

Questions

torrent January 27, 2026, 2:18am 7

See Will there ever be a "material.instancePositionNode" node?

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Title: How to Access instanceMatrix in Custom Vertex Shader with Three.js TSL (InstancedMesh)?

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