I see the problem you mention on my iPhone. What kind of type constant are you using on your textures when you generate them in gpuSimulator.createTexture();? I’ve ran into this issue before where desktops support THREE.FloatType but mobile devices only support THREE.HalfFloatType… should be why you’re seeing OES_texture_float_linear extension not supported
Here’s the solution I ended up using: GPGPUComputationRenderer in case that’s the cause of the clumping in positions you’re seeing.