You can’t because of the feedback loop
you have to use an intermediate texture to store it (The good idea is to use a PassPostProcess to duplicate it on the GPU)
Hm but why not use customMaterial and use method addUniform(‘diffuseTexture’, ‘sampler2D’), or perhaps use shaderMaterial…proceduraltexture has been there for a while not sure if it’s still being maintained
Cheers!