Understanding compute shader feedback via imageLoad

General TouchDesigner Discussion
1

I’m trying to create a feedback system using imageLoad, similar to what is used in the new ParticlesGPU comp. Although I’m struggling to get it to work with more complex code. Attached is a working .toe, which uses said method to simply increase the values of a texture. Although I’m not sure I’m doing it correctly, because it only works, or produces any output, for that matter, with line 43 implemented. If I don’t increment the value by 1 then the shader produces all zero values?

void Read(int index){
		ivec2 texPos = Index2XY(index);
		vec4 noise = imageLoad(mTDComputeOutputs[0], texPos);
	
		s.normState = float(noise);
		s.oldState = float(noise * 5);
		s.index = index;
}

void Code() { 

	//ADDING ONE, ONLY WAY IT WORKS?????????
	s.oldState = s.oldState + 1;
	//THIS BREAKS CODE?????????1
	//s.oldState = s.oldState;

	s.normState = float(s.oldState) / float(5);
}

void Write()
{
	ivec2 texPos = Index2XY(s.index);
	vec3 outOne = vec3(s.normState);
	vec3 outTwo = vec3(s.oldState);
	imageStore(mTDComputeOutputs[0], texPos, vec4(outOne,1));
	imageStore(mTDComputeOutputs[1], texPos, vec4(outTwo, 1));
}

void main()
{

	int index = int(gl_GlobalInvocationID.x + gl_GlobalInvocationID.y * gl_NumWorkGroups.x * gl_WorkGroupSize.x);

	if(uReset == 1) {

		ivec2 texPos = Index2XY(index);
		imageStore(mTDComputeOutputs[0], texPos, vec4(0));
		imageStore(mTDComputeOutputs[1], texPos, vec4(0));
	}
	else 
	{
		//ivec2 texPos = Index2XY(index);
		Read(index);
		Code();
		Write();
	}
}

Thanks for any assistance.

myCourse-imageLoad-forum22.toe (493.7 KB)