// Each #kernel tells which function to compile; you can have many kernels
#pragma kernel CSMain

// Create a RenderTexture with enableRandomWrite flag and set it with cs.SetTexture
RWTexture2D<float4> Result;
float4 color;
uint isFill;
uint isHorizontal;
uint texSize;
uint numPoints;
float minVal;
float maxVal;
float4 pointVals[1000];

[numthreads(8,8,1)]
void CSMain (uint3 id : SV_DispatchThreadID)
{
	Result[id.xy] = float4(0, 0, 0, 0);
	
	uint minValScaled = (uint)round(minVal * texSize);
	uint idx = (isHorizontal ? id.y : id.x);
	uint idy = (isHorizontal ? id.x : id.y);
	
	for (uint i = 0; i < numPoints; i++) {
		uint px = (uint)round(pointVals[i].x * texSize);
		uint py = (uint)round(pointVals[i].y * texSize);
		if (i > 0) {
			uint ppx = (uint)round(pointVals[i-1].x * texSize);
			uint ppy = (uint)round(pointVals[i-1].y * texSize);
			float slope = (pointVals[i].y - pointVals[i-1].y) / (pointVals[i].x - pointVals[i-1].x);
			uint valFromSlope = (uint)round(slope * (idx - ppx) + ppy);
			
			if (idx >= ppx && idx <= px && idy <= valFromSlope && idy >= minValScaled) {
				float alphaScale = isFill ? 1 : (((float)idy / (float)texSize) - minVal) / (maxVal - minVal);
				Result[id.xy] = float4(color.x, color.y, color.z, alphaScale * color.w);
				break;
			}
		}
	}
}