#pragma kernel CSMain

//Stores the spawn rule index & its probability chance
struct SpawnRuleChances
{
	int spawnRuleIndex;
	float probability;
};
//Stores the result which spawn rule should be executed at which position, including correct height
struct StampPosition
{
    float3 position;
};

Texture2D<float4> Input;
//float2 lastPosition;
uint texelLocationIncrement;
int maxJitter;
int stampsPerRow;
int randomSeed;
int textureResolution;
RWStructuredBuffer<StampPosition>results;

float Noise(int x, int y, int random)
{
    int n = x + y * 57 + random * 131;
    n = (n<<13) ^ n;
    return (1.0f - ( (n * (n * n * 15731 + 789221) +
            1376312589)&0x7fffffff)* 0.000000000931322574615478515625f);
}

[numthreads(8,8,1)]
void CSMain (uint3 id : SV_DispatchThreadID)
{
	if(id.x % (texelLocationIncrement) == 0 && id.y % texelLocationIncrement == 0)
	{
		int xPos = id.x;
		int yPos = id.y;
		int offsetX = lerp(-maxJitter, maxJitter, Noise(id.x,id.y,randomSeed + id.x));
		int offsetY = lerp(-maxJitter, maxJitter, Noise(id.x,id.y,randomSeed + id.y));
		uint2 posWithOffset = uint2(clamp(xPos + offsetX,0,textureResolution), clamp(yPos + offsetY,0,textureResolution));
    	results[id.x / texelLocationIncrement + (id.y / texelLocationIncrement) * stampsPerRow].position = float3(posWithOffset.x,Input[posWithOffset.xy].r,posWithOffset.y);
	}
}