// 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
RWStructuredBuffer<float> oldVegetation;
RWStructuredBuffer<float> vegetation;
int sizeX;
int sizeY;

int index(int x, int y){
    return x + sizeX *y;
}

float get(RWStructuredBuffer<float> array, int x, int y){
    int _index = index(x, y);
    if(_index<0 || _index >= sizeX * sizeY){
        return 0;
    }
    return array[_index];
}

float laplace(RWStructuredBuffer<float> array, int x, int y){
    return 0.2 * (get(array, x+1,y) +  get(array, x-1,y) + get(array, x,y+1) + get(array, x,y-1)) + 
    0.05 * (get(array, x+1,y+1) +  get(array, x+1,y-1) +  get(array, x-1,y+1) +  get(array, x-1,y-1)) -
    get(array, x, y);
}

[numthreads(8,8,1)]
void CSMain (uint3 id : SV_DispatchThreadID)
{
    int x = id.x;
    int y = id.y;
    // TODO: insert actual code here!
    vegetation[index(x, y)] = clamp(oldVegetation[x, y] + laplace(oldVegetation,x,y ),0,1);
}