Cell.compute

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

struct Cell
{
    int posx;
    int posy;
    int pre;
    int val;
};

RWStructuredBuffer<Cell> cells;
int width;
int height;

float rand(float2 st, float n) {
 	st = floor(st * n);
    return frac(sin(dot(st.xy, float2(12.9898,78.233)))*43758.5453123);
}

[numthreads(20,1,1)]
void Init (uint3 id : SV_DispatchThreadID)
{
    cells[id.x].posx = id.x%width;
    cells[id.x].posy = id.x/width;
    float r = rand(float2(id.x, 11), 10);
    cells[id.x].pre = r < 0.2 ? 1 : 0;
    cells[id.x].val = cells[id.x].pre;
};

[numthreads(20,1,1)]
void Process (uint3 id : SV_DispatchThreadID)
{
    int val = 0;
    int x = id.x % width;
    int y = id.y / width + 1;

    val += x - 1 >= 0 ? cells[id.x - 1].pre : 0;
    val += x + 1 < width ? cells[id.x + 1].pre : 0;

    if(y - 1 >= 0)
    {
        val += cells[id.x - width].pre;
        val += x - 1 >= 0 ? cells[id.x - width - 1].pre : 0;
        val += x + 1 < width ? cells[id.x - width + 1].pre : 0;
    }

    if(y + 1 < width)
    {
        val += cells[id.x + width].pre;
        val += x - 1 >= 0 ? cells[id.x + width - 1].pre : 0;
        val += x + 1 < width ? cells[id.x + width + 1].pre : 0;
    }

    if(val >= 3 && val <= 5)
    {
        cells[id.x].val = 1;
    }
    else
    {
        cells[id.x].val = 0;
    }
};

[numthreads(20,1,1)]
void Update (uint3 id : SV_DispatchThreadID)
{
    cells[id.x].pre = cells[id.x].val;
}