#version 430

// Game of life transfert shader

#define GOL_WIDTH 768

// Game Of Life Update Command
// NOTE: matches the structure defined on main program
struct GolUpdateCmd {
    uint x;         // x coordinate of the gol command
    uint y;         // y coordinate of the gol command
    uint w;         // width of the filled zone
    uint enabled;   // whether to enable or disable zone
};

// Local compute unit size
layout (local_size_x = 1, local_size_y = 1, local_size_z = 1) in;

// Output game of life grid buffer
layout(std430, binding = 1) buffer golBufferLayout
{
    uint golBuffer[]; // golBuffer[x, y] = golBuffer[x + GOL_WIDTH * y]
};

// Command buffer
layout(std430, binding = 3) readonly restrict buffer golUpdateLayout
{
    uint count;
    GolUpdateCmd commands[];
};

#define isInside(x, y) (((x) >= 0) && ((y) >= 0) && ((x) < GOL_WIDTH) && ((y) < GOL_WIDTH))
#define getBufferIndex(x, y) ((x) + GOL_WIDTH * (y))

void main()
{
    uint cmdIndex = gl_GlobalInvocationID.x;
    GolUpdateCmd cmd = commands[cmdIndex];

    for (uint x = cmd.x; x < (cmd.x + cmd.w); x++)
    {
        for (uint y = cmd.y; y < (cmd.y + cmd.w); y++)
        {
            if (isInside(x, y))
            {
                if (cmd.enabled != 0) atomicOr(golBuffer[getBufferIndex(x, y)], 1);
                else atomicAnd(golBuffer[getBufferIndex(x, y)], 0);
            }
        }
    }
}