import FluidGridData;

struct Params
{
    // read-write
    FluidGridData<float> velocityX;
    // read-write
    FluidGridData<float> velocityY;
    // read-write
    FluidGridData<float> velocityZ;
    // read-only
    FluidGridData<float> pressure;
};
ParameterBlock<Params> params;

[shader("compute")]
[numthreads(32, 8, 1)]
void project(uint3 dispatchThreadID : SV_DispatchThreadID)
{
    FluidGridData<float> velocityX = params.velocityX;
    FluidGridData<float> velocityY = params.velocityY;
    FluidGridData<float> velocityZ = params.velocityZ;
    FluidGridData<float> pressure = params.pressure;
    
    int x = dispatchThreadID.x + 1;
    int y = dispatchThreadID.y + 1;
    int z = dispatchThreadID.z + 1;
    if(x >= gridSize.x - 1 || y >= gridSize.y - 1 || z >= gridSize.z - 1) return;

    velocityX[x, y, z] -= 0.5f * (pressure[x + 1, y, z] - pressure[x - 1, y, z]) * gridSize.x;
    velocityY[x, y, z] -= 0.5f * (pressure[x, y + 1, z] - pressure[x, y - 1, z]) * gridSize.y;
    velocityZ[x, y, z] -= 0.5f * (pressure[x, y, z + 1] - pressure[x, y, z - 1]) * gridSize.z;
}