import FluidGridData;

struct Params
{
    // read-write: phi to add source to
    FluidGridData<float> phi;
    FluidGridData<float> density;
};
ParameterBlock<Params> params;

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

    // Add a spherical source and union it into the existing level set.
    float3 center = float3(gridParams.gridSize) * 0.5f;
    float radius = min(gridParams.gridSize.x, min(gridParams.gridSize.y, gridParams.gridSize.z)) * 0.25f;
    float3 pos = float3(x, y, z);
    float dist = length(pos - center);
    float sourcePhi = dist - radius;
    phi[x, y, z] = min(phi[x, y, z], sourcePhi);

    if (sourcePhi < 0.0f)
    {
        density[x, y, z] += 0.5f;
        density[x, y, z] = min(density[x, y, z], 1.0f);
    }
}