import FluidGridData;

struct Params
{
    FluidGridData<float> density;
};
ParameterBlock<Params> params;

struct VertexOut
{
    float4 position : SV_Position;
    float2 uv : UV;
};

[shader("vertex")]
VertexOut vertexMain(uint vertexId : SV_VertexID)
{
    VertexOut output;
    output.uv = float2((vertexId << 1) & 2, vertexId & 2);
    output.position = float4(output.uv * 2.0f - 1.0f, 0, 1);
    return output;
}

[shader("pixel")]
float4 fragmentMain(VertexOut input) : SV_Target
{
    FluidGridData<float> density = params.density;
    int x = int(input.uv.x * (gridSize.x - 2) + 1);
    int y = int(input.uv.y * (gridSize.y - 2) + 1);
    float d = density[x, y, 1];
    return float4(d, d, d, 1);
}