struct Constants
{
    float time;
};
Constants k : register(b0);

struct VSOutput
{
    float4 pos : SV_POSITION;
    float2 uv : TEXCOORD;
};

VSOutput vs(uint id : SV_VertexID)
{
    VSOutput output;
    float2 uv = float2((id << 1) & 2, id & 2);
    output.pos = float4(uv - 1, 0, 1);
    output.uv = uv;
    return output;
}

float4 ps(VSOutput input) : SV_Target
{
    float4 color = float4(0.5, 0, frac(k.time), 0.5);
    return color;
}