cbuffer constants : register(b0)
{
    float2 rn_screensize; // { 2 / width, -2 / height }
}

struct vertexdesc
{
    float2 position : POS;
    float3 color    : COL;
};

struct pixeldesc
{
    float4 position : SV_POSITION;
    float4 color    : COL;
};

pixeldesc VsMain(vertexdesc vertex)
{
    pixeldesc output;

    output.position = float4(vertex.position * rn_screensize - float2(1, -1), 0, 1);
    output.color    = float4(vertex.color, 1);

    return output;
}

float4 PsMain(pixeldesc pixel) : SV_TARGET
{
    return pixel.color;
}