[pixel shader]
float4 main(uniform float2 u) : sv_target
{
    return float4(saturate(u), saturate(u.x + 0.5), saturate(-1.2));
}

[test]
uniform 0 float4 0.7 -0.1 0.0 0.0
draw quad
probe all rgba (0.7, 0.0, 1.0, 0.0)