[pixel shader]
uniform float4 f;

float4 main() : sv_target
{
    return frac(f);
}

[test]
uniform 0 float4 -1.1 1.6 1.3 0.5
todo(glsl) draw quad
probe (0, 0) rgba (0.9, 0.6, 0.3, 0.5) 2