uniform half a, b, c;
uniform half4 d, e;
void main() {
    sk_FragColor.x = refract(a, b, c);
    sk_FragColor = refract(d, e, c);

    sk_FragColor.xy   = refract(half2(1,0),     half2(0,1),     0.5);
    sk_FragColor.xyz  = refract(half3(1,0,0),   half3(0,0,1),   0.5);
    sk_FragColor.xyzw = refract(half4(1,0,0,0), half4(0,0,0,1), 0.5);
}