third_party/skia/resources/sksl/shared/UnaryPositiveNegative.sksl

uniform half4 colorWhite, colorGreen, colorRed;

half4 main(float2 coords) {
    half2 x = colorWhite.rg;
    x = +x;
    x = -x;
    return x == half2(-1) ? colorGreen : colorRed;
}