1uniform half4 testInputs; // equals (-1.25, 0, 0.75, 2.25) 2uniform half4 colorGreen, colorRed; 3 4half4 main(float2 coords) { 5 half4 expected = half4(0); // derivative of a constant is zero 6 return (dFdx(testInputs.x) == expected.x && 7 dFdx(testInputs.xy) == expected.xy && 8 dFdx(testInputs.xyz) == expected.xyz && 9 dFdx(testInputs.xyzw) == expected.xyzw && 10 sign(dFdx(coords.xx)) == half2(1, 1) && 11 sign(dFdx(coords.yy)) == half2(0, 0) && 12 sign(dFdx(coords.xy)) == half2(1, 0)) ? colorGreen : colorRed; 13} 14