submodule/skia/resources/sksl/intrinsics/DFdx.sksl

   1 uniform half4 testInputs;  // equals (-1.25, 0, 0.75, 2.25)
   2 uniform half4 colorGreen, colorRed;
   3
   4 half4 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 }