message: Work around FXAA issue with Vulkan Adreno drivers.
  Fixes
diff: # define FXAA_GREEN_AS_LUMA 1
  #endif
  +// This substitute for the built-in "mix" function exists to work around #732, seen with Vulkan
  +// on the Pixel 3 + Android P.
  +vec4 lerp(vec4 x, vec4 y, float a) {
  + return x * (1.0 - a) + y * a;
  +}
  +
  /**
  G3D version of FXAA. See copyright and warranty statement below.
  @@ -635,7 +641,7 @@ FxaaFloat4 fxaa(
  // Keep some of the original contribution to avoid thin lines degrading completely
  // and overblurring. This is an addition to the original Lottes algorithm
  // rgbyB = sqrt(lerp(rgbyB * rgbyB, rgbyM * rgbyM, 0.25)); // Luminance preserving
  - rgbyB = mix(rgbyB, rgbyM, 0.25); // Faster
  + rgbyB = lerp(rgbyB, rgbyM, 0.25); // Faster
  # endif
  return rgbyB;
  }
  