cocos-creator-template/assets/chunks/surfaces/default-functions/skin.chunk

#include <surfaces/data-structures/standard>

#define CC_SURFACES_FRAGMENT_MODIFY_SHARED_DATA
void SurfacesFragmentModifySharedData(inout SurfacesMaterialData surfaceData)
{
#if CC_SURFACES_LIGHTING_SSS
  float sssStrength = surfaceData.sssParams.x;
  #if !CC_SURFACES_LIGHTING_DISABLE_DIFFUSE && CC_SURFACES_LIGHTING_DISABLE_SPECULAR
    // 0 - 0.9 is valid skin alpha without MSAA, 0 is valid skin alpha with MSAA
    surfaceData.baseColor.a = sssStrength * 0.9;
    // #if MSAA_ENABLE
      // surfaceData.baseColor.a = 1.0 - step(0.5, sssStrength);
    // #endif
  #endif
#endif
}