metalnessmapFragment top-level property
Implementation
String metalnessmapFragment = """
float metalnessFactor = metalness;
#ifdef USE_METALNESSMAP
vec4 texelMetalness = texture2D( metalnessMap, vUv );
// reads channel B, compatible with a combined OcclusionRoughnessMetallic (RGB) texture
metalnessFactor *= texelMetalness.b;
#endif
""";