faceDirection

src/renderers/shaders/ShaderChunk/normal_fragment_begin.glsl.js

@@ -1,11 +1,14 @@
 export default /* glsl */`
-#ifdef FLAT_SHADED
 
-	// Workaround for Adreno/Nexus5 not able able to do dFdx( vViewPosition ) ...
+// Workaround for Adreno/Nexus5 not able able to do dFdx( vViewPosition ) ...
+
+vec3 fdx = vec3( dFdx( vViewPosition.x ), dFdx( vViewPosition.y ), dFdx( vViewPosition.z ) );
+vec3 fdy = vec3( dFdy( vViewPosition.x ), dFdy( vViewPosition.y ), dFdy( vViewPosition.z ) );
+vec3 faceNormal = normalize( cross( fdx, fdy ) );
+
+#ifdef FLAT_SHADED
 
-	vec3 fdx = vec3( dFdx( vViewPosition.x ), dFdx( vViewPosition.y ), dFdx( vViewPosition.z ) );
-	vec3 fdy = vec3( dFdy( vViewPosition.x ), dFdy( vViewPosition.y ), dFdy( vViewPosition.z ) );
-	vec3 normal = normalize( cross( fdx, fdy ) );
+	vec3 normal = faceNormal;
 
 #else
 
@@ -37,4 +40,21 @@ export default /* glsl */`
 
 vec3 geometryNormal = normal;
 
+#ifdef DOUBLE_SIDED
+
+	// Workaround for Adreno GPUs gl_FrontFacing bug. See #15850 and #10331
+
+	float faceDirection = dot (vViewPosition, faceNormal) > 0. ? 1. : -1.;
+	//float faceDirection = gl_FrontFacing ? 1. : -1.;
+
+#elif FLIP_SIDED
+
+	float faceDirection = -1.;
+
+#else
+
+	float faceDirection = 1.;
+
+#endif
+
 `;

src/renderers/shaders/ShaderChunk/normal_fragment_maps.glsl.js

@@ -29,7 +29,7 @@ export default /* glsl */`
 
 	#else
 
-		normal = perturbNormal2Arb( -vViewPosition, normal, normalScale, normalMap );
+		normal = perturbNormal2Arb( -vViewPosition, normal, normalScale * faceDirection, normalMap );
 
 	#endif
 

src/renderers/shaders/ShaderChunk/normalmap_pars_fragment.glsl.js

@@ -36,20 +36,6 @@ export default /* glsl */`
 
 		mapN.xy *= normalScale;
 
-		#ifdef DOUBLE_SIDED
-
-			// Workaround for Adreno GPUs gl_FrontFacing bug. See #15850 and #10331
-
-			bool frontFacing = dot( cross( S, T ), N ) > 0.0;
-
-			mapN.xy *= ( float( frontFacing ) * 2.0 - 1.0 );
-
-		#else
-
-			mapN.xy *= ( float( gl_FrontFacing ) * 2.0 - 1.0 );
-
-		#endif
-
 		mat3 tsn = mat3( S, T, N );
 		return normalize( tsn * mapN );