GLTFLoader: Corrections to normalscale.

Author: donmccurdy

examples/js/loaders/GLTFLoader.js

@@ -2204,11 +2204,13 @@ THREE.GLTFLoader = ( function () {
 
 			pending.push( parser.assignTexture( material, 'normal', materialDef.normalTexture.index ) );
 
-			material.normalScale = new THREE.FloatNode( 1.0 );
+			// Normal map textures use OpenGL conventions:
+			// https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#materialnormaltexture
+			material.normalScale = new THREE.Vector2Node( 1.0, -1.0 );
 
 			if ( materialDef.normalTexture.scale !== undefined ) {
 
-				material.normalScale.value = materialDef.normalTexture.scale;
+				material.normalScale.value.multiplyScalar( materialDef.normalTexture.scale );
 
 			}
 
@@ -2246,14 +2248,6 @@ THREE.GLTFLoader = ( function () {
 
 			if ( materialDef.name !== undefined ) material.name = materialDef.name;
 
-			// Normal map textures use OpenGL conventions:
-			// https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#materialnormaltexture
-			// if ( material.normalScale ) {
-
-			// 	material.normalScale.y = - material.normalScale.y;
-
-			// }
-
 			if ( materialDef.extras ) material.userData = materialDef.extras;
 
 			if ( materialDef.extensions ) addUnknownExtensionsToUserData( extensions, material, materialDef );

examples/js/nodes/NodeLib.js

@@ -141,8 +141,10 @@ THREE.NodeLib.add( new THREE.FunctionNode( [
 	"	vec3 q1 = dFdy( eye_pos );",
 	"	vec2 st0 = dFdx( mUv.st );",
 	"	vec2 st1 = dFdy( mUv.st );",
-	"	vec3 S = normalize( q0 * st1.t - q1 * st0.t );",
-	"	vec3 T = normalize( -q0 * st1.s + q1 * st0.s );",
+	" float factor = sign( st1.t * st0.s - st0.t * st1.s );",
+	" factor *= float( gl_FrontFacing ) * 2.0 - 1.0;",
+	"	vec3 S = normalize( ( q0 * st1.t - q1 * st0.t ) * factor );",
+	"	vec3 T = normalize( ( -q0 * st1.s + q1 * st0.s ) * factor );",
 	"	vec3 N = normalize( surf_norm );",
 	"	vec3 mapN = map * 2.0 - 1.0;",
 	"	mapN.xy = scale * mapN.xy;",