Merge pull request #11857 from donmccurdy/feat-gltf-default-shading

[gltf] Use flat shading if normals are not included.

examples/js/loaders/GLTF2Loader.js

@@ -2204,6 +2204,21 @@ THREE.GLTF2Loader = ( function () {
 
 						}
 
+						if ( geometry.attributes.normal === undefined ) {
+
+							if ( material.flatShading !== undefined ) {
+
+								material.flatShading = true;
+
+							} else {
+
+								// TODO: Remove this backwards-compatibility fix after r87 release.
+								material.shading = THREE.FlatShading;
+
+							}
+
+						}
+
 						meshNode = new THREE.Mesh( geometry, material );
 						meshNode.castShadow = true;