Change metalness uniform value from 0 to 0.5(MeshStandardMaterial.metalness default value)

src/renderers/shaders/ShaderLib.js

@@ -87,7 +87,7 @@ var ShaderLib = {
 			{
 				emissive: { value: new Color( 0x000000 ) },
 				roughness: { value: 0.5 },
-				metalness: { value: 0 },
+				metalness: { value: 0.5 },
 				envMapIntensity: { value: 1 } // temporary
 			}
 		] ),