LDraw: don't clear already-loaded materials on load

Author: Floppy

examples/jsm/loaders/LDrawLoader.js

@@ -1885,7 +1885,7 @@ class LDrawLoader extends Loader {
 
 		}
 
-		this.setMaterials( materials );
+		this.addMaterials(materials);
 
 	}
 
@@ -1907,7 +1907,7 @@ class LDrawLoader extends Loader {
 		fileLoader.load( url, text => {
 
 			// Initializes the materials library with default materials
-			this.setMaterials( [] );
+			this.addMaterials([]);
 
 			this.partsCache
 				.parseModel( text )
@@ -1948,10 +1948,18 @@ class LDrawLoader extends Loader {
 
 	}
 
-	setMaterials( materials ) {
+	setMaterials(materials) {
+		this.clearMaterials();
+		this.addMaterials(materials);
+	}
 
+	clearMaterials() {
 		this.materialLibrary = {};
 		this.materials = [];
+	}
+
+	addMaterials(materials) {
+
 		for ( let i = 0, l = materials.length; i < l; i ++ ) {
 
 			this.addMaterial( materials[ i ] );