USDZExporter: Allow to pass {includeAnchoringProperties: false} as op…

…tions to anchor on wall or floor

examples/jsm/exporters/USDZExporter.js

@@ -25,6 +25,7 @@ class USDZExporter {
 				anchoring: { type: 'plane' },
 				planeAnchoring: { alignment: 'horizontal' }
 			},
+			includeAnchoringProperties: true,
 			quickLookCompatible: false,
 			maxTextureSize: 1024,
 		}, options );
@@ -198,6 +199,10 @@ function buildHeader() {
 
 function buildSceneStart( options ) {
 
+	const alignment = options.includeAnchoringProperties === true ? `
+		token preliminary:anchoring:type = "${options.ar.anchoring.type}"
+		token preliminary:planeAnchoring:alignment = "${options.ar.planeAnchoring.alignment}"
+	` : '';
 	return `def Xform "Root"
 {
 	def Scope "Scenes" (
@@ -211,10 +216,7 @@ function buildSceneStart( options ) {
 			}
 			sceneName = "Scene"
 		)
-		{
-		token preliminary:anchoring:type = "${options.ar.anchoring.type}"
-		token preliminary:planeAnchoring:alignment = "${options.ar.planeAnchoring.alignment}"
-
+		{${alignment}
 `;
 
 }