WebXRManager: Dynamically update camera list.

src/renderers/webxr/WebXRManager.js

@@ -36,7 +36,9 @@ function WebXRManager( renderer, gl ) {
 	cameraR.layers.enable( 2 );
 	cameraR.viewport = new Vector4();
 
-	var cameraVR = new ArrayCamera( [ cameraL, cameraR ] );
+	var cameras = [ cameraL, cameraR ];
+
+	var cameraVR = new ArrayCamera();
 	cameraVR.layers.enable( 1 );
 	cameraVR.layers.enable( 2 );
 
@@ -389,12 +391,23 @@ function WebXRManager( renderer, gl ) {
 
 			renderer.setFramebuffer( baseLayer.framebuffer );
 
+			var cameraVRNeedsUpdate = false;
+
+			// check if it's necessary to rebuild cameraVR's camera list
+
+			if ( views.length !== cameraVR.cameras.length ) {
+
+				cameraVR.cameras.length = 0;
+				cameraVRNeedsUpdate = true;
+
+			}
+
 			for ( var i = 0; i < views.length; i ++ ) {
 
 				var view = views[ i ];
 				var viewport = baseLayer.getViewport( view );
 
-				var camera = cameraVR.cameras[ i ];
+				var camera = cameras[ i ];
 				camera.matrix.fromArray( view.transform.matrix );
 				camera.projectionMatrix.fromArray( view.projectionMatrix );
 				camera.viewport.set( viewport.x, viewport.y, viewport.width, viewport.height );
@@ -405,6 +418,12 @@ function WebXRManager( renderer, gl ) {
 
 				}
 
+				if ( cameraVRNeedsUpdate === true ) {
+
+					cameraVR.cameras.push( camera );
+
+				}
+
 			}
 
 		}