Mirror: Copy camera.aspect. Fixes #11969

examples/js/Mirror.js

@@ -141,6 +141,7 @@ THREE.Mirror = function ( width, height, options ) {
 		mirrorCamera.up.reflect( normal ).negate();
 		mirrorCamera.lookAt( target );
 
+		mirrorCamera.aspect = camera.aspect;
 		mirrorCamera.near = camera.near;
 		mirrorCamera.far = camera.far;