avoid rendering geometry

examples/webgl_mirror_nodes.html

@@ -153,6 +153,7 @@
 
 				// MIRROR planes
 				var groundMirror = new THREE.Mirror( 100, 100, { clipBias: 0.003, textureWidth: WIDTH, textureHeight: HEIGHT } );
+				groundMirror.geometry.setDrawRange( 0, 0 ); // avoid rendering geometry
 
 				var mask = new THREE.SwitchNode( new THREE.TextureNode( decalDiffuse ), 'w' );
 				var maskFlip = new THREE.Math1Node( mask, THREE.Math1Node.INVERT );