ShadowNode: Inherit camera.layers only if shadow.camera.layers is not set

src/nodes/lighting/ShadowNode.js

@@ -569,7 +569,11 @@ class ShadowNode extends ShadowBaseNode {
 		const depthVersion = shadowMap.depthTexture.version;
 		this._depthVersionCached = depthVersion;
 
-		shadow.camera.layers.mask = camera.layers.mask;
+		if ( shadow.camera.layers.test( 0 ) === true ) {
+
+			shadow.camera.layers.mask = camera.layers.mask;
+
+		}
 
 		const currentRenderObjectFunction = renderer.getRenderObjectFunction();