ColladaLoader: Add warning when converting up axis. (#24338)

examples/jsm/loaders/ColladaLoader.js

@@ -4066,6 +4066,7 @@ class ColladaLoader extends Loader {
 
 		if ( asset.upAxis === 'Z_UP' ) {
 
+			console.warn( 'THREE.ColladaLoader: You are loading an asset with a Z-UP coordinate system. The loader just rotates the asset to transform it into Y-UP. The vertex data are not converted, see #24289.' );
 			scene.quaternion.setFromEuler( new Euler( - Math.PI / 2, 0, 0 ) );
 
 		}