feat(editor): implement element location update on

dragend

Replaced a placeholder console.log with a concrete implementation of the
`updateElementLocation` function in the `startModifyElement` event
listener. This function calculates a new angular position (`theta`)
based on the element's offset after dragging it in the editor and
updates the element's `theta-start` attribute accordingly. This change
leads to a more dynamic and interactive user experience in the editor by
allowing users to reposition elements visually and have those changes
reflected immediately.

assets/js/editor.js

@@ -180,7 +180,7 @@ function startModifyElement(event) {
 
   // Listen for "dragend" event to update the element's position
   event.target.addEventListener("dragend", function (event) {
-    console.log(event); // TODO: Display, obviously.
+    updateElementLocation(event);
   });
 
   var propertiesTitle = document.getElementById("propertiesTitle");
@@ -350,6 +350,11 @@ document.addEventListener("loadedQuackscapeScene", function (event) {
   }
 });
 
+function updateElementLocation(event) {
+  const theta = cartesianToTheta(event.detail.offset.x, event.detail.offset.z);
+  event.target.setAttribute("theta-start", theta);
+}
+
 function toggleDebugVisibility() {
   const debugElement = document.getElementById("propertiesDebug");
   debugElement.classList.toggle("hide");