fix: place player-built models using their stored position and rotation

DarkflameServer now normalizes UGC model LXFML around the model's own
origin and stores the model's world position and rotation in
properties_contents, the same as for prebuilt models. The property
viewer only applied that transform to prebuilt models, so every
player-built model rendered piled up at the origin.

Pass each UGC model's stored position and rotation to the LDD converter
and apply it to every brick (including flex parts) when building the
scene.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

app/templates/ldd/ldd.html.j2

@@ -277,7 +277,9 @@
       this.xmldata = ''
     }
 
-    AddScene(file){
+    // placement: optional THREE.Matrix4 that places this model in the property. DLU stores player-built
+    // (UGC) models normalized around their own origin, with the position and rotation in properties_contents.
+    AddScene(file, placement = null){
       let lxfmlfile = new DBURLFile(file,file)
       this.xmldata = lxfmlfile.read()
 
@@ -305,7 +307,9 @@
           for (let j = 0; j < childnodes.length ;j++) {
             let childnode = childnodes[j]
             if (childnode.nodeName == 'Brick'){
-              this.Bricks.push(new Brick(childnode))
+              let brick = new Brick(childnode)
+              brick.placement = placement
+              this.Bricks.push(brick)
             }
           }
         }
@@ -531,9 +535,9 @@
       }
     }
 
-    LoadScene(filename){
+    LoadScene(filename, placement = null){
       if(this.database.initok){
-        this.scene.AddScene(filename)
+        this.scene.AddScene(filename, placement)
       }
     }
 
@@ -608,6 +612,11 @@
                 n14, n24 ,n34, n44);
           }
 
+          // Move the brick from model space to its place on the property
+          if (bri.placement){
+            m.premultiply(bri.placement)
+          }
+
           let decoCount = 0
 
           for (const [partindex, part] of geo.Parts.entries()){
@@ -1033,10 +1042,14 @@
 
 
   //Start
+  // Player-built models with the position and rotation stored for them in properties_contents
   let lxfml_file_list = [
     {% for model in content %}
       {% if model.lot == 14 %}
-        "{{url_for('properties.get_model', id=model.id, file_format='lxfml', lod=lod)}}"{{ ", " if not loop.last else "" }}
+        {
+          "url": "{{url_for('properties.get_model', id=model.id, file_format='lxfml', lod=lod)}}",
+          "pos": {{ model.pos[0]|tojson }}
+        }{{ ", " if not loop.last else "" }}
       {% endif %}
     {% endfor %}
   ]
@@ -1047,7 +1060,13 @@
       let converter = new Converter()
       converter.LoadDBURL(ldddburl)
       for (let i = 0; i < lxfml_file_list.length; i++) {
-        converter.LoadScene(lxfml_file_list[i])
+        let pos = lxfml_file_list[i].pos
+        let placement = new THREE.Matrix4().compose(
+          new THREE.Vector3(pos.x, pos.y, pos.z),
+          new THREE.Quaternion(pos.rx, pos.ry, pos.rz, pos.rw),
+          new THREE.Vector3(1, 1, 1)
+        )
+        converter.LoadScene(lxfml_file_list[i].url, placement)
       }
       converter.Export('test.webgl')