Changes

Co-authored-by: Reifonas <211114984+Reifonas@users.noreply.github.com>

src/lib/convertIFC.ts

@@ -23,6 +23,13 @@ export async function convertIFCtoGLB(
 
   ifcApi.StreamAllMeshes(modelID, (mesh: WebIFC.FlatMesh) => {
     const placedGeometries = mesh.geometries;
+    const expressID = (mesh as unknown as { expressID?: number }).expressID ?? 0;
+
+    // One Group per IfcProduct → represents a single "element" (beam, plate…).
+    // userData is preserved by GLTFExporter as `extras` and survives reload.
+    const elementGroup = new THREE.Group();
+    elementGroup.name = `ifc_${expressID}`;
+    elementGroup.userData = { ifcElement: true, ifcId: expressID };
 
     for (let i = 0; i < placedGeometries.size(); i++) {
       const placedGeometry = placedGeometries.get(i);
@@ -38,8 +45,6 @@ export async function convertIFCtoGLB(
       );
 
       const geometry = new THREE.BufferGeometry();
-
-      // web-ifc vertex format: x, y, z, nx, ny, nz (6 floats per vertex)
       const positionArray = new Float32Array(verts.length / 2);
       const normalArray = new Float32Array(verts.length / 2);
 
@@ -57,10 +62,8 @@ export async function convertIFCtoGLB(
       geometry.setAttribute('normal', new THREE.BufferAttribute(normalArray, 3));
       geometry.setIndex(new THREE.BufferAttribute(indices, 1));
 
-      // Get or create material based on color
       const color = placedGeometry.color;
       const colorKey = (color.x * 255) << 16 | (color.y * 255) << 8 | (color.z * 255);
-
       let material = materials.get(colorKey);
       if (!material) {
         material = new THREE.MeshStandardMaterial({
@@ -75,16 +78,17 @@ export async function convertIFCtoGLB(
       }
 
       const mesh3 = new THREE.Mesh(geometry, material);
+      mesh3.userData = { ifcId: expressID };
 
-      // Apply placement transform
       const matrix = new THREE.Matrix4();
       matrix.fromArray(placedGeometry.flatTransformation);
       mesh3.applyMatrix4(matrix);
 
-      scene.add(mesh3);
-
+      elementGroup.add(mesh3);
       ifcGeometry.delete();
     }
+
+    if (elementGroup.children.length > 0) scene.add(elementGroup);
   });
 
   ifcApi.CloseModel(modelID);