showBoundingBox method

Implementation

Future showBoundingBox(ThermionAsset asset) async {
  if (_boundingBoxAssets.containsKey(asset)) {
    final bbAsset = await _boundingBoxAssets[asset]!.future;
    await scene.add(bbAsset);
    return;
  }

  var completer = Completer<ThermionAsset>();
  _boundingBoxAssets[asset] = completer;

  final boundingBox = await asset.getBoundingBox();

  final min = [
    boundingBox.center.x + boundingBox.min.x,
    boundingBox.center.y + boundingBox.min.y,
    boundingBox.center.z + boundingBox.min.z
  ];
  final max = [
    boundingBox.center.x + boundingBox.max.x,
    boundingBox.center.y + boundingBox.max.y,
    boundingBox.center.z + boundingBox.max.z
  ];

  // Create vertices for the bounding box wireframe
  // 8 vertices for a cube
  final vertices = Float32List(8 * 3);

  // Bottom vertices
  vertices[0] = min[0];
  vertices[1] = min[1];
  vertices[2] = min[2]; // v0
  vertices[3] = max[0];
  vertices[4] = min[1];
  vertices[5] = min[2]; // v1
  vertices[6] = max[0];
  vertices[7] = min[1];
  vertices[8] = max[2]; // v2
  vertices[9] = min[0];
  vertices[10] = min[1];
  vertices[11] = max[2]; // v3

  // Top vertices
  vertices[12] = min[0];
  vertices[13] = max[1];
  vertices[14] = min[2]; // v4
  vertices[15] = max[0];
  vertices[16] = max[1];
  vertices[17] = min[2]; // v5
  vertices[18] = max[0];
  vertices[19] = max[1];
  vertices[20] = max[2]; // v6
  vertices[21] = min[0];
  vertices[22] = max[1];
  vertices[23] = max[2]; // v7

  // Indices for lines (24 indices for 12 lines)
  final indices = Uint16List.fromList([
    // Bottom face
    0, 1, 1, 2, 2, 3, 3, 0,
    // Top face
    4, 5, 5, 6, 6, 7, 7, 4,
    // Vertical edges
    0, 4, 1, 5, 2, 6, 3, 7
  ]);

  // Create unlit material instance for the wireframe
  final materialInstancePtr =
      await withPointerCallback<TMaterialInstance>((cb) {
    MaterialProvider_createMaterialInstanceRenderThread(
        app.ubershaderMaterialProvider,
        false,
        true,
        false,
        false,
        false,
        false,
        false,
        false,
        0,
        false,
        false,
        0,
        false,
        0,
        0,
        false,
        0,
        false,
        0,
        false,
        0,
        false,
        false,
        false,
        0,
        0,
        0,
        false,
        0,
        false,
        0,
        false,
        0,
        false,
        0,
        false,
        false,
        false,
        cb);
  });

  final material = FFIMaterialInstance(materialInstancePtr, app);
  await material.setParameterFloat4(
      "baseColorFactor", 1.0, 1.0, 0.0, 1.0); // Yellow wireframe

  // Create geometry for the bounding box
  final geometry = Geometry(
    vertices,
    indices,
    primitiveType: PrimitiveType.LINES,
  );

  final bbAsset = await FilamentApp.instance!.createGeometry(
    geometry,
    animationManager,
    materialInstances: [material],
    keepData: false,
  ) as FFIAsset;

  await bbAsset.setCastShadows(false);
  await bbAsset.setReceiveShadows(false);

  TransformManager_setParent(Engine_getTransformManager(app.engine),
      bbAsset.entity, asset.entity, false);
  geometry.uvs.free();
  geometry.normals.free();
  geometry.vertices.free();
  geometry.indices.free();
  completer.complete(bbAsset);

  await scene.add(bbAsset);

  return bbAsset;
}