android – 如何在libgdx中获取模型实例的边界框？

我创建了一个模型(一个盒子)和100个实例,在世界各地移动.它们会被渲染到预期的位置.

我现在正在尝试实现光线拾取,但我发现所有100个实例都返回原始模型的相同边界框.为什么不为每个实例计算实际的边界框？

创建模型和实例：

public static void createModel() {
   ModelBuilder modelBuilder = new ModelBuilder();
   modelBuilder.begin();
   MeshPartBuilder tileBuilder;
   tileBuilder = modelBuilder.part("top",GL10.GL_TRIANGLES,Usage.Position | Usage.Normal | Usage.TextureCoordinates,new Material(ColorAttribute.createDiffuse(Color.WHITE)));
   tileBuilder.rect(-0.45f,0.1f,0.45f,-0.45f,0f,1f,0f);
   tileBuilder = modelBuilder.part("bottom",Usage.Position | Usage.Normal,...
   modelTile = modelBuilder.end();
}

public void createModelInstance(com.badlogic.gdx.assets.AssetManager assetManager) {
  Texture texTile = assetManager.get("textures/" + textureFile,Texture.class);
  Material mat = new Material(TextureAttribute.createDiffuse(texTilE));
  modelInstance = new ModelInstance(modelTilE); 
  modelInstance.nodes.get(0).parts.get(0).material.set(mat);
}

移动模型实例：

public void setCoordinates(Boolean animate,float x,float y,float z) {
  modelInstance.transform.setToTranslation(x,y,z);
  modelInstance.calculateTransforms();
}

射线拣选尝试：

public Boolean pickTile(int x,int y) {
  cam.update();
  Ray ray = cam.getPickRay(x,y);
  BoundingBox bb = new BoundingBox();
  for (int i=0;i<gameData.tiles.length;i++) {
    Log.i("ltower","checking " + i);
    gameData.tiles[i].getModelInstance().calculateBoundingBox(bb);
Log.i("ltower","BB: " + bb.getCenter().x + "," + bb.getCenter().y + "," + bb.getCenter().z);
    if (Intersector.intersectRayBoundsFast(ray,bb)) {
      gameData.tiles[i].SELEct();
      return true;
    }
  }
  return false;
}

日志：

01-05 05:27:18.934: I/ltower(2175): checking 0
01-05 05:27:18.984: I/ltower(2175): BB: 0.0,0.05,0.0
01-05 05:27:19.024: I/ltower(2175): checking 1
01-05 05:27:19.024: I/ltower(2175): BB: 0.0,0.0
01-05 05:27:19.044: I/ltower(2175): checking 2
01-05 05:27:19.064: I/ltower(2175): BB: 0.0,0.0
01-05 05:27:19.064: I/ltower(2175): checking 3
01-05 05:27:19.064: I/ltower(2175): BB: 0.0,0.0
01-05 05:27:19.064: I/ltower(2175): checking 4
01-05 05:27:19.064: I/ltower(2175): BB: 0.0,0.0
01-05 05:27:19.064: I/ltower(2175): checking 5
01-05 05:27:19.104: I/ltower(2175): BB: 0.0,0.0
01-05 05:27:19.104: I/ltower(2175): checking 6
01-05 05:27:19.104: I/ltower(2175): BB: 0.0,0.0 
...