How to calculate the height of a Model

Troubleshooting General Help
1

I'm loading a model from a MD2 file and trying to calculate the Model height to place it over the ground …

I'm getting the triangles from the child meshes … but something is going wrong with the result …

any other easy way to do it ?



look ath the code !


public class NodeUtil {

   public static float getHeight(Node node) {

      float top = 0;
      float bottom = 0;

      Vector3f[] foo = new Vector3f[3];
      Stack<Node> toInspect = new Stack<Node>();
      toInspect.push(node);

      while (!toInspect.isEmpty()) {
         Node current = (Node) toInspect.pop();
         Iterator iterator = current.getChildren().iterator();

         while (iterator.hasNext()) {
            Spatial element = (Spatial) iterator.next();

            if (element instanceof Node) {
               toInspect.push((Node) element);
            } else {
               if (element instanceof TriMesh) {
                  TriMesh mesh = (TriMesh) element;

                  for (int i = 0; i < mesh.getTotalTriangles(); i++) {
                     mesh.getTriangle(i, foo);
                     LoggingSystem.getLogger().info("foo[0].y=" + foo[0].y);

                     if (foo[0].y > top)
                        top = foo[0].y;
                     if (foo[1].y > top)
                        top = foo[1].y;
                     if (foo[2].y > top)
                        top = foo[2].y;

                     if (foo[0].y < bottom)
                        bottom = foo[0].y;
                     if (foo[1].y < bottom)
                        bottom = foo[1].y;
                     if (foo[2].y < bottom)
                        bottom = foo[2].y;
                  }
               }
            } // if node

         }
      }
      
      float height = top - bottom;
      LoggingSystem.getLogger().info("height = " + height);
      return height;
   }

}



and the character still is floating ...  :D


here is the code that I use at the update() method

   @Override
   protected void update(float interpolation) {

      // update the time to get the framerate
      timer.update();
      interpolation = timer.getTimePerFrame();
      // update the keyboard input (move the player around)
      input.update(interpolation);
      // update the chase camera to handle the player moving around.
      chaser.update(interpolation);
      // if escape was pressed, we exit
      if (KeyBindingManager.getKeyBindingManager().isValidCommand("exit")) {
         finished = true;
      }

      // We don't want the chase camera to go below the world, so always keep
      // it 2 units above the level.
      if (cam.getLocation().y < (page.getHeight(cam.getLocation()) + 2)) {
         cam.getLocation().y = page.getHeight(cam.getLocation()) + 2;
         cam.update();
      }

      // player.getLocalTranslation().y = page.getHeight(player
      // .getLocalTranslation().x, player.getLocalTranslation().z)
      // + (player.getHeight() / 2);

      float characterMinHeight = page.getHeight(player.getLocalTranslation())
            + (player.getHeight() / 2) + DISTANCE_FROM_THE_GROUND;

      if (!Float.isInfinite(characterMinHeight)
            && !Float.isNaN(characterMinHeight)) {
         player.getLocalTranslation().y = characterMinHeight;
      }

      // get the normal of the terrain at our current location. We then apply
      // it to the up vector
      // of the player.
      page.getSurfaceNormal(player.getLocalTranslation(), normal);
      if (normal != null) {
         player.rotateUpTo(normal);
      }

      // Because we are changing the scene (moving the skybox and player) we
      // need to update
      // the graph.
      scene.updateGeometricState(interpolation, true);
   }

1 Like
2

An easy way would be taking the height of the world bound. The accuracy of this depends on the kind of model bound you are using, of course.

3

good idea !

I have a class Player that loads the model from an MD2 file, after getting an WorldBound = null

I took a look and found that my method of model loading is not setting the boundingbox to the model

even after this change I still get null worldbound …



I think something is wrong at my loadmodelcode …


   private Node loadModel(DisplaySystem display) {
      Md2ToJme converter = new Md2ToJme();
      ByteArrayOutputStream BO = new ByteArrayOutputStream();

      URL textu = Player.class.getClassLoader().getResource(
            "media/models/alita/alita2.jpg");
      URL model = Player.class.getClassLoader().getResource(
            "media/models/alita/tris.md2");
      Node modelMD2 = null;

      try {
         converter.convert(model.openStream(), BO);
         modelMD2 = (Node) BinaryImporter.getInstance().load(
               new ByteArrayInputStream(BO.toByteArray()));
         modelMD2.setLocalScale(.3f);

         modelMD2.setModelBound(new BoundingBox());
         modelMD2.updateModelBound();

      } catch (IOException e) {
         LoggingSystem.getLogger().warning( " ---- ERROR : " + e.getMessage());
      }

      TextureState ts = display.getRenderer().createTextureState();
      ts.setEnabled(true);
      ts.setTexture(TextureManager.loadTexture(textu,
            Texture.MM_LINEAR_LINEAR, Texture.FM_LINEAR));
      modelMD2.setRenderState(ts);
      
      System.out.println("model.getWorldBound()=" + modelMD2.getWorldBound());

      return modelMD2;
   }



the system.out shows null world bound ... :(
4

there are two bounds at each location of the scenegraph…  A local (model) one that encompasses just that node or leaf on the graph and a "world" one that encompasses that node and any nodes or leafs below it.  The world one will not exist until it is generated via an updateWorldBound call.

5

Hey ! thanks



the character was getting sick of floating hehehehe

now its over tied to the ground …  :smiley: