modelloader.java

Pro Java 6 3D Game Development书中的源代码。本实例为ARMS

// ModelLoader.java
// Andrew Davison, September 2006, [e-mail]

/* The ModelLoader getModel() method expects a OBJ filename, for
   files in the Models/ subdirectory, and an optional y-axis 
   translation. The method returns a TransformGroup which can
   be used with other TGs to further position, rotate, or scale
   the model.

   List of models with their optional y-axis offsets:
     penguin.obj, sword.obj 1, humanoid.obj 0.8
     hand.obj 1, barbell.obj 0.25, longBox.obj, cone.obj 0.4
     heli.obj 0, matCube.obj 0.5, cubeSphere.obj 0.9

   The loaded model is scaled so it doesn't exceed MAX_SIZE units
   along any axis. This model's size is obtained from its bounding
   box.
*/


import java.io.*;
import java.net.*;

import javax.media.j3d.*;
import javax.vecmath.*;
import com.sun.j3d.loaders.*;
import com.sun.j3d.loaders.objectfile.*;



public class ModelLoader
{
  private static final String MODELS_DIR = "Models/";

  private static final double MAX_SIZE = 5.0;   
              // max size of model along any dimension

  private ObjectFile objFileloader;


  public ModelLoader()
  {  objFileloader = new ObjectFile();  } 


  public TransformGroup getModel(String fnm)
  {  return getModel(fnm, 0);  }


  public TransformGroup getModel(String fnm, double yMove)
  // returns tg --> model
  {
    // load the model
    BranchGroup modelBG = loadModel(fnm);
    if (modelBG == null)
      return null;

    double scaleFactor = getScaling(modelBG);

    // scale and move the model along the y-axis
    Transform3D t3d = new Transform3D();
    t3d.setScale(scaleFactor);
    t3d.setTranslation( new Vector3d(0,yMove,0));

    TransformGroup tg = new TransformGroup(t3d);
    tg.addChild(modelBG); 
    return tg;
  }  // end of getModel()


  private BranchGroup loadModel(String modelFnm)
  // load the OBJ model stored in modelFnm
  {
    String fnm = MODELS_DIR + modelFnm;
    System.out.println("Loading OBJ model from " + fnm);

    File file = new java.io.File(fnm);
    if (!file.exists()) {
      System.out.println("Could not find " + fnm);
      return null;
    }

    /* Convert the filename to a URL, so the OBJ file can 
       find MTL and image files in the Models/ subdirectory
       at runtime. */
    URL url = null;
    try {
      url = file.toURI().toURL();
    }
    catch(Exception e) {
      System.out.println(e);
      return null;
    }

    // read in the geometry from the file
    Scene scene = null;
    try {
      scene = objFileloader.load(url);
    }
	catch (FileNotFoundException e) {
	  System.out.println("Could not find " + fnm);
	  return null;
	}
	catch (ParsingErrorException e) {
	  System.out.println("Could not parse the contents of " + fnm);
	  System.out.println(e);
	  return null;
	}
	catch (IncorrectFormatException e) {
	  System.out.println("Incorrect format in " + fnm);
	  System.out.println(e);
	  return null;
	}

    // return the model's BranchGroup
    if(scene != null)
      return scene.getSceneGroup();
    else
      return null;
  }  // end of loadModel()



  private double getScaling(BranchGroup modelBG)
  // check the model's size and scale if too big
  {
    double scaleFactor = 1.0;
    BoundingBox boundBox = new BoundingBox( modelBG.getBounds());

    Point3d lower = new Point3d();
    boundBox.getLower(lower);
    // System.out.println("lower: " + lower);

    Point3d upper = new Point3d();
    boundBox.getUpper(upper);
    // System.out.println("upper: " + upper);

    // calculate model scaling
    double maxDim = getMaxDimension(lower, upper);
    if (maxDim > MAX_SIZE) {
      scaleFactor = MAX_SIZE/maxDim;
      System.out.println("Applying scaling factor: " + scaleFactor);
    }

    return scaleFactor;
  }  // end of getScaling()


  private double getMaxDimension(Point3d lower, Point3d upper)
  // calculate the max dimension
  {
    double max = 0;
    if ((upper.x - lower.x) > max) 
      max = upper.x - lower.x;
    if ((upper.y - lower.y) > max) 
      max = upper.y - lower.y;
    if ((upper.z - lower.z) > max) 
      max = upper.z - lower.z;
    return max;
  }  // end of getMaxDimension()

} // end of ModelLoader class