sprite3d.java

java3D game engine design of the source [three-dimensionalvirtualrealitynetworkprogram] - "virtual

// Sprite3D.java
// Andrew Davison, April 2005, [e-mail]

/* Sprite3D loads a 3D image from fnm, and places it at (0,0,0). 
   We assume that the object's actual position is (0,0) in the XZ plane. 
   The Y position will vary but probably the base of the object is 
   touching the XZ plane.

   Movements are restricted to the XZ plane and rotations
   around the Y-axis.

   An object cannot move off the floor, or travel through obstacles 
   (as defined in the Obstacles object). 
*/

import java.text.DecimalFormat;
import java.util.*;
import java.io.*;

import javax.media.j3d.*;
import javax.vecmath.*;


public class Sprite3D 
{
  private final static double OBS_FACTOR = 0.5;  
             // used to reduce radius of bounding sphere around Sprite
             // when testing for intersection with obstacles

  private TransformGroup objectTG;    // TG which the loaded object hangs off
  private Transform3D t3d, toMove, toRot;    // for manipulating objectTG's transform
  private Switch visSwitch;           // to make object visible/invisible

  private double radius;
  private boolean isActive;   // is the sprite active?

  private Obstacles obs;      // obstacles in the way of an object
  private DecimalFormat df;   // for simpler output during debugging


  public Sprite3D(String fnm, Obstacles obs)
  { 
    df = new DecimalFormat("0.###");  // 3 dp
    this.obs = obs;

    // load object and coords
    PropManager propMan = new PropManager(fnm, true);
    radius = propMan.getScale();      // assume radius == scale
    // System.out.println("radius: " + df.format(radius));

    // create switch for visibility 
    visSwitch = new Switch();
    visSwitch.setCapability(Switch.ALLOW_SWITCH_WRITE);
    visSwitch.addChild( propMan.getTG() );     // add object to switch
    visSwitch.setWhichChild( Switch.CHILD_ALL );   // make visible

    // create a new transform group for the object
    objectTG = new TransformGroup();
    objectTG.setCapability(TransformGroup.ALLOW_TRANSFORM_READ);
    objectTG.setCapability(TransformGroup.ALLOW_TRANSFORM_WRITE);
    objectTG.addChild( visSwitch );

    t3d = new Transform3D();
    toMove = new Transform3D();
    toRot = new Transform3D();
    isActive = true;
  }  // end of Sprite3D()


  public TransformGroup getTG()
  {  return objectTG; }


  public void setPosition(double xPos, double zPos)
  // move sprite to (xPos, zPos)
  { 
    Point3d currLoc = getCurrLoc();
    double xMove = xPos - currLoc.x;   // get offsets
    double zMove = zPos - currLoc.z;
    moveBy(xMove, zMove);
  } // end of setPosition()


  public boolean moveBy(double x, double z)
  // Move the sprite by offsets x and z, but only if within the floor
  // and there is no obstacle nearby.
  {
    if (isActive()) {
      Point3d nextLoc = tryMove(new Vector3d(x, 0, z));
      if (obs.nearObstacle(nextLoc, radius*OBS_FACTOR))
        return false;
      else {
        doMove( new Vector3d(x, 0, z) );   // inefficient recalc
        return true;
      }
    }
    else    // not active
      return false;
  }  // end of moveBy()


  private void doMove(Vector3d theMove)
  // Move the sprite by the amount in theMove
  {
    objectTG.getTransform( t3d );
    toMove.setTranslation(theMove);    // overwrite previous trans
    t3d.mul(toMove);
    objectTG.setTransform(t3d);
  }  // end of doMove()


  private Point3d tryMove(Vector3d theMove)
  /* Calculate the effect of the given translation but
     do not update the sprite's position until it's been
     tested.
  */
  { objectTG.getTransform( t3d );
    toMove.setTranslation(theMove);
    t3d.mul(toMove);
    Vector3d trans = new Vector3d();
    t3d.get( trans );
    // printTuple(trans, "nextLoc");
    return new Point3d( trans.x, trans.y, trans.z);
  }  // end of tryMove()


  public void doRotateY(double radians)
  // Rotate the sprite by radians amount around its y-axis
  {
    objectTG.getTransform( t3d );
    toRot.rotY(radians);   // overwrite previous rotation
    t3d.mul(toRot);
    objectTG.setTransform(t3d);
  } // end of doRotateY()


  public Point3d getCurrLoc()
  // Return t sprite's current location
  {        
    objectTG.getTransform( t3d );
    Vector3d trans = new Vector3d();
    t3d.get( trans );
    // printTuple(trans, "currLoc");
    return new Point3d( trans.x, trans.y, trans.z);
  } // end of getCurrLoc()


  public boolean isActive() 
  {  return isActive;  }

  public void setActive(boolean b)
  // Activity changes affect the sprite's visibility 
  { isActive = b;
    if (!isActive)
       visSwitch.setWhichChild( Switch.CHILD_NONE );   // make invisible
    else if (isActive)
      visSwitch.setWhichChild( Switch.CHILD_ALL );   // make visible
  } // end of setActive()


  protected void printTuple(Tuple3d t, String id)
  // used for debugging, here and in subclasses
  {
    System.out.println(id + " x: " + df.format(t.x) + 
				", " + id + " y: " + df.format(t.y) +
				", " + id + " z: " + df.format(t.z));
  }  // end of printTuple()


}  // end of Sprite3D class