CAMERA POSITION ???????

Question

hi ,
please PLEASE help me .
iam developing a cat and rat game.
i added a rat.3ds object to transform group (obj10) . its fine upto here. when my rat is moving forward i want to move the camere with my rat.
code is here
KeyBehavior keyBeh = new KeyBehavior( obj10);
keyBeh.setSchedulingBounds(new BoundingSphere(new Point3d(),1000.0));
obj10.addChild(keyBeh);
tg.addChild(obj10);
import java.awt.AWTEvent;
import java.awt.event.*;
import java.util.Enumeration;
import javax.media.j3d.*;
import javax.vecmath.*;
import com.sun.j3d.utils.universe.*;
import com.sun.j3d.utils.behaviors.vp.*;
public class KeyBehavior extends ViewPlatformBehavior
private static final double ROT_AMT = Math.PI / 36.0; // 5 degrees
private static final double MOVE_STEP = 0.2;
// hardwired movement vectors
private static final Vector3d FWD = new Vector3d(0,0,-MOVE_STEP);
private static final Vector3d BACK = new Vector3d(0,0,MOVE_STEP);
private static final Vector3d LEFT = new Vector3d(-MOVE_STEP,0,0);
private static final Vector3d RIGHT = new Vector3d(MOVE_STEP,0,0);
private static final Vector3d UP = new Vector3d(0,MOVE_STEP,0);
private static final Vector3d DOWN = new Vector3d(0,-MOVE_STEP,0);
// key names
private int forwardKey = KeyEvent.VK_UP;
private int backKey = KeyEvent.VK_DOWN;
private int leftKey = KeyEvent.VK_LEFT;
private int rightKey = KeyEvent.VK_RIGHT;
private WakeupCondition keyPress;
// for repeated calcs
private Transform3D t3d = new Transform3D();
private Transform3D toMove = new Transform3D();
private Transform3D toRot = new Transform3D();
private TransformGroup tg;
public KeyBehavior(TransformGroup tg)
this.tg = tg;
keyPress = new WakeupOnAWTEvent(KeyEvent.KEY_PRESSED);
} // end of KeyBehavior()
public void initialize()
{  wakeupOn( keyPress );  }
public void processStimulus(Enumeration criteria)
// respond to a keypress
WakeupCriterion wakeup;
AWTEvent[] event;
while( criteria.hasMoreElements() ) {
wakeup = (WakeupCriterion) criteria.nextElement();
if( wakeup instanceof WakeupOnAWTEvent ) {
event = ((WakeupOnAWTEvent)wakeup).getAWTEvent();
for( int i = 0; i < event.length; i++ ) {
if( event.getID() == KeyEvent.KEY_PRESSED )
processKeyEvent((KeyEvent)event[i]);
wakeupOn( keyPress );
} // end of processStimulus()
private void processKeyEvent(KeyEvent eventKey)
int keyCode = eventKey.getKeyCode();
// if(eventKey.isAltDown()) // key + <alt>
// altMove(keyCode);
// else
standardMove(keyCode);
} // end of processKeyEvent()
private void standardMove(int keycode)
{ if(keycode == forwardKey)
doMove(FWD);
else if(keycode == backKey)
doMove(BACK);
else if(keycode == leftKey)
// rotateY(ROT_AMT);
doMove(LEFT);
else if(keycode == rightKey)
// rotateY(-ROT_AMT);
doMove(RIGHT);
// else if (keycode == fireKey)
} // end of standardMove()
/* private void altMove(int keycode)
// moves viewer up or down, left or right
{ if(keycode == forwardKey)
doMove(UP);
else if(keycode == backKey)
doMove(DOWN);
else if(keycode == leftKey)
rotateY(ROT_AMT);
else if(keycode == rightKey)
rotateY(-ROT_AMT);;
} // end of altMove()*/
private void rotateY(double radians)
// rotate about y-axis
{ tg.getTransform(t3d);  
toRot.rotY(radians);
t3d.mul(toRot);
tg.setTransform(t3d);
} // end of rotateY()
private void doMove(Vector3d theMove)
{ tg.getTransform(t3d);
toMove.setTranslation(theMove);
t3d.mul(toMove);
tg.setTransform(t3d);
} // end of doMove()
} // end of KeyBehavior class
PLEASE HELP ME.
THANKS
SATISH

Answer 1

What you should do here is put the geometry for the rate below the view platform in the scene graph. That way, when the view platform (and hence the camera) moves, the rat moves with it.
or vice versa.
put the view platform below the transform group containing the rat so that when the rat moves, so does the viewing platform.
checkout the setPlatformGeometry method of ViewingPlatform (from the j3d utils library) to get an idea of how others have done this.