keybehavior.java

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

// KeyBehavior.java
// Andrew Davison, May 2003, [e-mail]

/* Use key presses to move the viewpoint and fire the gun.
   Movement is restricted to: forward, backwards, move left,
     move right, rotate left, rotate right, up, down.

   The behaviour is added to the user's viewpoint. 
   It extends ViewPlatformBehavior so that targetTG is available
   to it, the ViewPlatform's tranform.
*/

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 int fireKey = KeyEvent.VK_F;   // fire button

  private WakeupCondition keyPress;
  private AmmoManager ammoMan;

  // for repeated calcs
  private Transform3D t3d = new Transform3D();
  private Transform3D toMove = new Transform3D();
  private Transform3D toRot = new Transform3D();


  public KeyBehavior(AmmoManager am)
  { ammoMan = am;
    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[i].getID() == KeyEvent.KEY_PRESSED )
            processKeyEvent((KeyEvent)event[i]);
        }
      }
    }
    wakeupOn( keyPress );
  } // end of processStimulus()


  private void processKeyEvent(KeyEvent eventKey)
  {
    int keyCode = eventKey.getKeyCode();
    // System.out.println(keyCode);    

    if(eventKey.isAltDown())   // key + <alt>
      altMove(keyCode);
    else
      standardMove(keyCode);
  } // end of processKeyEvent()


  private void standardMove(int keycode)
  /* Make viewer moves forward or backward; 
     rotate left or right; fire gun */
  { if(keycode == forwardKey)
      doMove(FWD);
    else if(keycode == backKey)
      doMove(BACK);
    else if(keycode == leftKey)
      rotateY(ROT_AMT);
    else if(keycode == rightKey)
      rotateY(-ROT_AMT);
    else if (keycode == fireKey)
      ammoMan.fireBeam();
  } // 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)
      doMove(LEFT);
    else if(keycode == rightKey)
      doMove(RIGHT);
  }  // end of altMove()


  private void rotateY(double radians)
  // rotate about y-axis by radians
  { targetTG.getTransform(t3d);   // targetTG is the ViewPlatform's tranform
    toRot.rotY(radians);
    t3d.mul(toRot);
    targetTG.setTransform(t3d);
  } // end of rotateY()


  private void doMove(Vector3d theMove)
  { targetTG.getTransform(t3d);
    toMove.setTranslation(theMove);
    t3d.mul(toMove);
    targetTG.setTransform(t3d);
  } // end of doMove()


}  // end of KeyBehavior class