Re: [JAVA3D] Translating after rotating? - Local Coords

Jean-Robert D'Amore Tue, 09 Dec 2003 07:18:49 -0800

What you do is correct (as far as I know) cos you do something like M'=P-1*M*P where P is the passage matrix from the global base to the translated base. Hence you express the correct matrix in the global base...
Another way of doing it is to reinit the matrix to ID, but having previously stored the translation information int a vector. Then you can apply rotation and scale, and afterthat reset the translation component with your vector. That what's done in the OrbitBehavior class

Alessandro Borges wrote:

hi,
I am sorry if I miss the point, but I use the
following transform3d multiplication to get the
compound tranformation:


cpTransform = translate * refptInv * scale * rotation
* refPT

where
* refptInv is the inverse translation of refPT;
* refPT is the tuple3f coordinates of center of
rotation - take it as a translation transform;
* translate, scale, rotation are the transformations
to be applied on the object.


Alessandro



 --- Jean-Robert D'Amore <[EMAIL PROTECTED]>
escreveu: > Try by inverting the matrix
multiplication.

Let say you've got the matric M for the scene, and T
for the transform.
If you do M=M*T then the transform will be in local
coordinatyes. If you
do M=T*M then you have the transform in global
coordinates...
JR

Ben Logan wrote:

Could someone take a quick look at the following

class. The problem is

that when a rotation is performed and then a

translation the translation

takes place on the local coordinates. i.e it moves

the shape in the

direction of the rotation. I want the shape to be

moved in the same

direction whatever the rotation. Any help would be

much appreciated.

Thanks
Ben


public class MyPickTranslateBehavior extends

PickTranslateBehavior {

 protected WakeupCondition m_WakeupCondition =

null;

 private int x = 0;
 private int y = 0;
 private int x_last = 0;
 private int y_last = 0;

 private double y_angle = 0.0;
 private double x_factor = 0.02;

 int changeX;
 int changeY;

 private Transform3D modelTrans = null;
 private Transform3D transformY = null;
 private PickResult pickResult = null;
 private Node pickNode = null;
 private TransformGroup transformGroup = null;

 Canvas3D canvas;
 BranchGroup objRoot;
 Java3DFrame frame;

 float step = 0.005f; // was 0.01

 public MyPickTranslateBehavior(Java3DFrame f,

BranchGroup objRoot,

                                Canvas3D canvas,
                                BoundingSphere

bounds) {

   super(objRoot, canvas, bounds);
   this.frame = f;
   this.setBounds(bounds);
   this.canvas = canvas;
   this.objRoot = objRoot;

   transformGroup = new TransformGroup();
   modelTrans = new Transform3D();
   transformY = new Transform3D();

transformGroup.setCapability(TransformGroup.ALLOW_TRANSFORM_READ);

transformGroup.setCapability(TransformGroup.ALLOW_TRANSFORM_WRITE);

   //create the wakeupCriterion for the behavior
   WakeupCriterion criterionArray[] = new

WakeupCriterion[2];

   criterionArray[0] = new

WakeupOnAWTEvent(MouseEvent.MOUSE_PRESSED);

   criterionArray[1] = new

WakeupOnAWTEvent(MouseEvent.MOUSE_DRAGGED);

   //save the WakeupCriterion for the behavior
   m_WakeupCondition = new

WakeupOr(criterionArray);

 }

 public void initialize() { // initialize
   wakeupOn(m_WakeupCondition); //Apply the

initial WakeupCriterion

 }

 public void processStimulus(Enumeration criteria)

{ // processStimulus

   while (criteria.hasMoreElements()) {
     WakeupCriterion wakeUp = (WakeupCriterion)

criteria.nextElement();

     if (wakeUp instanceof WakeupOnAWTEvent) {
       AWTEvent[] evt = ( (WakeupOnAWTEvent)

wakeUp).getAWTEvent();

       try {
         processAWTEvent(evt);
       }
       catch (Exception e) {

       }
     }
   }
   //Assign the next WakeupCondition, so we are

notified again

   wakeupOn(m_WakeupCondition);
 }


 private void processAWTEvent(AWTEvent[] events) {

   for (int n = 0; n < events.length; n++) {

     if (events[n] instanceof MouseEvent) {

       MouseEvent eventPress = (MouseEvent)

events[n];

       if (eventPress.getModifiers() ==

MouseEvent.BUTTON1_MASK) {

         //System.out.println("LEFT MOUSE PRESSED

_ DOING ROTATION");

         if (eventPress.getID() ==

MouseEvent.MOUSE_PRESSED) {

      

pickCanvas.setShapeLocation(eventPress);

           pickResult = pickCanvas.pickClosest();

           if (pickResult != null) {
             pickNode = pickResult.getObject();
             transformGroup = (TransformGroup)
pickResult.getNode(PickResult.
                 TRANSFORM_GROUP);

             //System.out.println("DELETE MODE? "

frame.deleteMode());

             if (frame.deleteMode() == true) { //

So delete that shape

               try {
                 //no capability to detact the

branchgroup

transformGroup.removeAllChildren(); // Not yet
working

               }
               catch (Exception ex) {
                 System.out.println("DELETE

EXCEPTION : " +

ex.toString());
               }

             }

             else { // Setup rotation of that

shape

      

transformGroup.getTransform(modelTrans);

               x = x_last = eventPress.getX();
             }
           }
         }

         if (eventPress.getID() ==

MouseEvent.MOUSE_DRAGGED) {

           // Rotating the object around the Y

axis only

           x = eventPress.getX();

           y_angle = (x - x_last) * x_factor;

           transformY.rotY(y_angle);

           modelTrans.mul(modelTrans, transformY);

transformGroup.setTransform(modelTrans);

           x_last = x;
         }
       }


       if (eventPress.getModifiers() ==

MouseEvent.BUTTON3_MASK) {

         //System.out.println("RIGHT MOUSE PRESSED

_ DOING

TRANSLATION");

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--
D'Amore Jean-Robert
IT Systems
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Unit 5A, Crombie Lodge
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Re: [JAVA3D] Translating after rotating? - Local Coords

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