> From: Zak <[EMAIL PROTECTED]>
>
> I am trying to set up a routine that will check for movement of an object. I
want to be able to tell the location(coordinates of an object) relative to the
screen.
>
> How can I make it check all the time for changes in the object?
Try using the attached utility class. It should let you inquire the screen
position of a point on the object. It does this by transforming the point to
VWorld coordinates and then calculating the screen space position of the VWorld
point.
Doug
/*
* @(#)WindowToLocal.java 1.3 99/09/15 13:44:27
*
* Copyright (c) 1996-1999 Sun Microsystems, Inc. All Rights Reserved.
*
* Sun grants you ("Licensee") a non-exclusive, royalty free, license to use,
* modify and redistribute this software in source and binary code form,
* provided that i) this copyright notice and license appear on all copies of
* the software; and ii) Licensee does not utilize the software in a manner
* which is disparaging to Sun.
*
* This software is provided "AS IS," without a warranty of any kind. ALL
* EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING ANY
* IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR
* NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN AND ITS LICENSORS SHALL NOT BE
* LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING
* OR DISTRIBUTING THE SOFTWARE OR ITS DERIVATIVES. IN NO EVENT WILL SUN OR ITS
* LICENSORS BE LIABLE FOR ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT,
* INDIRECT, SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER
* CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF THE USE OF
* OR INABILITY TO USE SOFTWARE, EVEN IF SUN HAS BEEN ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGES.
*
* This software is not designed or intended for use in on-line control of
* aircraft, air traffic, aircraft navigation or aircraft communications; or in
* the design, construction, operation or maintenance of any nuclear
* facility. Licensee represents and warrants that it will not use or
* redistribute the Software for such purposes.
*/
/**
* Utility class for doing window->local or window->vworld transformations.
*
* Usage:
* // after the canvas and node are created
* WindowToLocal winToLocal = WindowToLocal(node, canvas);
* // node == null for window->vWorld
* ...
* // when we need to transform points (canvas location and node transforms
* // may have changed)
* windowToLocal.update(); // make sure transforms are up to date
*
* Point[] windowPts = <some window coords to transform>
* Point3d[] localPts = <the transformed local points >
* for (int i = 0; i < windowPts.length; i++) {
* winToLocal.transformPt(windowPts[i] , localPts[i]);
* }
*/
// standard j3d packages
import javax.media.j3d.*;
import javax.vecmath.*;
import java.awt.Point;
import java.awt.Dimension;
public class WindowToLocal {
Canvas3D canvas = null;
Node node = null;
// inquired/derived data
Transform3D imagePlateToVworld = new Transform3D();
Transform3D vWorldToLocal = new Transform3D();
Transform3D imagePlateToLocal = new Transform3D();
/**
* Creates a WindowToLocal object with no associated node or canvas.
* The canvas (and the node if vWorld to local transforms are wanted)
* must be set before transforming points
*/
public WindowToLocal() {};
/**
* Setup WindowToLocal to transform from window coordinates on the
* specified Canvas3D to VWorld coordinates
*/
public WindowToLocal(Canvas3D canvas) {
this.canvas = canvas;
this.node = null;
update();
}
/**
* Setup WindowToLocal to transform from window coordinates on the
* specified Canvas3D to the local coordinates of the specified node.
*/
public WindowToLocal(Node node, Canvas3D canvas) {
this.canvas = canvas;
this.node = node;
update();
}
/**
* Either create WindowToLocal() just before transforming points or call
* this method to ensure that the transforms are up to date. Note: if
* you are transforming several points, you only need to call this method
* once.
*/
public void update() {
if (this.canvas != null) {
canvas.getImagePlateToVworld(imagePlateToVworld);
//System.out.println("imagePlateToVworld = " + imagePlateToVworld);
if (this.node != null) {
node.getLocalToVworld(vWorldToLocal);
vWorldToLocal.invert();
} else {
vWorldToLocal.set(1.0);
}
//System.out.println("vWorldToLocal = " + vWorldToLocal);
// Make a composite transform:
// imagePlatePt = imagePlateToVworld * iplatePt
// localPt = vWorldToLocal * imagePlatePt;
// imagePlatePt = vWorldToLocal * imagePlateToVworld * iplatePt;
imagePlateToLocal.mul(vWorldToLocal, imagePlateToVworld);
//System.out.println("imagePlateToLocal = " + imagePlateToLocal);
}
}
/**
* Set the canvas and call update(). This will set up a Window->VWorld
* transform.
*/
public void update(Canvas3D canvas) {
this.canvas = canvas;
this.node = null;
update();
}
/**
* Set the node and canvas and call update(). This will set up a
* Window->Local transform.
*/
public void update(Node node, Canvas3D canvas) {
this.canvas = canvas;
this.node = node;
update();
}
/**
* Transform the point from Window to Local coords (or to VWorld coords
* if node == null)
*/
public void transformPt(Point windowPt, Point3d localPt) {
// TODO: throw some kind of error if node and canvas haven't been
// set
//System.out.println("windowPt = " + windowPt);
canvas.getPixelLocationInImagePlate(windowPt.x, windowPt.y,
localPt);
//System.out.println("imagePlatePt = " + localPt);
imagePlateToLocal.transform(localPt);
//System.out.println("local Pt = " + localPt);
}
}
/*
* @(#)WindowToLocalTest.java 1.4 99/09/15 13:44:28
*
* Copyright (c) 1996-1999 Sun Microsystems, Inc. All Rights Reserved.
*
* Sun grants you ("Licensee") a non-exclusive, royalty free, license to use,
* modify and redistribute this software in source and binary code form,
* provided that i) this copyright notice and license appear on all copies of
* the software; and ii) Licensee does not utilize the software in a manner
* which is disparaging to Sun.
*
* This software is provided "AS IS," without a warranty of any kind. ALL
* EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING ANY
* IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR
* NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN AND ITS LICENSORS SHALL NOT BE
* LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING
* OR DISTRIBUTING THE SOFTWARE OR ITS DERIVATIVES. IN NO EVENT WILL SUN OR ITS
* LICENSORS BE LIABLE FOR ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT,
* INDIRECT, SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER
* CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF THE USE OF
* OR INABILITY TO USE SOFTWARE, EVEN IF SUN HAS BEEN ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGES.
*
* This software is not designed or intended for use in on-line control of
* aircraft, air traffic, aircraft navigation or aircraft communications; or in
* the design, construction, operation or maintenance of any nuclear
* facility. Licensee represents and warrants that it will not use or
* redistribute the Software for such purposes.
*/
/**
* Test WindowToLocal utility. Use left (or main) mouse button to rotate,
* right (or meta + main) mouse button to create new points in the current
* z=0 plane in local coords
*/
// standard j3d packages
import javax.media.j3d.*;
import javax.vecmath.*;
// sun utility classes
import com.sun.j3d.utils.universe.*;
import com.sun.j3d.utils.geometry.ColorCube;
import com.sun.j3d.utils.behaviors.mouse.MouseRotate;
import com.sun.j3d.utils.applet.MainFrame;
import java.applet.Applet;
import java.awt.*;
import java.awt.event.*;
import java.util.Enumeration;
public class WindowToLocalTest extends Applet {
Canvas3D canvas;
WindowToLocal winToLocal = null;
Group primGroup;
Appearance primAppearance;
Point windowPt = new Point();
Point3d[] primPtArray = new Point3d[1];
Point3d primPt = new Point3d();
WakeupOr mouseWakeup;
public BranchGroup createSceneGraph() {
// create root of the branch graph
BranchGroup objRoot = new BranchGroup();
// create the TransformGroup
TransformGroup objTrans = new TransformGroup();
objTrans.setCapability(TransformGroup.ALLOW_TRANSFORM_READ);
objTrans.setCapability(TransformGroup.ALLOW_TRANSFORM_WRITE);
objRoot.addChild(objTrans);
// Create a group to add geometry to
primGroup = new Group();
primGroup.setCapability(Group.ALLOW_LOCAL_TO_VWORLD_READ);
primGroup.setCapability(Group.ALLOW_CHILDREN_READ);
primGroup.setCapability(Group.ALLOW_CHILDREN_WRITE);
primGroup.setCapability(Group.ALLOW_CHILDREN_EXTEND);
// create box so that we can add geometry to it's area
Point3d[] coords = new Point3d[5];
coords[0] = new Point3d( 0.0, 0.0, 0.0);
coords[1] = new Point3d( 0.5,-0.5, 0.0);
coords[2] = new Point3d( 0.5, 0.5, 0.0);
coords[3] = new Point3d(-0.5, 0.5, 0.0);
coords[4] = new Point3d(-0.5,-0.5, 0.0);
int [] lineLength = new int[1];
lineLength[0] = 5;
LineStripArray lineArray = new LineStripArray(5, LineArray.COORDINATES,
lineLength);
lineArray.setCoordinates(0, coords);
primAppearance = new Appearance();
primAppearance.setColoringAttributes(new ColoringAttributes());
Shape3D shape = new Shape3D(lineArray, primAppearance);
primGroup.addChild(shape);
objTrans.addChild(primGroup);
objRoot.addChild(new Callback());
MouseRotate mr = new MouseRotate();
mr.setTransformGroup(objTrans);
mr.setSchedulingBounds(new BoundingSphere(new Point3d(),1000));
objRoot.addChild(mr);
return objRoot;
}
public WindowToLocalTest(){
setLayout(new BorderLayout());
canvas = new Canvas3D(SimpleUniverse.getPreferredConfiguration());
add("Center", canvas);
// create a simple scene and attach it to virtual universe
Transform3D t = new Transform3D();
// set up a scene graph, this will also initialize "primGroup" and
// "primAppearance"
BranchGroup scene = createSceneGraph();
SimpleUniverse u = new SimpleUniverse(canvas);
// This will move the ViewPlatform back a bit so the
// objects in the scene can be viewed.
u.getViewingPlatform().setNominalViewingTransform();
u.addBranchGraph(scene);
//canvas.getView().setProjectionPolicy(View.PARALLEL_PROJECTION);
}
// allows this to be run as application as well as applet
public static void main(String[] argv){
new MainFrame(new WindowToLocalTest(),256,256);
}
public class Callback extends Behavior {
public void initialize(){
setSchedulingBounds(new BoundingSphere(new Point3d(),1000));
WakeupCriterion[] mouseEvents = new WakeupCriterion[2];
mouseEvents[0] = new WakeupOnAWTEvent(MouseEvent.MOUSE_PRESSED);
mouseEvents[1] = new WakeupOnAWTEvent(MouseEvent.MOUSE_DRAGGED);
mouseWakeup = new WakeupOr(mouseEvents);
wakeupOn(mouseWakeup);
}
public void processStimulus(Enumeration criteria){
WakeupOnAWTEvent awt=(WakeupOnAWTEvent) criteria.nextElement();
MouseEvent e=(MouseEvent) awt.getAWTEvent()[0];
if (e.isMetaDown()) {
if (winToLocal == null) {
// intialize the window to local utility
winToLocal = new WindowToLocal(primGroup, canvas);
} else {
winToLocal.update();
}
windowPt.x = e.getX();
windowPt.y = e.getY();
winToLocal.transformPt(windowPt, primPt);
BranchGroup primBG = new BranchGroup();
primPtArray[0] = primPt;
PointArray pointArray = new PointArray(1,
PointArray.COORDINATES);
pointArray.setCoordinates(0, primPtArray);
Shape3D shape = new Shape3D(pointArray, primAppearance);
primBG.addChild(shape);
primGroup.addChild(primBG);
}
wakeupOn(mouseWakeup);
}
}
}
