Thank you Mark for the interesting and instructive example.
1. It raises my hope that even large amounts of data points can be handled.
2. It show an elegant way to reuse the points while appearing to create them
and
3. It shows me a way how to read from an external data device. What kind of
sensor has it been?
In my case the usage of spheres is not just fancy stuff. Of course they look
nice, but they also carry information, as their radius will correspond to a
fourth dimension of information and their colour to their age.
Horst Walther
----- Original Message -----
From: "Mark Hood" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Thursday, July 10, 2003 1:43 AM
Subject: Re: [JAVA3D] adding objects to a life scene
> > Date: Wed, 9 Jul 2003 15:05:49 +0200
> > From: "Horst Walther (SiG)" <[EMAIL PROTECTED]>
> >
> > simple question: how can I add objects, e.g. simple spheres, to a life
> > graph?
> >
> > Background is: I like to dynamically add 3d-datapoints read from a
external
> > data feeding device each minute to even the same transformation group.
> > Depending on the users choice on the limit the oldest data points should
> > disappear then, while he still is able to rotate, translate an zoom it
> > manually.
>
> I had to do almost exactly the same thing to test various Sensor
> implementations: read positions from an array of Sensors, display the
> current Sensor positions, and display a history of past positions while
> allowing view manipulations as the positions are added.
>
> I used a PointArray to store 100000 past positions and updated them using
> by-reference semantics, reusing the individual points when the limit was
> reached. I tried using spheres but decided that I couldn't get enough
> past history displayed with acceptable performance.
>
> I've appended the Behavior I implemented. If you really need spheres it
> probably won't be too useful to you, but you might be able to combine
> parts of it with the code that's already been posted on this list. On
> the other hand, I think points are a good alternative if performance is a
> problem; you can use PointAttributes to make the points larger if you
> need to.
>
> -- Mark Hood
>
> /*
> * Copyright (c) 1996-2003 Sun Microsystems, Inc. All Rights Reserved.
> *
> * Redistribution and use in source and binary forms, with or without
> * modification, are permitted provided that the following conditions
> * are met:
> *
> * - Redistributions of source code must retain the above copyright
> * notice, this list of conditions and the following disclaimer.
> *
> * - Redistribution in binary form must reproduce the above copyright
> * notice, this list of conditions and the following disclaimer in
> * the documentation and/or other materials provided with the
> * distribution.
> *
> * Neither the name of Sun Microsystems, Inc. or the names of
> * contributors may be used to endorse or promote products derived
> * from this software without specific prior written permission.
> *
> * 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
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> * 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.
> *
> * You acknowledge that Software is not designed,licensed or intended
> * for use in the design, construction, operation or maintenance of
> * any nuclear facility.
> */
> import java.util.Enumeration ;
> import javax.media.j3d.* ;
> import javax.vecmath.* ;
> import com.sun.j3d.utils.behaviors.sensor.* ;
>
> /**
> * Read positions from an array of Sensors and displays them as points.
> * The current Sensor positions are displayed as gnomon echos. The
history of
> * past positions for each Sensor is displayed as trail of points.
> */
> public class SensorDisplayBehavior
> extends Behavior implements GeometryUpdater {
> /**
> * The total number of points to display. When this limit is reached
they
> * are reused. Note that all of them are always displayed, even in
the
> * initial condition when they are all [0, 0, 0].
> */
> final static int pointCount = 100000 ;
>
> SensorEventAgent eventAgent = null ;
> WakeupCondition wakeupConditions = null ;
> Transform3D t3d = new Transform3D() ;
>
> // Points updated from sensors reads.
> Vector3f[] newPoints = null ;
> int curNewPoint = 0 ;
>
> // Leaves a static trail of points behind each sensor.
> float[] points = new float[pointCount*3] ;
> PointArray pointArray = null ;
> int curPoint = 0 ;
>
> /**
> * Create a new SensorDisplayBehavior.
> *
> * @param s an array of Sensors
> * @param tg an array of TransformGroups for displaying the current
> * Sensor position; must map 1-1 with the Sensor array, and the
> * caller is responsible for adding them to a scene graph
> * @param scene the BranchGroup used to display the trail of past
> * positions
> */
> public SensorDisplayBehavior(Sensor[] s, TransformGroup[] tg,
> BranchGroup scene) {
>
> this.eventAgent = new SensorEventAgent(this) ;
> this.newPoints = new Vector3f[s.length] ;
>
> for (int i = 0 ; i < s.length ; i++) {
> newPoints[i] = new Vector3f() ;
> eventAgent.addSensorReadListener(s[i], new
ReadListener(tg[i])) ;
> }
>
> pointArray = new PointArray(pointCount,
> GeometryArray.COORDINATES |
> GeometryArray.BY_REFERENCE) ;
>
> pointArray.setCoordRefFloat(points) ;
> pointArray.setCapability(GeometryArray.ALLOW_REF_DATA_WRITE) ;
>
> Shape3D pointShape = new Shape3D(pointArray) ;
> scene.addChild(pointShape) ;
> }
>
> class ReadListener implements SensorReadListener {
> TransformGroup tg = null ;
>
> ReadListener(TransformGroup tg) {
> this.tg = tg ;
> tg.addChild(new SensorGnomonEcho(t3d, 0.02, 0.10, true)) ;
> }
>
> public void read(SensorEvent e) {
> e.getSensorRead(t3d) ;
> tg.setTransform(t3d) ;
> t3d.get(newPoints[curNewPoint++]) ;
> }
> }
>
> public void initialize() {
> wakeupConditions = new WakeupOnElapsedFrames(0) ;
> wakeupOn(wakeupConditions) ;
> }
>
> public void processStimulus(Enumeration e) {
> eventAgent.dispatchEvents() ;
> pointArray.updateData(this) ;
> wakeupOn(wakeupConditions) ;
> }
>
> public void updateData(Geometry g) {
> for (int i = 0 ; i < curNewPoint ; i++) {
> points[curPoint*3+0] = newPoints[i].x ;
> points[curPoint*3+1] = newPoints[i].y ;
> points[curPoint*3+2] = newPoints[i].z ;
>
> if (++curPoint == pointCount) curPoint = 0 ;
> }
>
> curNewPoint = 0 ;
> }
> }
>
>
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