[JAVA3D] Slow start-up time for simple Java 3D applications.

[Karen Dias]

Hi people;

I've been running some really simple Java 3D applications & the start-up
time is quite slow. I've included an example that part of one of the on-line
Java 3D tutorials on the net (I think I got it off the Sun site... anyway,
it's not important).  I was surprised to find out that it took about 3-4
seconds to start up.  Is this normal?  If so, I imagine the problem will be
greatly magnified if I have 100's or 1000's of entities in the scene graph.
Does anyone know why this happens?  Is it the time taken to compile the
scene graph?  I'm running on a PII-350 with 128MB RAM and my graphics
adapter is a Matrox Graphics MGA-G100 AGP with 4MB RAM.

Karen Dias,
Engineer, ISE


Here's the dinky example that takes up to 4 seconds to start. --- A single
rotating cube
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// HelloJava3Dd.java
//

import java.applet.Applet;
import java.awt.BorderLayout;
import java.awt.Frame;
import java.awt.event.*;
import java.awt.GraphicsConfiguration;
import com.sun.j3d.utils.applet.MainFrame;
import com.sun.j3d.utils.geometry.ColorCube;
import com.sun.j3d.utils.universe.*;
import javax.media.j3d.*;
import javax.vecmath.*;

import java.io.*;

//   HelloJava3Dd renders a single, rotated cube.

public class HelloJava3Dd extends Applet {

// createSceneGraph method

    public BranchGroup createSceneGraph() {

        // Create the root of the branch graph
        BranchGroup objRoot = new BranchGroup();

        // rotate object has a composite transformation matrix
        Transform3D rotate  = new Transform3D();
        Transform3D tempRotate = new Transform3D();

        rotate.rotX(Math.PI/4.0d);

        tempRotate.rotY(Math.PI/5.0d);

        rotate.mul(tempRotate);

        TransformGroup objRotate = new TransformGroup(rotate);

        // Create the transform group node and initialize it to the
        // identity matrix.  Add it to the root of the subgraph.
        TransformGroup objSpin = new TransformGroup();
        objSpin.setCapability(TransformGroup.ALLOW_TRANSFORM_WRITE);

        // First add objRotate, the static rotation of the cube to the
        // root node.
        objRoot.addChild(objRotate);

        // Then add the transform that will be used to spin the cube to
        // the Static Rotation Transform.
        objRotate.addChild(objSpin);

        // Create a simple shape leaf node and add it to the scene
        // graph.  ColorCube is a Convenience Utility class.
        objSpin.addChild(new ColorCube(0.4));

        // Next, create the Behavior object that performs the desired
operation
        // on the specified transform object and add it to the scene graph.
        Transform3D yAxis = new Transform3D();
        Alpha rotationAlpha = new Alpha(-1, 500);

        RotationInterpolator rotator = new
RotationInterpolator(rotationAlpha,
                objSpin, yAxis, 0.0f, (float) Math.PI*2.0f);

        // a bounding sphere specifies the region a behavior is active in
        BoundingSphere bounds = new BoundingSphere();
        rotator.setSchedulingBounds(bounds);
        objSpin.addChild(rotator);

        return objRoot;
    } // end of CreateSceneGraph method of HelloJava3Dd



    // Create a simple scene and attach it to the virtual universe

    public HelloJava3Dd() {
        setLayout(new BorderLayout());
        GraphicsConfiguration config =
           SimpleUniverse.getPreferredConfiguration();

        Canvas3D canvas3D = new Canvas3D(config);
        add("Center", canvas3D);

        BranchGroup scene = createSceneGraph();

        // SimpleUniverse is a Convenience Utility class
        SimpleUniverse simpleU = new SimpleUniverse(canvas3D);

        // This will move the ViewPlatform back a bit so the
        // objects in the scene can be viewed.
        simpleU.getViewingPlatform().setNominalViewingTransform();

        simpleU.addBranchGraph(scene);
    } // end of HelloJava3Dd (constructor)
    //  The following allows this to be run as an application
    //  as well as an applet

    public static void main(String[] args) {
        Frame frame = new MainFrame(new HelloJava3Dd(), 256, 256);
    } // end of main (method of HelloJava3Dd)

} // end of class HelloJava3Dd

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