This Java tip demonstrates the use of the GeometryInfo class and related classes.

This program creates a car shape (not a fancy car, though) using GeometryInfo objects. One GeometryInfo object specifies the side of the car using a polygon (not a triangle, nor a quad). The GeometryInfo and other classes convert the polygons into a triangle strips with normals.

Note that about half of the source code just specifies the input data to the GeometryInfo objects. The interesting part starts around line 210.

 import java.applet.Applet;
import java.awt.BorderLayout;
import java.awt.Frame;

import javax.media.j3d.Alpha;
import javax.media.j3d.AmbientLight;
import javax.media.j3d.Appearance;
import javax.media.j3d.Background;
import javax.media.j3d.BoundingSphere;
import javax.media.j3d.BranchGroup;
import javax.media.j3d.Canvas3D;
import javax.media.j3d.ColoringAttributes;
import javax.media.j3d.DirectionalLight;
import javax.media.j3d.LineArray;
import javax.media.j3d.LineAttributes;
import javax.media.j3d.LineStripArray;
import javax.media.j3d.Material;
import javax.media.j3d.PolygonAttributes;
import javax.media.j3d.RotationInterpolator;
import javax.media.j3d.Shape3D;
import javax.media.j3d.TransformGroup;
import javax.vecmath.Color3f;
import javax.vecmath.Vector3f;

import com.sun.j3d.utils.applet.MainFrame;
import com.sun.j3d.utils.geometry.GeometryInfo;
import com.sun.j3d.utils.geometry.NormalGenerator;
import com.sun.j3d.utils.geometry.Stripifier;
import com.sun.j3d.utils.geometry.Triangulator;
import com.sun.j3d.utils.universe.SimpleUniverse;

public class GeomInfoApp extends Applet {

  float[] createCoordinateData() {
    float[] data = new float[69 * 3]; // ******
    int i = 0;

    data[i++] = -1.3f;
    data[i++] = -0.3f;
    data[i++] = 0.3f; //0
    data[i++] = -0.9f;
    data[i++] = -0.3f;
    data[i++] = 0.3f; //1
    data[i++] = -0.8f;
    data[i++] = -0.1f;
    data[i++] = 0.3f; //2
    data[i++] = -0.6f;
    data[i++] = -0.1f;
    data[i++] = 0.3f; //3
    data[i++] = -0.5f;
    data[i++] = -0.3f;
    data[i++] = 0.3f; //4
    data[i++] = 0.2f;
    data[i++] = -0.3f;
    data[i++] = 0.3f; //5
    data[i++] = 0.3f;
    data[i++] = -0.1f;
    data[i++] = 0.3f; //6
    data[i++] = 0.5f;
    data[i++] = -0.1f;
    data[i++] = 0.3f; //7
    data[i++] = 0.6f;
    data[i++] = -0.3f;
    data[i++] = 0.3f; //8
    data[i++] = 1.3f;
    data[i++] = -0.3f;
    data[i++] = 0.3f; //9
    data[i++] = 1.2f;
    data[i++] = -0.1f;
    data[i++] = 0.3f; //10
    data[i++] = 0.5f;
    data[i++] = 0.0f;
    data[i++] = 0.3f; //11
    data[i++] = 0.1f;
    data[i++] = 0.3f;
    data[i++] = 0.3f; //12
    data[i++] = -0.5f;
    data[i++] = 0.3f;
    data[i++] = 0.3f; //13
    data[i++] = -1.1f;
    data[i++] = 0.0f;
    data[i++] = 0.3f; //14
    data[i++] = -1.3f;
    data[i++] = 0.0f;
    data[i++] = 0.3f; //15
    data[i++] = -1.3f;
    data[i++] = -0.3f;
    data[i++] = 0.3f; //16
    System.out.println("end polygon; total vertex count: " + i / 3);

    data[i++] = -1.3f;
    data[i++] = -0.3f;
    data[i++] = -0.3f; // 0 17
    data[i++] = -1.3f;
    data[i++] = 0.0f;
    data[i++] = -0.3f; // 1 18
    data[i++] = -1.1f;
    data[i++] = 0.0f;
    data[i++] = -0.3f; // 2 19
    data[i++] = -0.5f;
    data[i++] = 0.3f;
    data[i++] = -0.3f; // 3 20
    data[i++] = 0.1f;
    data[i++] = 0.3f;
    data[i++] = -0.3f; // 4 21
    data[i++] = 0.5f;
    data[i++] = 0.0f;
    data[i++] = -0.3f; // 5 22
    data[i++] = 1.2f;
    data[i++] = -0.1f;
    data[i++] = -0.3f; // 6 23
    data[i++] = 1.3f;
    data[i++] = -0.3f;
    data[i++] = -0.3f; // 7 24
    data[i++] = 0.6f;
    data[i++] = -0.3f;
    data[i++] = -0.3f; // 8 25
    data[i++] = 0.5f;
    data[i++] = -0.1f;
    data[i++] = -0.3f; // 9 26
    data[i++] = 0.3f;
    data[i++] = -0.1f;
    data[i++] = -0.3f; //10 27
    data[i++] = 0.2f;
    data[i++] = -0.3f;
    data[i++] = -0.3f; //11 28
    data[i++] = -0.5f;
    data[i++] = -0.3f;
    data[i++] = -0.3f; //12 29
    data[i++] = -0.6f;
    data[i++] = -0.1f;
    data[i++] = -0.3f; //13 30
    data[i++] = -0.8f;
    data[i++] = -0.1f;
    data[i++] = -0.3f; //14 31
    data[i++] = -0.9f;
    data[i++] = -0.3f;
    data[i++] = -0.3f; //15 32
    data[i++] = -1.3f;
    data[i++] = -0.3f;
    data[i++] = -0.3f; //16 33
    System.out.println("end polygon; total vertex count: " + i / 3);

    data[i++] = 1.3f;
    data[i++] = -0.3f;
    data[i++] = -0.3f; // 0 34
    data[i++] = 1.2f;
    data[i++] = -0.1f;
    data[i++] = -0.3f; // 1 35
    data[i++] = 1.2f;
    data[i++] = -0.1f;
    data[i++] = 0.3f; // 2 36
    data[i++] = 1.3f;
    data[i++] = -0.3f;
    data[i++] = 0.3f; // 3 37
    data[i++] = 1.3f;
    data[i++] = -0.3f;
    data[i++] = -0.3f; // 4 38
    System.out.println("end polygon; total vertex count: " + i / 3);

    data[i++] = 1.2f;
    data[i++] = -0.1f;
    data[i++] = -0.3f; // 0 39
    data[i++] = 0.5f;
    data[i++] = 0.0f;
    data[i++] = -0.3f; // 1 40
    data[i++] = 0.5f;
    data[i++] = 0.0f;
    data[i++] = 0.3f; // 2 41
    data[i++] = 1.2f;
    data[i++] = -0.1f;
    data[i++] = 0.3f; // 3 42
    data[i++] = 1.2f;
    data[i++] = -0.1f;
    data[i++] = -0.3f; // 4 43
    System.out.println("end polygon; total vertex count: " + i / 3);

    data[i++] = 0.5f;
    data[i++] = 0.0f;
    data[i++] = -0.3f; // 0 44
    data[i++] = 0.1f;
    data[i++] = 0.3f;
    data[i++] = -0.3f; // 1 45
    data[i++] = 0.1f;
    data[i++] = 0.3f;
    data[i++] = 0.3f; // 2 46
    data[i++] = 0.5f;
    data[i++] = 0.0f;
    data[i++] = 0.3f; // 3 47
    data[i++] = 0.5f;
    data[i++] = 0.0f;
    data[i++] = -0.3f; // 4 48
    System.out.println("end polygon; total vertex count: " + i / 3);

    data[i++] = 0.1f;
    data[i++] = 0.3f;
    data[i++] = -0.3f; // 0 49
    data[i++] = -0.5f;
    data[i++] = 0.3f;
    data[i++] = -0.3f; // 1 50
    data[i++] = -0.5f;
    data[i++] = 0.3f;
    data[i++] = 0.3f; // 2 51
    data[i++] = 0.1f;
    data[i++] = 0.3f;
    data[i++] = 0.3f; // 3 52
    data[i++] = 0.1f;
    data[i++] = 0.3f;
    data[i++] = -0.3f; // 4 53
    System.out.println("end polygon; total vertex count: " + i / 3);

    data[i++] = -0.5f;
    data[i++] = 0.3f;
    data[i++] = -0.3f; // 0 54
    data[i++] = -1.1f;
    data[i++] = 0.0f;
    data[i++] = -0.3f; // 1 55
    data[i++] = -1.1f;
    data[i++] = 0.0f;
    data[i++] = 0.3f; // 2 56
    data[i++] = -0.5f;
    data[i++] = 0.3f;
    data[i++] = 0.3f; // 3 57
    data[i++] = -0.5f;
    data[i++] = 0.3f;
    data[i++] = -0.3f; // 4 58
    System.out.println("end polygon; total vertex count: " + i / 3);

    data[i++] = -1.1f;
    data[i++] = 0.0f;
    data[i++] = -0.3f; // 0 59
    data[i++] = -1.3f;
    data[i++] = 0.0f;
    data[i++] = -0.3f; // 1 60
    data[i++] = -1.3f;
    data[i++] = 0.0f;
    data[i++] = 0.3f; // 2 61
    data[i++] = -1.1f;
    data[i++] = 0.0f;
    data[i++] = 0.3f; // 3 62
    data[i++] = -1.1f;
    data[i++] = 0.0f;
    data[i++] = -0.3f; // 4 63
    System.out.println("end polygon; total vertex count: " + i / 3);

    data[i++] = -1.3f;
    data[i++] = 0.0f;
    data[i++] = -0.3f; // 0 64
    data[i++] = -1.3f;
    data[i++] = -0.3f;
    data[i++] = -0.3f; // 1 65
    data[i++] = -1.3f;
    data[i++] = -0.3f;
    data[i++] = 0.3f; // 2 66
    data[i++] = -1.3f;
    data[i++] = 0.0f;
    data[i++] = 0.3f; // 3 67
    data[i++] = -1.3f;
    data[i++] = 0.0f;
    data[i++] = -0.3f; // 4 68
    System.out.println("end polygon; total vertex count: " + i / 3);

    // ****** This is the data for the hood, roof, trunk, front and rear
    // glass
    // ****** remove the comments markers below (slash-star) and (star
    // slash)
    // ****** and add the appropriate comment markers above.
    // ****** modification of other lines of code is necessary to use this
    // data
    // ****** one line above and two lines below
    /*
     * data[i++]= 1.3f; data[i++]= -0.3f; data[i++]=-0.3f; // 0 35
     * data[i++]= 1.2f; data[i++]= -0.1f; data[i++]=-0.3f; // 1 36
     * data[i++]= 0.5f; data[i++]= 0.0f; data[i++]=-0.3f; // 2 37 data[i++]=
     * 0.1f; data[i++]= 0.3f; data[i++]=-0.3f; // 3 38 data[i++]= -0.5f;
     * data[i++]= 0.3f; data[i++]=-0.3f; // 4 39 data[i++]= -1.1f;
     * data[i++]= 0.0f; data[i++]=-0.3f; // 5 40 data[i++]= -1.3f;
     * data[i++]= 0.0f; data[i++]=-0.3f; // 6 41 data[i++]= -1.3f;
     * data[i++]= -0.3f; data[i++]=-0.3f; // 7 42 data[i++]= -1.3f;
     * data[i++]= -0.3f; data[i++]= 0.3f; // 8 43 data[i++]= -1.3f;
     * data[i++]= 0.0f; data[i++]= 0.3f; // 9 44 data[i++]= -1.1f;
     * data[i++]= 0.0f; data[i++]= 0.3f; // 10 45 data[i++]= -0.5f;
     * data[i++]= 0.3f; data[i++]= 0.3f; // 11 46 data[i++]= 0.1f;
     * data[i++]= 0.3f; data[i++]= 0.3f; // 12 47 data[i++]= 0.5f;
     * data[i++]= 0.0f; data[i++]= 0.3f; // 13 48 data[i++]= 1.2f;
     * data[i++]= -0.1f; data[i++]= 0.3f; // 14 49 data[i++]= 1.3f;
     * data[i++]= -0.3f; data[i++]= 0.3f; // 15 50 data[i++]= 1.3f;
     * data[i++]= -0.3f; data[i++]=-0.3f; // 16 51 System.out.println("end
     * polygon; total vertex count: "+i/3);
     */
    // ****** end of the alternative polygon data
    return data;
  }

  Appearance createMaterialAppearance() {

    Appearance materialAppear = new Appearance();
    PolygonAttributes polyAttrib = new PolygonAttributes();
    polyAttrib.setCullFace(PolygonAttributes.CULL_NONE);
    materialAppear.setPolygonAttributes(polyAttrib);

    Material material = new Material();
    material.setDiffuseColor(new Color3f(1.0f, 0.0f, 0.0f));
    materialAppear.setMaterial(material);

    return materialAppear;
  }

  Appearance createWireFrameAppearance() {

    Appearance materialAppear = new Appearance();
    PolygonAttributes polyAttrib = new PolygonAttributes();
    polyAttrib.setPolygonMode(PolygonAttributes.POLYGON_LINE);
    materialAppear.setPolygonAttributes(polyAttrib);
    ColoringAttributes redColoring = new ColoringAttributes();
    redColoring.setColor(1.0f, 0.0f, 0.0f);
    materialAppear.setColoringAttributes(redColoring);

    return materialAppear;
  }

  /////////////////////////////////////////////////
  //
  // create scene graph branch group
  //
  public BranchGroup createSceneGraph(boolean wireFrame) {
    int total = 0;

    System.out.println("\n --- geometry debug information --- \n");

    float[] coordinateData = null;
    coordinateData = createCoordinateData();
    int[] stripCount = { 17, 17, 5, 5, 5, 5, 5, 5, 5 }; // ******
    //        int[] stripCount = {17,17,17}; // ******

    for (int i = 0; i < stripCount.length; i++) {
      System.out.println("stripCount[" + i + "] = " + stripCount[i]);
      total += stripCount[i];
    }

    if (total != coordinateData.length / 3) {
      System.out.println("  coordinateData vertex count: "
          + coordinateData.length / 3);
      System.out.println("stripCount total vertex count: " + total);
    }

    GeometryInfo gi = new GeometryInfo(GeometryInfo.POLYGON_ARRAY);
    gi.setCoordinates(coordinateData);
    gi.setStripCounts(stripCount);

    Triangulator tr = new Triangulator();
    //        Triangulator tr = new Triangulator(1);
    System.out.println("begin triangulation");
    tr.triangulate(gi);
    System.out.println("  END triangulation");
    gi.recomputeIndices();

    NormalGenerator ng = new NormalGenerator();
    ng.generateNormals(gi);
    gi.recomputeIndices();

    Stripifier st = new Stripifier();
    st.stripify(gi);
    gi.recomputeIndices();

    Shape3D part = new Shape3D();
    if (wireFrame == true)
      part.setAppearance(createWireFrameAppearance());
    else
      part.setAppearance(createMaterialAppearance());
    part.setGeometry(gi.getGeometryArray());

    /////////////////////////////

    BranchGroup contentRoot = new BranchGroup();

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

    objSpin.addChild(part);

    ////////////////////////
    LineStripArray lineArray = new LineStripArray(69,
        LineArray.COORDINATES, stripCount); //*****
    //        LineStripArray lineArray = new LineStripArray(51,
    // LineArray.COORDINATES, stripCount); //*****
    lineArray.setCoordinates(0, coordinateData);
    Appearance blueColorAppearance = new Appearance();
    ColoringAttributes blueColoring = new ColoringAttributes();
    blueColoring.setColor(0.0f, 0.0f, 1.0f);
    blueColorAppearance.setColoringAttributes(blueColoring);
    LineAttributes lineAttrib = new LineAttributes();
    lineAttrib.setLineWidth(2.0f);
    blueColorAppearance.setLineAttributes(lineAttrib);
    objSpin.addChild(new Shape3D(lineArray, blueColorAppearance));

    Alpha rotationAlpha = new Alpha(-1, 16000);

    RotationInterpolator rotator = new RotationInterpolator(rotationAlpha,
        objSpin);

    // a bounding sphere specifies a region a behavior is active
    // create a sphere centered at the origin with radius of 1
    BoundingSphere bounds = new BoundingSphere();
    rotator.setSchedulingBounds(bounds);
    objSpin.addChild(rotator);

    DirectionalLight lightD = new DirectionalLight();
    lightD.setDirection(new Vector3f(0.0f, -0.7f, -0.7f));
    lightD.setInfluencingBounds(bounds);
    contentRoot.addChild(lightD);

    AmbientLight lightA = new AmbientLight();
    lightA.setInfluencingBounds(bounds);
    contentRoot.addChild(lightA);

    Background background = new Background();
    background.setColor(1.0f, 1.0f, 1.0f);
    background.setApplicationBounds(bounds);
    contentRoot.addChild(background);

    // Let Java 3D perform optimizations on this scene graph.
    // contentRoot.compile();

    return contentRoot;
  } // end of CreateSceneGraph method of MobiusApp

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

  public GeomInfoApp(String[] args) {
    setLayout(new BorderLayout());
    Canvas3D canvas3D = new Canvas3D(null);
    add("Center", canvas3D);

    BranchGroup scene = createSceneGraph(args.length > 0);

    // 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 GeomInfoApp constructor

  //  The following allows this to be run as an application
  //  as well as an applet

  public static void main(String[] args) {
    System.out.print("GeomInfoApp - Java 3D API demo program\n");
    System.out.print("A demonstration of using the GeometryInfo class.\n");
    System.out.print("The blue lines show the input geometry - the red ");
    System.out
        .print("geometry was created by the GeometryInfo and other classes.\n");
    System.out.print("Running the program without any command line arguments will"+
  " show a solid object\n");
    System.out
        .print("Supplying any command line argument will show the wireframe.\n");
    System.out.print("http://www.sun.com/desktop/java3d\n");
    Frame frame = new MainFrame(new GeomInfoApp(args), 256, 256);
  } // end of main method of MobiusApp

} // end of class GeomInfoApp