Java tutorial
/* * TwistStripApp.java 1.0 98/12/30 * * Copyright (c) 1998 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. */ /* * Getting Started with the Java 3D API written in Java 3D * * TwistStripApp.java demonstrates back face culling. A 'twisted strip' is a * continuous surface with a two twists in it. (A Mobius strip has one twist) * The Class Strip creates a surface using a TriangleStripArray. A twist strip * is placed in a scene graph with a RotationInterpolator so the strip spins. As * the strip spins, when the back faces of the individual triangles face the * image plate, they disappear. * * One twisted strip is created using the inner class (Twist). This visual * object is rendered as filled polygons. A second twist visual object is made * from the same Geometry with a different Appearance to render as lines (only). * The line-only strip helps to see where the filled polygon strip is. */ import java.applet.Applet; import java.awt.BorderLayout; import java.awt.Frame; import javax.media.j3d.Alpha; 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.Geometry; import javax.media.j3d.PolygonAttributes; import javax.media.j3d.RotationInterpolator; import javax.media.j3d.Shape3D; import javax.media.j3d.TransformGroup; import javax.media.j3d.TriangleStripArray; import javax.vecmath.Color3f; import javax.vecmath.Point3d; import com.sun.j3d.utils.applet.MainFrame; import com.sun.j3d.utils.universe.SimpleUniverse; public class TwistStripApp extends Applet { ///////////////////////////////////////////////// // // create Twist visual object // public class Twist extends Shape3D { //////////////////////////////////////////// // // create twist subgraph // public Twist() { this.setGeometry(createGeometry()); this.setAppearance(createAppearance()); } // end of twist constructor Geometry createGeometry() { TriangleStripArray twistStrip; Color3f blue = new Color3f(0.0f, 0.0f, 1.0f); // create triangle strip for twist int N = 80; int stripCounts[] = { N }; twistStrip = new TriangleStripArray(N, TriangleStripArray.COORDINATES | TriangleStripArray.COLOR_3, stripCounts); double a; int v; for (v = 0, a = 0.0; v < N; v += 2, a = v * 2.0 * Math.PI / (N - 2)) { twistStrip.setCoordinate(v, new Point3d(0.7 * Math.sin(a) + 0.2 * Math.cos(a), 0.3 * Math.sin(a), 0.7 * Math.cos(a) + 0.2 * Math.cos(a))); twistStrip.setCoordinate(v + 1, new Point3d(0.7 * Math.sin(a) - 0.2 * Math.cos(a), -0.3 * Math.sin(a), 0.7 * Math.cos(a) - 0.2 * Math.cos(a))); twistStrip.setColor(v, blue); twistStrip.setColor(v + 1, blue); } return twistStrip; } // create Appearance for Twist Strip // // this method creates the default Appearance for the // twist strip. The commented line of code containting // the setCullFace will fix the problem of half of the // Twisted Strip disappearing. Appearance createAppearance() { Appearance twistAppear = new Appearance(); PolygonAttributes polyAttrib = new PolygonAttributes(); // polyAttrib.setCullFace(PolygonAttributes.CULL_NONE); twistAppear.setPolygonAttributes(polyAttrib); return twistAppear; } } // end of class Twist ///////////////////////////////////////////////// // // create scene graph branch group // public BranchGroup createSceneGraph() { 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); Shape3D twist = new Twist(); objSpin.addChild(twist); // Duplicate the twist strip geometry and set the // appearance of the new Shape3D object to line mode // without culling. // Add the POLYGON_FILLED and POLYGON_LINE strips // in the scene graph at the same point. // This will show the triangles of the original Mobius strip that // are clipped. The PolygonOffset is set to prevent stitching. PolygonAttributes polyAttrib = new PolygonAttributes(); polyAttrib.setCullFace(PolygonAttributes.CULL_NONE); polyAttrib.setPolygonMode(PolygonAttributes.POLYGON_LINE); polyAttrib.setPolygonOffset(0.001f); Appearance polyAppear = new Appearance(); polyAppear.setPolygonAttributes(polyAttrib); objSpin.addChild(new Shape3D(twist.getGeometry(), polyAppear)); 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); // make background white Background background = new Background(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 TwistStripApp // Create a simple scene and attach it to the virtual universe public TwistStripApp() { setLayout(new BorderLayout()); Canvas3D canvas3D = new Canvas3D(null); 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 TwistStripApp constructor // The following method allows this to be run as an application public static void main(String[] args) { System.out.println("TwistStripApp - Java 3D API version 1.1"); System.out.print("See \"Getting Started with the Java 3D API\""); System.out.println(" (section 2.6)"); System.out.println("This program demonstrates back face culling."); System.out.print("In this program two visual objects rotate, "); System.out.println("one wireframe and one solid surface."); System.out.print("The wire frame is visible only when components"); System.out.println(" of the surface are culled."); Frame frame = new MainFrame(new TwistStripApp(), 256, 256); } // end of main method of TwistStripApp } // end of class TwistStripApp