The use of two collision detectors to overcome the
import java.awt.BorderLayout;
import java.awt.Button;
import java.awt.Frame;
import java.awt.Panel;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Enumeration;
import javax.media.j3d.AmbientLight;
import javax.media.j3d.Appearance;
import javax.media.j3d.Behavior;
import javax.media.j3d.BoundingSphere;
import javax.media.j3d.Bounds;
import javax.media.j3d.BranchGroup;
import javax.media.j3d.Canvas3D;
import javax.media.j3d.DirectionalLight;
import javax.media.j3d.IndexedQuadArray;
import javax.media.j3d.Locale;
import javax.media.j3d.Material;
import javax.media.j3d.PhysicalBody;
import javax.media.j3d.PhysicalEnvironment;
import javax.media.j3d.Shape3D;
import javax.media.j3d.Transform3D;
import javax.media.j3d.TransformGroup;
import javax.media.j3d.View;
import javax.media.j3d.ViewPlatform;
import javax.media.j3d.VirtualUniverse;
import javax.media.j3d.WakeupCriterion;
import javax.media.j3d.WakeupOnCollisionEntry;
import javax.media.j3d.WakeupOnCollisionExit;
import javax.media.j3d.WakeupOnCollisionMovement;
import javax.media.j3d.WakeupOr;
import javax.vecmath.Color3f;
import javax.vecmath.Point3d;
import javax.vecmath.Point3f;
import javax.vecmath.Vector3d;
import javax.vecmath.Vector3f;
import com.sun.j3d.utils.picking.behaviors.PickTranslateBehavior;
/**
* This class demonstrates the use of two collision detectors to overcome the
* problem of an object colliding with more than one object at a time. The white
* cube is movable by dragging it with the right mouse button.
*
* @see CollisionDetector2
* @author I.J.Palmer
* @version 1.0
*/
public class SimpleCollision2 extends Frame implements ActionListener {
protected Canvas3D myCanvas3D = new Canvas3D(null);
protected Button exitButton = new Button("Exit");
protected BoundingSphere bounds = new BoundingSphere(new Point3d(0.0, 0.0,
0.0), 100.0);
/** Transform for the left cube. */
protected TransformGroup leftGroup;
/** Transform for the right cube */
protected TransformGroup rightGroup;
/**
* Transform for the movable cube. This has read, write and pick reporting
* capabilities enabled.
*/
protected TransformGroup moveGroup;
/** The left static cube. */
protected Shape3D leftCube;
/** The right static cube. */
protected Shape3D rightCube;
/** The movable cube that will collide with the other two cubes */
protected Shape3D moveCube;
/**
* This builds the view branch of the scene graph.
*
* @return BranchGroup with viewing objects attached.
*/
protected BranchGroup buildViewBranch(Canvas3D c) {
BranchGroup viewBranch = new BranchGroup();
Transform3D viewXfm = new Transform3D();
viewXfm.set(new Vector3f(0.0f, 0.0f, 10.0f));
TransformGroup viewXfmGroup = new TransformGroup(viewXfm);
ViewPlatform myViewPlatform = new ViewPlatform();
PhysicalBody myBody = new PhysicalBody();
PhysicalEnvironment myEnvironment = new PhysicalEnvironment();
viewXfmGroup.addChild(myViewPlatform);
viewBranch.addChild(viewXfmGroup);
View myView = new View();
myView.addCanvas3D(c);
myView.attachViewPlatform(myViewPlatform);
myView.setPhysicalBody(myBody);
myView.setPhysicalEnvironment(myEnvironment);
return viewBranch;
}
/**
* This adds some lights to the content branch of the scene graph.
*
* @param b
* The BranchGroup to add the lights to.
*/
protected void addLights(BranchGroup b) {
Color3f ambLightColour = new Color3f(0.5f, 0.5f, 0.5f);
AmbientLight ambLight = new AmbientLight(ambLightColour);
ambLight.setInfluencingBounds(bounds);
Color3f dirLightColour = new Color3f(1.0f, 1.0f, 1.0f);
Vector3f dirLightDir = new Vector3f(-1.0f, -1.0f, -1.0f);
DirectionalLight dirLight = new DirectionalLight(dirLightColour,
dirLightDir);
dirLight.setInfluencingBounds(bounds);
b.addChild(ambLight);
b.addChild(dirLight);
}
/**
* Creates the content branch of the scene graph.
*
* @return BranchGroup with content attached.
*/
protected BranchGroup buildContentBranch() {
//First create a different appearance for each cube
Appearance app1 = new Appearance();
Appearance app2 = new Appearance();
Appearance app3 = new Appearance();
Color3f ambientColour1 = new Color3f(1.0f, 0.0f, 0.0f);
Color3f ambientColour2 = new Color3f(1.0f, 1.0f, 0.0f);
Color3f ambientColour3 = new Color3f(1.0f, 1.0f, 1.0f);
Color3f emissiveColour = new Color3f(0.0f, 0.0f, 0.0f);
Color3f specularColour = new Color3f(1.0f, 1.0f, 1.0f);
Color3f diffuseColour1 = new Color3f(1.0f, 0.0f, 0.0f);
Color3f diffuseColour2 = new Color3f(1.0f, 1.0f, 0.0f);
Color3f diffuseColour3 = new Color3f(1.0f, 1.0f, 1.0f);
float shininess = 20.0f;
app1.setMaterial(new Material(ambientColour1, emissiveColour,
diffuseColour1, specularColour, shininess));
app2.setMaterial(new Material(ambientColour2, emissiveColour,
diffuseColour2, specularColour, shininess));
app3.setMaterial(new Material(ambientColour3, emissiveColour,
diffuseColour3, specularColour, shininess));
//Build the vertex array for the cubes. We can use the same
//data for each cube so we just define one set of data
IndexedQuadArray indexedCube = new IndexedQuadArray(8,
IndexedQuadArray.COORDINATES | IndexedQuadArray.NORMALS, 24);
Point3f[] cubeCoordinates = { new Point3f(1.0f, 1.0f, 1.0f),
new Point3f(-1.0f, 1.0f, 1.0f),
new Point3f(-1.0f, -1.0f, 1.0f),
new Point3f(1.0f, -1.0f, 1.0f), new Point3f(1.0f, 1.0f, -1.0f),
new Point3f(-1.0f, 1.0f, -1.0f),
new Point3f(-1.0f, -1.0f, -1.0f),
new Point3f(1.0f, -1.0f, -1.0f) };
Vector3f[] cubeNormals = { new Vector3f(0.0f, 0.0f, 1.0f),
new Vector3f(0.0f, 0.0f, -1.0f),
new Vector3f(1.0f, 0.0f, 0.0f),
new Vector3f(-1.0f, 0.0f, 0.0f),
new Vector3f(0.0f, 1.0f, 0.0f), new Vector3f(0.0f, -1.0f, 0.0f) };
int cubeCoordIndices[] = { 0, 1, 2, 3, 7, 6, 5, 4, 0, 3, 7, 4, 5, 6, 2,
1, 0, 4, 5, 1, 6, 7, 3, 2 };
int cubeNormalIndices[] = { 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3,
3, 3, 4, 4, 4, 4, 5, 5, 5, 5 };
indexedCube.setCoordinates(0, cubeCoordinates);
indexedCube.setNormals(0, cubeNormals);
indexedCube.setCoordinateIndices(0, cubeCoordIndices);
indexedCube.setNormalIndices(0, cubeNormalIndices);
//Create the three cubes
leftCube = new Shape3D(indexedCube, app1);
rightCube = new Shape3D(indexedCube, app2);
moveCube = new Shape3D(indexedCube, app3);
//Define some user data so that we can print meaningful messages
leftCube.setUserData(new String("left cube"));
rightCube.setUserData(new String("right cube"));
//Create the content branch and add the lights
BranchGroup contentBranch = new BranchGroup();
addLights(contentBranch);
//Set up the transform to position the left cube
Transform3D leftGroupXfm = new Transform3D();
leftGroupXfm.set(new Vector3d(-1.5, 0.0, 0.0));
leftGroup = new TransformGroup(leftGroupXfm);
//Set up the transform to position the right cube
Transform3D rightGroupXfm = new Transform3D();
rightGroupXfm.set(new Vector3d(1.5, 0.0, 0.0));
rightGroup = new TransformGroup(rightGroupXfm);
//Create the movable cube's transform with a scale and
//a translation. Set up the
//capabilities so it can be moved by the behaviour
Transform3D moveXfm = new Transform3D();
moveXfm.set(0.7, new Vector3d(0.0, 2.0, 1.0));
moveGroup = new TransformGroup(moveXfm);
moveGroup.setCapability(TransformGroup.ALLOW_TRANSFORM_WRITE);
moveGroup.setCapability(TransformGroup.ALLOW_TRANSFORM_READ);
moveGroup.setCapability(TransformGroup.ENABLE_PICK_REPORTING);
//Create the behaviour to move the movable cube
PickTranslateBehavior pickTranslate = new PickTranslateBehavior(
contentBranch, myCanvas3D, bounds);
contentBranch.addChild(pickTranslate);
//Create and add the two colision detectors
CollisionDetector2 myColDetLeft = new CollisionDetector2(leftCube,
bounds);
contentBranch.addChild(myColDetLeft);
CollisionDetector2 myColDetRight = new CollisionDetector2(rightCube,
bounds);
contentBranch.addChild(myColDetRight);
//Set up the scene graph
contentBranch.addChild(moveGroup);
contentBranch.addChild(leftGroup);
contentBranch.addChild(rightGroup);
moveGroup.addChild(moveCube);
leftGroup.addChild(leftCube);
rightGroup.addChild(rightCube);
return contentBranch;
}
/** Process exit button's action to quit */
public void actionPerformed(ActionEvent e) {
if (e.getSource() == exitButton) {
dispose();
System.exit(0);
}
}
public SimpleCollision2() {
VirtualUniverse myUniverse = new VirtualUniverse();
Locale myLocale = new Locale(myUniverse);
myLocale.addBranchGraph(buildViewBranch(myCanvas3D));
myLocale.addBranchGraph(buildContentBranch());
setTitle("SimpleWorld");
setSize(400, 400);
setLayout(new BorderLayout());
Panel bottom = new Panel();
bottom.add(exitButton);
add(BorderLayout.CENTER, myCanvas3D);
add(BorderLayout.SOUTH, bottom);
exitButton.addActionListener(this);
setVisible(true);
}
public static void main(String[] args) {
SimpleCollision2 sw = new SimpleCollision2();
}
}
/**
* A simple collision detector class. This responds to a collision event by
* printing a message with information about the type of collision event and the
* object involved. This is a variation of the CollisionDetector class that
* prints information about the object that is associated with this behaviour
* rather than the object that has been collided with. An example of its use is
* given in the SimpleCollision2 class.
*
* @author I.J.Palmer
* @version 1.0
* @see CollisionDetector
* @see SimpleCollision2
*/
class CollisionDetector2 extends Behavior {
/** The shape that is being watched for collisions. */
protected Shape3D collidingShape;
/** The separate criteria that trigger this behaviour */
protected WakeupCriterion[] theCriteria;
/** The result of the 'OR' of the separate criteria */
protected WakeupOr oredCriteria;
/**
* @param theShape
* Shape3D that is to be watched for collisions.
* @param theBounds
* Bounds that define the active region for this behaviour
*/
public CollisionDetector2(Shape3D theShape, Bounds theBounds) {
collidingShape = theShape;
setSchedulingBounds(theBounds);
}
/**
* This sets up the criteria for triggering the behaviour. It creates an
* entry, exit and movement trigger, OR's these together and then sets the
* OR'ed criterion as the wake up condition.
*/
public void initialize() {
theCriteria = new WakeupCriterion[3];
WakeupOnCollisionEntry startsCollision = new WakeupOnCollisionEntry(
collidingShape);
WakeupOnCollisionExit endsCollision = new WakeupOnCollisionExit(
collidingShape);
WakeupOnCollisionMovement moveCollision = new WakeupOnCollisionMovement(
collidingShape);
theCriteria[0] = startsCollision;
theCriteria[1] = endsCollision;
theCriteria[2] = moveCollision;
oredCriteria = new WakeupOr(theCriteria);
wakeupOn(oredCriteria);
}
/**
* This is where the work is done. This identifies the type of collision
* (entry, exit or movement) and prints a message stating that an object has
* collided with this object. The userData field of the shape associated
* with this collision detector # is used to identify the object. Finally,
* the wake up condition is set to be the OR'ed criterion again.
*/
public void processStimulus(Enumeration criteria) {
while (criteria.hasMoreElements()) {
WakeupCriterion theCriterion = (WakeupCriterion) criteria
.nextElement();
if (theCriterion instanceof WakeupOnCollisionEntry) {
System.out.println("Collided with "
+ collidingShape.getUserData());
} else if (theCriterion instanceof WakeupOnCollisionExit) {
System.out.println("Stopped colliding with "
+ collidingShape.getUserData());
} else {
System.out.println("Moved whilst colliding with "
+ collidingShape.getUserData());
}
}
wakeupOn(oredCriteria);
}
}
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