1. Movement (Paul Klee Signatures)
CBP 2006
Comp3063

2. CBP 2006
Comp3063

3. Threads
CBP 2006
Comp3063

4. Using a Thread CBP 2006 Comp3063 public void run() { while (true) {
if(running == true) {
.. Call Thing’s move() here ..
try {
Thread.sleep(100); }
catch (InterruptedException e) {
System.out.println(e);
return;
This is an infinite loop
Go further only if RUNNING
suspend this thread a bit to allow other user actions
CBP 2006
Comp3063

5. Game engine Physics : Speeds
Let’s say we have speed
vX = 10;
X = 50
X = 60
X = 70
X = 80
This says we get the new x by adding on the extra x due to the speed vX
x = x + vX
CBP 2006
Comp3063

6. Movement (Constant Speed)
public void step() {
x = x + vX;
if(x > canvas.getCanvasWidth() ) vX = -vX;
if(x < 0) vX = -vX;
// Something similar for the y-direction }
CBP 2006
Comp3063

7. Game engine Physics : Speedsx y
x = x + vX
y = y + vY vX vY
CBP 2006
Comp3063

8. Bouncing vX vX unchanged vY vY = -vY vX vY Before collision
After collision
CBP 2006
Comp3063

9. How to make a “Trap” for balls ?
Bouncing (Soft Walls)
vX = 0.5*vX
vY = -0.5*vY
How to make a “Trap” for balls ?
CBP 2006
Comp3063

10. Collision Detection -1-
boundBox
Rectangle boundBox = new Rectangle();
boundBox.setRect(x,y,width,height);
rectangle1
rectangle2
intersects
if(boundBox.intersects(otherBoundBox)) {
contact = true; }
rectangle1.intersects(rectangle2)
CBP 2006
Comp3063

11. Collision Detection -2-
thing1
thing2
(xC,yC)
radiusThing
separation
double radiusThing1 = thing1.getRadius();
double radiusThing2 = thing2.getRadius();
double separation = Math.sqrt( (xCThing1 - xCThing2)*(xCThing1 - xCThing2) +
(yCThing1 - yCThing2)*(yCThing1 - yCThing2) );
if ( separation <= (radiusThing1 + radiusThing2) ) collision = true;
else collision = false;
CBP 2006
Comp3063

12. Philosophy of Interactions
game objects will collide
so each must get info where others are
game objects ask each other
gObj
- Or -
game objects will collide
so each must get info where others are
gameCanvas mediates this info
canvas
CBP 2006
Comp3063

13. Message Passing in DrawCanvas
Iterator it = gameObjectList.iterator();
while(it.hasNext())
GameObject sourceGobj = (GameObject) it.next();
Iterator it2 = gameObjectList.iterator();
while(it2.hasNext()) {
GameObject targetGobj = (GameObject) it2.next();
if( targetGobj != sourceGobj) {
sourceGobj.xchangeImplicitMessage(targetGobj); }
CBP 2006
Comp3063

14. Interact Then Step DrawCanvas Class Send interaction Messages
while (true) {
Iterator it = gameObjectList.iterator();
while(it.hasNext()) {
GameObject sourceGobj = (GameObject) it.next();
Iterator it2 = gameObjectList.iterator();
while(it2.hasNext()) {
GameObject targetGobj = (GameObject) it2.next();
if( targetGobj != sourceGobj) {
sourceGobj.xchangeImplicitMessage(targetGobj); }
Iterator it3 = gameObjectList.iterator();
while(it3.hasNext()) {
GameObject sourceGobj = (GameObject) it3.next();
sourceGobj.step();
Send interaction
Messages
Call step() to
Update positions
DrawCanvas Class
CBP 2006
Comp3063

15. GameObject class Get interaction Messages step() updates position
public void xchangeImplicitMessage(GameObject otherGobj) {
isCollided = isCollision(otherGobj);
if(isCollided == true) {
collidedGobj = otherGobj;
System.out.println("GameObject:: "+otherGobj+" collided w "+this); }
Get interaction
Messages
public void step() {
if( collidedGobj != null) {
respondToCollision(collidedGobj); }
x += vX;
y += vY;
boundBox.setRect(x,y,width,height);
collidedGobj = null;
step() updates position
GameObject class
CBP 2006
Comp3063

16. Sequence Diagram for Messaging
CBP 2006
Comp3063

17. Adding JComponents to the GUI
public Target(double x, double y, double wwidth, double hheight, DrawCanvas canvas){
super(x,y,canvas);
this.width = wwidth;
this.height = hheight;
color = Color.green;
boundBox.setRect(x,y,width,height);
score = 0;
JLabel label1 = new JLabel("Score");
scoreField = new JTextField("0",10);
JPanel p1 = new JPanel();
p1.add(label1);
p1.add(scoreField);
canvas.gui.addScoreBox(p1); }
Make GUI component
CBP 2006
Comp3063