Ball Physics

Yea read up on the physics of projectiles.

http://www.glenbrook.k12.il.us/GBSSCI/PHYS/CLASS/vectors/vectoc.html

- Get the equations

- Youll need the weight of the balls

- A value for your virtual gravity

- Make the time scalable

(so events can take more/less time without changing values)

- Make the number of balls variable to start with.

- Make the ball widths variable to start with

- Essentially make everything variable

And for the love of god dont use a different thread for every sprite.

Do a search of the forums for the many other people who have

implemented collision detection and bouncing for balls.

here is a thread from last week:

http://forum.java.sun.com/thread.jspa?threadID=759410

TuringPesta at 2007-7-14 20:42:39 >

That's true; if you allow the user to adjust the accelleration due to gravity then toggling becomes just setting it to zero.

I suppose you could toggle that way even if you're not adjusting gravity on the fly. I tend to avoid things like that because it's mixing semantics in a way, but there's nothing wrong with it.

paulcwa at 2007-7-21 10:01:51 >

I'm using the same logic but with separate class for Ball

Ball Class has

class Ball{

int ballx, bally, vx,vy;

int size = 10;

public Ball()

{

this.ballx = 0;

this.bally = 0;

this.vx = 2;

this.vy = 2;

}

void Move(int canvasWidth, canvasHeight)

{

ballx += vx;

bally += vy;

if ((ballx < 0) || (bally + size > canvasWidth ))

{

vx = -vx;

ballx += vx;

}

if ((bally < 0) || (bally + size > canvasHeight)))

{

vy = -vy;

bally += vy;

}

}

void paint(Graphics g)

{

g.fillArc(this.ballx, this.bally,size, size, 0, 360);

}

}

and the canvas class has

class can extends Canvas implements Runnable

{

int numBall;

Ball ball[]

public can()

{

ball = new Ball[3]; // max 3 balls

balls[0] = new Ball();

numBall = 1;

(new Thread(this)).start();

}

public void paint(Graphics g)

{

for(int i = 0; i < numBall; i++){

ball.Move (getWidth(), getHeight());

ball.paint(g);

}

}

public void run()

{

try{

Thread.sleep(20);

}

catch(Exception e){

}

repaint();

}

public void keyPressed(int keyCode) {

int action = getGameAction(keyCode);

switch (action) {

case LEFT:

if (numBalls > 1) {

// decrement the counter

numBall = numBall - 1;

ball[numBall] = null;

}

break;

case RIGHT:

// Increase the number of threads

if (numBall < ball.length) {

ball[numBall] = new Ball();

// increment the counter

numBall = numBall + 1;

}

break;

}

}

}

On pressing right, its creating the new ball but its taking the same ballx , bally as the previous ball

its the problem with the thread right?

i'm starting the thread in constructor. i need to do it using single thread, please guide me.

Thanks

drrpbsa at 2007-7-21 10:01:51 >