2d collision detection trouble
Post: #1
Hey guys,
I'm working on a brick breaker game for the iPhone, and I've run into a little trouble. Right now I can draw bricks to the screen, move the paddle, launch the ball, etc.
The collision detection works fine with ball->paddle, but with ball->brick there are some issues.
When the ball collides with the side of a brick and is also touching another brick, it pretty much plows through the brick instead of bouncing off (the x-velocity is supposed to *= -1).
My code is included below - would you mind looking through it to see if I can make any changes to fix this problem?
Thanks a lot guys,
Steve
I'm working on a brick breaker game for the iPhone, and I've run into a little trouble. Right now I can draw bricks to the screen, move the paddle, launch the ball, etc.
The collision detection works fine with ball->paddle, but with ball->brick there are some issues.
When the ball collides with the side of a brick and is also touching another brick, it pretty much plows through the brick instead of bouncing off (the x-velocity is supposed to *= -1).
My code is included below - would you mind looking through it to see if I can make any changes to fix this problem?
Code:
////////////////////
// This code runs 30 time/second
// It checks for collisions
// and updates views on the screen
// Located in main view controller
////////////////////
-(void)onTimer{
if(playing){
if(platformView.MOVED==YES) [platformView refresh:platform];
[ball update];
[ballView refresh:ball];
if(ball.position.y+ball.radius>=platform.position.y)
[ball checkCollisions:ball withPlatform:platform];
for(NSInteger i=0; i<=level1.numBricks; i++){
brickView = [level1.bricks objectAtIndex:i];
if([ball checkCollisions:ball withBrick:brickView]==YES){
NSLog(@"%d", i);
if(brickView.life==2){
[brickView setBackgroundColor:[UIColor orangeColor]];
}
else if(brickView.life==1){
[brickView setBackgroundColor:[UIColor yellowColor]];
}
else if(brickView.life==0){
[brickView removeFromSuperview];
brickView.position = CGPointMake(0, 0);
brickView.width = 0;
brickView.height = 0;
}
}
}
}
if(ball.position.y>=460){
playing=NO;
}
}
///////////////////////
// This is the collision detection code
// Located in the "Ball.m" ball object class
/////////////////////
-(BOOL)checkCollisions:(Ball *)aBall withBrick:(BrickView *)aBrick
{
if(CGRectIntersectsRect([aBall getRect],[aBrick getRect])){
CGPoint balVel = aBall.velocity;
CGPoint balPos = aBall.position;
CGPoint brickPos = aBrick.position;
aBrick.life--;
NSLog(@"balPos.x %f", balPos.x);
NSLog(@"-rad %f", balPos.x-aBall.radius);
NSLog(@"+rad %f", balPos.x+aBall.radius);
NSLog(@"brickPos.x %f",brickPos.x);
NSLog(@"+width %f",brickPos.x+aBrick.width);
if((balPos.x-aBall.radius)>=(brickPos.x+aBrick.width)-1){
balPos.x = brickPos.x+aBrick.width-1;
balVel.x*=-1;
}
else if((balPos.x+aBall.radius)<=brickPos.x+1){
balPos.x = brickPos.x+1;
balVel.y*=-1;
}
else{
balVel.y*=-1;
}
aBall.position = balPos;
aBall.velocity = balVel;
[aBall update];
return YES;
}
}Thanks a lot guys,
Steve
Post: #2Quote: if((balPos.x-aBall.radius)>=(brickPos.x+aBrick.width)-1){
I think you'll need to consider what these values are depending on if the ball comes from the left or right side.
Howling Moon Software - CrayonBall for Mac and iPhone, Contract Game Dev Work
Post: #3
I was able to fix the problem. I guess I was just overthinking everything. Here's the working code:
Code:
//Check if ball is colliding with either side of the brick
if(balPos.x>brickPos.x+aBrick.width || balPos.x<brickPos.x){
balVel.x*=-1; //Change x velocity
}
//If ball is colliding with top or bottom of brick
else{
balVel.y*=-1; //Change y velocity
}
//Update ball position using new velocity
aBall.velocity = balVel;
[aBall update];
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