How do I get a particle effect to follow my sprite in cocos2d? - iphone

Question

I want a snow particle effect to follow my sprite and I tried some methods but all that ends up happening is the snow will just stay still instead of following. I did this one tutorial (will post as soon as I find it) thats shows how it do it with fire but didn't work out at all. Any tutorials or suggestions will be appreciated. I believe i have to add some kind of code to the snippet part where it says create enemy off screen.
[self schedule:#selector(gameLogicboss:) interval:180 ];
[self schedule:#selector(updateboss:)];
-(void)addTarget1 {
Boss *target1 = nil;
if ((arc4random() % 2) == 0) {{
target1 = [WeakAndFastBoss boss];
}} else {
target1 = [WeakAndFastBoss boss];
}
// Determine where to spawn the target along the Y axis
CGSize winSize = [[CCDirector sharedDirector] winSize];
int minY = target1.contentSize.height/2;
int maxY = winSize.height - target1.contentSize.height/2;
int rangeY = maxY - minY;
int actualY = (arc4random() % rangeY) + minY;
// Create the target slightly off-screen along the right edge,
// and along a random position along the Y axis as calculated above
target1.position = ccp(winSize.width + (target1.contentSize.width/2), actualY);
[self addChild:target1 ];
// Determine speed of the target
int minDuration = target1.minMoveDuration;
int maxDuration = target1.maxMoveDuration;
int rangeDuration = maxDuration - minDuration;
int actualDuration = (arc4random() % rangeDuration) + minDuration;
// Create the actions
id actionMove = [CCMoveTo actionWithDuration:actualDuration position:ccp(-target1.contentSize.width/2, actualY)];
id actionMoveDone = [CCCallFuncN actionWithTarget:self
selector:#selector(spriteMoveFinished:)];
[target1 runAction:[CCSequence actions:actionMove, actionMoveDone, nil]];
target1.tag = 1;
[_targets addObject:target1];
}
-(void)gameLogicboss:(ccTime)dt {
[self addTarget1];
iterations_++;
}
- (void)updateboss:(ccTime)dt {
CGRect projectileRect = CGRectMake(projectile.position.x - (projectile.contentSize.width/2), projectile.position.y - (projectile.contentSize.height/2), projectile.contentSize.width, projectile.contentSize.height);
BOOL bossHit = FALSE;
NSMutableArray *targetsToDelete = [[NSMutableArray alloc] init];
for (CCSprite *target1 in _targets) {
CGRect target1Rect = CGRectMake(target1.position.x - (target1.contentSize.width/2), target1.position.y - (target1.contentSize.height/2), target1.contentSize.width, target1.contentSize.height);
if (CGRectIntersectsRect(projectileRect, target1Rect)) {
//[targetsToDelete addObject:target];
bossHit = TRUE;
Boss *boss = (Boss *)target1;
boss.hp--;
if (boss.hp <= 0) {
_score ++;
[targetsToDelete addObject:target1];
}
break;
}
}
for (CCSprite *target in targetsToDelete) {
[_targets removeObject:target];
[self removeChild:target cleanup:YES];
_projectilesDestroyed++;
if (_projectilesDestroyed > 2) {
}
}
if (bossHit) {
//[projectilesToDelete addObject:projectile];
[[SimpleAudioEngine sharedEngine] playEffect:#"explosion.caf"];
}
[targetsToDelete release];
}
-(void)spriteMoveFinishedboss:(id)sender {
CCSprite *sprite = (CCSprite *)sender;
[self removeChild:sprite cleanup:YES];
GameOverScene *gameOverScene = [GameOverScene node];
[gameOverScene.layer.label setString:#"You Lose"];
[[CCDirector sharedDirector] replaceScene:gameOverScene];
if (sprite.tag == 1) { // target
[_targets removeObject:sprite];
} else if (sprite.tag == 2) { // projectile
[_projectiles removeObject:sprite];
}
}

Answer 1

I Have found this, at CCParticleSystem.h
/** #typedef tCCPositionType
possible types of particle positions
/
typedef enum {
/* Living particles are attached to the world and are unaffected by emitter repositioning. */
kCCPositionTypeFree,
/** Living particles are attached to the world but will follow the emitter repositioning.
Use case: Attach an emitter to an sprite, and you want that the emitter follows the sprite.
*/
kCCPositionTypeRelative,
/** Living particles are attached to the emitter and are translated along with it. */
kCCPositionTypeGrouped,
you should set it like
myparticleSystem.positionType=kCCPositionTypeGrouped;
Hope it helps.

Answer 2

You don't need to update the particle emitter's position with the sprite.
You can add a particle system to the sprite as a child.
The particle system does need to be typed as such:
CCParticleSystem * booster = [CCParticleSystem particleWithFile:#"boosterParticles.plist"];
//customize your particles' options
//assuming you have a sprite defined as _motherShip
[_motherShip addChild:booster];
/*
* now that the particles are the _motherShip's child, you must remember
* to set the position relative to the mothership's origin...
*/
particles.position = ccp(15,0);
...So now whenever _motherShip.position changes, the booster will follow. It will even rotate with the ship.

Answer 3

Very simple logic without getting into code:
I spawn a sprite and give it a location (x, y).
For each sprite, I also spawn a CCParticleSystem, give it the required particle type, spawn rates etc.
The CCParticleSystem location is now set to be the same (x,y) location as the sprite, and it should get updated as the sprite's (x,y) location is update.
As the sprite and the CCParticleSystem move around, this location (x, y) is getting updates constantly at random in your schedule method per the interval step time.
Hope that makes sense.

Answer 4

I do this
vehicleParticleSystem = [CCParticleSystemQuad particleWithFile:#"vehicleParticle.plist"];
vehicleParticleSystem.position = ccp(_ship.position.x - _ship.contentSize.width/3, _ship.position.y - _ship.contentSize.height/3);
if (UI_USER_INTERFACE_IDIOM() != UIUserInterfaceIdiomPad) {
vehicleParticleSystem.scale = 0.5;
}
[self addChild:vehicleParticleSystem z:-1];
and update its position with this
- (void) updateParticleSystem:(ccTime)dt {
vehicleParticleSystem.position = ccp(_ship.position.x - _ship.contentSize.width/3, _ship.position.y - _ship.contentSize.height/3);
}
which is called in the -(void) update:(ccTime)dt method.
The ship is moved by the user via a joypad.
hope this helps. The positioning for the particle is slightly behind the vehicle for an engine effect.

Answer 5

Did you tried to update your particle position taking advantage of the update method?
I'm doing something like the following lines in one of my games and it works as I think you expect
-(void) update:(CCTime)delta{
_sprite.position = CGPointMake(newXPosition, newYPosition);
_fire.position = CGPointMake(_sprite.position.x, _sprite.position.y);
}
I hope it helps!