iphone - 粒子引擎问题

Question

我正在实现粒子引擎，这是我的代码：

-(id) init
{
    // always call "super" init
    // Apple recommends to re-assign "self" with the "super" return value
    if( (self=[super init] )) 
    {
        self.isTouchEnabled = YES;
        emitter = [[CCParticleMeteor alloc] init];
        emitter.texture     =   [[CCTextureCache sharedTextureCache] addImage:@"stars.png"];
        emitter.position    =   ccp( 240, 160 );
        [self addChild:emitter];

    }
    return self;
}
-(BOOL) ccTouchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    [self ccTouchesMoved:touches withEvent:event];
    return YES;
}
-(BOOL) ccTouchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
    UITouch *myTouch    =   [touches anyObject];
    CGPoint location    =   [myTouch locationInView:[myTouch view]];
    CGPoint point       =   [[CCDirector sharedDirector] convertToGL:location];
    emitter.position    =   ccp(point.x , point.y);
    return YES;
}

这是屏幕截图：

这是我想要的：

1-我想改变效果的方向（意味着火焰向上移动但我想向下）。

2-我想改变火焰的颜色。

如果可以的话请帮忙.....

Answer 1

1) 快速查看粒子系统文档可以让您使用角度或重力 - 尝试将它们设置为不同的值，即

emitter.angle = <the angle you want>

2) 编辑 stars.png 为你想要的颜色？