动画化CAEmitterCell颜色属性

Question

我有一个CAEmitterCell，我已经设置了一个特定的颜色。文档中说，这个属性是可动的。，我想为我的游戏中不同的玩家(所有的人都在一开始就选择他们的颜色)在多个不同的颜色之间动画。

这是我设置EmitterCell时的：

//
    // Emitter Cells
    //

    // 'New Emitter' cell configuration
    newEmitter = [CAEmitterCell emitterCell];
    newEmitter.scaleSpeed = 10;
    newEmitter.lifetime = 2.481715;
    newEmitter.velocity = 332.3636968085106;
    newEmitter.contents = newemitterImg;
    newEmitter.name = @"New Emitter";
    newEmitter.color = [[UIColor colorWithRed:0.50 green:0.00 blue:1.00 alpha:1.00] CGColor];
    newEmitter.scaleRange = 4.178236607142859;
    newEmitter.lifetimeRange = 1.6;
    newEmitter.greenRange = -2.775558e-17;
    newEmitter.birthRate = 40;
    newEmitter.emissionRange = -6.283185306666667;
    newEmitter.scale = 0;

    //
    // Emitter Cell Chains
    //
    emitter.emitterCells = [NSArray arrayWithObjects:newEmitter, nil];

这里是我测试颜色变化的地方--在这种情况下，只是在两种不同的颜色之间跳跃：

-(void)changeColor {

    if (color == 0) {
        color = 1;
        NSLog(@"color = 1");

        [UIView animateWithDuration:1.5 delay:0 options:0 animations:^{
            newEmitter.color = [[UIColor colorWithRed:0.50 green:0.00 blue:1.00 alpha:1.00] CGColor];
        } completion:^(BOOL finished) {[self performSelector:@selector(changeColor) withObject:nil afterDelay:2];}];
    } else {
        color = 0;
        NSLog(@"color = 0");
        [UIView animateWithDuration:1.5 delay:0 options:0 animations:^{
            newEmitter.color = [[UIColor colorWithRed:1.00 green:0.50 blue:0.10 alpha:1.00] CGColor];
        } completion:^(BOOL finished) {[self performSelector:@selector(changeColor) withObject:nil afterDelay:2];}];
    }

}

然而，当我运行这个颜色时，颜色不会改变。我是否在这里误解了“动画”的本质，还是只需要对CAEmitterCell进行不同的处理？

Answer 1

CAEmitterCells实际上是不同的。要使动画在它们上工作，您需要采取以下步骤：

1.为您的CAEmitterCell指定名称，例如：

newEmitter.name = @"fire";

2.通过CAEmitterLayer实例访问此发射器的动画属性：

//Set first before doing CABasicAnimation so it sticks
newEmitter.redSpeed = 1.0;

//Access the property with this key path format: @"emitterCells.<name>.<property>"
CABasicAnimation *anim = [CABasicAnimation animationWithKeyPath:@"emitterCells.fire.redSpeed"];
anim.fromValue = @(0.0);
anim.toValue = @(1.0);
anim.duration = 1.5;
anim.fillMode = kCAFillModeForwards;
[emitter addAnimation:anim forKey:@"emitterAnim"];

Answer 2

试试这个：

    [newEmitter.emitterCells[0] setColor:[[UIColor yellowColor] CGColor]];

Answer 3

您可以使用这些属性来绘制发射器的颜色。

newEmitter.redSpeed = 1.0;
newEmitter.greenSpeed = 1.0;
newEmitter.blueSpeed = 1.0;