Question

我正试图在水龙头之间保持节奏。但是，我随机获得了巨大的价值，我不知道为什么。

@implementation GameScene
{
   CFTimeInterval previousFrameTime;
   SKLabelNode* myLabel;
}

-(void)didMoveToView:(SKView *)view {
   previousTimeFrame = 0.0f;
   myLabel = [SKLabelNode labelNodeWithFontNamed:@"Chalkduster"];

   myLabel.text = @" ";
   myLabel.fontSize = 12;
   myLabel.position = CGPointMake(CGRectGetMidX(self.frame), CGRectGetMidY(self.frame));
[self addChild:myLabel];
}

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
    myLabel.text = [NSSTring stringWithFormat: @"%f", previousFrameTime];
}

//Called every frame
-(void)update:(CFTimeInterval)currentTime {
    //get the time between frames
    previousFrameTime = CACurrentMediaTime() - previousFrameTime;
}

输出： 0.65323 0.93527 1.65326 5866.42930＆lt; - ???? 2.52442 5.23156 5888.21345＆lt; - ?????

导致这些随机跳跃的原因是什么？

Answer 1

这条线似乎对我不了解：

previousFrameTime = CACurrentMediaTime() - previousFrameTime;

让我们来看看如果你精确地点击每一秒，这将是如何工作的：

1.) previousFrameTime = 1000 - 0; (1000)
2.) previousFrameTime = 1001 - 1000; (1)
3.) previousFrameTime = 1002 - 1; (1001)
4.) previousFrameTime = 1003 - 1001; (2)

Answer 2

时间增量计算是正确的，但您必须记录上次测量的时间，而不是最后计算的时间间隔，所以......

CFTimeInterval currentMediaTime = CACurrentMediaTime();
CFTimeInterval currentInterval  = currentMediaTime - previousFrameTime;

// use currentInterval however you were using previousFrameTime, but now the
// previous time should be recorded as the current time

previousFrameTime = currentMediaTime;

iOS之间的时间点击

2 个答案: