Question

我一直试图用加速度计移动UIImageView，但是我遇到了一个问题。当我尝试平滑数据并计算出从原始位置加速数据时，值返回无穷大。我不太确定我做错了什么！

这是我的代码：

- (void)viewDidLoad {
    gameObjects = [NSMutableArray arrayWithObjects: nil];

    UIImageView* mainChar = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 50, 50)];
    [mainChar setCenter:CGPointMake(screenHeight/2, screenWidth/2)];
    mainChar.image = [UIImage imageNamed:@"dot.png"];
    [self.view insertSubview:mainChar atIndex:2];
    [gameObjects addObject:mainChar];
    mainChar = nil;

    AvData = [NSMutableArray arrayWithObjects: nil];

    motionManager = [[CMMotionManager alloc] init];
    motionManager.deviceMotionUpdateInterval = 20;

    [motionManager startAccelerometerUpdatesToQueue:[NSOperationQueue mainQueue] withHandler:^(CMAccelerometerData* accelerationData, NSError* error) {
    if (defaultData == nil) {defaultData = accelerationData;}
    [self accelerometerUpdate:accelerationData];
}];
}

-(void) accelerometerUpdate:(CMAccelerometerData*)aData {

    //Accelerometer Smoothing
    [AvData addObject:aData];
    if ([AvData count] >= 20) {[AvData removeObjectAtIndex:0];}
    float avX = 0;
    float avY = 0;
    float avZ = 0;
    for (int i = 0; i < [AvData count]; i++) {
        avX = avX + [[AvData objectAtIndex:i] acceleration].x;
        avY = avY + [[AvData objectAtIndex:i] acceleration].y;
        avZ = avZ + [[AvData objectAtIndex:i] acceleration].z;
    }

    avX = avX/([AvData count] - 1);
    avY = avY/([AvData count] - 1);
    avZ = avZ/([AvData count] - 1);

    //Calculate the delta from original device acceleration value
    float accX = defaultData.acceleration.x - avX;
    float accY = defaultData.acceleration.y - avY;
    //float accZ = defaultData.acceleration.z - avZ;

    NSLog([NSString stringWithFormat:@"%f", accY]);

    UIImageView* mainChar = [gameObjects objectAtIndex:0];

    [mainChar setCenter:CGPointMake(mainChar.center.x + accX, mainChar.center.y + accY)]; 
    //accX and accY are infinity for some reason, and so the image disappears!

    mainChar = nil;
}

奇怪的是，当我NSLog accY时，它返回一个正确的值。我做错了什么？

Answer 1

脱离我的头顶：

当你到达这些界限时：

avX = avX /（[AvData count] - 1）; avY = avY /（[AvData count] - 1）; avZ = avZ /（[AvData count] - 1）;

如果此时count == 1，则代码将除以零。我希望崩溃，但如果没有，结果将是无限或NAN。（我希望NAN，但是如果它没有抛出异常，它可能会返回INF。我需要测试它或查看它以确定。）

加速度计计算导致inf

1 个答案: