ios – 计算指南针到特定坐标而不是北方的方向

2019年8月4日 187次阅读

我无法正确使用此算法.我正试图制作一个指向某个位置的指南针,而不仅仅是指向北方.出了点问题.我花了很多时间试图解决这个问题,但我找不到它.有任何想法吗？

- (void)locationManager:(CLLocationManager *)manager didUpdateHeading:(CLHeading *)newHeading{

double distanceEast = (location.longitude > 0 && otherLocation.longitude < 0) ? 180 - location.longitude + otherLocation.longitude - -180: otherLocation.longitude - location.longitude;

    if (distanceEast < 0) {
        distanceEast += 360;
    }

    double distanceWest = (location.longitude < 0 && otherLocation.longitude > 0) ? -180 - location.longitude - 180 - otherLocation.longitude : location.longitude - otherLocation.longitude;

    if (distanceWest < 0) {
        distanceWest += 360;
    }

    float latitudinalDifference = (otherLocation.latitude - location.latitude);
    float longitudinalDifference = fmin(distanceEast,distanceWest);

    float arcTan = atan(longitudinalDifference / latitudinalDifference);

        float oldRadian = (-manager.heading.trueHeading *M_PI /180.0f)+arcTan+M_PI;
        float newRadian = (-newHeading.trueHeading *M_PI /180.0f)+arcTan+M_PI;

        CABasicAnimation *animation;
        animation=[CABasicAnimation animationWithKeyPath:@"transform.rotation"];
        animation.fromValue = [NSNumber numberWithFloat:oldRadian];
        animation.toValue = [NSNumber numberWithFloat:newRadian];
        animation.duration = 0.5f;
        directionsArrow.layer.anchorPoint = CGPointMake(0.5, 0.5);

        [directionsArrow.layer addAnimation:animation forKey:@"rotationCompass"];
        directionsArrow.transform = CGAffineTransformMakeRotation(newRadian);
}

最佳答案

double lon = location.longitude - otherLocation.longitude;
double y = sin(lon) * cos(otherLocation.latitude);
double x = cos(location.latitude) * sin(otherLocation.latitude) - sin(location.latitude) * cos(otherLocation.latitude) * cos(lon);
double angle = atan2(y, x);

角度是两个位置之间的轴承.

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