从2个位置获取角度

Question

我有2个物体,当我移动一个物体时,我想从另一个物体获得角度.

例如:

Object1X = 211.000000, Object1Y = 429.000000
Object2X = 246.500000, Object2Y = 441.500000

我在阳光下尝试过以下各种变化:

double radians = ccpAngle(Object1,Object2);
double degrees = ((radians * 180) / Pi); 

但我只是得到2.949023返回我想要45度等的东西.

Answer 1

这个其他答案有帮助吗？

如何将atan2()映射到0-360度

我写得像这样:

- (CGFloat) pointPairToBearingDegrees:(CGPoint)startingPoint secondPoint:(CGPoint) endingPoint
{
    CGPoint originPoint = CGPointMake(endingPoint.x - startingPoint.x, endingPoint.y - startingPoint.y); // get origin point to origin by subtracting end from start
    float bearingRadians = atan2f(originPoint.y, originPoint.x); // get bearing in radians
    float bearingDegrees = bearingRadians * (180.0 / M_PI); // convert to degrees
    bearingDegrees = (bearingDegrees > 0.0 ? bearingDegrees : (360.0 + bearingDegrees)); // correct discontinuity
    return bearingDegrees;
}

运行代码:

CGPoint p1 = CGPointMake(10, 10);
CGPoint p2 = CGPointMake(20,20);

CGFloat f = [self pointPairToBearingDegrees:p1 secondPoint:p2];

这将返回45.

希望这可以帮助.

Answer 2

我修改了@tomas的解决方案以简化.很可能(这对我来说)这个数学将被频繁调用.

在我的化身中,你必须自己执行两点之间的差异(或者如果你很幸运,(0,0)已经是你的一个点).计算的值是从(0,0)开始的点的方向.是的,这很简单,如果你真的想要,你可以内联它.我更喜欢更易读的代码.

我还将它转换为函数调用:

CGFloat CGPointToDegree(CGPoint point) {
  // Provides a directional bearing from (0,0) to the given point.
  // standard cartesian plain coords: X goes up, Y goes right
  // result returns degrees, -180 to 180 ish: 0 degrees = up, -90 = left, 90 = right
  CGFloat bearingRadians = atan2f(point.y, point.x);
  CGFloat bearingDegrees = bearingRadians * (180. / M_PI);
  return bearingDegrees;
}

如果您不想要负值,则需要自行转换.负值对我来说没问题 - 不需要进行不必要的计算.

我在cocos2d环境中使用它,这就是我所说的:(在数学上,我们正在平移平面以产生p0原点.因此p0从p1(p0- p0= {0,0})中减去.当平面是角度时,角度不变翻译.)

CGPoint p0 = self.position;
CGPoint p1 = other.position;
CGPoint pnormal = ccpSub(p1, p0);
CGFloat angle = CGPointToDegree(pnormal);

ccpSub 由cocos2d提供,它是一个元组的减法 - 你可以自己做,如果你没有那个

除此之外:使用CG___命名方案将上述方法命名为通常不礼貌的方式,该方案将函数标识为部分CoreGraphics- 因此,如果要将其重命名为MyConvertCGPointToBearing()或者FredLovesWilma()您应该这样做.

Answer 3

以下是我在Swift中为感兴趣的人做的事情,它是基于@bshirley上面的回答w /一些修改来帮助匹配calayer旋转系统:

extension CGPoint {
    func angle(to comparisonPoint: CGPoint) -> CGFloat {
        let originX = comparisonPoint.x - self.x
        let originY = comparisonPoint.y - self.y
        let bearingRadians = atan2f(Float(originY), Float(originX))
        var bearingDegrees = CGFloat(bearingRadians).degrees
        while bearingDegrees < 0 {
            bearingDegrees += 360
        }
        return bearingDegrees
    }
}

extension CGFloat {
    var degrees: CGFloat {
        return self * CGFloat(180.0 / M_PI)
    }
}

这提供了这样的坐标系:

        270
180              0
        90

用法:

point.angle(to: point2)
CGPoint.zero.angle(to: CGPoint(x: 0, y: 1)) // 90