Objective c 使用iosapi获取从北向的角度

以下是我想要的：

我知道O点和X点的坐标。是否有可能使用iOS方法找到V角（从北向的角度）？

是的

#import <math.h>

float a = -1 * atan2(y1 - y0, x1 - x0);
if (a >= 0) {
    a += M_PI / 2;
} else if (a < 0 && a >= -M_PI / 2) {
    a += M_PI / 2;
} else {
    a += 2 * M_PI + M_PI / 2;
}
if (a > 2 * M_PI) a -= 2 * M_PI;

#导入
浮点数a=-1*atan2（y1-y0，x1-x0）；
如果（a>=0）{
a+=M_PI/2；
}否则如果（a<0&&a>=-M\u PI/2）{
a+=M_PI/2；
}否则{
a+=2*M_-PI+M_-PI/2；
}
如果（a>2*M_-PI）a-=2*M_-PI；

现在

a

将包含以弧度为单位的角度，间隔

0…2 PI

甚至不需要任何特定于iOS的API。请记住：iOS仍然具有libc的所有功能。

是的

#import <math.h>

float a = -1 * atan2(y1 - y0, x1 - x0);
if (a >= 0) {
    a += M_PI / 2;
} else if (a < 0 && a >= -M_PI / 2) {
    a += M_PI / 2;
} else {
    a += 2 * M_PI + M_PI / 2;
}
if (a > 2 * M_PI) a -= 2 * M_PI;

#导入
浮点数a=-1*atan2（y1-y0，x1-x0）；
如果（a>=0）{
a+=M_PI/2；
}否则如果（a<0&&a>=-M\u PI/2）{
a+=M_PI/2；
}否则{
a+=2*M_-PI+M_-PI/2；
}
如果（a>2*M_-PI）a-=2*M_-PI；

现在

a

将包含以弧度为单位的角度，间隔

0…2 PI

---

甚至不需要任何特定于iOS的API。请记住：iOS仍然具有libc的所有功能。

不确定user529758的回答是否解决了这个问题，我认为这是关于将东方的0度改为北方的0度。下面的代码工作-关键线是第四条线，从东向北变化0度

-(CGFloat) bearingFromNorthBetweenStartPoint: (CGPoint)startPoint andEndPoint:(CGPoint) endPoint {

// get origin point of the Vector
CGPoint origin = CGPointMake(endPoint.x - startPoint.x, endPoint.y - startPoint.y);

// get bearing in radians
CGFloat bearingInRadians = atan2f(origin.y, origin.x);

// convert to bearing in radians to degrees
CGFloat bearingInDegrees = bearingInRadians * (180.0 / M_PI);

// convert the bearing so that it takes from North as 0 / 360 degrees, rather than from East as 0 degrees
bearingInDegrees = 90 + bearingInDegrees;

// debug comments:
if (bearingInDegrees >= 0)
{
    NSLog(@"Bearing >=0 in Degrees %.1f degrees", bearingInDegrees );
}

else
{
    bearingInDegrees = 360 + bearingInDegrees;
    NSLog(@"Bearing in Degrees %.1f degrees", bearingInDegrees );
}

return bearingInDegrees;

}

---

不确定user529758的答案是否解决了这个问题，我认为这个问题是关于将东方的角度改为0度，将北方的角度改为0度。下面的代码工作-关键线是第四条线，从东向北变化0度

-(CGFloat) bearingFromNorthBetweenStartPoint: (CGPoint)startPoint andEndPoint:(CGPoint) endPoint {

// get origin point of the Vector
CGPoint origin = CGPointMake(endPoint.x - startPoint.x, endPoint.y - startPoint.y);

// get bearing in radians
CGFloat bearingInRadians = atan2f(origin.y, origin.x);

// convert to bearing in radians to degrees
CGFloat bearingInDegrees = bearingInRadians * (180.0 / M_PI);

// convert the bearing so that it takes from North as 0 / 360 degrees, rather than from East as 0 degrees
bearingInDegrees = 90 + bearingInDegrees;

// debug comments:
if (bearingInDegrees >= 0)
{
    NSLog(@"Bearing >=0 in Degrees %.1f degrees", bearingInDegrees );
}

else
{
    bearingInDegrees = 360 + bearingInDegrees;
    NSLog(@"Bearing in Degrees %.1f degrees", bearingInDegrees );
}

return bearingInDegrees;

}

---

@VladBogdan事实上我花了45分钟才弄明白如何正确地做。你要求坐标旋转-PI/2…，这并没有让我的生活更轻松：D@VladBogdan事实上，我花了45分钟才弄明白如何正确地做这件事。你要求坐标旋转-PI/2…，这并没有让我的生活更轻松：D