Angle between two lines is wrong

Question

I want to get angles between two line. So I used this code.

---

int posX = (ScreenWidth) >> 1;

int posY = (ScreenHeight) >> 1;

double radians, de         


        

Answer 1

If you have 3 points and want to calculate an angle between them here is a quick and correct way of calculating the right angle value:

double AngleBetweenThreePoints(CGPoint pointA, CGPoint pointB, CGPoint pointC)
{
    CGFloat a = pointB.x - pointA.x;
    CGFloat b = pointB.y - pointA.y;
    CGFloat c = pointB.x - pointC.x;
    CGFloat d = pointB.y - pointC.y;

    CGFloat atanA = atan2(a, b);
    CGFloat atanB = atan2(c, d);

    return atanB - atanA;
} 

This will work for you if you specify point on one of the lines, intersection point and point on the other line.