Get angle from 2 positions

Question

I have 2 objects and when I move one, I want to get the angle from the other.

For example:

Object1X = 211.000000, Object1Y = 429.000000
Object2X = 24         


        

Answer 1

Does this other answer help?

How to map atan2() to degrees 0-360

I've written it like this:

- (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;
}

Running the code:

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

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

And this returns 45.

Hope this helps.