I need to calculate the angle between lines. I need to calculate atan. So I am using such code
static inline CGFloat angleBetweenLinesInRadians2(CGPoint line1Start, CGPoint line1End)
{
CGFloat dx = 0, dy = 0;
dx = line1End.x - line1Start.x;
dy = line1End.y - line1Start.y;
NSLog(@"\ndx = %f\ndy = %f", dx, dy);
CGFloat rads = fabs(atan2(dy, dx));
return rads;
}
But I can't get over 180 degrees(( After 179 deg going 178..160..150 and so on.
I need to rotate on 360 degrees. How can I do it? What's wrong?
maby this helps:
//Tells the receiver when one or more fingers associated with an event move within a view or window.
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
NSArray *Touches = [touches allObjects];
UITouch *first = [Touches objectAtIndex:0];
CGPoint b = [first previousLocationInView:[self imgView]]; //prewious position
CGPoint c = [first locationInView:[self imgView]]; //current position
CGFloat rad1 = angleBetweenLinesInRadians2(center, b); //first angel
CGFloat rad2 = angleBetweenLinesInRadians2(center, c); //second angel
CGFloat radAngle = fabs(rad2 - rad1); //angel between two lines
if (tempCount <= gradus)
{
[imgView setTransform: CGAffineTransformRotate([imgView transform], radAngle)];
tempCount += radAngle;
}
}
atan2
returns results in [-180,180] (or -pi, pi in radians). To get results from 0,360 use:
float radians = atan2(dy, dx);
if (radians < 0) {
radians += M_PI*2.0f;
}
It should be noted that it is typical to express rotations in [-pi,pi] and thusly you can just use the result of atan2
without worrying about the sign.
Remove the fabs
call and simply make it:
CGFloat rads = atan2(dy, dx);
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