我需要计算两条线之间的夹角。我需要计算反正切函数atan。所以我使用以下代码:
```
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;
}
但是我无法旋转超过180度(在179度之后变成178、160、150等等)。
我需要360度旋转。该怎么做?有什么问题吗?
也许这可以帮助:
//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;
}
}
TWO_PI
。 - Ron Warholic