CGAffineTransformMakeRotation goes the other way after 180 degrees (-3.14)
- by TheKillerDev
So,
i am trying to do a very simple disc rotation (2d), according to the user touch on it, just like a DJ or something.
It is working, but there is a problem, after certain amount of rotation, it starts going backwards, this amount is after 180 degrees or as i saw in while logging the angle, -3.14 (pi).
I was wondering, how can i achieve a infinite loop, i mean, the user can keep rotating and rotating to any side, just sliding his finger?
Also a second question is, is there any way to speed up the rotation?
Here is my code right now:
#import <UIKit/UIKit.h>
@interface Draggable : UIImageView {
CGPoint firstLoc;
UILabel * fred;
double angle;
}
@property (assign) CGPoint firstLoc;
@property (retain) UILabel * fred;
@end
@implementation Draggable
@synthesize fred, firstLoc;
- (id)initWithFrame:(CGRect)frame {
self = [super initWithFrame:frame];
angle = 0;
if (self) {
// Initialization code
}
return self;
}
-(void)handleObject:(NSSet *)touches
withEvent:(UIEvent *)event
isLast:(BOOL)lst
{
UITouch *touch =[[[event allTouches] allObjects] lastObject];
CGPoint curLoc = [touch locationInView:self];
float fromAngle = atan2( firstLoc.y-self.center.y,
firstLoc.x-self.center.x );
float toAngle = atan2( curLoc.y-(self.center.y+10),
curLoc.x-(self.center.x+10));
float newAngle = angle + (toAngle - fromAngle);
NSLog(@"%f",newAngle);
CGAffineTransform cgaRotate = CGAffineTransformMakeRotation(newAngle);
self.transform = cgaRotate;
if (lst)
angle = newAngle;
}
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
UITouch *touch =[[[event allTouches] allObjects] lastObject];
firstLoc = [touch locationInView:self];
};
-(void) touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
[self handleObject:touches withEvent:event isLast:NO];
};
-(void) touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
[self handleObject:touches withEvent:event isLast:YES];
}
@end
And in the ViewController:
UIImage *tmpImage = [UIImage imageNamed:@"theDisc.png"];
CGRect cellRectangle;
cellRectangle = CGRectMake(-1,self.view.frame.size.height,tmpImage.size.width ,tmpImage.size.height );
dragger = [[Draggable alloc] initWithFrame:cellRectangle];
[dragger setImage:tmpImage];
[dragger setUserInteractionEnabled:YES];
dragger.layer.anchorPoint = CGPointMake(.5,.5);
[self.view addSubview:dragger];
I am open to new/cleaner/more correct ways of doing this too.
Thanks in advance.
