CGAffineTransformMakeRotation not working well

Question

I have a game where you have "specks" and "connectors".

I make a UIImageView that connects two "specks"… but as you can see (if the picture works), when the specks are almost on top of each other, like on the left, it doesn't work. This is my code… and I was wondering how you would make the rotation more accurate in that sort of situation.

UIImageView *connector = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"RedConnector.png"]];
        connector.contentMode = UIViewContentModeScaleToFill;
        connector.hidden = NO;
        connector.alpha = 1;

        connector.frame = CGRectMake(0, 0, [self DistanceBetweenPoints:speck1.center :speck2.center], 7);
        connector.center = CGPointMake((speck1.center.x + speck2.center.x)/2, (speck1.center.y + speck2.center.y)/2);
//This is where the prob is:
        connector.transform = CGAffineTransformMakeRotation(tanh((speck2.center.y - speck1.center.y)/(speck2.center.x - speck1.center.x)) );
        [Connectors addObject:connector];
        [self.view addSubview:connector];

"DistanceBetweenPoints" is not the problem. That works fine. Also, I know the center AND the frame is sort of redundant-- I'll work that out later. Third of all, I have made sure that two specks are never directly on top of each other (to never divide by zero). Last of all, I STILL WANT THESE TO BE UIIMAGEVIEWS!! So I can change the image and animate them so it looks like electricity flowing from speck to speck.

If anybody could show me how to make the rotation more accurate, it would be greatly appreciated. Thanks!

Answer 1

You should use atan2(y,x), not tanh(y/x). That is, you want the arctangent, not the hyperbolic tangent.