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Re: CABasicAnimation, CALayers, and rotation
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Re: CABasicAnimation, CALayers, and rotation


  • Subject: Re: CABasicAnimation, CALayers, and rotation
  • From: Graham Cox <email@hidden>
  • Date: Wed, 5 Nov 2008 11:42:07 +1100


On 5 Nov 2008, at 11:30 am, Michael A. Crawford wrote:

By default, positive angle values assigned to a rotation animation result in counter clockwise rotation. Is there a way to cause the rotation to occur in the clock-wise direction, with positive values? For example, consider a needle rotating in a compass. As the needle rotates in a clockwise direction the value that the needle points to increases (up until it wraps around, of course).

In mathematics, it is conventional that increasing angular values imply counter-clockwise rotation, because a standard coordinate system has its origin in the lower left corner, with the y axis extending upwards from there.


Can't you just negate the angular value? Multiply it by -1 for example.

There's no convention that I know of that says that "east" has a greater value than "north" - you might find that not insisting on that will make life easier.

hth, Graham
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