Re: rotating an object around the center of a view
Re: rotating an object around the center of a view
- Subject: Re: rotating an object around the center of a view
- From: Ken Tozier <email@hidden>
- Date: Sun, 4 Mar 2007 15:01:04 -0500
On Mar 4, 2007, at 2:59 PM, Erik Buck wrote:
Your solution seems workable but very strange to me.
Why rotate the "dial" instead of rotating the coordinate system in
which the dial is drawn ?
Because the clock face and all it's parts are rendered in the same
view. If I rotate the view coordinates, the whole clock rotates not
just the hands.
Why invert and then re-invert the simple translation matrix ? Do
you have some objection to the following ?
translateXBy: ox yBy: oy
rotateByDegrees: (timeInSeconds * -6.0f)
translateXBy: -ox yBy: -oy
Inverting the offset matrix does exactly the same thing without
having to manually plug in the positive and negative x, y offsets
before and after the rotate.
Ken
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