Re: Inviting to comment on Cocoa categories
Re: Inviting to comment on Cocoa categories
- Subject: Re: Inviting to comment on Cocoa categories
- From: "Kyle Sluder" <email@hidden>
- Date: Mon, 10 Nov 2008 05:40:28 -0500
On Sun, Nov 9, 2008 at 10:58 PM, Michael Ash <email@hidden> wrote:
> Whoops, you're right. Still, NSAffineTransform can obviously do
> translations, so surely this objection does not make sense?
It's a gut reaction. Not being a linear algebra guru, I'm wondering
if it's done to avoid confusion; perhaps it's rather easy to create a
case in which a set of rotations and translations looks like it should
map one way but does another. If I remember correctly, matrix
multiplication does not distribute over matrix addition, and since a
transformation matrix stack is essentially a product of sums, the API
designers might, as you suggest, have simply left the functionality
out for the sake of clarity.
Interestingly enough, I can't recall seeing any graphics API that
provided rotation around a point. I know DirectX doesn't.
--Kyle Sluder
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