On Aug 31, 2010, at 3:43 PM, Kenneth Russell wrote: > On Tue, Aug 31, 2010 at 3:39 PM, Chris Marrin <cmar...@apple.com> wrote: >> >> On Aug 31, 2010, at 3:25 PM, Maciej Stachowiak wrote: >> >>> >>> On Aug 31, 2010, at 2:06 PM, Chris Marrin wrote: >>> >>>> >>>> On Aug 31, 2010, at 11:48 AM, Kenneth Russell wrote: >>>> >>>>> On Tue, Aug 31, 2010 at 11:05 AM, David Hyatt <hy...@apple.com> wrote: >>>>>> On Aug 31, 2010, at 10:36 AM, Chris Marrin wrote: >>>>>> >>>>>>> Or should we get rid of Vector3, added the functionality it needs to >>>>>>> FloatPoint3D and use that? Ken Russell already has plans to do add the >>>>>>> functions to FloatPoint3D, so I would vote for that. >>>>>> >>>>>> I would vote for this. I don't think the geometry classes should move >>>>>> to wtf. >>>>> >>>>> I'd like to unify the math, geometry, and linear algebra classes that >>>>> are scattered around the WebKit tree -- for example, FloatPoint, >>>>> FloatPoint3D, FloatRect, FloatSize, the classes under >>>>> WebCore/platform/graphics/transforms/, these Complex and Vector3 >>>>> types, ... -- under a directory like WebCore/math, remove duplicate >>>>> functionality, and provide a cohesive set of interfaces that can be >>>>> easily used by other modules like graphics and audio. >>>> >>>> It would be nice if we could do this unification and then later on we can >>>> enhance it so the classes play nice together. For instance, >>>> TransformationMatrix deals with many, but not all of the other geometric >>>> classes. You can't cast between FloatPoint and FloatPoint3D, etc. Maybe we >>>> could also use this opportunity to change TransformationMatrix to Matrix. >>>> The current name is such a mouthful. And we might also want to think about >>>> changing FloatPoint3D to FloatPoint3. That would make it more natural if >>>> and when we want to add a FloatPoint4. We should also change >>>> AffineTransform to AffineMatrix so it matches Matrix. >>> >>> Mathematically, you can have an affine transform, or a matrix that >>> represents an affine transform. And there's such a thing as an affine space >>> (in fact IntPoint and IntSize form an affine space). But there's no such >>> thing as an affine matrix. >> >> Sure there is. It's a matrix that performs affine transformations. >> Mathematically it's represented as a 3x3 matrix, but like others, we just >> represent it as a linear transformation matrix (2x2) plus a 2D translation >> value. I think the name AffineMatrix is descriptive because, unlike a >> general 3x3 matrix, our truncated representation can only handle affine >> transformations. > > Chris, based on the precision of Maciej's reply, I suspect you do not > want to get into a semantic argument here... :) > > http://www.google.com/search?q=affine+matrix
Oh, Ken, I'll argue about anything, you know that :-) Yes, I did the Google search and you're right that the term is not in common usage (although I still maintain it's a completely reasonable term). The reason I think it's meaningful is because it really is a matrix of sorts, but a specialized one that handles only affine transformations. We could call it AffineTransform, but then why not call our 4x4 matrix HomogeneousTransform? I'd just like to be consistent. ----- ~Chris cmar...@apple.com _______________________________________________ webkit-dev mailing list webkit-dev@lists.webkit.org http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev
