Re: API for matrix manipulation

Hi,

related to this:  Is there any work ongoing to tie these (or more generic
vector / matrix) classes to OpenCL / WebCL for faster computation across
CPUs and GPUs?

- Lars

On Mon, Mar 14, 2011 at 5:17 PM, Chris Marrin <cmarrin@apple.com> wrote:

>
> On Mar 14, 2011, at 7:56 AM, João Eiras wrote:
>
> Hi.
>
> Given that a number of API are being developed that require complex
> matricial calculations (transforms, device orientation, web gl), I
> would suggest that perhaps an API with a big number of common
> calculations could be made available ? And a proper way to represent
> them. Perhaps, the best way to add this would be to extend the Math
> object with things like.
>
> Math.mAdd(m1, m2)
> Math.mSub(m1, m2)
> Math.mMult(m1, m2)
> Math.mDiv(m1, m2)
> Math.mInverse(m1)
> Math.mGaussianReduce(m1)
> Math.mRank(m1)
> Math.mRank(m1)
>
> Being the matrix an array like object like (could even be one of those
> fast arrays like ArrayBuffer).
>
> # {
> #  w: <width>,
> #  h: <height>,
> #  length: <width * heigth>
> #  0: ...,
> #  1: ...,
> #  2: ...
> #  (...)
> # }
>
> Comments or is something already being worked on ?
>
>
> There are already 2 such classes: SVGMatrix and CSSMatrix. The former is an
> affine transformation matrix (commonly misnamed a "2x3 matrix") and the
> latter is a 3D homogeneous transformation matrix (commonly correctly named a
> "4x4 matrix").
>
> We added CSSMatrix to the CSS Transform Spec to give us the same
> functionality as SVG Matrix, but for 3D transforms. Therefore both of these
> classes are pretty light on their operators. It might be useful to discuss
> "one matrix to rule them all", which could be used in place of the current
> classes and with more functionality. But it's important not to go too far
> down this path, or you'll end up defining classes for Points, Lines, Planes,
> Bounding Boxes and View Volumes with dozens of functions. Down that path
> lies madness.
>
> I think the current spec handles the more complex (inverse and multiply)
> and more commonly used (scale, rotate, translate) functions. I'm not sure
> what adding and subtracting 2 matrices means, and division is handled by
> inverse and multiply. The others seem pretty domain specific for a general
> class. And remember you can (and many people have) created JS libraries to
> add funcrtions to the built-in matrix classes. I wrote one:
>
>
> https://cvs.khronos.org/svn/repos/registry/trunk/public/webgl/sdk/demos/webkit/resources/J3DIMath.js
>
> which uses CSSMatrix if it exists and uses JS otherwise. It exposed some
> interesting deficiencies in the current CSSMatrix class. There are several
> bugs on WebKit to address these and other issues of matrix efficiency and
> functionality: 23799 <https://bugs.webkit.org/show_bug.cgi?id=23799>,
> 28850 <https://bugs.webkit.org/show_bug.cgi?id=28850>, 50633<https://bugs.webkit.org/show_bug.cgi?id=50633>
> , 52488 <https://bugs.webkit.org/show_bug.cgi?id=52488>. Perhaps it would
> be useful to open these (or similar) bugs on the w3c bug system?
>
> That's where I believe we are on the Matrix front.
>
> -----
> ~Chris
> cmarrin@apple.com
>
>
>
>
>