[openvrml-develop] Re: VrmlMatrix

[Braden M. <br...@en...>]

[Starting a new thread since this has nothing to do with Peter Meier's
problem.]

On Tue, 2001-10-09 at 16:47, S.K.Bose wrote:
> In the process of adding VrmlMatrix class (having 4X4 elements in
> row-major order), I had some discussion with Braden about interface
> issues. I am having opinion to have overloading operators "*" and "*=" to
> do multiplication of two matrices. I know multiplication of two matrices
> is not commutative (A*B != B*A). But if I write "A*B" --- it means I want
> to do multiplication from "left to right" (B is post multiplied with A)
> not from "right to left". Is there any scope of ambiguity exist by having
> such operators in VrmlMatrix class?

In general, class interfaces should not provide multiple means of doing
the exact same thing. The methods MMleft() and MMright() provide the
necessary functionality; and I prefer this approach as it is consistent
with the ECMAScript VrmlMatrix definition. (In general, I think we
should match method names with the ECMAScript definition, where our
VrmlMatrix does the same thing.)

Some other issues:

        * The constructor that takes a float[4][4] should be made
          explicit. I don't think automatic conversions from that type
          are desirable.
        * By the same token, I think the cast operators to float* and 
          Matrix& should be dropped. Someone who wants a pointer to the
          first element can get it easily enough using
        float * f = &myVrmlMatrix[0];
        * operator[] should return a float (&)[4]. This maintains static
          type checking of the array size.
        * Rather than have the static method identity(), why not just
          have the default constructor create an identity matrix?

-- 
Braden McDaniel                           e-mail: <br...@en...>
<http://endoframe.com>                    Jabber: <br...@ja...>