Re: polygon normals and spherical co-ordinate systems

tektoy <no@xxxxxxxxxxxx> writes:

> Just wondering why while most math books / courses (and internet math
> sites) seem to give the obligatory references to polar, spherical as
> well as cartesian co-ordinate systems.
>
> But when I get to computer graphics texts or usage it seems to me
> vector normals are the norm and polar/ spherical usage is rare or
> simply never mentioned.
>
> Yet it seems to my (admittedly limited) understanding that for some
> applications, ie a simple 3d object viewing, where all we ever do is
> rotate a model, describing polygon normals with a spherical system
> would mean that things like rotation, back face culling and shading
> would be quicker and easier to do, than doing the same using vector
> math.
>
> Am I missing something important here?, or is spherical co-ordinate
> usage simply come to (mathmaticly speaking) an evolutionary dead end?
>
>
> Regards.
>

Others have pointed out some of the difficulties in using spherical
coordinates for transformations. But they are a very useful way of
looking at light transfer issues in ray tracing and radiosity-like
calculations.

--
-Stephen H. Westin
Any information or opinions in this message are mine: they do not
represent the position of Cornell University or any of its sponsors.
.

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