Re: More on: OGL View Matrix --> pfChan view matrix

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Angus Dorbie (dorbie++at++sgi.com)
Fri, 12 Jun 1998 13:36:29 -0700

Angus Dorbie wrote:
>
> More on model matrix inversion to viewing matrix.
>
> If anyone out there is curious about why transposing the
> model matrix worked instead of inverting the viewing matrix
> on the earlier thread (I got some questions) it's because
> they are equivalent operations for an orthogonal (I think
> that's the term) matrix.
>
> Note that the purpose was not to switch the row-column
> order due to some difference between the matrix storage
> in Performer & OpenGL, the purpose was to invert the
> matrix to switch from viewing matrix (which OpenGL modelview
> matrix stack uses) to modelling matrix which a Performer
> channel to use.

Looks like this is wrong, you should have to invert the matrix.
Transpose will work for rotations but not translations so
inverting is safer, transposing the matrix _shouldn't_ work.

>
> Thanks to Don Hatch for clearing this up.
>
> Cheers,Angus.

-- 
"Only the mediocre are always at their best." -- Jean Giraudoux 


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