[Fluxus] set projection transform

[gabor papp]

Scott wrote:
> Which reminds me, I added:
>     (define/override (on-size width height)
>       (with-gl-context
>        (lambda ()
>          (fluxus-reshape-callback width height)
>      (set-fov last-fovy last-near last-far)    ;; reset FOV for new window
> size
>      )))
> 
> to my drflux (which now correctly supports resizing the window correctly) -
> can' t remember if this got into master.
i don't think so, although it looks quite useful. shouldn't we put 
set-fov into master also?

> Otherwise - I don't think we have a way to set the projection xfm directly,
> so that would be cool and support some off-axis frustums.
i quickly added a (set-projection-transform) function. it's not properly 
tested yet, althought there is one thing to note: 
(get-projection-transform) gets the projection matrix from opengl, and 
(set-projection-transform) only works during the next rendering phase. 
so if you set the transform, you can get the matrix only in the next frame.

best,
gabor