To the best of my knowledge there is no built-in GL functionality to do just render any old scene in a spherical projection.  Something like an environment map is pre-computed as a bitmap before being textured.  You can render into a framebuffer (FBO), which GEM supports, and then apply corrective texturing to geometry.  You will need to upload a grid (newWave might work) and then use a vertex shader to apply the deforms to the vertices and texcoords. 

On 7/25/07, wolfgang schwarzenbrunner <schwarz@gen-control.com> wrote:
assuming that maybe no one read that thread as it was sent on weekend :)
(or is that question really that "not of interest"?) i send it again and
hope for some reaction.... sorry

as gemwin features things like stereoscopic display alternatives i was
wondering if it might be easy to implement something that distorts the
complete gemwin output in a polar coordinate system (for projecting in
domes and planetariums).

it might be not too hard to build something like that using snap2tex a
sphere and some adjustments in the texture coordinates. but somehow i
sense a strong smell that openGL might feature such things "directly"

two examples what i mean by "polar coordinte system" are attached

best
wolgang


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