Angus Dorbie (dorbie++at++bitch.reading.sgi.com)
Thu, 6 Mar 1997 22:03:18 +0000
those who want to try something beyond simple planar
reflective surfaces read on.
I've just uploaded a performer based example of realistic
environment mapping of the scene on an object to the silicon
graphics machine "sgigate". So you can obtain it using
anonymous ftp. You'll find it here:
/usr/people/ftp/pub/Performer/RealityCentre/env_map.tar.Z
The approach is to render the entire scene to the six faces
of a cube map in the framebuffer. This image data is then read
into texture memory and a distortion mesh is drawn which maps
the cube texture to an environment map image in the framebuffer.
This environment map image is then read into texture memory and
used when rendering with pfTexGen SPHEREMAP to produce an
accurately reflective object in the final scene, provided that
the original images were drawn from the object position and
aligned to the viewing vector.
In the example this environment map is is used to add a reflective
shading term to a textured object, rather than doing the usual chrome
shiny thing.
This demo only works on Infinite Reality with performer 2.1 due to broken
texture readback from the framebuffer but I expect performer 2.2
release to solve this problem. The code should then work on most
platforms.
Cheers,Angus.
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