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Submitted by , posted on 04 April 2002
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Image Description, by
I'm working on a realtime raytracer in my spare time
and have decided to release a demo (WIN32 platform)
and some images of what I'm doing.
The raytracer gets its main speed increase from
adaptive subsampling, i.e. I start by tracing the four
corners of a N*N rectangle and compare color values.
If the difference is too big, I subdivide the N*N into
four N/2*N/2 rectangles and process those recursively
and so on until I have reached pixel accuracy or the
color differences have become too small to matter, in
which case I let OpenGL draw the rectangle using
interpolation. Texturemapping is done by the raytacer,
not OpenGL.
The demo uses an initial rectangle size of 4*4 for the
tracing since I want to show thin cylinders (casting
thin shadows too) that sometimes will take up less
than 4 pixels wide and risk flickering if I take a
larger initial blockwidth. The demo runs fine in
320x240 on my PIII 900.
The top four images are stills from scenes in the
demo, the bottom left is another scene and the bottom
right is the same as the bottom left but showing only
those pixels that are actually traced (shown as full
white pixels here). All the black in that picture is
where interpolated pixels go in the real picture.
You can find more pictures, a download and a full
explanation of the engine at:
http://home.tiscali.be/slinline/trezebees.html
Cheers,
Nils Desle
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