 |
Submitted by , posted on 30 May 2001
|
 |
Image Description, by
I started work on this raytracer project a while ago, but just recently
purchased 'Computer Graphics -Principles and Practice' - stonking good book
(if not slightly overwhelming!!) But I had heard that raytracers were easy
to program and looked nice, so I dove in. The book had the intersection
formulas for a couple primitives (plane+sphere+polygon) and so I coded those
in.
Lighting is just basic phong lighting (N dot D + specular) and in the big
purple picture you can see and example of a bug I was experiencing, in which
the negative values (Resulting from the phong equation) were creating a very
bright bump in the centre, which was odd, because I only had two lights!!
But I solved the problem, and the picture looked good, so I saved it.
Lights can have linear, quadratic, and constant attenuation...(although
wrong values of linear+quadratic attenuation cause wierd colors alongside
the border of the attenuation area)
Shadows are calculated using normal raytracing prodcedures (no shadow
volumes or maps, although I would like to use shadow maps for softer
shadows) The only interesting feature is a 'soft shadow sphere' feature,
which creates a group of lights with low intensities to fake area lights.
There is reflection- no refraction. (need more time to wrap my head around
it!) And support for basic surfaces, using perlin noise (which I am
currently doing very wrong... the noise is not band limited!) as well as a
checker function.
Looking at the POV- source has been very helpful, at least in terms of
structuring the program....
Output is just to RAW files, it also outputs a depth map channel, based on T
from the ray equation, I'm not sure if this is more, or less accurate for
making stereograms then basic Z-buffers. (can someone who knows tell me?)
Anyway, if you have any questions, just ask!
|
|