[sldev] Re: [VWR] Real-time Raytracing

[Boroondas Gupte]

Lawson English schrieb:
> How compatible would the already-built SL content be for a ray-traced
> based viewer?
The 'content' being based on prims that can probably easily be described
by parametric surfaces, it would be very compatible, I'd say.
> Would everything have to be pre-converted,
At the moment everything has to be converted to triangles. With ray
tracing you'd actually save that pre-conversion step.
> converted-on-the-fly,
This could be done for the ground, for sculpties and other yet-to-come
free-form or free-form-like surfaces. The already mentioned Phillipp
Slusallek et al. describe this here:

Carsten Benthin, Ingo Wald, and Philipp Slusallek, Interactive Ray
Tracing of Free-Form Surfaces
<http://graphics.cs.uni-sb.de/Publications/2004/FreeFormRT_Afrigraph2004.pdf>,
Proceedings of Afrigraph 2004, Stellenbosch (Cape Town), South Africa,
November 3-5, 2004
(from http://graphics.cs.uni-sb.de/~slusallek/publications.html)
> or do existing ray-tracing algorithms handle OpenGL geometry already? 
OpenGL geometry is based on triangles (if we only consider surfaces, not
lines and points which are also supported). There are triangle based
ray-tracing algorithms and in fact the very first *real time*
ray-tracers operated on triangles only.

But in almost all cases where you've got some simpler geometric
description of an object than its mash you'd want to use that simpler
description directly for rendering to achieve higher image quality while
having to cache (or even generate) less data. Problem is, those 'simpler
descriptions' (parametric equations, mostly) might be more expensive to
intersect with a ray than plain triangles, but for "good" shapes like
spheres and cubes it shouldn't make a too big difference.

I'm really looking forward to have hardware accelerated ray-tracing
support on mass market computers. Might take quite some time till
that'll happen, though.

Boroondas
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