ray tracing is not the ONLY way to create realistic shadows and reflection effects
No, it\'s not the only way, but it\'s the most accurate, since it doesn\'t rely on tricks to fake the final effect (like reflection mapping does, in example), but instead calculates a more physically-correct light path.
Using refmapping to fake reflections or shadowmaps to have fast soft shadows are common things when dealing with prerendered imagery, specially in animation, when every per-frame rendering time reduction is welcome.
When accuracy is more important than speed, then you start using raytracing as a tool of choice. Don\'t think raytracing is limited to the classical shadow /reflection /refraction effects: it comes handy whenever you need to be able to take samples around your scene in a wider way (using in example different BRDFs) and you don\'t need to limit yourself only to the points you are directly projecting on screen. Correct blurred reflection, ambient occlusion, correct translucency are just examples.
There seems to be some confusion about the \'nothing uses curves\' sentence. Yes, the modeling software can use curves and surfaces instead of polygons: I am referring to the mathematical representation of your object if you are in example creating a nurbs model.
But for efficiency\'s sake this mathematical representation has to be later converted into something else in order to be represented on a screen: the method of choice usually consists in approximating it with a polygon mesh, which is tasselated more densely in accordance to how much you must get close to the theorical surface representation.
So bbum, yes, you are modeling your glass with a revolved nurbs surface, but what you see is just a mesh approximating your model (you\'re in maya, so hitting 1-2-3 will show you different degrees of approximation).
I will not say it\'s impossible to directly deal with surfaces during the rendering process: it\'s just less efficient at the end.
high-quality ray-tracers (for movies), like POV-RAY uses CSG - Composite Solid Geometry (I hope CSG is the abbrev. of this).
Ahem, sorry, but POV-RAY, with all the respect I have for a product that was the first renderer I had in my hands quite a few years ago, s not exactly a movie-quality raytracer. Main issue: efficiency. You just can\'t deal movie-quality frames with its speed and memory management. A better example of raytracer would have been Mental Ray, but it also tasselates surfaces at the end. Other famous renderers, like PRMAN, while offering superior-quality surface representation and displacement effects, just rely on a different tasselation method, called micropolygon tasselation (or dicing).
This is all for now.
b
