scott wrote:

> The lighting model implemented in POV is about the simplest available, 
> what was first used on 3D cards 10 years ago.  Today there are far more 
> accurate models used, you must have heard names like Cook-Torrence, 
> Blinn etc, if you've never looked outside of POV you wouldn't know they 
> existed.

That would explain how... I didn't know they existed. :-D

So, what exactly do these correctly predict that POV-Ray currently doesn't?

(BTW, POV-Ray offers several kinds of scattering media, but I can never 
seem to tell the difference between them. Is that normal?)

> They start to model the microfacets on a surface and produce 
> lighting results based on the geometry and physics of the microfacets 
> (eg occlusion, self-shadowing etc).

So how does that affect the end visual result? Are we talking about a 
big difference or a subtle one?

> Then there's anisotropic materials 
> like brushed metal, where the properties are different depending on 
> which direction the light is coming from.

How about something that can do metalic paint? That would be nice...

> AFAIK POV already uses some clever techniques for speeding up tracing 
> complex scenes (try adding 100000 spheres to your ray tracer and compare 
> the speed with POV...).  But there are plenty more new techniques out 
> there that are certainly worth investigating, some of them quite recent.

LOL! I think POV-Ray probably beats the crap out of my ray tracer with 
just 1 sphere. ;-) But hell yeah, faster == better!

> NURBS are not isosurfaces though.

Oh. Wait, you mean they're parametric surfaces then?

> What the nVidia demo does is to 
> generate the triangle mesh on the fly from the isosurface formula.  So 
> when you zoom in, it can create more detail over a small area, and when 
> you zoom out it doesn't need so much detail, but of course it needs it 
> over a bigger area. It gives the impression that there *are* billions of 
> triangles, but in reality it only draws the ones that you can see, small 
> enough that you can't tell they are triangles.  Clever eh?

Does it add more triangles to the areas of greatest curvature and fewer 
to the flat areas?

Even so, I would think that something like heavily textured rock would 
take an absurd number of triangles to capture every tiny crevice. And 
how do you avoid visible discontinuities as the LoD changes? And...

> Same way as 
> you can drive for an hour around the island on "Test Drive Unlimited", 
> seeing billions of triangles, but of course it doesn't try to draw them 
> (or even have them in RAM) all at once.

I often look at a game like HL and wonder how it's even possible. I 
mean, you walk through the map for, like, 20 minutes before you get to 
the other end. The total polygon count must be spine-tinglingly huge. 
And yet, even on a machine with only a few MB of RAM, it works. How can 
it store so much data at once? (Sure, on a more modern game, much of the 
detail is probably generated on the fly. But even so, maps are *big*...)

>> Mmm, OK. Well my graphics card is only a GeForce 7800 GTX, so I had 
>> assumed it would be too under-powered to play it at much about 0.02 FPS.
> 
> Nah, on low detail it should certainly be playable.

Mmm, OK.

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