RE: [Algorithms] VIPM With T&L - what about roam

[Tom F. <to...@mu...>]

> From: Mark Duchaineau [mailto:duc...@ll...]

[snip]

> b) I don't see why you want to use per-vert lighting with
> geometry LOD.  In my experience this gives horrible
> artifacts.  Again the technology trend is to get enough
> processing power post texture lookup to allow all the lighting
> effects to happen there with no lighting control needed at
> all at the verts.  Right now you can get a complete
> dynamic lighting environment (i.e. equivalent to an
> infinite number of light sources on an infinite sphere)
> for diffuse-only shading using a color and normal
> texture with cube environment maps and multitextures.
> With a second cube lookup after the first you can get
> specular for the infinite number of light sources (right now
> no hardware that I know of allows this second lookup
> on the results of the first--paletted textures are a
> total hack as a substitute). You would need some
> blending to approximate local lighting as you
> move from one region of geometry to the next,
> but I think that could work fairly well.  I just don't see
> why the L in T&L is at all useful in the long run.  Another
> nice thing about putting all your lighting data in the
> textures is that you don't have to send it over the
> saturated AGP bus.

Ideally, you want a texture-based lighting approach, but with the hard work
done by the graphics card, not the CPU. I use bumpmapping (of any of the
three types), for exactly the reasons you state - it pops far less - but
ideally I'd want to pass the normal vector (or some analagous info) into the
card and have it compute the necessary UV offsets, etc. So there is still
some sort of shading info that needs sending to the card, which is all we
care about for bandwidth calculations.

> Still, I think the idea is great: getting really fast updates
> as you slide from low- to high-res and back in a chunk
> for progressive streams, with a handful of cheap index
> tweeks that are write-only ops.  I will add that to my
> bag of tricks...

A convert! :-)

> --Mark D.

Tom Forsyth - Muckyfoot bloke.
Whizzing and pasting and pooting through the day.