RE: [Algorithms] Terrain performance comparisons

[Tom F. <tom...@bl...>]

>   -- progressive vertex arrays are way cool as replacements for
>      ROAM "triangles".  I'm getting 100M tri/sec with PVAs as the
>      primitives in my latest experimental ROAM-like renderer with
>      sliding progression on a radeon 9700 pro.

If anyone can hear me over the noise :-), I'd love to hear the gritty
details of this.

TomF

> -----Original Message-----
> From: gda...@li... 
> [mailto:gda...@li...] On 
> Behalf Of Mark Duchaineau
> Sent: 26 July 2003 01:07
> To: gda...@li...
> Subject: Re: [Algorithms] Terrain performance comparisons
> 
> 
> I will toss in one message to the terrain opinion fest:
> 
>   -- Jonathan's idea about coherence-exploitation leading to
>      a cycle of death completely forgets the idea of
>      "split-merge until time's up" that was in the original
>      ROAM paper.
> 
>   -- if you want 60Hz absolutely solid, the ONLY known method
>      (that scales to big terrain and has any claims of
>      accuracy) is ROAM-like systems with the "time's up" option,
>      as far as I know (any other contenders?).  I don't count
>      "threshhold feedback" schemes -- they are not guaranteed
>      solid (without, ehem, guarantees of frame coherence!).
> 
>   -- Chunking is critical to eliminating CPU work.  Latest ROAM's
>      spend all their time creating fractal detail, not doing
>      CLOD "thinking".
> 
>   -- Chunking can be dynamic.  The linux ROAM 2 work in progress
>      produces detail on the fly, and presumably could re-produce
>      it as needed if you change the terrain.  Of course tossing
>      something like ocean waves into a terrain engine will be a
>      little awkward...but the computation of the waves will likely
>      dominate the CPU anyway (do it on the GPU???).  You still
>      need chunk CLOD for a big ocean.  BTW, is "chunk CLOD"
>      and oxymoron? ;-)
> 
>   -- progressive vertex arrays are way cool as replacements for
>      ROAM "triangles".  I'm getting 100M tri/sec with PVAs as the
>      primitives in my latest experimental ROAM-like renderer with
>      sliding progression on a radeon 9700 pro.
> 
>   -- split-merge dual queues and PVAs are great for very wacky
>      geometry, e.g. isosurfaces of 3D fully developed turbulent
>      fluid flow.  Maybe you can toss your whole game world into
>      a 3D hierarchy (think tetrahedron bintree) with PVAs per tet.
>      That's where I'm headed...
> 
> Cheers,
> 
> --Mark D