RE: [Algorithms] Doing lighting on CLOD (ROAM) terrain

[Jon W. <hp...@mi...>]

I'm using GLspeak here, but you can translate to D3D if necessary:

You can use TexGen in NORMAL_MAP mode to get coordinates suitable for 
diffuse lighting, and REFLECTION_MAP mode to get coordinates suitable 
for specular; each texture coordinate output can then be collapsed to 
a 1D texture using the texture matrix, or it can point into a cube 
map texture that you orient appropriately.

Other ways to get the lighting into each vertex on a height field 
include calculating lighting and specify it as a vertex color, or to 
specify it as a 1D texture coordinate up-front; the former is 4 bytes 
per vertex; the lattr 2 bytes (SHORT texture coordinate assumed).

Last, you can just turn on lighting and let the card/driver deal with 
it.

I don't know why you'd need to re-calculate the light map when the 
camera/viewer is moving, though? Is the viewer an implicit light 
source? Else, you'd only need to re-calculate when the light is 
moving, which seems less intensive. The TexGen methods of course 
don't have problems with that, as you can orient the matrices once 
per frame (if you use EYE_SPACE texgen).

Cheers,

			/ h+


> -----Original Message-----
> From: gda...@li...
> [mailto:gda...@li...]On Behalf Of Phil
> Scadden
> Sent: Tuesday, February 26, 2002 12:35 PM
> To: gda...@li...
> Subject: [Algorithms] Doing lighting on CLOD (ROAM) terrain
> 
> 
> Running into a lighting issue with CLOD implimentation, putting a 
> 1D texture 
> over the terrain. How to do it? Calculating normals on patch is either 
> compute-intensive or memory intensive if caching. Calculating 
> lightmap when
> camera moving with the observer is similarly tricky. Ideas anyone??
> 
> 
> ----------------------------------------------------------
> Phil Scadden, Institute of Geological and Nuclear Sciences
> 41 Bell Rd South, PO Box 30368, Lower Hutt, New Zealand
> Ph +64 4 5704821, fax +64 4 5704603
> 
> 
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