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ToolTech
01-29-2002, 08:15 AM
Has anybody seen any method in any extension that could draw a mesh using z values from a texture (Luminance or depth) and (x,y) values ranging from (-1,-1) to (1,1)

This could be extremely usefull in landscape presentation and shadow volume generation...

Any vendor interested in creating this ?? Please contact me in such case...

/Anders

zed
01-29-2002, 12:45 PM
sort of like displacement mapping?
whats this i read about opengl2.0 maybe not having some sort of tesselation program this IMHO is vital

MikeC
01-30-2002, 02:14 PM
Yes, this would be a (restrictive) form of displacement mapping.

I don't think it's 100% set in stone yet as to whether 2.0 will include tesselation - even if it doesn't, I suspect it'll come fairly soon after.

Displacement mapping isn't in the same ballpark as evaluators, pn_triangles etc though - it's a very different beast, and I'm not optimistic about seeing it anytime soon. Look at the logical diagram of the GL2 pipeline; like GL1.x and D3D, there's absolutely no data path from texture memory into the vertex processor. It might be possible on particular architectures, but it's so far from the core GL2 model that I don't see it getting into an ARB spec.

ToolTech
01-31-2002, 12:54 AM
But even if there are no direct pipeline between texel data and vertex data, the dat is still located in Graphics memory so it would be possible to do a fast patch creation on the GPU HW without going to PC mem ?

I would like to create a shadow depth map and contain it in the GPU mem and let the GPU create the patch according to a scan line converion algo. This way I would get a very fast creation of shadow volumes.....

Now I have to get the image back to PC mem and do the scan convertion in the PC and then push it back using VARs.. The glreadPixel is so slow...