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On 13 Jan 2003 19:43:49 -0500, "Rafal 'Raf256' Maj" <raf### [at] raf256 com> wrote:
> oh and I forgot, Imho for shapes where calculations are *very* expensive
> (like isosurfaces) we whould use comples shapes to bound them, or even
> hierarchies
you can't ?
> isosurface is bounded with:
> ..a very complex mesh (10,000 faces[1])
> ..and this compelx mesh is bounded with simple mesh (100 faces)
> ..and simple mesh is finaly bounded by box
mesh over mesh? have you actually measured difference between rendering of
square builded from two trinagles and from thousend of triangles?
> [1] - this complex mesh can be builded automaticly
'builded automaticly' means probably tesselation process, are you aware how
good tesselation is complicated? some methods are even patended! tesselation
needs a lot of calculations, too.
> by trace funcion
using 'trace' function you can get points _on_ isosurface but bounding
requires surface _around_ isosurface. moreover 'trace' sends ray to get
intersection, so you probably will need more intersection tests with your
'optimization' than without.
ABX
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