RE: [Algorithms] VIPM and UV texturing

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

Er... with the usual type of VIPM, you don't generate texture coords, or
indeed any new vertices,  at all. All you do is throw one point away and
collapse the edge onto the other one.

There are variants where you generate some sort of new "average" midpoint,
but (a) the quality improvement isn't very large and (b) it is quite a bit
less efficient to render, because for a given LoD, you have vertices that
are used by lower LoDs, but not the current one, which causes problems.

A related question is how to calculate texture coords (and other attributes)
when creating subdiv surfaces. I just use linear - seems to work OK with my
data, but others prefer to use other methods, such as use the subdiv surface
method, but on the attributes data. This gives excellent results BUT it is
possibly covered by a sneaky Pixar patent. It's still unclear exactly what
this patent covers (as with all patents, it's extremely vague), but there
may be some prior art that we can hide behind :-) In any case, simpler
methods such as Loop subdivision is often perfectly acceptable for
attributes, since perfect C1/G1 is not actually needed in most cases.

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

> -----Original Message-----
> From: Mark Wayland [mailto:mwa...@to...]
> Sent: 08 August 2000 00:58
> To: gda...@li...
> Subject: [Algorithms] VIPM and UV texturing
> 
> 
> Hey all,
> 
> For those of you who are using/experimenting with VIPM, how are you
> generating your texture coords when the mesh is reduced ?  Do 
> you all assume
> planar mapping or what ?
> Any info or discussion on this topic would be appreciated.
> 
> Thanks,
> 
> Mark