Re: Interactive animation

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Jim Helman (jimh++at++surreal)
Wed, 20 Jul 94 15:21:29 -0700

You can do real-time vertex interpolation in Performer 1.2 using
draw callbacks. For better performance, you could move the
interpolation computations to the APP process or to another
asynchronous process by multibuffering the geometry yourself, e.g.
switch between 3 copies of the geometry under a pfSwitch node.
This is how the lake demo handles moving water. Since the vertex
arrays in pfGeoSets are exposed, there's no problem handling
dynamic geometry at full speed. But it does take a bit of coding.

Geometric morphing (linear combination of multiple sources) is not
only common in standard animation packages (e.g. Wavefront's
Kinemation), it's also very useful for making smooth level-of-
detail transitions. And, as the production houses doing character
animation (e.g. MediaLab Paris, Colossal Pictures, etc.) have
found, morphing complex characters in real-time really sucks up a
lot of floating point CPU cycles, so such applications are perfect
candidates for a multiprocessor Onyx with Performer.

So, we know it's important for Performer to handle this
transparently and to have ways of importing morph animation data
from packages which support it. But we're not sure what
mechanisms to support. Our SIGGRAPH '94 paper mentions a simple
prototype implementation of morphing. Anyone having an opinion
on whether we should support a particular package's notion of
animation can send me email with suggestions.

rgds,

-jim helman

jimh++at++surreal.asd.sgi.com
415/390-1151

  From: "John Forster" <john_f++at++manserv.manchester.sgi.com>
  Date: Wed, 20 Jul 1994 13:35:32 +0100
  To: info-performer++at++sgi.sgi.com
  Subject: Interactive animation
   
          Is there anything in Performer, now or planned, which will help
          key frame animation sequences for models to be loaded from traditional
          animation packages and provided realtime interpolation between the
          keyframes initiated by user input ? If not, broadly speaking what
          approach would be recomended to achieve this realtime vertex
          interpolation in the performer environment ?
   
   
                  Regards
   
                          JOhnF
   

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