Jean-Luc Dery (dery++at++Discreet.COM)
Tue, 21 Apr 1998 17:01:30 -0400
We are having problems with the way the channel viewpoint is being updated. Our
channel viewpoint steps every time the channel frame rate drops from 60Hz to
30Hz due to scene complexity. This happens only during the transitions. We are
quite sure that the problem comes from the way the channel viewpoint is managed
within our Performer based application since when frame rate is stable (30Hz or
60Hz), the viewpoint movements are perfectly fluid. The problem occurs only
when the frame rate changes. The value used for the viewpoint setting is
computed and updated in a parallele process which always runs at 60Hz.
Is the channel viewpoint set in the APP from pfChannel API frame conherent in
the 3 stage APP CULL DRAW pipeline? I would suspect so since the pfChannel is a
libpf object.
When the frame rate drops at frame 5 (D3) in the phase lock mode
frame 1 2 3 4 5 6 7
APP A1 | A2 | A3 | A4 | A5 | A6 | A7
CULL | C1 | C2 | C3 | C4 | C5 | C6
DRAW | | D1 | D2 | D3.|. | D5
Is the viewpoint used to draw at frame 7 (D5) really set from A5 ?
How can we guaranty channel viewpoint fluid movement, or what could we be doing
wrong that could cause the stepping in our application. Is there a need to
interpolate viewpoint when frame rate changes.
Thanks in advance for any help,
Jean-Luc
-- _____________________________________________________________________________Jean-Luc Dery Discreet Logic System Engineer 10 Duke Street 3-D Graphics Technology Montreal (Quebec), Canada, H3C 2L7 Tel: (514) 954-7239 Email: jean-lucD++at++discreet.com Fax: (514) 393-0110 _____________________________________________________________________________ ======================================================================= List Archives, FAQ, FTP: http://www.sgi.com/Technology/Performer/ Submissions: info-performer++at++sgi.com Admin. requests: info-performer-request++at++sgi.com
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