When to change scene hooks

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Reed Whittington (reedwhit++at++skips.dseg.ti.com)
Thu, 11 Nov 93 14:39:05 CST


Hello Performer Group,

My Performer application is for a tank simulation:

Im trying to implement gun stabalization.

My tank (the ownship) is modeled as chained DCS's :

  pfGroup* TankRoot = pfNewGroup();

  pfAddChild(ownship->dcs_hull, LoadFile(hull_file, NULL ));
  pfAddChild(TankRoot, ownship->dcs_hull);

  pfAddChild(ownship->dcs_tur, LoadFile(tur_file, NULL ));
  pfAddChild(ownship->dcs_hull, ownship->dcs_tur);

  pfAddChild(ownship->dcs_gun, LoadFile(gun_file, NULL ));
  pfAddChild(ownship->dcs_tur, ownship->dcs_gun);

  pfAddChild(scene, TankRoot);

My sim loop looks something like this (adapted from perfly):

SimLoop:
{
  updateView
    - update channel views
   
  pfFrame (draw frame N)

  updateSim ( for frame N+1 )
    - get sim inputs
    - calculate new values
    - adjust ownship DCS's (these are direct hooks into the scene)
      pfDCSRot( ownship->dcs_tur, ownship->tur_heading, 0.0, 0.0 );
      do gun stabalization
      pfDCSRot( ownship->dcs_gun, 0.0, ownship->gun_pitch, 0.0 );
}

My question is:

Will adjusting the ownship DCS's after pfFrame cause a DCS to shift
during a Cull/Draw? If so what can I do to get around this. I
don't want to have to adjust the DCS's in updateView because of
turret stabalization calculations that need access to intermediate
transformation matrix values after a DCSRot for the turret.

Thanks in advance.

--Reed

********************************
Reed Whittington
Texas Instruments
Visual Simulation Technology Development
MS 8518
6620 Chase Oaks Blvd.
Plano, Texas 75086

(214) 575-6761 off
(214) 575-6771 fax
reedwhit++at++dseg.ti.com
********************************


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