[x3d-public] HUD Proto example clarification

[Holger Seelig]

To prevent jitter and jerkiness the specification is a good reference point:

http://www.web3d.org/documents/specifications/19775-1/V3.3/Part01/concepts.html#ExecutionModel


a) Update camera based on currently bound Viewpoint's position and 
orientation.
b) Evaluate input from sensors.
c) Evalute routes.
d) If any events were generated from steps b and c, go to step b and 
continue.
e) If particle system evaluation is to take place, evaluate the particle 
systems here.
f) If physics model evaluation is to take place, evaluate the physics model.
g) Render scene

It is important to update the camera, and evaluate routes before the 
scene is rendered to prevent jerkiness.

Holger


Am 25.10.2016 um 04:50 schrieb Andreas Plesch:
>
> On Oct 24, 2016 5:37 PM, "Don Brutzman" <brutzman at nps.edu
> <mailto:brutzman at nps.edu>> wrote:
>  >
>  > On 10/24/2016 7:41 AM, Andreas Plesch wrote:
>  >>
>  >> Looking for nice Protos to check out, I came across the HUD proto here:
>  >>
>  >>
> http://x3dgraphics.com/examples/X3dForWebAuthors/Chapter14-Prototypes/HeadsUpDisplayPrototypeIndex.html
>  >
>  >
>  > Thanks for the feedback.  Several side-effect issues
> noticed/fixed/uploaded.
>  >
>  > Must say that Cobweb response is excellent, with no apparent
> jerkiness whatsoever when navigating.  Far better than some players I've
> seen - for example BS Contact is very wiggly.  Instant Reality is OK
> (but it neglects to load the relative image for a nearby Inline when
> running on localhost).
>
> Interesting, could not really be cors related?
>
>  >
> http://x3dgraphics.com/examples/X3dForWebAuthors/Chapter14-Prototypes/HeadsUpDisplayExampleCobweb.html
>  >
>  >
>  >> Comments explains that its screenOffset field is the offset position
> for HUD relative to current view location.
>  >>
>  >> But, in fact, screenOffset seems to be the offset relative to the
> local coordinate system within which the ProtoInstance is used. For
> example, the example instance has a Z offset of -5 which puts it
> (sensibly) in front of the current viewpoint at -10, not behind it at -15.
>  >>
>  >> Is that understanding correct ?
>  >
>  >
>  > Yes.  The appinfo for screenOffset assumes that the HUD is at the top
> level of the scene, and the current view location is wherever the user
> has navigated.  So the screenOffset is in that local coordinate system.
>
> Ok. I start to see the intention.
>
>  > Suggestion for a better description?  Perhaps a warning to avoid nesting?
>
> I thought the way to use the proto screenOffset actually relative to the
> viewpoint location would be to have a viewpoint position of 0 0 0 and
> wrap both in a Transform which seemed like a good solution but perhaps
> the ProximitySensors offsets would not be correct then.
>
> I would suggest to revise the screenOffset appinfo to refer to the local
> coordinate system ? Or simply "Initial position; resulting offset to
> view location is maintained." ?
>
>  > Meanwhile the other example has a "twist in the knickers" - aha
> incorrect ExternProtoDeclare reference - now fixed.
>  >
>  >
> http://X3dGraphics.com/examples/X3dForWebAuthors/Chapter14-Prototypes/HudKelpForestIndex.x3d
>  >
>  > These changes are checked into sourceforge... some delays uploading,
> will likely occur later tonite.
>  >
>  > all the best, Don
>  > --
>  > Don Brutzman  Naval Postgraduate School, Code USW/Br brutzman at nps.edu
> <mailto:brutzman at nps.edu>
>  > Watkins 270,  MOVES Institute, Monterey CA 93943-5000 USA
>   +1.831.656.2149
>  > X3D graphics, virtual worlds, navy robotics
> http://faculty.nps.edu/brutzman
>
>
>
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-- 
Holger Seelig
Mediengestalter Digital – Digital Media Designer

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Germany

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E-Mail:   holger.seelig at create3000.de
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Future to the fantasy ★ ★