[x3d-public] X3D minutes 11 FEB 2022: , X3D4 Particle Systems component review, adding enabled field to X3DParticleEmitterNode ?

[Brutzman, Donald (Don) (CIV)]

Attendees: Anita Havele, Vince Marchetti, Dick Puk, Don Brutzman.  Regrets: Nicholas Polys, John Carlson.


  1.  Completed X3D4 Particle Systems component review.  All Mantis issues updated and resolved.  Latest modifications highlighted via CSS with corresponding Mantis issues documented using /title/ attributes.



  *   X3D4 Architecture, clause 37 Particle Systems component
  *   https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4-CD1/Part01/components/particleSystems.html


a. Improved issue notes, WindPhysicsModel:


  *   Mantis 464: 40.4.10 WindPhysicsModel - Question on Speed
  *   https://www.web3d.org/member-only/mantis/view.php?id=464
  *   Related issue: Mantis 768.  Deferred to X3D 4.1


Likely pressure equation for future use will be based on difference between particle speed and wind speed.

Note that the turbulence definition (regarding variability of wind direction) also needs improvement. For example, can highly turbulent wind stop or reverse direction?



b. New deficiency noted: how do you turn off an emitter node?

No /enabled/ field is present.  Possibly /speed/ might be zero, but then particle geometry would still be present and perhaps pulsing...  Possibly a Switch node might hide it, but then the browser writer likely just turns it off anyway to save computational resources, which is functionally equivalent to enabled FALSE.

We discussed in some depth... Have raises an issue in Mantis, here posted publicly.  We seek comment, and decide (hopefully next week) whether it is something to be accomplished in X3D 4.0 or else deferred to X3D 4.1.



  *   Mantis 1380: ability to disable/enable X3DParticleEmitterNode
  *   https://www.web3d.org/member-only/mantis/view_all_bug_page.php

Authors are unable to easily turn particle emitter nodes on or off.

X3DParticleEmitterNode (and implementing nodes) need field:

   SFBool [in out] enabled TRUE

Implementation is simple for browsers. This field has no impact on legacy content.

Current workarounds:
* Possibly /speed/ might be zero, but then a particle would still be present and pulsing...
* Possibly a Switch node might hide the emitter, but then the browser writer likely turns it off anyway to save computational resources, which is functionally equivalent to enabled FALSE.

Of related note: X3DParticlePhysicsModelNode in this component does include an enabled field, for identical purposes.


Vince discussed his Browser Review document noting X3D support, we hope to look at this draft further next week.
No member-only information included on this page.

Hope everybody has another great week.  Have fun with X3D!

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 https:// faculty.nps.edu/brutzman

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