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

Wed Feb 16 07:04:44 PST 2022

Well, we were not thinking of particle consumers.  Perhaps you might run a recording of one in reverse.

Dick and I reviewed the two issues for WindPhysicsModel node again yesterday in Mantis.  We did consider some possibility of allowing negative numbers in gustiness, to encourage creation of whorls and tornadoes, but decided not to. Since previously posted prose allows variation of direction, even if not explicitly permitting or forbidding reversals of wind direction, it seems sufficient for current state of maturity in X3D4.

Looking ahead to X3D4.1, we foresee the possibility of adding details like that.  There are several places where authors might want more control.  We’ve closed one issue and pushed the other to 4.1.  So we are now finished with Particle Systems spec until that fine future day.

*	X3D4 Architecture, Particle Systems component, 40.4.10 WindPhysicsModel
*	https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4-CD1/Part01/components/particleSystems.html#WindPhysicsModel 

The gustiness specifies how much the wind speed varies from the average value defined by the speed field. The wind speed variation is calculated once per frame and applied equally to all particles.

The turbulence field specifies how much the wind acts directly in line with the direction, and how much variation is applied in directions other than the wind direction. A turbulence value of 0 means no turbulence, while a turbulence value of 1 means maximum turbulence. This is determined per-particle to model how the particle is affected by turbulence.

If anyone wants to offer particle models for the X3D Examples Archives, that will be welcome.

Enjoy the cool wind in your screen with X3D4!   = 8-)

all the best, Don

-- 

Don Brutzman  Naval Postgraduate School, Code USW/Br        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

From: Joseph D Williams <joedwil at earthlink.net> 
Sent: Saturday, February 12, 2022 12:07 AM
To: John Carlson <yottzumm at gmail.com>; Brutzman, Donald (Don) (CIV) <brutzman at nps.edu>
Cc: X3D Public Mailing List (x3d-public at web3d.org) <x3d-public at web3d.org>
Subject: RE: [x3d-public] X3D minutes 11 FEB 2022: ,X3D4 Particle Systems component review,adding enabled field to X3DParticleEmitterNode ?

*	So maybe something that goes -1 (backwards),

Something, but not this thing or else needs to change the name. What is the word for the reverse of an emitter? 

40.4.5 ParticleSystem

Contains this field called createParticles and another named enabled

createP starts and stops and operates not like an enabled, which would kill all rather than just stop new. I think all the rest of controls are in there. If e/d moved upto X3DParticleEmitterNode  then also move cP unless, and why not, allow emitter

 to be an MF then add e/d amd cP for each emitter😊

Fun and Lock,

Joe

From: John Carlson <mailto:yottzumm at gmail.com> 
Sent: Friday, February 11, 2022 1:19 PM
To: Brutzman, Donald (Don) (CIV) <mailto:brutzman at nps.edu> 
Cc: X3D Public Mailing List (x3d-public at web3d.org) <mailto:x3d-public at web3d.org> 
Subject: Re: [x3d-public] X3D minutes 11 FEB 2022: ,X3D4 Particle Systems component review,adding enabled field to X3DParticleEmitterNode ?

It also might be good to enable a kind of slo-mo effect, if not already handled.  Also an emitter going in reverse.

So maybe something that goes -1 (backwards), 0 (disabled), 1 (enabled), and various slo-mo settings in-between.   This would be a weighted factor on speed, where speed provides the maximum speed without the slo-mo setting.

On Fri, Feb 11, 2022 at 12:54 PM John Carlson <yottzumm at gmail.com <mailto:yottzumm at gmail.com> > wrote:

I think it would be better to offer a transition from enabled to disabled and back.   But perhaps that’s max speed and min speed?

But I agree that enabled is a good start, and adding a field for full on and full off with no transition is a good idea.   One might think of scenes where a door is shut.

I’m not sure if full on/full off matches physical reality.   I can think of examples like bombs, volcanoes and dropping things though.

A combination of min/max speed and on/off would cover the cases I’m thinking of.

John 

On Fri, Feb 11, 2022 at 12:36 PM Brutzman, Donald (Don) (CIV) <brutzman at nps.edu <mailto:brutzman at nps.edu> > wrote:

Tweeted:

*     X3D meeting minutes 11 FEB 2022: #X3D4 Architecture Particle Systems component review.  Community question: is it OK to add 'enabled' field to all emitter nodes, providing simpler animation control by authors and end users?

*     https://twitter.com/Web3DConsortium/status/1492205445120815105 <https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Ftwitter.com%2FWeb3DConsortium%2Fstatus%2F1492205445120815105&data=04%7C01%7Cbrutzman%40nps.edu%7C26d329a6836d4e040ca008d9edfeaa8e%7C6d936231a51740ea9199f7578963378e%7C0%7C0%7C637806058903230703%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=cjrkV8DYziUiPpwfBMD%2FAkW5LImU3ekxihQv0GRsmss%3D&reserved=0> 

Request: if anyone has links or screenshots of Particle System models in X3D4, we are happy to share them publicly. Thanks in advance for all posts.

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 <http://faculty.nps.edu/brutzman> 

From: Brutzman, Donald (Don) (CIV) <brutzman at nps.edu <mailto:brutzman at nps.edu> > 
Sent: Friday, February 11, 2022 9:28 AM
To: X3D Public Mailing List (x3d-public at web3d.org <mailto:x3d-public at web3d.org> ) <x3d-public at web3d.org <mailto:x3d-public at web3d.org> >
Cc: Brutzman, Donald (Don) (CIV) <brutzman at nps.edu <mailto:brutzman at nps.edu> >
Subject: X3D minutes 11 FEB 2022: , X3D4 Particle Systems component review, adding enabled field to X3DParticleEmitterNode ?

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 <http://faculty.nps.edu/brutzman> 

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