[x3d-public] X3DParticleEmitter node inherit from X3DChildNode (rather than X3DNode)

[Brutzman, Donald (Don) (CIV)]

Thanks for these followups Michalis.

Also: we didn't have time to go over that on the meeting, but I wanted to
point out my notes on particle emitter and X3DChildNode in "X3D agenda 3 MAR
2022: announcements, Mantis issues, NurbsSweptSurface NurbsSwungSurface,
planning" . In short: X3DParticleEmitterNode should not be X3DChildNode. The
current spec is already correct.

 

3. We talked at one point about making particle system emitter an
X3DChildNode.   I looked at spec,

https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4-CD1/Part01/
components/particleSystems.html

, and this would be wrong. The current state of spec is good:
X3DParticleEmitterNode is supposed to be placed within
ParticleSystem.emitter field. And ParticleSystem is a X3DShapeNode (which is
already X3DChildNode).  So, let's not change anything here. It wouldn't be
valid to allow X3DParticleEmitterNode directly inside some grouping nodes.

The current specification works for particle emitter nodes, fully agreed
about that.  Let's press a just little bit farther please.

 

The recent motivation for making X3DParticleEmitter node inherit from
X3DChildNode (rather than X3DNode) is to allow these nodes to appear as root
nodes in a scene, rather than solely within a ParticleSystem node's emitter
field.

 

*	Mantis 836: 04.3.2 Root nodes - Additional nodes need to be allowed
as root nodes 
*	https://www.web3d.org/member-only/mantis/view.php?id=836 

 

*	X3D4 Architecture, 40.3.1 X3DParticleEmitterNode
*
https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4-CD1/Part01/
components/particleSystems.html#X3DParticleEmitterNode

 

*	X3D4 Architecture, 4.4.2.3 Interface hierarchy
*
https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4-CD1/Part01/
concepts.html#InterfaceHierarchy

 

This might be useful for facilitating DEF/USE re-use of such emitters in a
scene with multiple particle emitters.

 

That might also be considered an obscure and perhaps unhelpful use case
(since emitters are then allowed to appear in many places within a model's
scene graph.  I'm OK with (= can live with) either approach.

 

So, staying conservative, especially at this stage of development:  does
anyone have a better rationale for making the emitter nodes allowed as child
nodes?

 

Absent any other reasons for changing we'll simply keep it unchanged as
you've indicated.  Thanks for consideration of this small X3D4 model design
point.

 

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

 

-----Original Message-----
From: Michalis Kamburelis <michalis.kambi at gmail.com> 
Sent: Friday, March 4, 2022 5:09 PM
To: GPU Group <gpugroup at gmail.com>
Cc: Brutzman, Donald (Don) (CIV) <brutzman at nps.edu>; X3D Public Mailing List
(x3d-public at web3d.org) <x3d-public at web3d.org>
Subject: Re: [x3d-public] X3D minutes 3 MAR 2022: announcements, SpotLight
default values, NurbsSweptSurface NurbsSwungSurface found in FreeWrl,
planning X3DOM WebXR

Thank you all for the good meeting!

[.].

 

Also: we didn't have time to go over that on the meeting, but I wanted to
point out my notes on particle emitter and X3DChildNode in "X3D agenda 3 MAR
2022: announcements, Mantis issues, NurbsSweptSurface NurbsSwungSurface,
planning" . In short: X3DParticleEmitterNode should not be X3DChildNode. The
current spec is already correct.

 

Regards,

Michalis

 

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