[x3d-public] ProtoBody completeness in nested Protos

Tue Apr 26 09:11:45 PDT 2022

Hi Don,

Thanks for chiming in.

On Tue, Apr 26, 2022 at 11:44 AM Brutzman, Donald (Don) (CIV)
<brutzman at nps.edu> wrote:

> Wanted to point out that embedding ExternProtoDeclare within ProtoDeclare only impacts scoping (visibility) of the ExternProto.
>
>
>
> Common design pattern for large scenes is to put all ExternProtoDeclare statements at top of model, so that ProtoInstances might be used anywhere.  Also avoids repeated loading of such prototypes.
>

Do you have more examples of such a design, eg. putting
ExternProtoDeclare at the top, and then using ProtoInstances inside
other ProtoDeclare ProtoBodys ? The CircleFishLod proto is the only
example I could find sofar.

Such design may not function very reliably due to the separated
Execution Contexts inside Protos as discussed. In fact, the spec.
would discourage such a design as far as I understand it unless
Execution Contexts are meant to be inherited down from parents/hosts
(which may lead to DEF/USE name conflicts).

> Alternatively for reliability an author might put ExternProtoDeclare within ProtoDeclare so that it is always available.  If embedded, that ExternProtoDeclare will not be visible outside of the ProtoDeclare.  This might be preferable or undesirable, depending on modeler’s re-use plans (or possibly ProtoDeclare author’s design intentions).
>
> Of note is that ProtoBody content model does allow inclusion of ExternProtoDeclare as valid.  See bottom of following diagram to confirm.
>

Yes. I could not think of a reason why it should not be allowed.

All the best, Andreas

> From: x3d-public <x3d-public-bounces at web3d.org> On Behalf Of GPU Group
> Sent: Monday, April 25, 2022 6:09 AM
> To: X3D Graphics public mailing list <x3d-public at web3d.org>
> Subject: Re: [x3d-public] ProtoBody completeness in nested Protos
>
>
>
> freewrl loads extern proto scenes as whole scene files, but as 'dead' scenery like a library file: in binary form, ready to binary deep copy parts to live scenery, but node initialization functions not yet called, and not rendered. Subsequent # references to the same scene file use the same loaded library scene. So any ProtoDeclares outside the ProtoBody would be resolved.
>
> -Doug
>
> PS this relates to:
>
> PROTOTYPE STYLE IMPORTS
>
> I had mentioned a prototype style import for gltf use:
>
> Shape { url=”library.gltf#shapeName” }
>
> Similar to how we load extern protos as a whole ‘dead’ scene, and then do binary deep copies where used in the live scene to make live.
>
> But interestingly, the same goes for x3d scenery – don’t need glTF, don’t need extern protos in library scene, don’t need Inline or IMPORT.
>
> So the concept could be tested first with x3d scenery.
>
> Shape { url=’library.x3dv#shapeName }
>
> And then extended to gltf.
>
> /PROTOTYPE STYLE IMPORTS
>
>
>
> On Sun, Apr 24, 2022 at 10:43 PM Brutzman, Donald (Don) (CIV) <brutzman at nps.edu> wrote:
>
> Actually please look a little more closely at that (admittedly tricky)
> example.
>
> * CircleFish is an ExternProto, separately defined in another file
> * CircleFishLod is a ProtoDeclare defined in that first file,
> CircleFishLodPrototype.x3d
> * CircleFishLod ProtoBody contains two ProtoInstance copies of CircleFish
> * CircleFishLod ProtoDeclare is then followed by a CircleFishLod
> ProtoInstance (again  in CircleFishLodPrototype.x3d)
>
> So I would expect an X3D Browser to
>
> a. load ExternProtoDeclare      CircleFish
> b. build ProtoDeclare                CircleFishLod
> c. create inner ProtoInstance  CircleFish for use
> d. create outer ProtoInstance CircleFishLod
>
> Order of steps might vary a bit, but those are the dependencies.  Good luck
> sir.
>
> 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: x3d-public <x3d-public-bounces at web3d.org> On Behalf Of Andreas Plesch
> Sent: Sunday, April 24, 2022 9:08 PM
> To: X3D Graphics public mailing list <x3d-public at web3d.org>
> Subject: [x3d-public] ProtoBody completeness in nested Protos
>
> ProtoDeclarations may use ProtoInstances of other Protos inside their
> ProtoBody definitions.
>
> For example, the CircleFishLod proto here:
>
> https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fx3dgraphic
> s.com%2Fexamples%2FX3dForWebAuthors%2FKelpForestExhibit%2FCircleFishLodProto
> typeIndex.html&data=05%7C01%7Cbrutzman%40nps.edu%7C0b4a867ba9874e371f9b0
> 8da267152fa%7C6d936231a51740ea9199f7578963378e%7C0%7C0%7C637864565880708349%
> 7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwi
> LCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=upr4eckI8axT7MO5fAUvAWfyBzUJfhTwqcp
> BuH7tZjc%3D&reserved=0
>
> uses ProtoInstances of the CircleFish proto.
>
> A more extreme case of nesting is:
>
> https://www.web3d.org/x3d/content/examples/ConformanceNist/Miscellaneous/PRO
> TO/fivedeepnestingIndex.html
>
> where Proto1 uses ProtoInstance of Proto2 inside its ProtoBody. Proto2
> itself uses a ProtoInstance of Proto3 inside its ProtoBody. And so on to
> five levels deep.
>
> The second example with the deep nesting currently works with x3dom but the
> seemingly simpler CircleFishLod proto does not.
>
> The reason is that x3dom expects the complete definition of a proto to be
> contained in its ProtoBody. However, The CircleFishLod proto only contains
> the CircleFish ProtoInstances in the body but not the associated CircleFish
> ProtoDeclaration which for some reason occurs outside the CircleFishLod
> ProtoBody (and outside the CircleFishLod ProtoDeclaration).
>
> Expecting the ProtoBody to be complete and self-contained seems rather
> natural. Is x3dom too strict in this regard, or is there an oversight in the
> example ? There is not much guidance in the spec., if any.
>
> Thanks, Andreas
>
> --
> Andreas Plesch
> Waltham, MA 02453
>
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-- 
Andreas Plesch
Waltham, MA 02453