[x3d-public] Using IMPORT / EXPORT to selectively include parts of glTF file in X3D, and multiply them as much as necessary

Mon Apr 4 23:30:03 PDT 2022

Correct.  Also, the reason an author might want to do this is easily to
ROUTE events from parent scene to child scene, or vice versa.  Much less
work than creating a prototype, too.

*	https://www.web3d.org/x3d/content/X3dTooltips.html#IMPORT

IMPORT provides ROUTE access to a node that has a corresponding EXPORT
statement within an Inline scene. These connections allow event values to be
passed via ROUTE statements between a parent model and a child Inline model.
Hint: it is good practice to place IMPORT statements next to corresponding
Inline scenes for readability.
Hint: see EXPORT statement for corresponding functionality within the
related Inline model.
Warning: corresponding parent-scene IMPORT and child Inline-scene EXPORT
statements are necessary in order to ROUTE values between a parent model and
a child Inline model.
Hint: X3D Architecture 4.4.6 Import/Export semantics
https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4-CD1/Part01/
concepts.html#ImportExportsemantics

*	https://www.web3d.org/x3d/content/X3dTooltips.html#EXPORT

EXPORT exposes a local node for ROUTE passing of event values when the
current Scene is included via Inline by a parent external world. These
connections allow event values to be exchanged via ROUTE statements between
a parent model and a child Inline model.
Hint: you can place EXPORT statements after Scene tag to show interfaces at
top.
Hint: see IMPORT statement for corresponding functionality in the parent
external world.
Warning: EXPORT statements are not allowed in prototype declarations.
Warning: corresponding parent-scene IMPORT and child Inline-scene EXPORT
statements are necessary in order to ROUTE values between a parent model and
a child Inline model.
Hint: X3D Architecture 4.4.6 Import/Export semantics
https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4-CD1/Part01/
concepts.html#ImportExportsemantics

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: x3d-public <x3d-public-bounces at web3d.org> On Behalf Of Michalis
Kamburelis
Sent: Monday, April 4, 2022 8:00 PM
To: John Carlson <yottzumm at gmail.com>
Cc: X3D Graphics public mailing list <x3d-public at web3d.org>
Subject: Re: [x3d-public] Using IMPORT / EXPORT to selectively include parts
of glTF file in X3D, and multiply them as much as necessary

The idea of IMPORT / EXPORT is that you use EXPORT within the "inner" file,
and then you use Inline and IMPORT statements in the "outer" file to bring
nodes from inner file into the outer file namespace.

Regards,

Michalis

W dniu wt., 5.04.2022 o 04:39 John Carlson <yottzumm at gmail.com
<mailto:yottzumm at gmail.com> > napisał(a):

Looks super-exciting Michalis.    I haven't had much chance to work with
IMPORT/EXPORT.   Can including file export to an included file?

J

On Mon, Apr 4, 2022 at 9:23 PM Michalis Kamburelis <michalis.kambi at gmail.com
<mailto:michalis.kambi at gmail.com> > wrote:

( No real avocados were hurt while generating screenshots for this email :)
)

I started to write an answer to Doug email "Other ways to use gltf >
like ExternProto" and then I realized that I just pursue a different
approach, so I may as well create a new thread. The goal is similar:
how to get *part* of glTF scene into X3D file? But here I decided to
do it using IMPORT / EXPORT + Inline, not ExternProto.

I thought that IMPORT / EXPORT may be nice, as IMPORT / EXPORT have an
explicit purpose "make something available to the outer scene".

So I tried how far can I take it. And  implemented it in
CGE/view3dscene, and made demos :) You can now use IMPORT / EXPORT to
selectively take (and reuse as many times as you wish) parts of inner
glTF models inside outer X3D file.

1. Older demo: I have already used this approach for animations in
glTF in CGE/view3dsdcene, i.e. I export them from glTF and you can
IMPORT and control them. See
https://github.com/castle-engine/demo-models/tree/master/blender/skinned_ani
mation
<https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.co
m%2Fcastle-engine%2Fdemo-models%2Ftree%2Fmaster%2Fblender%2Fskinned_animatio
n&data=04%7C01%7Cbrutzman%40nps.edu%7C90fe545048fe487a05a108da16b073ac%7C6d9
36231a51740ea9199f7578963378e%7C0%7C0%7C637847244970756710%7CUnknown%7CTWFpb
GZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C
3000&sdata=y5Mh8sqteN6MFYSFuR3vlJevG%2FTWs0wUQqxjCjQvmvY%3D&reserved=0> 
, file skinned_anim_run_animations_from_x3d.x3dv does

"""
DEF InlinedAnimations Inline {
   url "skinned_anim.glb"
}
IMPORT InlinedAnimations.jump AS jump
IMPORT InlinedAnimations.walk AS walk
"""

and then it can start  animations jump, walk. They are just TimeSensor
nodes in X3D. I can ROUTE events to them.

2. I have now extended this approach to glTF materials (X3D Appearance
nodes) and transformation groups and cameras (X3D Viewpoint /
OrthoViewpoint nodes). I can export anything named from glTF this way.

See
https://github.com/michaliskambi/x3d-tests/tree/master/gltf/avocado_and_expo
rts
<https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.co
m%2Fmichaliskambi%2Fx3d-tests%2Ftree%2Fmaster%2Fgltf%2Favocado_and_exports&d
ata=04%7C01%7Cbrutzman%40nps.edu%7C90fe545048fe487a05a108da16b073ac%7C6d9362
31a51740ea9199f7578963378e%7C0%7C0%7C637847244970756710%7CUnknown%7CTWFpbGZs
b3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C300
0&sdata=9jRLppQrO0q6GPqX9tOEAR62mXEw8vWR3NzSS1HRVPE%3D&reserved=0> 
and attached screenshot with scene that can reuse Avocado appearance,
or transformation, or mesh.

It looks like this:

"""
Switch {
  children DEF InlinedAvocado Inline {
    url "glTF/Avocado.gltf"
  }
}
IMPORT InlinedAvocado.Avocado_2 AS AvocadoMeshes
IMPORT InlinedAvocado.CastleEncoded_2256_Avocado_d AS AvocadoAppearance
IMPORT InlinedAvocado.Avocado AS AvocadoTransform

Shape {
  appearance USE AvocadoAppearance
  geometry IndexedFaceSet { ... }
}
...
"""

3. Why IMPORT / EXPORT? I felt this way there's less extra concepts.

  A. Do not want to see original glTF? Then place "Inline" inside "Switch".

  B. Writing "IMPORT" is simpler than ExternProto, no need to repeat
the node declaration.

4. To make this work:

  A. The browser must make sure to generate EXPORT for all named
things when importing glTF file.

  B. The browser must be more tolerant for USE clauses than spec.

    X3D spec says (
https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4-CD1/Part01/
components/networking.html#IMPORTStatement
) """Nodes imported into an X3D scene using the IMPORT statement may
not be instanced via the USE statement. """. I decided to ignore this
limit now in CGE/view3dscene, you can reUSE nodes you get with IMPORT.

    There seems to be no drawback from this. We only resolve USE
looking at IMPORTed names if the name cannot be found in non-imported
nodes. And it makes IMPORT / EXPORT much more powerful, also for
X3D<->X3D interaction.

5. Note: I'm not really trying to make a case that "IMPORT / EXPORT is
a better approach than ExternProto". They both seem reasonable
approaches. I just decided to test IMPORT / EXPORT approach to the
fullest, and I dabbled with it already in the demo with
skinned_anim_run_animations_from_x3d.x3dv .

Regards,
Michalis

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