Internet Engineering Task Force L.R. van Kammen
Internet-Draft 5 September 2023
Intended status: Informational
XR Fragments
draft-XRFRAGMENTS-leonvankammen-00
Abstract
This draft offers a specification for 4D URLs & navigation, to link
3D scenes and text together with- or without a network-connection.
The specification promotes spatial addressibility, sharing,
navigation, query-ing and tagging interactive (text)objects across
for (XR) Browsers.
XR Fragments allows us to enrich existing dataformats, by recursive
use of existing proven technologies like URI Fragments
(https://en.wikipedia.org/wiki/URI_fragment) and BibTeX notation.
Almost every idea in this document is demonstrated at
https://xrfragment.org (https://xrfragment.org)
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 8 March 2024.
Copyright Notice
Copyright (c) 2023 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
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Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Core principle . . . . . . . . . . . . . . . . . . . . . . . 3
3. Conventions and Definitions . . . . . . . . . . . . . . . . . 3
4. List of URI Fragments . . . . . . . . . . . . . . . . . . . . 4
5. List of metadata for 3D nodes . . . . . . . . . . . . . . . . 5
6. Navigating 3D . . . . . . . . . . . . . . . . . . . . . . . . 5
7. Embedding 3D content . . . . . . . . . . . . . . . . . . . . 6
8. Text in XR (tagging,linking to spatial objects) . . . . . . . 6
8.1. Default Data URI mimetype . . . . . . . . . . . . . . . . 9
8.2. URL and Data URI . . . . . . . . . . . . . . . . . . . . 10
8.3. BibTeX as lowest common denominator for tagging/
triples . . . . . . . . . . . . . . . . . . . . . . . . . 11
8.4. XR Text (w. BibTeX) example parser . . . . . . . . . . . 13
9. HYPER copy/paste . . . . . . . . . . . . . . . . . . . . . . 14
10. XR Fragment queries . . . . . . . . . . . . . . . . . . . . . 15
10.1. including/excluding . . . . . . . . . . . . . . . . . . 15
10.2. Query Parser . . . . . . . . . . . . . . . . . . . . . . 16
10.3. XR Fragment URI Grammar . . . . . . . . . . . . . . . . 17
11. Security Considerations . . . . . . . . . . . . . . . . . . . 17
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 17
1. Introduction
How can we add more features to existing text & 3D scenes, without
introducing new dataformats?
Historically, there's many attempts to create the ultimate
markuplanguage or 3D fileformat.
However, thru the lens of authoring, their lowest common denominator
is still: plain text.
XR Fragments allows us to enrich/connect existing dataformats, by
recursive use of existing technologies:
1. addressibility and navigation of 3D scenes/objects: URI Fragments
(https://en.wikipedia.org/wiki/URI_fragment) + src/href spatial
metadata
2. hasslefree tagging across text and spatial objects using BibTeX
(https://en.wikipedia.org/wiki/BibTeX) 'tags' as appendix (see
visual-meta (https://visual-meta.info) e.g.)
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| NOTE: The chapters in this document are ordered from highlevel to
| lowlevel (technical) as much as possible
2. Core principle
XR Fragments strives to serve (nontechnical/fuzzy) humans first, and
machine(implementations) later, by ensuring hasslefree text-vs-
thought feedback loops.
This also means that the repair-ability of machine-matters should be
human friendly too (not too complex).
| "When a car breaks down, the ones *without* turbosupercharger are
| easier to fix"
Let's always focus on average humans: the 'fuzzy symbolical mind'
must be served first, before serving the greater 'categorized
typesafe RDF hive mind' (https://en.wikipedia.org/wiki/Borg)).
| Humans first, machines (AI) later.
3. Conventions and Definitions
+===============+=============================================+
| definition | explanation |
+===============+=============================================+
| human | a sentient being who thinks fuzzy, absorbs, |
| | and shares thought (by plain text, not |
| | markuplanguage) |
+---------------+---------------------------------------------+
| scene | a (local/remote) 3D scene or 3D file |
| | (index.gltf e.g.) |
+---------------+---------------------------------------------+
| 3D object | an object inside a scene characterized by |
| | vertex-, face- and customproperty data. |
+---------------+---------------------------------------------+
| metadata | custom properties of text, 3D Scene or |
| | Object(nodes), relevant to machines and a |
| | human minority (academics/developers) |
+---------------+---------------------------------------------+
| XR fragment | URI Fragment with spatial hints like |
| | #pos=0,0,0&t=1,100 e.g. |
+---------------+---------------------------------------------+
| src | (HTML-piggybacked) metadata of a 3D object |
| | which instances content |
+---------------+---------------------------------------------+
| href | (HTML-piggybacked) metadata of a 3D object |
| | which links to content |
+---------------+---------------------------------------------+
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| query | an URI Fragment-operator which queries |
| | object(s) from a scene like #q=cube |
+---------------+---------------------------------------------+
| visual-meta | visual-meta (https://visual.meta.info) data |
| | appended to text/books/papers which is |
| | indirectly visible/editable in XR. |
+---------------+---------------------------------------------+
| requestless | opposite of networked metadata (RDF/HTML |
| metadata | requests can easily fan out into framerate- |
| | dropping, hence not used a lot in games). |
+---------------+---------------------------------------------+
| FPS | frames per second in spatial experiences |
| | (games,VR,AR e.g.), should be as high as |
| | possible |
+---------------+---------------------------------------------+
| introspective | inward sensemaking ("I feel this belongs to |
| | that") |
+---------------+---------------------------------------------+
| extrospective | outward sensemaking ("I'm fairly sure John |
| | is a person who lives in oklahoma") |
+---------------+---------------------------------------------+
| ◻ | ascii representation of an 3D object/mesh |
+---------------+---------------------------------------------+
Table 1
4. List of URI Fragments
+==========+=========+==============+============================+
| fragment | type | example | info |
+==========+=========+==============+============================+
| #pos | vector3 | #pos=0.5,0,0 | positions camera to xyz- |
| | | | coord 0.5,0,0 |
+----------+---------+--------------+----------------------------+
| #rot | vector3 | #rot=0,90,0 | rotates camera to xyz- |
| | | | coord 0.5,0,0 |
+----------+---------+--------------+----------------------------+
| #t | vector2 | #t=500,1000 | sets animation-loop range |
| | | | between frame 500 and 1000 |
+----------+---------+--------------+----------------------------+
| #...... | string | #.cubes | object(s) of interest |
| | | #cube | (fragment to object name |
| | | | or class mapping) |
+----------+---------+--------------+----------------------------+
Table 2
| xyz coordinates are similar to ones found in SVG Media Fragments
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5. List of metadata for 3D nodes
+=======+========+================+============================+
| key | type | example (JSON) | info |
+=======+========+================+============================+
| name | string | "name": "cube" | available in all 3D |
| | | | fileformats & scenes |
+-------+--------+----------------+----------------------------+
| class | string | "class": | available through custom |
| | | "cubes" | property in 3D fileformats |
+-------+--------+----------------+----------------------------+
| href | string | "href": | available through custom |
| | | "b.gltf" | property in 3D fileformats |
+-------+--------+----------------+----------------------------+
| src | string | "src": | available through custom |
| | | "#q=cube" | property in 3D fileformats |
+-------+--------+----------------+----------------------------+
Table 3
Popular compatible 3D fileformats: .gltf, .obj, .fbx, .usdz, .json
(THREEjs), COLLADA and so on.
| NOTE: XR Fragments are file-agnostic, which means that the
| metadata exist in programmatic 3D scene(nodes) too.
6. Navigating 3D
Here's an ascii representation of a 3D scene-graph which contains 3D
objects ◻ and their metadata:
+--------------------------------------------------------+
| |
| index.gltf |
| │ |
| ├── ◻ buttonA |
| │ └ href: #pos=1,0,1&t=100,200 |
| │ |
| └── ◻ buttonB |
| └ href: other.fbx | <-- file-agnostic (can be .gltf .obj etc)
| |
+--------------------------------------------------------+
An XR Fragment-compatible browser viewing this scene, allows the end-
user to interact with the buttonA and buttonB.
In case of buttonA the end-user will be teleported to another
location and time in the *current loaded scene*, but buttonB will
*replace the current scene* with a new one, like other.fbx.
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7. Embedding 3D content
Here's an ascii representation of a 3D scene-graph with 3D objects
◻ which embeds remote & local 3D objects ◻ (without)
using queries:
+--------------------------------------------------------+ +-------------------------+
| | | |
| index.gltf | | ocean.com/aquarium.fbx |
| │ | | │ |
| ├── ◻ canvas | | └── ◻ fishbowl |
| │ └ src: painting.png | | ├─ ◻ bass |
| │ | | └─ ◻ tuna |
| ├── ◻ aquariumcube | | |
| │ └ src: ://rescue.com/fish.gltf#q=bass%20tuna | +-------------------------+
| │ |
| ├── ◻ bedroom |
| │ └ src: #q=canvas |
| │ |
| └── ◻ livingroom |
| └ src: #q=canvas |
| |
+--------------------------------------------------------+
An XR Fragment-compatible browser viewing this scene, lazy-loads and
projects painting.png onto the (plane) object called canvas (which is
copy-instanced in the bed and livingroom).
Also, after lazy-loading ocean.com/aquarium.gltf, only the queried
objects bass and tuna will be instanced inside aquariumcube.
Resizing will be happen accordingly to its placeholder object
aquariumcube, see chapter Scaling.
8. Text in XR (tagging,linking to spatial objects)
We still think and speak in simple text, not in HTML or RDF.
The most advanced human will probably not shout FIRE!
in
case of emergency.
Given the new dawn of (non-keyboard) XR interfaces, keeping text as
is (not obscuring with markup) is preferred.
Ideally metadata must come *later with* text, but not *obfuscate* the
text, or *in another* file.
| Humans first, machines (AI) later (core principle (#core-
| principle)
This way:
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1. XR Fragments allows hasslefree XR text
tagging, using BibTeX metadata *at the end of content* (like
visual-meta (https://visual.meta.info)).
2. XR Fragments allows hasslefree textual
tagging, spatial tagging, and supra tagging, by mapping 3D/text
object (class)names using BibTeX 'tags'
3. inline BibTeX 'tags' are the minimum required *requestless
metadata*-layer for XR text, RDF/JSON is great (but fits better
in the application-layer)
4. Default font (unless specified otherwise) is a modern monospace
font, for maximized tabular expressiveness (see the core
principle (#core-principle)).
5. anti-pattern: hardcoupling a mandatory *obtrusive markuplanguage*
or framework with an XR browsers (HTML/VRML/Javascript) (see the
core principle (#core-principle))
6. anti-pattern: limiting human introspection, by immediately
funneling human thought into typesafe, precise, pre-categorized
metadata like RDF (see the core principle (#core-principle))
This allows recursive connections between text itself, as well as 3D
objects and vice versa, using *BibTeX-tags* :
+--------------------------------------------------+
| My Notes |
| |
| The houses seen here are built in baroque style. |
| |
| @house{houses, <----- XR Fragment triple/tag: phrase-matching BibTeX
| url = {#.house} <------------------- XR Fragment URI
| } |
+--------------------------------------------------+
This allows instant realtime tagging of objects at various scopes:
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+====================================+=============================+
| scope | matching algo |
+====================================+=============================+
| textual | now automatically tagged |
| | with 'house' (incl. |
| | plaintext src child nodes) |
+------------------------------------+-----------------------------+
| spatial | "class":"house" (because of |
| | {#.house}) are now |
| | automatically tagged with |
| | 'house' (incl. child nodes) |
+------------------------------------+-----------------------------+
| supra | text- or spatial-object(s) |
| | (non-descendant nodes) |
| | elsewhere, named 'house', |
| | are automatically tagged |
| | with 'house' (current node |
| | to root node) |
+------------------------------------+-----------------------------+
| omni | text- or spatial-object(s) |
| | (non-descendant nodes) |
| | elsewhere, containing |
| | class/name 'house', are |
| | automatically tagged with |
| | 'house' (too node to all |
| | nodes) |
+------------------------------------+-----------------------------+
| infinite | (non-descendant nodes) |
| | elsewhere, containing |
| | class/name 'house' or |
| | 'houses', are automatically |
| | tagged with 'house' (too |
| | node to all nodes) |
+------------------------------------+-----------------------------+
Table 4
This empowers the enduser spatial expressiveness (see the core
principle (#core-principle)): spatial wires can be rendered, words
can be highlighted, spatial objects can be highlighted/moved/scaled,
links can be manipulated by the user.
The simplicity of appending BibTeX 'tags' (humans first, machines
later) is also demonstrated by visual-meta (https://visual-meta.info)
in greater detail.
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1. The XR Browser needs to offer a global setting/control to adjust
tag-scope with at least range: [text, spatial, text+spatial,
supra, omni, infinite]
2. The XR Browser should always allow the human to view/edit the
BibTex metadata manually, by clicking 'toggle metadata' on the
'back' (contextmenu e.g.) of any XR text, anywhere anytime.
| NOTE: infinite matches both 'house' and 'houses' in text, as well
| as spatial objects with "class":"house" or name "house". This
| multiplexing of id/category is deliberate because of the core
| principle (#core-principle).
8.1. Default Data URI mimetype
The src-values work as expected (respecting mime-types), however:
The XR Fragment specification bumps the traditional default browser-
mimetype
text/plain;charset=US-ASCII
to a green eco-friendly:
text/plain;charset=utf-8;bibtex=^@
This indicates that any bibtex metadata starting with @ will
automatically get filtered out and:
* automatically detects textual links between textual and spatial
objects
It's concept is similar to literate programming. Its implications
are that local/remote responses can now:
* (de)multiplex/repair human text and requestless metadata (see the
core principle (#core-principle))
* no separated implementation/network-overhead for metadata (see the
core principle (#core-principle))
* ensuring high FPS: HTML/RDF historically is too 'requesty' for
game studios
* rich send/receive/copy-paste everywhere by default, metadata being
retained (see the core principle (#core-principle))
* less network requests, therefore less webservices, therefore less
servers, and overall better FPS in XR
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| This significantly expands expressiveness and portability of human
| text, by *postponing machine-concerns to the end of the human
| text* in contrast to literal interweaving of content and
| markupsymbols (or extra network requests, webservices e.g.).
For all other purposes, regular mimetypes can be used (but are not
required by the spec).
To keep XR Fragments a lightweight spec, BibTeX is used for text-
spatial object mappings (not a scripting language or RDF e.g.).
| Applications are also free to attach any JSON(LD / RDF) to spatial
| objects using custom properties (but is not interpreted by this
| spec).
8.2. URL and Data URI
+--------------------------------------------------------------+ +------------------------+
| | | author.com/article.txt |
| index.gltf | +------------------------+
| │ | | |
| ├── ◻ article_canvas | | Hello friends. |
| │ └ src: ://author.com/article.txt | | |
| │ | | @friend{friends |
| └── ◻ note_canvas | | ... |
| └ src:`data:welcome human @...` | | } |
| | +------------------------+
| |
+--------------------------------------------------------------+
The enduser will only see welcome human and Hello friends rendered
spatially. The beauty is that text (AND visual-meta) in Data URI
promotes rich copy-paste. In both cases, the text gets rendered
immediately (onto a plane geometry, hence the name '_canvas'). The
XR Fragment-compatible browser can let the enduser access visual-
meta(data)-fields after interacting with the object (contextmenu
e.g.).
The mapping between 3D objects and text (src-data) is simple:
Example:
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+------------------------------------------------------------------------------------+
| |
| index.gltf |
| │ |
| └── ◻ rentalhouse |
| └ class: house |
| └ ◻ note |
| └ src:`data: todo: call owner |
| @house{owner, |
| url = {#.house} |
| }` |
+------------------------------------------------------------------------------------+
Attaching visualmeta as src metadata to the (root) scene-node hints
the XR Fragment browser. 3D object names and classes map to name of
visual-meta glossary-entries. This allows rich interaction and
interlinking between text and 3D objects:
1. When the user surfs to https://.../index.gltf#AI the XR
Fragments-parser points the enduser to the AI object, and can
show contextual info about it.
2. When (partial) remote content is embedded thru XR Fragment
queries (see XR Fragment queries), its related visual-meta can be
embedded along.
8.3. BibTeX as lowest common denominator for tagging/triples
| "When a car breaks down, the ones *without* turbosupercharger are
| easier to fix"
Unlike XML or JSON, the typeless, unnested, everything-is-text nature
of BibTeX tags is a great advantage for introspection.
In a way, the RDF project should welcome it as a missing sensemaking
precursor to (eventual) extrospective RDF.
BibTeX-appendices are already used in the digital AND physical world
(academic books, visual-meta (https://visual-meta.info)), perhaps due
to its terseness & simplicity.
In that sense, it's one step up from the .ini fileformat (which has
never leaked into the physical book-world):
1. frictionless copy/pasting (by
humans) of (unobtrusive) content AND metadata
2. an introspective 'sketchpad' for metadata, which can (optionally)
mature into RDF later
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+====================+=================+=================+
| characteristic | UTF8 Plain Text | RDF |
| | (with BibTeX) | |
+====================+=================+=================+
| perspective | introspective | extrospective |
+--------------------+-----------------+-----------------+
| structure | fuzzy | precise |
| | (sensemaking) | |
+--------------------+-----------------+-----------------+
| space/scope | local | world |
+--------------------+-----------------+-----------------+
| everything is text | yes | no |
| (string) | | |
+--------------------+-----------------+-----------------+
| leaves (dictated) | yes | no |
| text intact | | |
+--------------------+-----------------+-----------------+
| markup language | just an | ~4 different |
| | appendix | |
+--------------------+-----------------+-----------------+
| polyglot format | no | yes |
+--------------------+-----------------+-----------------+
| easy to copy/paste | yes | up to |
| content+metadata | | application |
+--------------------+-----------------+-----------------+
| easy to write/ | yes | depends |
| repair for layman | | |
+--------------------+-----------------+-----------------+
| easy to | yes (fits on A4 | depends |
| (de)serialize | paper) | |
+--------------------+-----------------+-----------------+
| infrastructure | selfcontained | (semi)networked |
| | (plain text) | |
+--------------------+-----------------+-----------------+
| freeform tagging/ | yes, terse | yes, verbose |
| annotation | | |
+--------------------+-----------------+-----------------+
| can be appended to | yes | up to |
| text-content | | application |
+--------------------+-----------------+-----------------+
| copy-paste text | yes | up to |
| preserves metadata | | application |
+--------------------+-----------------+-----------------+
| emoji | yes | depends on |
| | | encoding |
+--------------------+-----------------+-----------------+
| predicates | free | semi pre- |
| | | determined |
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+--------------------+-----------------+-----------------+
| implementation/ | no | depends |
| network overhead | | |
+--------------------+-----------------+-----------------+
| used in (physical) | yes (visual- | no |
| books/PDF | meta) | |
+--------------------+-----------------+-----------------+
| terse non-verb | yes | no |
| predicates | | |
+--------------------+-----------------+-----------------+
| nested structures | no | yes |
+--------------------+-----------------+-----------------+
Table 5
8.4. XR Text (w. BibTeX) example parser
Here's a naive XR Text (de)multiplexer in javascript (which also
supports visual-meta start/end-blocks):
xrtext = {
decode: {
text: (str) => {
let meta={}, text='', last='', data = '';
str.split(/\r?\n/).map( (line) => {
if( !data ) data = last === '' && line.match(/^@/) ? line[0] : ''
if( data ){
if( line === '' ){
xrtext.decode.bibtex(data.substr(1),meta)
data=''
}else data += `${line}\n`
}
text += data ? '' : `${line}\n`
last=line
})
return {text, meta}
},
bibtex: (str,meta) => {
let st = [meta]
str
.split(/\r?\n/ )
.map( s => s.trim() ).join("\n") // be nice
.replace( /}@/, "}\n@" ) // to authors
.replace( /},}/, "},\n}" ) // which struggle
.replace( /^}/, "\n}" ) // with writing single-line BibTeX
.split( /\n/ ) //
.filter( c => c.trim() ) // actual processing:
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.map( (s) => {
if( s.match(/(^}|-end})/) && st.length > 1 ) st.shift()
else if( s.match(/^@/) ) st.unshift( st[0][ s.replace(/(-start|,)/g,'') ] = {} )
else s.replace( /(\w+)\s*=\s*{(.*)}(,)?/g, (m,k,v) => st[0][k] = v )
})
return meta
}
},
encode: (text,meta) => {
if( text === false ){
if (typeof meta === "object") {
return Object.keys(meta).map(k =>
typeof meta[k] == "string"
? ` ${k} = {${meta[k]}},`
: `${ k.match(/[}{]$/) ? k.replace('}','-start}') : `${k},` }\n` +
`${ xrtext.encode( false, meta[k])}\n` +
`${ k.match(/}$/) ? k.replace('}','-end}') : '}' }\n`
.split("\n").filter( s => s.trim() ).join("\n")
)
.join("\n")
}
return meta.toString();
}else return `${text}\n${xrtext.encode(false,meta)}`
}
}
var {meta,text} = xrtext.decode.text(str) // demultiplex text & bibtex
meta['@foo{'] = { "note":"note from the user"} // edit metadata
xrtext.encode(text,meta) // multiplex text & bibtex back together
| above can be used as a startingpoint for LLVM's to translate/
| steelman to any language.
9. HYPER copy/paste
The previous example, offers something exciting compared to simple
copy/paste of 3D objects or text. XR Fragment allows HYPER-copy/
paste: time, space and text interlinked. Therefore, the enduser in
an XR Fragment-compatible browser can copy/paste/share data in these
ways:
1. time/space: 3D object (current animation-loop)
2. text: TeXt object (including BibTeX/visual-meta if any)
3. interlinked: Collected objects by visual-meta tag
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10. XR Fragment queries
Include, exclude, hide/shows objects using space-separated strings:
* #q=cube
* #q=cube -ball_inside_cube
* #q=* -sky
* #q=-.language .english
* #q=cube&rot=0,90,0
* #q=price:>2 price:<5
It's simple but powerful syntax which allows css-like class/
id-selectors with a searchengine prompt-style feeling:
1. queries are showing/hiding objects *only* when defined as src
value (prevents sharing of scene-tampered URL's).
2. queries are highlighting objects when defined in the top-Level
(browser) URL (bar).
3. search words like cube and foo in #q=cube foo are matched against
3D object names or custom metadata-key(values)
4. search words like cube and foo in #q=cube foo are matched against
tags (BibTeX) inside plaintext src values like @cube{redcube, ...
e.g.
5. # equals #q=*
6. words starting with . like .german match class-metadata of 3D
objects like "class":"german"
7. words starting with . like .german match class-metadata of
(BibTeX) tags in XR Text objects like @german{KarlHeinz, ... e.g.
| *For example*: #q=.foo is a shorthand for #q=class:foo, which will
| select objects with custom property class:foo. Just a simple
| #q=cube will simply select an object named cube.
* see an example video here
(https://coderofsalvation.github.io/xrfragment.media/queries.mp4)
10.1. including/excluding
+==========+=================================================+
| operator | info |
+==========+=================================================+
| * | select all objects (only useful in src custom |
| | property) |
+----------+-------------------------------------------------+
| - | removes/hides object(s) |
+----------+-------------------------------------------------+
| : | indicates an object-embedded custom property |
| | key/value |
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+----------+-------------------------------------------------+
| . | alias for "class" :".foo" equals class:foo |
+----------+-------------------------------------------------+
| > < | compare float or int number |
+----------+-------------------------------------------------+
| / | reference to root-scene. |
| | Useful in case of (preventing) showing/hiding |
| | objects in nested scenes (instanced by src) (*) |
+----------+-------------------------------------------------+
Table 6
| * = #q=-/cube hides object cube only in the root-scene (not nested
| cube objects)
| #q=-cube hides both object cube in the root-scene AND
| nested skybox objects |
» example implementation
(https://github.com/coderofsalvation/xrfragment/blob/main/src/3rd/js/
three/xrf/q.js) » example 3D asset
(https://github.com/coderofsalvation/xrfragment/blob/main/example/
assets/query.gltf#L192) » discussion
(https://github.com/coderofsalvation/xrfragment/issues/3)
10.2. Query Parser
Here's how to write a query parser:
1. create an associative array/object to store query-arguments as
objects
2. detect object id's & properties foo:1 and foo (reference regex:
/^.*:[><=!]?/ )
3. detect excluders like -foo,-foo:1,-.foo,-/foo (reference regex:
/^-/ )
4. detect root selectors like /foo (reference regex: /^[-]?\// )
5. detect class selectors like .foo (reference regex: /^[-]?class$/
)
6. detect number values like foo:1 (reference regex: /^[0-9\.]+$/ )
7. expand aliases like .foo into class:foo
8. for every query token split string on :
9. create an empty array rules
10. then strip key-operator: convert "-foo" into "foo"
11. add operator and value to rule-array
12. therefore we we set id to true or false (false=excluder -)
13. and we set root to true or false (true=/ root selector is
present)
14. we convert key '/foo' into 'foo'
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15. finally we add the key/value to the store like store.foo =
{id:false,root:true} e.g.
| An example query-parser (which compiles to many languages) can be
| found here
| (https://github.com/coderofsalvation/xrfragment/blob/main/src/
| xrfragment/Query.hx)
10.3. XR Fragment URI Grammar
reserved = gen-delims / sub-delims
gen-delims = "#" / "&"
sub-delims = "," / "="
| Example: ://foo.com/my3d.gltf#pos=1,0,0&prio=-5&t=0,100
+=============================+=================================+
| Demo | Explanation |
+=============================+=================================+
| pos=1,2,3 | vector/coordinate argument e.g. |
+-----------------------------+---------------------------------+
| pos=1,2,3&rot=0,90,0&q=.foo | combinators |
+-----------------------------+---------------------------------+
Table 7
11. Security Considerations
Since XR Text contains metadata too, the user should be able to set
up tagging-rules, so the copy-paste feature can :
* filter out sensitive data when copy/pasting (XR text with
class:secret e.g.)
12. IANA Considerations
This document has no IANA actions.
13. Acknowledgments
TODO acknowledge.
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