This draft offers a specification for embedding macros in existing 3D scenes/assets, to offer simple interactions and configure the renderer further.
Together with URI Fragments, it allows for rich immersive experiences without the need of a complicated sandboxed scripting languages.

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.
Their lowest common denominator is: (co)authoring using plain text.
Therefore, XR Macros allows us to enrich/connect existing dataformats, by offering a polyglot notation based on existing notations:

getting/setting common used 3D properties using querystring- or JSON-notation
querying 3D properties using the lightweight searchengine notation used in XR Fragments

NOTE: The chapters in this document are ordered from highlevel to lowlevel (technical) as much as possible

Core principle

XR Macros use querystrings, but are HTML-agnostic (though pseudo-XR Fragment browsers can be implemented on top of HTML/Javascript).
XR Macros represents setting/getting common used properties found in all popular 3D frameworks/(game)editors/internet browsers.
XR Macros acts as simple eventhandlers for URI Fragments

Conventions and Definitions

See appendix below in case certain terms are not clear.

List of XR Macros

(XR) Macros can be embedded in 3D assets/scenes.
Macros enrich existing spatial content with a lowcode, limited logic-layer, by recursive (economic) use of the querystring syntax (which search engines and XR Fragments already uses.
This is done by allowing string/integer variables, and the | symbol to roundrobin variable values.
Macros also act as events, so more serious scripting languages can react to them as well.

Usecase: click object

custom property	value	trigger when
!clickme	bg=1,1,1&foo=2	object clicked

Usecase: conditional click object

custom property	value	trigger when
#	foo=1	scene
!clickme	q=foo>2&bg=1,1,1	object clicked and foo > 2

when a user clicks an object with the custom properties above, it should set the backgroundcolor to 1,1,1 when foo is greater than 2 (see previous example)

Usecase: click object (roundrobin)

custom property	value	trigger when
!clickme	day\|noon\|night	object clicked
day	bg=1,1,1	roundrobin
noon	bg=0.5,0.5,0.5	roundrobin
night	bg=0,0,0&foo=2	roundrobin

when a user clicks an object with the custom properties above, it should trigger either day noon or night in roundrobin fashion.

Usecase: click object, URI fragment and scene load

custom property	value	trigger when
#	random	scene loaded
#random	random	URL contains #random
!random	day\|noon\|night	#random, # or click
day	bg=1,1,1	roundrobin
noon	bg=0.5,0.5,0.5	roundrobin
night	bg=0,0,0&foo=2	roundrobin

custom property	value	trigger when
!random	day	noon
!day	bg=1,1,1	clicked in contextmenu
!noon	bg=0.5,0.5,0.5	clicked in contextmenu
!night	bg=0,0,0&foo=2	clicked in contextmenu

The XR Browser should offer a contextmenu with these options when more than one !-macro is present on an object.

Security Considerations

IANA Considerations

This document has no IANA actions.

Acknowledgments

Appendix: Definitions

definition	explanation
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.
XR fragments	URI Fragment with spatial hints like `#pos=0,0,0&t=1,100` e.g.
query	an URI Fragment-operator which queries object(s) from a scene like `#q=cube`
FPS	frames per second in spatial experiences (games,VR,AR e.g.), should be as high as possible
`◻`	ascii representation of an 3D object/mesh
(un)obtrusive	obtrusive: wrapping human text/thought in XML/HTML/JSON obfuscates human text into a salad of machine-symbols and words

XR Macros

Abstract