First pass at defining tracked sources #1361

cabanier · 2024-03-02T18:44:14Z

Maksims · 2024-03-02T19:18:32Z

A few quick questions based on spec:

Input source can "move" from trackedSources to inputSources lists and back? Is it the same XRInputSource instance, or a new object?
If it is a new object, but they represent the same real thing, let's say the user takes a controller in hand, and now the input source moves from tracked to primary list, is there information for the developer to associate a previous instance with a new one?

cabanier · 2024-03-02T19:27:35Z

A few quick questions based on spec:

Input source can "move" from trackedSources to inputSources lists and back? Is it the same XRInputSource instance, or a new object

It is the same object.

AdaRoseCannon · 2024-03-05T20:06:56Z

/facetoface

toji

A few initial comments, but overall I think this is good. Looking forward to discussing in depth at the F2F!

toji · 2024-03-07T19:26:52Z

index.bs

-    1. [=list/Remove=] each {{XRInputSource}} in |removed| from |session|'s [=list of active XR input sources=].
-    1. Fire an {{XRInputSourcesChangeEvent}} named {{inputsourceschange!!event}} on |session| with {{XRInputSourcesChangeEvent/removed}} set to |removed|.
+    1. [=list/Remove=] each {{XRInputSource}} in |removed primary sources| from |session|'s [=list of active XR input sources=].
+    1. ire an {{XRInputSourcesChangeEvent}} named {{inputsourceschange!!event}} on |session| with {{XRInputSourcesChangeEvent/removed}} set to |removed primary sources|.


Suggested change

1. ire an {{XRInputSourcesChangeEvent}} named {{inputsourceschange!!event}} on |session| with {{XRInputSourcesChangeEvent/removed}} set to |removed primary sources|.

1. If |removed primary sources| is not empty, fire an {{XRInputSourcesChangeEvent}} named {{inputsourceschange!!event}} on |session| with {{XRInputSourcesChangeEvent/removed}} set to |removed primary sources|.

toji · 2024-03-07T19:32:09Z

index.bs


 Note: The user agent MAY fire this event when an input source temporarily loses both position and orientation tracking. It is recommended that this only be done for physical handheld controller input sources. It is not recommended that this event be fired when this happens for tracked hand input sources, because this will happen often, nor is it recommended when this happens for tracker object input sources, since this makes it harder for the application to maintain a notion of identity.

 </div>

 <div class="algorithm" data-algorithm="on-input-source-change">

-When the <dfn for="XRSession" export lt="change input source">{{XRInputSource/handedness}}, {{XRInputSource/targetRayMode}}, {{XRInputSource/profiles}}, or presence of a {{XRInputSource/gripSpace}} for any [=XR input source=]s change</dfn> for {{XRSession}} |session|, the user agent MUST run the following steps:
+When the <dfn for="XRSession" export lt="change input source">{{XRInputSource/handedness}}, {{XRInputSource/targetRayMode}}, {{XRInputSource/profiles}}, presence of a {{XRInputSource/gripSpace}} or the state of the [=primary input source=] or [=tracked input source=] for any [=XR input source=]s change</dfn> for {{XRSession}} |session|, the user agent MUST run the following steps:


This reads somewhat confusingly to me. I believe you are trying to say that the algorithm should fire if an input source switched from primary to tracked or visa-versa, but "the state of the primary input source or tracked input source" makes it sound like any state change (like a button press) could trigger this.

Not 100% confident in what a better phrasing would be, but perhaps something like this?

Suggested change

When the <dfn for="XRSession" export lt="change input source">{{XRInputSource/handedness}}, {{XRInputSource/targetRayMode}}, {{XRInputSource/profiles}}, presence of a {{XRInputSource/gripSpace}} or the state of the [=primary input source=] or [=tracked input source=] for any [=XR input source=]s change</dfn> for {{XRSession}} |session|, the user agent MUST run the following steps:

When the <dfn for="XRSession" export lt="change input source">{{XRInputSource/handedness}}, {{XRInputSource/targetRayMode}}, {{XRInputSource/profiles}}, presence of a {{XRInputSource/gripSpace}} or the status as a [=primary input source=] or [=tracked input source=] for any [=XR input source=]s change</dfn> for {{XRSession}} |session|, the user agent MUST run the following steps:

toji · 2024-03-07T19:40:54Z

index.bs

@@ -2482,6 +2526,34 @@ The <dfn attribute for="XRInputSourcesChangeEvent">added</dfn> attribute is a [=

 The <dfn attribute for="XRInputSourcesChangeEvent">removed</dfn> attribute is a [=/list=] of {{XRInputSource}}s that were removed from the {{XRSession}} at the time of the event.

+XRTrackedSourcesChangeEvent {#xrtrackedsourceschangeevent-interface}


This doesn't need to be a different interface from XRInputSourcesChangeEvent. They're both identical in structure, and if devs want to introspect them to figure out it it's a primary or tracked event they can look at the event name.

I don't remember if this was discussed at the face to face?
I think we need a different event otherwise existing experiences will start getting additional events that they won't know how to handle.

To clarify: We can how a different event but still have it use the same interface. The same way that we have a single MouseEvent interface that is provided for mousedown, mouseup, and click events. The proposal here is not to push everything into a single event, it's to re-use the data structure returned with the separate events for input vs. tracked sources.

This issue is still outstanding. If you removed the XRTrackedSourcesChangeEvent and XRTrackedSourcesChangeEventInit and changed the trackedsourceschange event to use XRInputSourcesChangeEvent then I think this is mergable.

toji · 2024-03-07T19:41:28Z

index.bs

+    1. If |added primary sources| or |removed primary sources| are not empty, fire an {{XRInputSourcesChangeEvent}} named {{inputsourceschange!!event}} on |session| with{{XRInputSourcesChangeEvent/added}} set to |added primary sources| and {{XRInputSourcesChangeEvent/removed}} set to |removed primary sources|.
+    1. [=list/Remove=] each {{XRInputSource}} in |removed tracked sources| from |session|'s [=list of active XR tracked sources=].
+    1. [=list/Extend=] |session|'s [=list of active XR input sources=] with |added tracked sources|.
+    1. If |added tracked sources| or |removed tracked sources| are not empty, fire an {{XRTrackedSourcesChangeEvent}} named {{trackedsourceschange!!event}} on |session| with {{XRTrackedSourcesChangeEvent/added}} set to |added tracked sources| and {{XRTrackedSourcesChangeEvent/removed}} set to |removed tracked sources|.


See note below about the event type.

toji · 2024-03-07T19:58:15Z

index.bs

@@ -1890,7 +1934,7 @@ Note: {{XRInputSource}}s in an {{XRSession}}'s {{XRSession/inputSources}} array

 An [=XR input source=] is a <dfn>primary input source</dfn> if it supports a <dfn>primary action</dfn>. The [=primary action=] is a platform-specific action that, when engaged, produces {{XRSession/selectstart}}, {{XRSession/selectend}}, and {{XRSession/select}} events. Examples of possible [=primary action=]s are pressing a trigger, touchpad, or button, speaking a command, or making a hand gesture. If the platform guidelines define a recommended primary input then it should be used as the [=primary action=], otherwise the user agent is free to select one. The device MUST support at least one [=primary input source=].

-An [=XR input source=] is an <dfn>auxiliary input source</dfn> if it does not support a [=primary action=], for example [=transient input sources=] associated with secondary screen touches on a multitouch device.
+An [=XR input source=] is an <dfn>tracked input source</dfn> if it does not support a [=primary action=], for example [=transient input sources=] associated with secondary screen touches on a multitouch device.


I feel like the example used here is probably worth updating? The current one is a bit difficult to reason about. Also, the example should probably be non-normative. Maybe something like:

Suggested change

An [=XR input source=] is an <dfn>tracked input source</dfn> if it does not support a [=primary action=], for example [=transient input sources=] associated with secondary screen touches on a multitouch device.

An [=XR input source=] is an <dfn>tracked input source</dfn> if it does not support a [=primary action=]. These inputs are primarily intended to provide pose data.

Note: An example of a [=tracked input source=] would be tracking attachments for a users legs or a prop. Tracked hands may also be considered a [=tracked input source=] if there is no gesture recognition being performed to detect [=primary action=]s.

This probably also warrants a clarification in the WebXR Gamepads module that tracked input source MAY still expose gamepad data.

I think we should also have a discussion about what the various spaces on the tracked sources mean? For example, targetRaySpace is somewhat nonsensical for a tracking puck, but still makes some sense for tracked hands or controllers that aren't held. But for a device that isn't firing any select events a "targetRay" is kind of a funny minsomer.

I'm comfortable with some cognitive dissonance in this area, since it's a relatively late addition, but I wouldn't mind it if we could provide some guidance for how future implementers should think about these spaces if we can.

cabanier · 2024-07-08T15:23:45Z

@toji I thought we resolved all the issues with tracked sources. Can we merge this?

toji · 2024-10-21T14:14:05Z

Apologies on the fact that this hasn't been merged yet, and thank you for the ping. There is one outstanding issue (using XRInputSourcesChangeEvent instead of XRTrackedSourcesChangeEvent) and then I'm comfortable merging it.

toji

LGTM, thank you!

First pass at defining tracked sources

1cc1abe

Some refining on tracked sources

dc603b5

cabanier force-pushed the trackedsources branch from 87d81f0 to dc603b5 Compare March 3, 2024 02:58

cabanier marked this pull request as ready for review March 5, 2024 18:15

probot-label bot added the face-to-face label Mar 5, 2024

rename auxiliary to tracked

b1f3e57

toji reviewed Mar 7, 2024

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Yonet removed the face-to-face label Mar 26, 2024

Address @toji's review comments

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cabanier requested a review from toji October 21, 2024 03:20

address review comments

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toji approved these changes Oct 21, 2024

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toji merged commit 27cd3d1 into immersive-web:main Oct 21, 2024
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First pass at defining tracked sources #1361

First pass at defining tracked sources #1361

cabanier commented Mar 2, 2024 •

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	1. ire an {{XRInputSourcesChangeEvent}} named {{inputsourceschange!!event}} on \|session\| with {{XRInputSourcesChangeEvent/removed}} set to \|removed primary sources\|.
	1. If \|removed primary sources\| is not empty, fire an {{XRInputSourcesChangeEvent}} named {{inputsourceschange!!event}} on \|session\| with {{XRInputSourcesChangeEvent/removed}} set to \|removed primary sources\|.

	When the <dfn for="XRSession" export lt="change input source">{{XRInputSource/handedness}}, {{XRInputSource/targetRayMode}}, {{XRInputSource/profiles}}, presence of a {{XRInputSource/gripSpace}} or the state of the [=primary input source=] or [=tracked input source=] for any [=XR input source=]s change</dfn> for {{XRSession}} \|session\|, the user agent MUST run the following steps:
	When the <dfn for="XRSession" export lt="change input source">{{XRInputSource/handedness}}, {{XRInputSource/targetRayMode}}, {{XRInputSource/profiles}}, presence of a {{XRInputSource/gripSpace}} or the status as a [=primary input source=] or [=tracked input source=] for any [=XR input source=]s change</dfn> for {{XRSession}} \|session\|, the user agent MUST run the following steps:

		@@ -2482,6 +2526,34 @@ The <dfn attribute for="XRInputSourcesChangeEvent">added</dfn> attribute is a [=

		The <dfn attribute for="XRInputSourcesChangeEvent">removed</dfn> attribute is a [=/list=] of {{XRInputSource}}s that were removed from the {{XRSession}} at the time of the event.

		XRTrackedSourcesChangeEvent {#xrtrackedsourceschangeevent-interface}

-An [=XR input source=] is an <dfn>tracked input source</dfn> if it does not support a [=primary action=], for example [=transient input sources=] associated with secondary screen touches on a multitouch device.
+An [=XR input source=] is an <dfn>tracked input source</dfn> if it does not support a [=primary action=]. These inputs are primarily intended to provide pose data.
+Note: An example of a [=tracked input source=] would be tracking attachments for a users legs or a prop. Tracked hands may also be considered a [=tracked input source=] if there is no gesture recognition being performed to detect [=primary action=]s.

First pass at defining tracked sources #1361

First pass at defining tracked sources #1361

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cabanier commented Mar 2, 2024 •

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