[webvr] Why does entering VR need to be on user interaction?

Sean McBeth sean.mcbeth at gmail.com
Wed Sep 21 01:30:54 UTC 2016

Unfortunately, gamepad buttons don't fire events, you poll for their state
in your animation loop, so you would not be able to trigger requestPresent
using the Vive controller.

There had been some talk in this mailing list (or was it the Slack group?)
previously that "talk about link-traversal" is going on. I think that
conversation is here: https://github.com/w3c/webvr/issues/30.

At the very least, this keeps the BuzzFeeds of the world from popping ads
in our HMDs without our consent.

In the past, to make triggering the event a little easier, I've listened
for the entire window's touchend or mouseup or keyup events. That makes it
a lot easier to trigger when you're wearing an HMD.

On Tue, Sep 20, 2016 at 9:20 PM, Michael Chang <flux.blackcat at gmail.com>

> In the latest chromium build:
> VrDisplay.RequestPresent must happen in a user gesture. (Click, touch,
> etc.)
> If you want the page to automatically enter VR (say, from a settimeout),
> you get this error now
> Uncaught (in promise) DOMException: API can only be initiated by a user
>> gesture.
> I want to understand the thought process behind this decision.
> To my understanding, Chrome requires user interaction to go Full Screen
> because some old person might get tricked into thinking the browser is now
> their OS and they're entering their credit card to phishing, which is a
> security concern.
> Am I wrong that is the only reason? How is that relevant to VR though? Why
> is a user gesture required to enter VR?
> *I want to argue that adding an extra button press to enter VR is bad
> friction on both user and developer end.* I know it sounds minor, and
> probably a crap ton of hand holding do-not-put-your-hands-and-legs-outside-of-the-vehicle
> decision making that goes into making Chrome, but it worries me a lot.
> On the User End
> Recall the wonderful discussion we had in the other thread about the
> future of VR, and building the metaverse and linking to other pages which
> are also VR. How incredibly bad would that user experience be if every time
> you link somewhere in VR, you have to take off your headset, go back to
> your desk and find the mouse, then click on enter VR, in which every
> website might have a different way of doing so?
> On the Developer End
> From a developer's perspective, it's bad enough we have to constantly take
> our headsets off and on just to find out what's going on inside there. Take
> for example, Unreal Engine's VR developer mode being really awesome because
> it knows when you've taken off or on the HMD
> <https://www.youtube.com/watch?v=cZJmh881FCo>. This is developer
> friendly, there's very little friction between the editor and entering VR.
> I don't know how you guys develop VR and I've tried several methods to
> make it friction free.
> My VR Development Style
> My first method is developing in HMD all the time, using a combination of Virtual
> Desktop <http://store.steampowered.com/app/382110/> launching chromium
> and having its home page be localhost:8000 and a voice command to reload
> the page. This is neat because I can still type in Sublime Text in VR, and
> still see WebVR live-reloading and everything still works.
> My current method is having a setTimeout automatically enter me in VR (1
> second after page reload) and I just have the HMD on my head and pull it
> down when I need to see something, and just hit reload. This method no
> longer works.
> So what do I do now? I guess I can bind a Vive button to enter VR? How
> janky is this? Why do we have to do these hacks to enter VR, when WebVR is
> about VR content and having to worry about how to enter VR is just friction
> that shouldn't be there?
> Please, if anyone has insight, power to roll back this decision, or just
> want to discuss this issue, hit reply below.
> _______________________________________________
> web-vr-discuss mailing list
> web-vr-discuss at mozilla.org
> https://mail.mozilla.org/listinfo/web-vr-discuss

*Sean T. McBeth*
Lead VR Engineer
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