Merge pull request #1105 from Manishearth/primary-views-active

Manishearth · web-flow · commit de372087e951 · 2020-07-23T23:35:48.000-07:00
Primary views MUST always be active
diff --git a/index.bs b/index.bs
@@ -1323,7 +1323,7 @@ A [=view=] has an associated <dfn for="view">projection matrix</dfn> which is a
 
 A [=view=] has an associated <dfn for="view">eye</dfn> which is an {{XREye}} describing which eye this view is expected to be shown to. If the view does not have an intrinsically associated eye (the display is monoscopic, for example) this value MUST be set to {{XREye/"none"}}.
 
-A [=view=] has an <dfn for="view">active</dfn> flag that may change through the lifecycle of an {{XRSession}}. [=Primary views=] SHOULD always have the [=view/active=] flag set to <code>true</code>.
+A [=view=] has an <dfn for="view">active</dfn> flag that may change through the lifecycle of an {{XRSession}}. [=Primary views=] MUST always have the [=view/active=] flag set to <code>true</code>.
 
 Note: Many HMDs will request that content render two [=views=], one for the left eye and one for the right, while most magic window devices will only request one [=view=], but applications should never assume a specific view configuration. For example: A magic window device may request two views if it is capable of stereo output, but may revert to requesting a single view for performance reasons if the stereo output mode is turned off. Similarly, HMDs may request more than two views to facilitate a wide field of view or displays of different pixel density.
 
@@ -1390,9 +1390,9 @@ When the [=view/active=] flag of any [=view=] in the [=XRSession/list of views=]
 Primary and Secondary Views {#primary-and-secondary-views}
 ----------
 
-A [=view=] is a <dfn>primary view</dfn> when rendering to it is necessary for an immersive experience.
+A [=view=] is a <dfn>primary view</dfn> when rendering to it is necessary for an immersive experience. [=Primary views=] MUST be [=view/active=] for the entire duration of the {{XRSession}}.
 
-A [=view=] is a <dfn>secondary view</dfn> when it is possible for content to choose to not render to it and still produce a working immersive experience. When content chooses to not render to these views, the user-agent MAY be able to reconstruct them via reprojection.
+A [=view=] is a <dfn>secondary view</dfn> when it is possible for content to choose to not render to it and still produce a working immersive experience. When content chooses to not render to these views, the user-agent MAY be able to reconstruct them via reprojection. Secondary views MUST NOT be [=view/active=] unless the "[=secondary view/secondary-views=]" feature is enabled.
 
 <div class="example">
 Examples of [=primary views=] include the main mono view for a handheld AR session, the main two stereo views for headworn AR/VR sessions, or all of the wall views for a CAVE session.
