From 813613628db87f09014330a9c508b079454198e6 Mon Sep 17 00:00:00 2001
From: Manish Goregaokar <manishsmail@gmail.com>
Date: Thu, 4 Apr 2019 17:40:18 -0700
Subject: [PATCH] Add XRSession.viewerSpace

---
 components/script/dom/webidls/XRSession.webidl |  1 +
 components/script/dom/xrsession.rs             |  6 ++++++
 components/script/dom/xrspace.rs               | 17 ++++++++++++++---
 3 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/components/script/dom/webidls/XRSession.webidl b/components/script/dom/webidls/XRSession.webidl
index 5f2cfb23929..f22918d469d 100644
--- a/components/script/dom/webidls/XRSession.webidl
+++ b/components/script/dom/webidls/XRSession.webidl
@@ -20,6 +20,7 @@ interface XRSession : EventTarget {
   readonly attribute XREnvironmentBlendMode environmentBlendMode;
 
   readonly attribute XRRenderState renderState;
+  readonly attribute XRSpace viewerSpace;
 
   // // Methods
   Promise<XRReferenceSpace> requestReferenceSpace(XRReferenceSpaceOptions options);
diff --git a/components/script/dom/xrsession.rs b/components/script/dom/xrsession.rs
index bf7dcb92258..c8394be5230 100644
--- a/components/script/dom/xrsession.rs
+++ b/components/script/dom/xrsession.rs
@@ -21,6 +21,7 @@ use crate::dom::vrdisplay::VRDisplay;
 use crate::dom::xrlayer::XRLayer;
 use crate::dom::xrreferencespace::XRReferenceSpace;
 use crate::dom::xrrenderstate::XRRenderState;
+use crate::dom::xrspace::XRSpace;
 use crate::dom::xrstationaryreferencespace::XRStationaryReferenceSpace;
 use dom_struct::dom_struct;
 use std::rc::Rc;
@@ -82,6 +83,11 @@ impl XRSessionMethods for XRSession {
         )
     }
 
+    // https://immersive-web.github.io/webxr/#dom-xrsession-viewerspace
+    fn ViewerSpace(&self) -> DomRoot<XRSpace> {
+        XRSpace::new_viewerspace(&self.global(), &self)
+    }
+
     /// https://immersive-web.github.io/webxr/#dom-xrsession-requestanimationframe
     fn UpdateRenderState(&self, init: &XRRenderStateInit) -> Rc<Promise> {
         let p = Promise::new(&self.global());
diff --git a/components/script/dom/xrspace.rs b/components/script/dom/xrspace.rs
index d9bbad8cd86..8948ac03c8e 100644
--- a/components/script/dom/xrspace.rs
+++ b/components/script/dom/xrspace.rs
@@ -18,6 +18,7 @@ use webvr_traits::WebVRFrameData;
 pub struct XRSpace {
     eventtarget: EventTarget,
     session: Dom<XRSession>,
+    is_viewerspace: bool,
 }
 
 impl XRSpace {
@@ -25,13 +26,21 @@ impl XRSpace {
         XRSpace {
             eventtarget: EventTarget::new_inherited(),
             session: Dom::from_ref(session),
+            is_viewerspace: false,
         }
     }
 
-    #[allow(unused)]
-    pub fn new(global: &GlobalScope, session: &XRSession) -> DomRoot<XRSpace> {
+    fn new_viewerspace_inner(session: &XRSession) -> XRSpace {
+        XRSpace {
+            eventtarget: EventTarget::new_inherited(),
+            session: Dom::from_ref(session),
+            is_viewerspace: true,
+        }
+    }
+
+    pub fn new_viewerspace(global: &GlobalScope, session: &XRSession) -> DomRoot<XRSpace> {
         reflect_dom_object(
-            Box::new(XRSpace::new_inherited(session)),
+            Box::new(XRSpace::new_viewerspace_inner(session)),
             global,
             XRSpaceBinding::Wrap,
         )
@@ -47,6 +56,8 @@ impl XRSpace {
     pub fn get_pose(&self, base_pose: &WebVRFrameData) -> RigidTransform3D<f64> {
         if let Some(reference) = self.downcast::<XRReferenceSpace>() {
             reference.get_pose(base_pose)
+        } else if self.is_viewerspace {
+            XRSpace::viewer_pose_from_frame_data(base_pose)
         } else {
             unreachable!()
         }