Auto merge of #23159 - Manishearth:rigid-transforms, r=asajeffrey

Update XR code to use rigid transforms and new pose/transform stuff from the spec

This updates our XR code to use euclid's new [RigidTransform3D type](https://github.com/servo/euclid/pull/328), which is more efficent and convenient to work with.

It additionally brings us up to speed with the spec:

 - `XRViewerPose` was made a subclass of `XRPose` (https://github.com/immersive-web/webxr/pull/496)
 - `XRView.viewMatrix` was removed in favor of `XRRigidTransform.inverse.matrix` (https://github.com/immersive-web/webxr/pull/531)
 - `XRRigidTransform.inverse` is an attribute (https://github.com/immersive-web/webxr/pull/560)
 - `XRRigidTransform` now validates positions in its constructor (https://github.com/immersive-web/webxr/pull/568)

Furthermore, it adds support for `XRRigidTransform.matrix`.

While fixing this I also noticed that our view matrix code was incorrect, we calculated view matrices as `pose.to_column_major_array()`, whereas it *should* be `pose.inverse().to_row_major_array()` (since Euclid uses row vectors, whenever the spec says it wants a column major array we should use `.to_row_major_array()` since all web specs implicitly use column vectors). For 3DOF devices poses are mostly rotations anyway, so the effective transpose behaved _like_ an inversion, but was incorrect.

This PR gets rid of `view.viewMatrix` anyway, however I felt like I should mention this discrepancy, since otherwise the replacement of `view.viewMatrix` with `view.transform.inverse.matrix` doesn't make sense

r? @jdm

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1 files changed, 21 insertions, 7 deletions

diff --git a/components/script/dom/xrviewerpose.rs b/components/script/dom/xrviewerpose.rs
index af26b23aeb1..717fdcea16e 100644
--- a/components/script/dom/xrviewerpose.rs
+++ b/components/script/dom/xrviewerpose.rs
@@ -2,35 +2,49 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
+use crate::dom::bindings::codegen::Bindings::XRViewBinding::XREye;
 use crate::dom::bindings::codegen::Bindings::XRViewerPoseBinding;
 use crate::dom::bindings::codegen::Bindings::XRViewerPoseBinding::XRViewerPoseMethods;
-use crate::dom::bindings::reflector::{reflect_dom_object, Reflector};
+use crate::dom::bindings::reflector::reflect_dom_object;
 use crate::dom::bindings::root::DomRoot;
 use crate::dom::globalscope::GlobalScope;
+use crate::dom::xrpose::XRPose;
+use crate::dom::xrrigidtransform::XRRigidTransform;
+use crate::dom::xrsession::XRSession;
 use crate::dom::xrview::XRView;
 use dom_struct::dom_struct;
+use euclid::RigidTransform3D;
 use js::conversions::ToJSValConvertible;
 use js::jsapi::{Heap, JSContext};
 use js::jsval::{JSVal, UndefinedValue};
+use webvr_traits::WebVRFrameData;
 
 #[dom_struct]
 pub struct XRViewerPose {
-    reflector_: Reflector,
+    pose: XRPose,
     views: Heap<JSVal>,
 }
 
 impl XRViewerPose {
-    fn new_inherited() -> XRViewerPose {
+    fn new_inherited(transform: &XRRigidTransform) -> XRViewerPose {
         XRViewerPose {
-            reflector_: Reflector::new(),
+            pose: XRPose::new_inherited(transform),
             views: Heap::default(),
         }
     }
 
     #[allow(unsafe_code)]
-    pub fn new(global: &GlobalScope, left: &XRView, right: &XRView) -> DomRoot<XRViewerPose> {
+    pub fn new(
+        global: &GlobalScope,
+        session: &XRSession,
+        pose: RigidTransform3D<f64>,
+        data: &WebVRFrameData,
+    ) -> DomRoot<XRViewerPose> {
+        let left = XRView::new(global, session, XREye::Left, &pose, &data);
+        let right = XRView::new(global, session, XREye::Right, &pose, &data);
+        let transform = XRRigidTransform::new(global, pose);
         let pose = reflect_dom_object(
-            Box::new(XRViewerPose::new_inherited()),
+            Box::new(XRViewerPose::new_inherited(&transform)),
             global,
             XRViewerPoseBinding::Wrap,
         );
@@ -38,7 +52,7 @@ impl XRViewerPose {
         unsafe {
             let cx = global.get_cx();
             rooted!(in(cx) let mut jsval = UndefinedValue());
-            let vec = vec![DomRoot::from_ref(left), DomRoot::from_ref(right)];
+            let vec = vec![left, right];
             vec.to_jsval(cx, jsval.handle_mut());
             pose.views.set(jsval.get());
         }