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, 8 insertions, 9 deletions

diff --git a/components/script/dom/xrstationaryreferencespace.rs b/components/script/dom/xrstationaryreferencespace.rs
index e8349ef3581..ddba9aaa20b 100644
--- a/components/script/dom/xrstationaryreferencespace.rs
+++ b/components/script/dom/xrstationaryreferencespace.rs
@@ -6,12 +6,12 @@ use crate::dom::bindings::codegen::Bindings::XRStationaryReferenceSpaceBinding;
 use crate::dom::bindings::codegen::Bindings::XRStationaryReferenceSpaceBinding::XRStationaryReferenceSpaceSubtype;
 use crate::dom::bindings::reflector::reflect_dom_object;
 use crate::dom::bindings::root::DomRoot;
-use crate::dom::window::Window;
+use crate::dom::globalscope::GlobalScope;
 use crate::dom::xrreferencespace::XRReferenceSpace;
 use crate::dom::xrrigidtransform::XRRigidTransform;
 use crate::dom::xrsession::XRSession;
 use dom_struct::dom_struct;
-use euclid::{Rotation3D, Transform3D};
+use euclid::{RigidTransform3D, Rotation3D, Vector3D};
 use webvr_traits::WebVRFrameData;
 
 #[dom_struct]
@@ -34,16 +34,16 @@ impl XRStationaryReferenceSpace {
     }
 
     pub fn new(
-        window: &Window,
+        global: &GlobalScope,
         session: &XRSession,
         ty: XRStationaryReferenceSpaceSubtype,
     ) -> DomRoot<XRStationaryReferenceSpace> {
-        let transform = XRRigidTransform::identity(window);
+        let transform = XRRigidTransform::identity(global);
         reflect_dom_object(
             Box::new(XRStationaryReferenceSpace::new_inherited(
                 session, ty, &transform,
             )),
-            window,
+            global,
             XRStationaryReferenceSpaceBinding::Wrap,
         )
     }
@@ -53,11 +53,10 @@ impl XRStationaryReferenceSpace {
     /// Gets pose represented by this space
     ///
     /// Does not apply originOffset, use get_viewer_pose instead
-    pub fn get_pose(&self, base_pose: &WebVRFrameData) -> Transform3D<f64> {
+    pub fn get_pose(&self, base_pose: &WebVRFrameData) -> RigidTransform3D<f64> {
         // XXXManishearth add floor-level transform for floor-level and disable position in position-disabled
         let pos = base_pose.pose.position.unwrap_or([0., 0., 0.]);
-        let translation =
-            Transform3D::create_translation(pos[0] as f64, pos[1] as f64, pos[2] as f64);
+        let translation = Vector3D::new(pos[0] as f64, pos[1] as f64, pos[2] as f64);
         let orient = base_pose.pose.orientation.unwrap_or([0., 0., 0., 0.]);
         let rotation = Rotation3D::quaternion(
             orient[0] as f64,
@@ -65,6 +64,6 @@ impl XRStationaryReferenceSpace {
             orient[2] as f64,
             orient[3] as f64,
         );
-        translation.pre_mul(&rotation.to_transform())
+        RigidTransform3D::new(rotation, translation)
     }
 }