Move XRRigidTransform to using RigidTransform3D

1 files changed, 19 insertions, 36 deletions

diff --git a/components/script/dom/xrrigidtransform.rs b/components/script/dom/xrrigidtransform.rs
index ad7cbe7543b..c32d0f75838 100644
--- a/components/script/dom/xrrigidtransform.rs
+++ b/components/script/dom/xrrigidtransform.rs
@@ -13,7 +13,7 @@ use crate::dom::bindings::root::{Dom, DomRoot};
 use crate::dom::dompointreadonly::DOMPointReadOnly;
 use crate::dom::window::Window;
 use dom_struct::dom_struct;
-use euclid::{Rotation3D, Transform3D};
+use euclid::{RigidTransform3D, Rotation3D, Transform3D, Vector3D};
 
 #[dom_struct]
 pub struct XRRigidTransform {
@@ -21,9 +21,7 @@ pub struct XRRigidTransform {
     position: Dom<DOMPointReadOnly>,
     orientation: Dom<DOMPointReadOnly>,
     #[ignore_malloc_size_of = "defined in euclid"]
-    translate: Transform3D<f64>,
-    #[ignore_malloc_size_of = "defined in euclid"]
-    rotate: Rotation3D<f64>,
+    transform: RigidTransform3D<f64>,
 }
 
 impl XRRigidTransform {
@@ -31,7 +29,7 @@ impl XRRigidTransform {
         position: &DOMPointReadOnly,
         orientation: &DOMPointReadOnly,
     ) -> XRRigidTransform {
-        let translate = Transform3D::create_translation(
+        let translate = Vector3D::new(
             position.X() as f64,
             position.Y() as f64,
             position.Z() as f64,
@@ -42,12 +40,12 @@ impl XRRigidTransform {
             orientation.Z() as f64,
             orientation.W() as f64,
         );
+        let transform = RigidTransform3D::new(rotate, translate);
         XRRigidTransform {
             reflector_: Reflector::new(),
             position: Dom::from_ref(position),
             orientation: Dom::from_ref(orientation),
-            translate,
-            rotate,
+            transform,
         }
     }
 
@@ -101,37 +99,22 @@ impl XRRigidTransformMethods for XRRigidTransform {
     }
     // https://immersive-web.github.io/webxr/#dom-xrrigidtransform-inverse
     fn Inverse(&self) -> DomRoot<XRRigidTransform> {
-        // An XRRigidTransform is a rotation and a translation,
-        // i.e. T * R
-        //
-        // Its inverse is (T * R)^-1
-        //    = R^-1 * T^-1
-        //    = R^-1 * T^-1 * (R * R^-1)
-        //    = (R^-1 * T^-1 * R) * R^-1
-        //    = T' * R^-1
-        //    = T' * R'
-        //
-        //  (R^-1 * T^-1 * R) is a translation matrix, and R^-1 is a
-        //  rotation matrix, so we can use these in the new rigid transform
-        let r_1 = self.rotate.inverse();
-        let t_1 = self
-            .translate
-            .inverse()
-            .expect("translation matrices should be invertible");
-        let t_p = r_1
-            .to_transform()
-            .post_mul(&t_1)
-            .post_mul(&self.rotate.to_transform());
-
         let global = self.global();
-        let position =
-            DOMPointReadOnly::new(&global, t_p.m41.into(), t_p.m42.into(), t_p.m43.into(), 1.);
+        let inverse = self.transform.inverse();
+
+        let position = DOMPointReadOnly::new(
+            &global,
+            inverse.translation.x.into(),
+            inverse.translation.y.into(),
+            inverse.translation.z.into(),
+            1.,
+        );
         let orientation = DOMPointReadOnly::new(
             &global,
-            r_1.i.into(),
-            r_1.j.into(),
-            r_1.k.into(),
-            r_1.r.into(),
+            inverse.rotation.i.into(),
+            inverse.rotation.j.into(),
+            inverse.rotation.k.into(),
+            inverse.rotation.r.into(),
         );
         XRRigidTransform::new(global.as_window(), &position, &orientation)
     }
@@ -141,6 +124,6 @@ impl XRRigidTransform {
     pub fn matrix(&self) -> Transform3D<f64> {
         // Spec says the orientation applies first,
         // so post-multiply (?)
-        self.translate.post_mul(&self.rotate.to_transform())
+        self.transform.to_transform()
     }
 }