Add proper get_pose for XRSpaces

components/script/dom/xrreferencespace.rs

@@ -55,6 +55,9 @@ impl XRReferenceSpaceMethods for XRReferenceSpace {
 
 impl XRReferenceSpace {
     /// Gets pose of the viewer with respect to this space
+    ///
+    /// This is equivalent to `get_pose(self).inverse() * get_pose(viewerSpace)`, however
+    /// we specialize it to be efficient
     pub fn get_viewer_pose(&self, base_pose: &WebVRFrameData) -> RigidTransform3D<f64> {
         let pose = self.get_unoffset_viewer_pose(base_pose);
 
@@ -72,7 +75,8 @@ impl XRReferenceSpace {
             stationary.get_unoffset_viewer_pose(base_pose)
         } else {
             // non-subclassed XRReferenceSpaces exist, obtained via the "identity"
-            // type. The pose does not depend on the base pose.
+            // type. These poses are equivalent to the viewer pose and follow the headset
+            // around, so the viewer is always at an identity transform with respect to them
             RigidTransform3D::identity()
         }
     }
@@ -82,7 +86,25 @@ impl XRReferenceSpace {
     /// The reference origin used is common between all
     /// get_pose calls for spaces from the same device, so this can be used to compare
     /// with other spaces
-    pub fn get_pose(&self, _: &WebVRFrameData) -> RigidTransform3D<f64> {
-        unimplemented!()
+    pub fn get_pose(&self, base_pose: &WebVRFrameData) -> RigidTransform3D<f64> {
+        let pose = self.get_unoffset_pose(base_pose);
+
+        // This may change, see https://github.com/immersive-web/webxr/issues/567
+        let offset = self.transform.get().transform();
+        offset.post_mul(&pose)
+    }
+
+    /// Gets pose represented by this space
+    ///
+    /// Does not apply originOffset, use get_viewer_pose instead if you need it
+    pub fn get_unoffset_pose(&self, base_pose: &WebVRFrameData) -> RigidTransform3D<f64> {
+        if let Some(stationary) = self.downcast::<XRStationaryReferenceSpace>() {
+            stationary.get_unoffset_pose(base_pose)
+        } else {
+            // non-subclassed XRReferenceSpaces exist, obtained via the "identity"
+            // type. These are equivalent to the viewer pose and follow the headset
+            // around
+            XRSpace::viewer_pose_from_frame_data(base_pose)
+        }
     }
 }

components/script/dom/xrspace.rs

@@ -11,7 +11,7 @@ use crate::dom::globalscope::GlobalScope;
 use crate::dom::xrreferencespace::XRReferenceSpace;
 use crate::dom::xrsession::XRSession;
 use dom_struct::dom_struct;
-use euclid::RigidTransform3D;
+use euclid::{RigidTransform3D, Rotation3D, Vector3D};
 use webvr_traits::WebVRFrameData;
 
 #[dom_struct]
@@ -39,16 +39,6 @@ impl XRSpace {
 }
 
 impl XRSpace {
-    /// Gets pose of the viewer with respect to this space
-    #[allow(unused)]
-    pub fn get_viewer_pose(&self, base_pose: &WebVRFrameData) -> RigidTransform3D<f64> {
-        if let Some(reference) = self.downcast::<XRReferenceSpace>() {
-            reference.get_viewer_pose(base_pose)
-        } else {
-            unreachable!()
-        }
-    }
-
     /// Gets pose represented by this space
     ///
     /// The reference origin used is common between all
@@ -62,4 +52,17 @@ impl XRSpace {
             unreachable!()
         }
     }
+
+    pub fn viewer_pose_from_frame_data(data: &WebVRFrameData) -> RigidTransform3D<f64> {
+        let pos = data.pose.position.unwrap_or([0., 0., 0.]);
+        let translation = Vector3D::new(pos[0] as f64, pos[1] as f64, pos[2] as f64);
+        let orient = data.pose.orientation.unwrap_or([0., 0., 0., 0.]);
+        let rotation = Rotation3D::quaternion(
+            orient[0] as f64,
+            orient[1] as f64,
+            orient[2] as f64,
+            orient[3] as f64,
+        );
+        RigidTransform3D::new(rotation, translation)
+    }
 }

components/script/dom/xrstationaryreferencespace.rs

@@ -10,8 +10,9 @@ use crate::dom::globalscope::GlobalScope;
 use crate::dom::xrreferencespace::XRReferenceSpace;
 use crate::dom::xrrigidtransform::XRRigidTransform;
 use crate::dom::xrsession::XRSession;
+use crate::dom::xrspace::XRSpace;
 use dom_struct::dom_struct;
-use euclid::{RigidTransform3D, Rotation3D, Vector3D};
+use euclid::RigidTransform3D;
 use webvr_traits::WebVRFrameData;
 
 #[dom_struct]
@@ -55,15 +56,17 @@ impl XRStationaryReferenceSpace {
     /// Does not apply originOffset, use get_viewer_pose on XRReferenceSpace instead
     pub fn get_unoffset_viewer_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 = 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,
-            orient[1] as f64,
-            orient[2] as f64,
-            orient[3] as f64,
-        );
-        RigidTransform3D::new(rotation, translation)
+        XRSpace::viewer_pose_from_frame_data(base_pose)
+    }
+
+    /// Gets pose represented by this space
+    ///
+    /// Does not apply originOffset, use get_pose on XRReferenceSpace instead
+    pub fn get_unoffset_pose(&self, _: &WebVRFrameData) -> RigidTransform3D<f64> {
+        // XXXManishearth add floor-level transform for floor-level and disable position in position-disabled
+
+        // The eye-level pose is basically whatever the headset pose was at t=0, which
+        // for most devices is (0, 0, 0)
+        RigidTransform3D::identity()
     }
 }