Compute view matrix from viewer pose

components/script/dom/vrdisplay.rs

@@ -173,6 +173,14 @@ impl VRDisplay {
             VRDisplayBinding::Wrap,
         )
     }
+
+    pub fn left_eye_params_offset(&self) -> [f32; 3] {
+        self.left_eye_params.get().offset_array()
+    }
+
+    pub fn right_eye_params_offset(&self) -> [f32; 3] {
+        self.right_eye_params.get().offset_array()
+    }
 }
 
 impl Drop for VRDisplay {

components/script/dom/vreyeparameters.rs

@@ -61,6 +61,10 @@ impl VREyeParameters {
 
         eye_parameters
     }
+
+    pub fn offset_array(&self) -> [f32; 3] {
+        self.parameters.borrow().offset
+    }
 }
 
 impl VREyeParametersMethods for VREyeParameters {

components/script/dom/xrframe.rs

@@ -5,13 +5,11 @@
 use crate::dom::bindings::codegen::Bindings::XRFrameBinding;
 use crate::dom::bindings::codegen::Bindings::XRFrameBinding::XRFrameMethods;
 use crate::dom::bindings::codegen::Bindings::XRViewBinding::XREye;
-use crate::dom::bindings::inheritance::Castable;
 use crate::dom::bindings::reflector::{reflect_dom_object, DomObject, Reflector};
 use crate::dom::bindings::root::{Dom, DomRoot};
 use crate::dom::globalscope::GlobalScope;
 use crate::dom::xrreferencespace::XRReferenceSpace;
 use crate::dom::xrsession::XRSession;
-use crate::dom::xrstationaryreferencespace::XRStationaryReferenceSpace;
 use crate::dom::xrview::XRView;
 use crate::dom::xrviewerpose::XRViewerPose;
 use dom_struct::dom_struct;
@@ -55,16 +53,21 @@ impl XRFrameMethods for XRFrame {
 
     /// https://immersive-web.github.io/webxr/#dom-xrframe-getviewerpose
     fn GetViewerPose(&self, reference: &XRReferenceSpace) -> Option<DomRoot<XRViewerPose>> {
-        if let Some(_) = reference.downcast::<XRStationaryReferenceSpace>() {
-            // For 3DOF devices all three kinds of reference spaces are identical
-            // FIXME(#23070, Manishearth) support originOffset
-            let left = XRView::new(&self.global(), &self.session, XREye::Left, &self.data);
-            let right = XRView::new(&self.global(), &self.session, XREye::Right, &self.data);
-            Some(XRViewerPose::new(&self.global(), &left, &right))
-        } else {
-            // FIXME(#23070, Manishearth) support identity reference spaces
-            // depends on https://github.com/immersive-web/webxr/issues/565
-            None
-        }
+        let pose = reference.get_viewer_pose(&self.data);
+        let left = XRView::new(
+            &self.global(),
+            &self.session,
+            XREye::Left,
+            &pose,
+            &self.data,
+        );
+        let right = XRView::new(
+            &self.global(),
+            &self.session,
+            XREye::Right,
+            &pose,
+            &self.data,
+        );
+        Some(XRViewerPose::new(&self.global(), &left, &right))
     }
 }

components/script/dom/xrsession.rs

@@ -56,6 +56,10 @@ impl XRSession {
         self.display.xr_present(self, None, Some(p));
     }
 
+    pub fn display(&self) -> &VRDisplay {
+        &self.display
+    }
+
     pub fn set_layer(&self, layer: &XRLayer) {
         self.base_layer.set(Some(layer))
     }

components/script/dom/xrview.rs

@@ -10,6 +10,7 @@ use crate::dom::globalscope::GlobalScope;
 use crate::dom::vrframedata::create_typed_array;
 use crate::dom::xrsession::XRSession;
 use dom_struct::dom_struct;
+use euclid::Transform3D;
 use js::jsapi::{Heap, JSContext, JSObject};
 use std::ptr::NonNull;
 use webvr_traits::WebVRFrameData;
@@ -39,6 +40,7 @@ impl XRView {
         global: &GlobalScope,
         session: &XRSession,
         eye: XREye,
+        pose: &Transform3D<f64>,
         data: &WebVRFrameData,
     ) -> DomRoot<XRView> {
         let ret = reflect_dom_object(
@@ -47,16 +49,29 @@ impl XRView {
             XRViewBinding::Wrap,
         );
 
-        let (proj, view) = if eye == XREye::Left {
-            (&data.left_projection_matrix, &data.left_view_matrix)
+        let vr_display = session.display();
+
+        // XXXManishearth compute and cache projection matrices on the Display
+        let (proj, offset) = if eye == XREye::Left {
+            (
+                &data.left_projection_matrix,
+                vr_display.left_eye_params_offset(),
+            )
         } else {
-            (&data.right_projection_matrix, &data.right_view_matrix)
+            (
+                &data.right_projection_matrix,
+                vr_display.right_eye_params_offset(),
+            )
         };
 
+        let offset =
+            Transform3D::create_translation(offset[0] as f64, offset[1] as f64, offset[2] as f64);
+        let view = pose.post_mul(&offset).cast().to_column_major_array();
+
         let cx = global.get_cx();
         unsafe {
             create_typed_array(cx, proj, &ret.proj);
-            create_typed_array(cx, view, &ret.view);
+            create_typed_array(cx, &view, &ret.view);
         }
         ret
     }