Add XRFrame.getPose()

components/script/dom/webidls/XRFrame.webidl

@@ -9,5 +9,6 @@ interface XRFrame {
   readonly attribute XRSession session;
 
   [Throws] XRViewerPose? getViewerPose(XRReferenceSpace referenceSpace);
+  [Throws] XRPose? getPose(XRSpace space, XRSpace relativeTo);
   // XRInputPose? getInputPose(XRInputSource inputSource, optional XRReferenceSpace referenceSpace);
 };

components/script/dom/xrframe.rs

@@ -9,8 +9,10 @@ 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::xrpose::XRPose;
 use crate::dom::xrreferencespace::XRReferenceSpace;
 use crate::dom::xrsession::XRSession;
+use crate::dom::xrspace::XRSpace;
 use crate::dom::xrviewerpose::XRViewerPose;
 use dom_struct::dom_struct;
 use webvr_traits::WebVRFrameData;
@@ -67,4 +69,19 @@ impl XRFrameMethods for XRFrame {
             &self.data,
         )))
     }
+
+    /// https://immersive-web.github.io/webxr/#dom-xrframe-getpose
+    fn GetPose(
+        &self,
+        space: &XRSpace,
+        relative_to: &XRSpace,
+    ) -> Result<Option<DomRoot<XRPose>>, Error> {
+        if self.session != space.session() || self.session != relative_to.session() {
+            return Err(Error::InvalidState);
+        }
+        let space = space.get_pose(&self.data);
+        let relative_to = relative_to.get_pose(&self.data);
+        let pose = relative_to.inverse().pre_mul(&space);
+        Ok(Some(XRPose::new(&self.global(), pose)))
+    }
 }