From 89fac8be5cca24b1d67259d8f27bd829e188a632 Mon Sep 17 00:00:00 2001
From: Manish Goregaokar <manishsmail@gmail.com>
Date: Fri, 24 Apr 2020 12:25:16 -0700
Subject: [PATCH] Add XRJointSpace

---
 components/script/dom/bindings/trace.rs       |  1 +
 components/script/dom/mod.rs                  |  1 +
 .../script/dom/webidls/XRJointSpace.webidl    |  8 +++
 components/script/dom/xrjointspace.rs         | 60 +++++++++++++++++++
 components/script/dom/xrspace.rs              |  5 ++
 5 files changed, 75 insertions(+)
 create mode 100644 components/script/dom/webidls/XRJointSpace.webidl
 create mode 100644 components/script/dom/xrjointspace.rs

diff --git a/components/script/dom/bindings/trace.rs b/components/script/dom/bindings/trace.rs
index 7a15870e917c..c2543cc984bd 100644
--- a/components/script/dom/bindings/trace.rs
+++ b/components/script/dom/bindings/trace.rs
@@ -554,6 +554,7 @@ unsafe_no_jsmanaged_fields!(
     webxr_api::Frame,
     webxr_api::InputSource,
     webxr_api::InputId,
+    webxr_api::Joint,
     webxr_api::HitTestId,
     webxr_api::HitTestResult
 );
diff --git a/components/script/dom/mod.rs b/components/script/dom/mod.rs
index 5c2ab9783163..7365fe36a18a 100644
--- a/components/script/dom/mod.rs
+++ b/components/script/dom/mod.rs
@@ -579,6 +579,7 @@ pub mod xrinputsource;
 pub mod xrinputsourcearray;
 pub mod xrinputsourceevent;
 pub mod xrinputsourceschangeevent;
+pub mod xrjointspace;
 pub mod xrlayer;
 pub mod xrmediabinding;
 pub mod xrpose;
diff --git a/components/script/dom/webidls/XRJointSpace.webidl b/components/script/dom/webidls/XRJointSpace.webidl
new file mode 100644
index 000000000000..0815a73ec58d
--- /dev/null
+++ b/components/script/dom/webidls/XRJointSpace.webidl
@@ -0,0 +1,8 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+// https://github.com/immersive-web/webxr-hands-input/blob/master/explainer.md
+
+[SecureContext, Exposed=Window, Pref="dom.webxr.hands.enabled"]
+interface XRJointSpace: XRSpace {};
diff --git a/components/script/dom/xrjointspace.rs b/components/script/dom/xrjointspace.rs
new file mode 100644
index 000000000000..4b31b0bc6a2c
--- /dev/null
+++ b/components/script/dom/xrjointspace.rs
@@ -0,0 +1,60 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+use crate::dom::bindings::reflector::reflect_dom_object;
+use crate::dom::bindings::root::DomRoot;
+use crate::dom::globalscope::GlobalScope;
+use crate::dom::xrsession::{ApiPose, XRSession};
+use crate::dom::xrspace::XRSpace;
+use dom_struct::dom_struct;
+use euclid::RigidTransform3D;
+use webxr_api::{BaseSpace, Frame, InputId, Joint, JointFrame, Space};
+
+#[dom_struct]
+pub struct XRJointSpace {
+    xrspace: XRSpace,
+    #[ignore_malloc_size_of = "defined in rust-webxr"]
+    input: InputId,
+    #[ignore_malloc_size_of = "defined in rust-webxr"]
+    joint: Joint,
+}
+
+impl XRJointSpace {
+    pub fn new_inherited(session: &XRSession, input: InputId, joint: Joint) -> XRJointSpace {
+        XRJointSpace {
+            xrspace: XRSpace::new_inherited(session),
+            input,
+            joint,
+        }
+    }
+
+    #[allow(unused)]
+    pub fn new(
+        global: &GlobalScope,
+        session: &XRSession,
+        input: InputId,
+        joint: Joint,
+    ) -> DomRoot<XRJointSpace> {
+        reflect_dom_object(Box::new(Self::new_inherited(session, input, joint)), global)
+    }
+
+    pub fn space(&self) -> Space {
+        let base = BaseSpace::Joint(self.input, self.joint);
+        let offset = RigidTransform3D::identity();
+        Space { base, offset }
+    }
+
+    pub fn frame<'a>(&self, frame: &'a Frame) -> Option<&'a JointFrame> {
+        frame
+            .inputs
+            .iter()
+            .find(|i| i.id == self.input)
+            .and_then(|i| i.hand.as_ref())
+            .and_then(|h| h.get(self.joint))
+    }
+
+    pub fn get_pose(&self, frame: &Frame) -> Option<ApiPose> {
+        self.frame(frame).map(|f| f.pose).map(|t| t.cast_unit())
+    }
+}
diff --git a/components/script/dom/xrspace.rs b/components/script/dom/xrspace.rs
index b4a26b7b8bbb..66dd5b44e70f 100644
--- a/components/script/dom/xrspace.rs
+++ b/components/script/dom/xrspace.rs
@@ -8,6 +8,7 @@ use crate::dom::bindings::root::{Dom, DomRoot, MutNullableDom};
 use crate::dom::eventtarget::EventTarget;
 use crate::dom::globalscope::GlobalScope;
 use crate::dom::xrinputsource::XRInputSource;
+use crate::dom::xrjointspace::XRJointSpace;
 use crate::dom::xrreferencespace::XRReferenceSpace;
 use crate::dom::xrsession::{cast_transform, ApiPose, XRSession};
 use dom_struct::dom_struct;
@@ -61,6 +62,8 @@ impl XRSpace {
     pub fn space(&self) -> Space {
         if let Some(rs) = self.downcast::<XRReferenceSpace>() {
             rs.space()
+        } else if let Some(j) = self.downcast::<XRJointSpace>() {
+            j.space()
         } else if let Some(source) = self.input_source.get() {
             let base = if self.is_grip_space {
                 BaseSpace::Grip(source.id())
@@ -86,6 +89,8 @@ impl XRSpace {
     pub fn get_pose(&self, base_pose: &Frame) -> Option<ApiPose> {
         if let Some(reference) = self.downcast::<XRReferenceSpace>() {
             reference.get_pose(base_pose)
+        } else if let Some(joint) = self.downcast::<XRJointSpace>() {
+            joint.get_pose(base_pose)
         } else if let Some(source) = self.input_source.get() {
             // XXXManishearth we should be able to request frame information
             // for inputs when necessary instead of always loading it