Added first-cut implementation of XR layers

14 files changed, 519 insertions, 15 deletions

diff --git a/components/script/dom/mod.rs b/components/script/dom/mod.rs
index dcc9af258cd..9ae4274a194 100644
--- a/components/script/dom/mod.rs
+++ b/components/script/dom/mod.rs
@@ -535,9 +535,8 @@ pub mod videotracklist;
 pub mod virtualmethods;
 pub mod vttcue;
 pub mod vttregion;
-pub mod webgl_extensions;
-pub use self::webgl_extensions::ext::*;
 pub mod webgl2renderingcontext;
+pub mod webgl_extensions;
 pub mod webgl_validations;
 pub mod webglactiveinfo;
 pub mod webglbuffer;
@@ -577,6 +576,8 @@ pub mod xrinputsource;
 pub mod xrinputsourcearray;
 pub mod xrinputsourceevent;
 pub mod xrinputsourceschangeevent;
+pub mod xrlayer;
+pub mod xrmediabinding;
 pub mod xrpose;
 pub mod xrreferencespace;
 pub mod xrrenderstate;
@@ -584,9 +585,13 @@ pub mod xrrigidtransform;
 pub mod xrsession;
 pub mod xrsessionevent;
 pub mod xrspace;
+pub mod xrsubimage;
 pub mod xrsystem;
 pub mod xrtest;
 pub mod xrview;
 pub mod xrviewerpose;
 pub mod xrviewport;
+pub mod xrwebglbinding;
 pub mod xrwebgllayer;
+pub mod xrwebglsubimage;
+pub use self::webgl_extensions::ext::*;
diff --git a/components/script/dom/webidls/XRLayer.webidl b/components/script/dom/webidls/XRLayer.webidl
new file mode 100644
index 00000000000..eb967abf091
--- /dev/null
+++ b/components/script/dom/webidls/XRLayer.webidl
@@ -0,0 +1,63 @@
+/* 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://immersive-web.github.io/layers/#xrlayertype
+[SecureContext, Exposed=Window, Pref="dom.webxr.layers.enabled"]
+interface XRLayer {
+  readonly attribute unsigned long pixelWidth;
+  readonly attribute unsigned long pixelHeight;
+
+//  attribute boolean blendTextureSourceAlpha;
+//  attribute boolean chromaticAberrationCorrection;
+
+  void destroy();
+};
+//
+// TODO: Implement the layer types
+//
+// [SecureContext, Exposed=Window, Pref="dom.webxr.enabled"]
+// interface XRProjectionLayer : XRLayer {
+//   readonly attribute boolean ignoreDepthValues;
+// };
+//
+// [SecureContext, Exposed=Window, Pref="dom.webxr.layers.enabled"]
+// interface XRQuadLayer : XRLayer {
+//   readonly attribute XRLayerLayout layout;
+//   attribute XRRigidTransform transform;
+//
+//   attribute float width;
+//   attribute float height;
+// };
+//
+// [SecureContext, Exposed=Window, Pref="dom.webxr.layers.enabled"]
+// interface XRCylinderLayer : XRLayer {
+//   readonly attribute XRLayerLayout layout;
+//   attribute XRReferenceSpace referenceSpace;
+//
+//   attribute XRRigidTransform transform;
+//   attribute float radius;
+//   attribute float centralAngle;
+//   attribute float aspectRatio;
+// };
+//
+// [SecureContext, Exposed=Window, Pref="dom.webxr.layers.enabled"]
+// interface XREquirectLayer : XRLayer {
+//   readonly attribute XRLayerLayout layout;
+//   attribute XRReferenceSpace referenceSpace;
+//
+//   attribute XRRigidTransform transform;
+//   attribute float radius;
+//   attribute float scaleX;
+//   attribute float scaleY;
+//   attribute float biasX;
+//   attribute float biasY;
+// };
+//
+// [SecureContext, Exposed=Window, Pref="dom.webxr.layers.enabled"]
+// interface XRCubeLayer : XRLayer {
+//   readonly attribute XRLayerLayout layout;
+//   attribute XRReferenceSpace referenceSpace;
+//
+//   attribute DOMPoint orientation;
+// };
diff --git a/components/script/dom/webidls/XRMediaBinding.webidl b/components/script/dom/webidls/XRMediaBinding.webidl
new file mode 100644
index 00000000000..9ea40de56a4
--- /dev/null
+++ b/components/script/dom/webidls/XRMediaBinding.webidl
@@ -0,0 +1,18 @@
+/* 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://immersive-web.github.io/layers/#xrmediabindingtype
+[SecureContext, Exposed=Window, Pref="dom.webxr.layers.enabled"]
+interface XRMediaBinding {
+  constructor(XRSession session);
+
+//  XRQuadLayer createQuadVideoLayer(HTMLVideoElement video, optional XRMediaLayerInit init = {});
+//  XRCylinderLayer createCylinderVideoLayer(HTMLVideoElement video, optional XRMediaLayerInit init = {});
+//  XREquirectLayer createEquirectVideoLayer(HTMLVideoElement video, optional XRMediaLayerInit init = {});
+};
+
+dictionary XRMediaLayerInit {
+  XRLayerLayout layout = "mono";
+  boolean invertStereo = false;
+};
diff --git a/components/script/dom/webidls/XRRenderState.webidl b/components/script/dom/webidls/XRRenderState.webidl
index e361ced6597..708df1f20eb 100644
--- a/components/script/dom/webidls/XRRenderState.webidl
+++ b/components/script/dom/webidls/XRRenderState.webidl
@@ -2,6 +2,8 @@
  * 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/. */
 
+typedef (XRWebGLLayer or XRLayer) XRGenericLayer;
+
 // https://immersive-web.github.io/webxr/#xrrenderstate-interface
 
 dictionary XRRenderStateInit {
@@ -9,6 +11,7 @@ dictionary XRRenderStateInit {
   double depthFar;
   double inlineVerticalFieldOfView;
   XRWebGLLayer baseLayer;
+  sequence<XRGenericLayer> layers;
 };
 
 [SecureContext, Exposed=Window, Pref="dom.webxr.enabled"] interface XRRenderState {
diff --git a/components/script/dom/webidls/XRSubImage.webidl b/components/script/dom/webidls/XRSubImage.webidl
new file mode 100644
index 00000000000..9dbbd089928
--- /dev/null
+++ b/components/script/dom/webidls/XRSubImage.webidl
@@ -0,0 +1,9 @@
+/* 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://immersive-web.github.io/layers/#xrsubimagetype
+[SecureContext, Exposed=Window, Pref="dom.webxr.layers.enabled"]
+interface XRSubImage {
+  readonly attribute XRViewport viewport;
+};
diff --git a/components/script/dom/webidls/XRWebGLBinding.webidl b/components/script/dom/webidls/XRWebGLBinding.webidl
new file mode 100644
index 00000000000..08617561b36
--- /dev/null
+++ b/components/script/dom/webidls/XRWebGLBinding.webidl
@@ -0,0 +1,44 @@
+/* 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://immersive-web.github.io/layers/#XRWebGLBindingtype
+[SecureContext, Exposed=Window, Pref="dom.webxr.layers.enabled"]
+interface XRWebGLBinding {
+  constructor(XRSession session, XRWebGLRenderingContext context);
+
+//  readonly attribute double nativeProjectionScaleFactor;
+
+//  XRProjectionLayer createProjectionLayer(GLenum textureTarget, optional XRProjectionLayerInit init = {});
+//  XRQuadLayer createQuadLayer(GLenum textureTarget, XRLayerInit init);
+//  XRCylinderLayer createCylinderLayer(GLenum textureTarget, XRLayerInit init);
+//  XREquirectLayer createEquirectLayer(GLenum textureTarget, XRLayerInit init);
+//  XRCubeLayer createCubeLayer(XRLayerInit init);
+
+  XRWebGLSubImage? getSubImage(XRLayer layer, XRFrame frame); // for mono layers
+  XRWebGLSubImage? getViewSubImage(XRLayer layer, XRView view); // for stereo layers
+};
+
+dictionary XRProjectionLayerInit {
+  boolean depth = true;
+  boolean stencil = false;
+  boolean alpha = true;
+  double scaleFactor = 1.0;
+};
+
+dictionary XRLayerInit {
+  required unsigned long pixelWidth;
+  required unsigned long pixelHeight;
+  XRLayerLayout layout = "mono";
+  boolean depth = false; // This is a change from typical WebGL initialization, but feels appropriate.
+  boolean stencil = false;
+  boolean alpha = true;
+};
+
+enum XRLayerLayout {
+  "mono",
+  "stereo",
+  "stereo-left-right",
+  "stereo-top-bottom"
+};
+
diff --git a/components/script/dom/webidls/XRWebGLSubImage.webidl b/components/script/dom/webidls/XRWebGLSubImage.webidl
new file mode 100644
index 00000000000..f25552d533e
--- /dev/null
+++ b/components/script/dom/webidls/XRWebGLSubImage.webidl
@@ -0,0 +1,11 @@
+/* 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://immersive-web.github.io/layers/#xrwebglsubimagetype
+[SecureContext, Exposed=Window, Pref="dom.webxr.layers.enabled"]
+interface XRWebGLSubImage : XRSubImage {
+  readonly attribute WebGLTexture colorTexture;
+  readonly attribute WebGLTexture? depthStencilTexture;
+  readonly attribute unsigned long? imageIndex;
+};
diff --git a/components/script/dom/xrlayer.rs b/components/script/dom/xrlayer.rs
new file mode 100644
index 00000000000..e70cdb5085a
--- /dev/null
+++ b/components/script/dom/xrlayer.rs
@@ -0,0 +1,53 @@
+/* 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::codegen::Bindings::XRLayerBinding::XRLayerBinding::XRLayerMethods;
+use crate::dom::bindings::reflector::Reflector;
+use crate::dom::bindings::root::Dom;
+use crate::dom::webglrenderingcontext::WebGLRenderingContext;
+use crate::dom::xrsession::XRSession;
+use dom_struct::dom_struct;
+use euclid::Size2D;
+use webxr_api::Viewport;
+
+#[dom_struct]
+pub struct XRLayer {
+    reflector: Reflector,
+    session: Dom<XRSession>,
+    context: Dom<WebGLRenderingContext>,
+    size: Size2D<u32, Viewport>,
+}
+
+impl XRLayerMethods for XRLayer {
+    /// https://immersive-web.github.io/layers/#dom-xrlayer-pixelwidth
+    fn PixelWidth(&self) -> u32 {
+        self.size.width
+    }
+
+    /// https://immersive-web.github.io/layers/#dom-xrlayer-pixelheight
+    fn PixelHeight(&self) -> u32 {
+        self.size.height
+    }
+
+    /// https://immersive-web.github.io/layers/#dom-xrlayer-destroy
+    fn Destroy(&self) {
+        // TODO: Implement this
+    }
+}
+
+impl XRLayer {
+    #[allow(dead_code)]
+    pub fn new_inherited(
+        session: &XRSession,
+        context: &WebGLRenderingContext,
+        size: Size2D<u32, Viewport>,
+    ) -> XRLayer {
+        XRLayer {
+            reflector: Reflector::new(),
+            session: Dom::from_ref(session),
+            context: Dom::from_ref(context),
+            size: size,
+        }
+    }
+}
diff --git a/components/script/dom/xrmediabinding.rs b/components/script/dom/xrmediabinding.rs
new file mode 100644
index 00000000000..b0b6a0ac69c
--- /dev/null
+++ b/components/script/dom/xrmediabinding.rs
@@ -0,0 +1,35 @@
+/* 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::reflector::Reflector;
+use crate::dom::bindings::root::Dom;
+use crate::dom::bindings::root::DomRoot;
+use crate::dom::window::Window;
+use crate::dom::xrsession::XRSession;
+use dom_struct::dom_struct;
+
+#[dom_struct]
+pub struct XRMediaBinding {
+    reflector: Reflector,
+    session: Dom<XRSession>,
+}
+
+impl XRMediaBinding {
+    pub fn new_inherited(session: &XRSession) -> XRMediaBinding {
+        XRMediaBinding {
+            reflector: Reflector::new(),
+            session: Dom::from_ref(session),
+        }
+    }
+
+    pub fn new(global: &Window, session: &XRSession) -> DomRoot<XRMediaBinding> {
+        reflect_dom_object(Box::new(XRMediaBinding::new_inherited(session)), global)
+    }
+
+    #[allow(non_snake_case)]
+    pub fn Constructor(global: &Window, session: &XRSession) -> DomRoot<XRMediaBinding> {
+        XRMediaBinding::new(global, session)
+    }
+}
diff --git a/components/script/dom/xrrenderstate.rs b/components/script/dom/xrrenderstate.rs
index 199e029ee7d..d174af531d0 100644
--- a/components/script/dom/xrrenderstate.rs
+++ b/components/script/dom/xrrenderstate.rs
@@ -2,15 +2,18 @@
  * 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::cell::DomRefCell;
 use crate::dom::bindings::codegen::Bindings::XRRenderStateBinding::XRRenderStateMethods;
+use crate::dom::bindings::codegen::UnionTypes::XRWebGLLayerOrXRLayer as RootedXRWebGLLayerOrXRLayer;
 use crate::dom::bindings::num::Finite;
 use crate::dom::bindings::reflector::{reflect_dom_object, DomObject, Reflector};
-use crate::dom::bindings::root::{DomRoot, MutNullableDom};
+use crate::dom::bindings::root::{Dom, DomRoot, MutNullableDom};
 use crate::dom::globalscope::GlobalScope;
+use crate::dom::xrlayer::XRLayer;
 use crate::dom::xrwebgllayer::XRWebGLLayer;
-
 use dom_struct::dom_struct;
 use std::cell::Cell;
+use webxr_api::SwapChainId;
 
 #[dom_struct]
 pub struct XRRenderState {
@@ -19,6 +22,42 @@ pub struct XRRenderState {
     depth_far: Cell<f64>,
     inline_vertical_fov: Cell<Option<f64>>,
     layer: MutNullableDom<XRWebGLLayer>,
+    layers: DomRefCell<Vec<XRWebGLLayerOrXRLayer>>,
+}
+
+#[unrooted_must_root_lint::must_root]
+#[derive(Clone, JSTraceable, MallocSizeOf)]
+pub enum XRWebGLLayerOrXRLayer {
+    XRWebGLLayer(Dom<XRWebGLLayer>),
+    XRLayer(Dom<XRLayer>),
+}
+
+impl XRWebGLLayerOrXRLayer {
+    #[allow(unrooted_must_root)]
+    fn from_ref(layer: &RootedXRWebGLLayerOrXRLayer) -> XRWebGLLayerOrXRLayer {
+        match layer {
+            RootedXRWebGLLayerOrXRLayer::XRWebGLLayer(ref layer) => {
+                XRWebGLLayerOrXRLayer::XRWebGLLayer(Dom::from_ref(layer))
+            },
+            RootedXRWebGLLayerOrXRLayer::XRLayer(ref layer) => {
+                XRWebGLLayerOrXRLayer::XRLayer(Dom::from_ref(layer))
+            },
+        }
+    }
+
+    pub fn swap_chain_id(&self) -> Option<SwapChainId> {
+        match self {
+            XRWebGLLayerOrXRLayer::XRWebGLLayer(layer) => Some(layer.swap_chain_id()),
+            XRWebGLLayerOrXRLayer::XRLayer(_) => None,
+        }
+    }
+
+    pub fn swap_buffers(&self) {
+        match self {
+            XRWebGLLayerOrXRLayer::XRWebGLLayer(layer) => layer.swap_buffers(),
+            XRWebGLLayerOrXRLayer::XRLayer(_) => (),
+        }
+    }
 }
 
 impl XRRenderState {
@@ -27,13 +66,16 @@ impl XRRenderState {
         depth_far: f64,
         inline_vertical_fov: Option<f64>,
         layer: Option<&XRWebGLLayer>,
+        layers: &[XRWebGLLayerOrXRLayer],
     ) -> XRRenderState {
+        debug_assert!(layer.is_none() || layers.is_empty());
         XRRenderState {
             reflector_: Reflector::new(),
             depth_near: Cell::new(depth_near),
             depth_far: Cell::new(depth_far),
             inline_vertical_fov: Cell::new(inline_vertical_fov),
             layer: MutNullableDom::new(layer),
+            layers: DomRefCell::new(layers.iter().cloned().collect()),
         }
     }
 
@@ -43,6 +85,7 @@ impl XRRenderState {
         depth_far: f64,
         inline_vertical_fov: Option<f64>,
         layer: Option<&XRWebGLLayer>,
+        layers: &[XRWebGLLayerOrXRLayer],
     ) -> DomRoot<XRRenderState> {
         reflect_dom_object(
             Box::new(XRRenderState::new_inherited(
@@ -50,18 +93,21 @@ impl XRRenderState {
                 depth_far,
                 inline_vertical_fov,
                 layer,
+                layers,
             )),
             global,
         )
     }
 
     pub fn clone_object(&self) -> DomRoot<Self> {
+        let layers = self.layers.borrow();
         XRRenderState::new(
             &self.global(),
             self.depth_near.get(),
             self.depth_far.get(),
             self.inline_vertical_fov.get(),
             self.layer.get().as_ref().map(|x| &**x),
+            &layers,
         )
     }
 
@@ -78,6 +124,19 @@ impl XRRenderState {
     pub fn set_layer(&self, layer: Option<&XRWebGLLayer>) {
         self.layer.set(layer)
     }
+    pub fn set_layers(&self, layers: &[RootedXRWebGLLayerOrXRLayer]) {
+        *self.layers.borrow_mut() = layers.iter().map(XRWebGLLayerOrXRLayer::from_ref).collect();
+    }
+    pub fn with_layers<F, R>(&self, f: F) -> R
+    where
+        F: FnOnce(&[XRWebGLLayerOrXRLayer]) -> R,
+    {
+        let layers = self.layers.borrow();
+        f(&*layers)
+    }
+    pub fn has_layer(&self) -> bool {
+        self.layer.get().is_some() || !self.layers.borrow().is_empty()
+    }
 }
 
 impl XRRenderStateMethods for XRRenderState {
diff --git a/components/script/dom/xrsession.rs b/components/script/dom/xrsession.rs
index 3396ca669c1..53e6c492b68 100644
--- a/components/script/dom/xrsession.rs
+++ b/components/script/dom/xrsession.rs
@@ -31,7 +31,6 @@ use crate::dom::xrreferencespace::XRReferenceSpace;
 use crate::dom::xrrenderstate::XRRenderState;
 use crate::dom::xrsessionevent::XRSessionEvent;
 use crate::dom::xrspace::XRSpace;
-use crate::dom::xrwebgllayer::XRWebGLLayer;
 use crate::realms::InRealm;
 use crate::task_source::TaskSource;
 use dom_struct::dom_struct;
@@ -52,7 +51,6 @@ use webxr_api::{
 #[dom_struct]
 pub struct XRSession {
     eventtarget: EventTarget,
-    base_layer: MutNullableDom<XRWebGLLayer>,
     blend_mode: XREnvironmentBlendMode,
     mode: XRSessionMode,
     visibility_state: Cell<XRVisibilityState>,
@@ -88,7 +86,6 @@ impl XRSession {
     ) -> XRSession {
         XRSession {
             eventtarget: EventTarget::new_inherited(),
-            base_layer: Default::default(),
             blend_mode: session.environment_blend_mode().into(),
             mode,
             visibility_state: Cell::new(XRVisibilityState::Visible),
@@ -119,7 +116,7 @@ impl XRSession {
         } else {
             None
         };
-        let render_state = XRRenderState::new(global, 0.1, 1000.0, ivfov, None);
+        let render_state = XRRenderState::new(global, 0.1, 1000.0, ivfov, None, &[]);
         let input_sources = XRInputSourceArray::new(global);
         let ret = reflect_dom_object(
             Box::new(XRSession::new_inherited(
@@ -355,7 +352,14 @@ impl XRSession {
             // Step 6-7: XXXManishearth handle inlineVerticalFieldOfView
 
             if self.is_immersive() {
-                let swap_chain_id = pending.GetBaseLayer().map(|layer| layer.swap_chain_id());
+                let swap_chain_id = pending
+                    .GetBaseLayer()
+                    .map(|layer| layer.swap_chain_id())
+                    .or_else(|| {
+                        self.active_render_state.get().with_layers(|layers| {
+                            layers.get(0).and_then(|layer| layer.swap_chain_id())
+                        })
+                    });
                 self.session.borrow_mut().set_swap_chain(swap_chain_id);
             } else {
                 self.update_inline_projection_matrix()
@@ -367,10 +371,9 @@ impl XRSession {
         }
 
         // Step 2
-        let base_layer = match self.active_render_state.get().GetBaseLayer() {
-            Some(layer) => layer,
-            None => return,
-        };
+        if !self.active_render_state.get().has_layer() {
+            return;
+        }
 
         // Step 3: XXXManishearth handle inline session
 
@@ -395,7 +398,15 @@ impl XRSession {
 
         frame.set_active(false);
         if self.is_immersive() {
-            base_layer.swap_buffers();
+            if let Some(base_layer) = self.active_render_state.get().GetBaseLayer() {
+                base_layer.swap_buffers();
+            } else {
+                self.active_render_state.get().with_layers(|layers| {
+                    for layer in layers {
+                        layer.swap_buffers();
+                    }
+                });
+            }
             self.session.borrow_mut().render_animation_frame();
         } else {
             self.session.borrow_mut().start_render_loop();
@@ -513,6 +524,23 @@ impl XRSessionMethods for XRSession {
             return Err(Error::InvalidState);
         }
 
+        // TODO: add spec link for this step once XR layers has settled down
+        // https://immersive-web.github.io/layers/
+        if init.baseLayer.is_some() && init.layers.is_some() {
+            return Err(Error::InvalidState);
+        }
+
+        // TODO: add spec link for this step once XR layers has settled down
+        // https://immersive-web.github.io/layers/
+        if init
+            .layers
+            .as_ref()
+            .map(|layers| layers.is_empty())
+            .unwrap_or(false)
+        {
+            return Err(Error::InvalidState);
+        }
+
         let pending = self
             .pending_render_state
             .or_init(|| self.active_render_state.get().clone_object());
@@ -546,7 +574,8 @@ impl XRSessionMethods for XRSession {
             pending.set_inline_vertical_fov(fov);
         }
         if let Some(ref layer) = init.baseLayer {
-            pending.set_layer(Some(&layer))
+            pending.set_layer(Some(&layer));
+            pending.set_layers(&[]);
         }
 
         if init.depthFar.is_some() || init.depthNear.is_some() {
@@ -554,6 +583,14 @@ impl XRSessionMethods for XRSession {
                 .borrow_mut()
                 .update_clip_planes(*pending.DepthNear() as f32, *pending.DepthFar() as f32);
         }
+
+        // TODO: add spec link for this step once XR layers has settled down
+        // https://immersive-web.github.io/layers/
+        if let Some(ref layers) = init.layers {
+            pending.set_layer(None);
+            pending.set_layers(layers);
+        }
+
         Ok(())
     }
 
diff --git a/components/script/dom/xrsubimage.rs b/components/script/dom/xrsubimage.rs
new file mode 100644
index 00000000000..2be59d48d3b
--- /dev/null
+++ b/components/script/dom/xrsubimage.rs
@@ -0,0 +1,23 @@
+/* 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::codegen::Bindings::XRSubImageBinding::XRSubImageBinding::XRSubImageMethods;
+use crate::dom::bindings::reflector::Reflector;
+use crate::dom::bindings::root::Dom;
+use crate::dom::bindings::root::DomRoot;
+use crate::dom::xrviewport::XRViewport;
+use dom_struct::dom_struct;
+
+#[dom_struct]
+pub struct XRSubImage {
+    reflector: Reflector,
+    viewport: Dom<XRViewport>,
+}
+
+impl XRSubImageMethods for XRSubImage {
+    /// https://immersive-web.github.io/layers/#dom-xrsubimage-viewport
+    fn Viewport(&self) -> DomRoot<XRViewport> {
+        DomRoot::from_ref(&self.viewport)
+    }
+}
diff --git a/components/script/dom/xrwebglbinding.rs b/components/script/dom/xrwebglbinding.rs
new file mode 100644
index 00000000000..27435aa3ddc
--- /dev/null
+++ b/components/script/dom/xrwebglbinding.rs
@@ -0,0 +1,109 @@
+/* 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::codegen::Bindings::XRWebGLBindingBinding::XRWebGLBindingBinding::XRWebGLBindingMethods;
+use crate::dom::bindings::codegen::UnionTypes::WebGLRenderingContextOrWebGL2RenderingContext as RootedWebGLRenderingContextOrWebGL2RenderingContext;
+use crate::dom::bindings::reflector::reflect_dom_object;
+use crate::dom::bindings::reflector::Reflector;
+use crate::dom::bindings::root::Dom;
+use crate::dom::bindings::root::DomRoot;
+use crate::dom::webgl2renderingcontext::WebGL2RenderingContext;
+use crate::dom::webglrenderingcontext::WebGLRenderingContext;
+use crate::dom::window::Window;
+use crate::dom::xrframe::XRFrame;
+use crate::dom::xrlayer::XRLayer;
+use crate::dom::xrsession::XRSession;
+use crate::dom::xrview::XRView;
+use crate::dom::xrwebglsubimage::XRWebGLSubImage;
+use dom_struct::dom_struct;
+
+#[dom_struct]
+pub struct XRWebGLBinding {
+    reflector: Reflector,
+    session: Dom<XRSession>,
+    context: WebGLRenderingContextOrWebGL2RenderingContext,
+}
+
+// TODO: Should this live somewhere else?
+#[unrooted_must_root_lint::must_root]
+#[derive(Clone, JSTraceable, MallocSizeOf)]
+pub enum WebGLRenderingContextOrWebGL2RenderingContext {
+    WebGLRenderingContext(Dom<WebGLRenderingContext>),
+    WebGL2RenderingContext(Dom<WebGL2RenderingContext>),
+}
+
+impl WebGLRenderingContextOrWebGL2RenderingContext {
+    #[allow(unrooted_must_root)]
+    fn from_ref(
+        context: &RootedWebGLRenderingContextOrWebGL2RenderingContext,
+    ) -> WebGLRenderingContextOrWebGL2RenderingContext {
+        match context {
+            RootedWebGLRenderingContextOrWebGL2RenderingContext::WebGLRenderingContext(
+                ref context,
+            ) => WebGLRenderingContextOrWebGL2RenderingContext::WebGLRenderingContext(
+                Dom::from_ref(context),
+            ),
+            RootedWebGLRenderingContextOrWebGL2RenderingContext::WebGL2RenderingContext(
+                ref context,
+            ) => WebGLRenderingContextOrWebGL2RenderingContext::WebGL2RenderingContext(
+                Dom::from_ref(context),
+            ),
+        }
+    }
+}
+
+impl XRWebGLBindingMethods for XRWebGLBinding {
+    /// https://immersive-web.github.io/layers/#dom-xrwebglbinding-getsubimage
+    fn GetSubImage(&self, _layer: &XRLayer, _frame: &XRFrame) -> Option<DomRoot<XRWebGLSubImage>> {
+        // TODO: Implement this
+        None
+    }
+
+    /// https://immersive-web.github.io/layers/#dom-xrwebglbinding-getviewsubimage
+    fn GetViewSubImage(
+        &self,
+        _layer: &XRLayer,
+        _view: &XRView,
+    ) -> Option<DomRoot<XRWebGLSubImage>> {
+        // TODO: Implement this
+        None
+    }
+}
+
+impl XRWebGLBinding {
+    pub fn new_inherited(
+        session: &XRSession,
+        context: &WebGLRenderingContextOrWebGL2RenderingContext,
+    ) -> XRWebGLBinding {
+        XRWebGLBinding {
+            reflector: Reflector::new(),
+            session: Dom::from_ref(session),
+            context: context.clone(),
+        }
+    }
+
+    pub fn new(
+        global: &Window,
+        session: &XRSession,
+        context: &WebGLRenderingContextOrWebGL2RenderingContext,
+    ) -> DomRoot<XRWebGLBinding> {
+        reflect_dom_object(
+            Box::new(XRWebGLBinding::new_inherited(session, context)),
+            global,
+        )
+    }
+
+    #[allow(non_snake_case)]
+    pub fn Constructor(
+        global: &Window,
+        session: &XRSession,
+        context: RootedWebGLRenderingContextOrWebGL2RenderingContext,
+    ) -> DomRoot<XRWebGLBinding> {
+        XRWebGLBinding::new(
+            global,
+            session,
+            &WebGLRenderingContextOrWebGL2RenderingContext::from_ref(&context),
+        )
+    }
+}
diff --git a/components/script/dom/xrwebglsubimage.rs b/components/script/dom/xrwebglsubimage.rs
new file mode 100644
index 00000000000..0331d36c4c2
--- /dev/null
+++ b/components/script/dom/xrwebglsubimage.rs
@@ -0,0 +1,35 @@
+/* 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::codegen::Bindings::XRWebGLSubImageBinding::XRWebGLSubImageBinding::XRWebGLSubImageMethods;
+use crate::dom::bindings::root::Dom;
+use crate::dom::bindings::root::DomRoot;
+use crate::dom::webgltexture::WebGLTexture;
+use crate::dom::xrsubimage::XRSubImage;
+use dom_struct::dom_struct;
+
+#[dom_struct]
+pub struct XRWebGLSubImage {
+    xr_sub_image: XRSubImage,
+    color_texture: Dom<WebGLTexture>,
+    depth_stencil_texture: Option<Dom<WebGLTexture>>,
+    image_index: Option<u32>,
+}
+
+impl XRWebGLSubImageMethods for XRWebGLSubImage {
+    /// https://immersive-web.github.io/layers/#dom-xrwebglsubimage-colortexture
+    fn ColorTexture(&self) -> DomRoot<WebGLTexture> {
+        DomRoot::from_ref(&self.color_texture)
+    }
+
+    /// https://immersive-web.github.io/layers/#dom-xrwebglsubimage-depthstenciltexture
+    fn GetDepthStencilTexture(&self) -> Option<DomRoot<WebGLTexture>> {
+        self.depth_stencil_texture.as_deref().map(DomRoot::from_ref)
+    }
+
+    /// https://immersive-web.github.io/layers/#dom-xrwebglsubimage-imageindex
+    fn GetImageIndex(&self) -> Option<u32> {
+        self.image_index
+    }
+}