5 files changed, 49 insertions, 3 deletions

diff --git a/components/script/dom/webglbuffer.rs b/components/script/dom/webglbuffer.rs
index 0fedc762f4c..66b287e347f 100644
--- a/components/script/dom/webglbuffer.rs
+++ b/components/script/dom/webglbuffer.rs
@@ -95,6 +95,14 @@ impl WebGLBuffer {
             let _ = self.renderer.send(CanvasMsg::WebGL(WebGLCommand::DeleteBuffer(self.id)));
         }
     }
+
+    pub fn is_deleted(&self) -> bool {
+        self.is_deleted.get()
+    }
+
+    pub fn target(&self) -> Option<u32> {
+        self.target.get()
+    }
 }
 
 impl Drop for WebGLBuffer {
diff --git a/components/script/dom/webglframebuffer.rs b/components/script/dom/webglframebuffer.rs
index 93522addf35..06c0095b1c9 100644
--- a/components/script/dom/webglframebuffer.rs
+++ b/components/script/dom/webglframebuffer.rs
@@ -17,6 +17,8 @@ use webrender_traits::{WebGLCommand, WebGLFramebufferBindingRequest};
 pub struct WebGLFramebuffer {
     webgl_object: WebGLObject,
     id: u32,
+    /// target can only be gl::FRAMEBUFFER at the moment
+    target: Cell<Option<u32>>,
     is_deleted: Cell<bool>,
     #[ignore_heap_size_of = "Defined in ipc-channel"]
     renderer: IpcSender<CanvasMsg>,
@@ -27,6 +29,7 @@ impl WebGLFramebuffer {
         WebGLFramebuffer {
             webgl_object: WebGLObject::new_inherited(),
             id: id,
+            target: Cell::new(None),
             is_deleted: Cell::new(false),
             renderer: renderer,
         }
@@ -54,6 +57,7 @@ impl WebGLFramebuffer {
     }
 
     pub fn bind(&self, target: u32) {
+        self.target.set(Some(target));
         let cmd = WebGLCommand::BindFramebuffer(target, WebGLFramebufferBindingRequest::Explicit(self.id));
         self.renderer.send(CanvasMsg::WebGL(cmd)).unwrap();
     }
@@ -64,6 +68,14 @@ impl WebGLFramebuffer {
             let _ = self.renderer.send(CanvasMsg::WebGL(WebGLCommand::DeleteFramebuffer(self.id)));
         }
     }
+
+    pub fn is_deleted(&self) -> bool {
+        self.is_deleted.get()
+    }
+
+    pub fn target(&self) -> Option<u32> {
+        self.target.get()
+    }
 }
 
 impl Drop for WebGLFramebuffer {
diff --git a/components/script/dom/webglrenderbuffer.rs b/components/script/dom/webglrenderbuffer.rs
index a63bd1c975a..dd4ef931661 100644
--- a/components/script/dom/webglrenderbuffer.rs
+++ b/components/script/dom/webglrenderbuffer.rs
@@ -17,6 +17,7 @@ use webrender_traits::WebGLCommand;
 pub struct WebGLRenderbuffer {
     webgl_object: WebGLObject,
     id: u32,
+    ever_bound: Cell<bool>,
     is_deleted: Cell<bool>,
     #[ignore_heap_size_of = "Defined in ipc-channel"]
     renderer: IpcSender<CanvasMsg>,
@@ -27,6 +28,7 @@ impl WebGLRenderbuffer {
         WebGLRenderbuffer {
             webgl_object: WebGLObject::new_inherited(),
             id: id,
+            ever_bound: Cell::new(false),
             is_deleted: Cell::new(false),
             renderer: renderer,
         }
@@ -54,6 +56,7 @@ impl WebGLRenderbuffer {
     }
 
     pub fn bind(&self, target: u32) {
+        self.ever_bound.set(true);
         self.renderer.send(CanvasMsg::WebGL(WebGLCommand::BindRenderbuffer(target, self.id))).unwrap();
     }
 
@@ -63,4 +66,12 @@ impl WebGLRenderbuffer {
             let _ = self.renderer.send(CanvasMsg::WebGL(WebGLCommand::DeleteRenderbuffer(self.id)));
         }
     }
+
+    pub fn is_deleted(&self) -> bool {
+        self.is_deleted.get()
+    }
+
+    pub fn ever_bound(&self) -> bool {
+        self.ever_bound.get()
+    }
 }
diff --git a/components/script/dom/webglrenderingcontext.rs b/components/script/dom/webglrenderingcontext.rs
index 540523323ac..70379e772d2 100644
--- a/components/script/dom/webglrenderingcontext.rs
+++ b/components/script/dom/webglrenderingcontext.rs
@@ -1331,6 +1331,21 @@ impl WebGLRenderingContextMethods for WebGLRenderingContext {
             .unwrap()
     }
 
+    // https://www.khronos.org/registry/webgl/specs/latest/1.0/#5.14.5
+    fn IsBuffer(&self, buffer: Option<&WebGLBuffer>) -> bool {
+        buffer.map_or(false, |buf| buf.target().is_some() && !buf.is_deleted())
+    }
+
+    // https://www.khronos.org/registry/webgl/specs/latest/1.0/#5.14.6
+    fn IsFramebuffer(&self, frame_buffer: Option<&WebGLFramebuffer>) -> bool {
+        frame_buffer.map_or(false, |buf| buf.target().is_some() && !buf.is_deleted())
+    }
+
+    // https://www.khronos.org/registry/webgl/specs/latest/1.0/#5.14.7
+    fn IsRenderbuffer(&self, render_buffer: Option<&WebGLRenderbuffer>) -> bool {
+        render_buffer.map_or(false, |buf| buf.ever_bound() && !buf.is_deleted())
+    }
+
     // https://www.khronos.org/registry/webgl/specs/latest/1.0/#5.14.9
     fn IsShader(&self, shader: Option<&WebGLShader>) -> bool {
         shader.map_or(false, |s| !s.is_deleted() || s.is_attached())
diff --git a/components/script/dom/webidls/WebGLRenderingContext.webidl b/components/script/dom/webidls/WebGLRenderingContext.webidl
index b534c2aeb61..3ed1c8cdb31 100644
--- a/components/script/dom/webidls/WebGLRenderingContext.webidl
+++ b/components/script/dom/webidls/WebGLRenderingContext.webidl
@@ -602,11 +602,11 @@ interface WebGLRenderingContextBase
     //[WebGLHandlesContextLoss] GLsizeiptr getVertexAttribOffset(GLuint index, GLenum pname);
 
     void hint(GLenum target, GLenum mode);
-    //[WebGLHandlesContextLoss] GLboolean isBuffer(WebGLBuffer? buffer);
+    [WebGLHandlesContextLoss] GLboolean isBuffer(WebGLBuffer? buffer);
     //[WebGLHandlesContextLoss] GLboolean isEnabled(GLenum cap);
-    //[WebGLHandlesContextLoss] GLboolean isFramebuffer(WebGLFramebuffer? framebuffer);
+    [WebGLHandlesContextLoss] GLboolean isFramebuffer(WebGLFramebuffer? framebuffer);
     //[WebGLHandlesContextLoss] GLboolean isProgram(WebGLProgram? program);
-    //[WebGLHandlesContextLoss] GLboolean isRenderbuffer(WebGLRenderbuffer? renderbuffer);
+    [WebGLHandlesContextLoss] GLboolean isRenderbuffer(WebGLRenderbuffer? renderbuffer);
     [WebGLHandlesContextLoss] GLboolean isShader(WebGLShader? shader);
     [WebGLHandlesContextLoss] GLboolean isTexture(WebGLTexture? texture);
     void lineWidth(GLfloat width);