Draw WebVR security overlay with a non-reprojected viewport

chrome/browser/android/vr_shell/vr_shell.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/android/vr_shell/vr_shell.h"
 
 #include "base/metrics/histogram_macros.h"
 #include "chrome/browser/android/vr_shell/ui_elements.h"
 #include "chrome/browser/android/vr_shell/ui_scene.h"
 #include "chrome/browser/android/vr_shell/vr_compositor.h"
@@ skipping 227 matching lines @@
   CHECK(gl::GetGLImplementation() != gl::kGLImplementationNone ||
         gl::init::InitializeGLOneOff());
 
   content_texture_id_ = content_texture_handle;
   ui_texture_id_ = ui_texture_handle;
 
   gvr_api_->InitializeGl();
   std::vector<gvr::BufferSpec> specs;
   specs.push_back(gvr_api_->CreateBufferSpec());
   render_size_ = specs[0].GetSize();
+
+  // For WebVR content
+  specs.push_back(gvr_api_->CreateBufferSpec());
+
   swap_chain_.reset(new gvr::SwapChain(gvr_api_->CreateSwapChain(specs)));
 
   vr_shell_renderer_.reset(new VrShellRenderer());
   buffer_viewport_list_.reset(
       new gvr::BufferViewportList(gvr_api_->CreateEmptyBufferViewportList()));
+  buffer_viewport_list_->SetToRecommendedBufferViewports();
+
   buffer_viewport_.reset(
       new gvr::BufferViewport(gvr_api_->CreateBufferViewport()));
+
+  overlay_left_viewport_.reset(
+      new gvr::BufferViewport(gvr_api_->CreateBufferViewport()));
+  buffer_viewport_list_->GetBufferViewport(GVR_LEFT_EYE,
+                                           overlay_left_viewport_.get());
+  overlay_left_viewport_->SetSourceBufferIndex(1);
+  overlay_left_viewport_->SetReprojection(GVR_REPROJECTION_NONE);
+
+  overlay_right_viewport_.reset(
+      new gvr::BufferViewport(gvr_api_->CreateBufferViewport()));
+  buffer_viewport_list_->GetBufferViewport(GVR_RIGHT_EYE,
+                                           overlay_right_viewport_.get());
+  overlay_right_viewport_->SetSourceBufferIndex(1);
+  overlay_right_viewport_->SetReprojection(GVR_REPROJECTION_NONE);
 }
 
 void VrShell::UpdateController(const gvr::Vec3f& forward_vector) {
   controller_->UpdateState();
   std::unique_ptr<VrGesture> gesture = controller_->DetectGesture();
 
   // TODO(asimjour) for now, scroll is sent to the main content.
   if (gesture->type == WebInputEvent::GestureScrollBegin ||
       gesture->type == WebInputEvent::GestureScrollUpdate ||
       gesture->type == WebInputEvent::GestureScrollEnd) {
@@ skipping 150 matching lines @@
     // it. For now, removing it seems working fine.
     gvr_api_->ApplyNeckModel(head_pose, 1.0f);
   }
 
   // Bind back to the default framebuffer.
   frame.BindBuffer(0);
 
   if (webvr_mode_) {
     DrawWebVr();
     if (!webvr_secure_origin_) {
+      buffer_viewport_list_->SetBufferViewport(buffer_viewport_list_->GetSize(),
+          *overlay_left_viewport_);
+      buffer_viewport_list_->SetBufferViewport(buffer_viewport_list_->GetSize(),

[klausw (use chromium instead), 2016/10/17 23:03:18]

Using GetSize() twice seems weird. Does the SetToRecommendedBufferViewports()
above create a two-element list (0=left eye, 1=right eye), and this appends
items 2=overlay left, 3=overlay right?

+          *overlay_right_viewport_);
+
+      // Bind back to the second default framebuffer.

[klausw (use chromium instead), 2016/10/17 23:03:18]

These comments are confusing. Can you rephrase this one and the one above to
something like this?

// Render to the main viewport set.
frame.BindBuffer(0);
...
// Render to the overlay viewport set.
frame.BindBuffer(1);

For bonus points, use a constant instead of a hardcoded "1" here and in
SetSourceBufferIndex above?

+      frame.BindBuffer(1);
       DrawWebVrOverlay(target_time.monotonic_system_time_nanos);
     }
 
     // When using async reprojection, we need to know which pose was used in
     // the WebVR app for drawing this frame. Due to unknown amounts of
     // buffering in the compositor and SurfaceTexture, we read the pose number
     // from a corner pixel. There's no point in doing this for legacy
     // distortion rendering since that doesn't need a pose, and reading back
     // pixels is an expensive operation. TODO(klausw): stop doing this once we
     // have working no-compositor rendering for WebVR.
@@ skipping 197 matching lines @@
 void VrShell::DrawWebVrOverlay(int64_t present_time_nanos) {
   // Draw WebVR security warning overlays for each eye. This uses the
   // eye-from-head matrices but not the pose, goal is to place the icons in an
   // eye-relative position so that they follow along with head rotations.
 
   gvr::Mat4f left_eye_view_matrix =
       gvr_api_->GetEyeFromHeadMatrix(GVR_LEFT_EYE);
   gvr::Mat4f right_eye_view_matrix =
       gvr_api_->GetEyeFromHeadMatrix(GVR_RIGHT_EYE);
 
+  // Don't need to clear, since we're drawing over the entire render target.

[klausw (use chromium instead), 2016/10/17 23:03:18]

Please delete this comment, it conflicts with the glClear immediately below.

+  glClear(GL_COLOR_BUFFER_BIT);
+
   buffer_viewport_list_->GetBufferViewport(GVR_LEFT_EYE,
                                            buffer_viewport_.get());
   DrawWebVrEye(left_eye_view_matrix, *buffer_viewport_, present_time_nanos);
   buffer_viewport_list_->GetBufferViewport(GVR_RIGHT_EYE,
                                            buffer_viewport_.get());
   DrawWebVrEye(right_eye_view_matrix, *buffer_viewport_, present_time_nanos);
 }
 
 void VrShell::DrawWebVrEye(const gvr::Mat4f& view_matrix,
                            const gvr::BufferViewport& params,
@@ skipping 215 matching lines @@
            const JavaParamRef<jobject>& ui_web_contents,
            jlong ui_window_android) {
   return reinterpret_cast<intptr_t>(new VrShell(
       env, obj, content::WebContents::FromJavaWebContents(content_web_contents),
       reinterpret_cast<ui::WindowAndroid*>(content_window_android),
       content::WebContents::FromJavaWebContents(ui_web_contents),
       reinterpret_cast<ui::WindowAndroid*>(ui_window_android)));
 }
 
 }  // namespace vr_shell