WebVR: add angular velocity estimate to pose

chrome/browser/android/vr_shell/vr_shell_gl.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_gl.h"
 
 #include <limits>
 #include <utility>
 
 #include "base/android/jni_android.h"
@@ skipping 21 matching lines @@
 #include "ui/gl/gl_surface.h"
 #include "ui/gl/init/gl_factory.h"
 
 namespace vr_shell {
 
 namespace {
 // TODO(mthiesse): If gvr::PlatformInfo().GetPosePredictionTime() is ever
 // exposed, use that instead (it defaults to 50ms on most platforms).
 static constexpr int64_t kPredictionTimeWithoutVsyncNanos = 50000000;
 
+// Time offset used for calculating angular velocity from a pair

[cjgrant, 2017/03/24 21:15:40]

nit: Most editors can be used to auto-format comment blocks.  A few of the
comments don't wrap properly.  "git cl format" might also do it.

[klausw, 2017/03/24 22:13:29]

I was using auto format, but Emacs for some reason defaults to 70 columns.
Fixed.

+// of predicted poses. The precise value shouldn't matter as long as
+// it's nonzero and much less than a frame.
+static constexpr int64_t kAngularVelocityEpsilonNanos = 1000000;
+
 static constexpr float kZNear = 0.1f;
 static constexpr float kZFar = 1000.0f;
 
 static constexpr float kReticleWidth = 0.025f;
 static constexpr float kReticleHeight = 0.025f;
 
 static constexpr float kLaserWidth = 0.01f;
 
 // Angle (radians) the beam down from the controller axis, for wrist comfort.
 static constexpr float kErgoAngleOffset = 0.26f;
@@ skipping 1211 matching lines @@
 
   TRACE_EVENT1("input", "VrShellGl::SendVSync", "frame", frame_index);
 
   gvr::ClockTimePoint target_time = gvr::GvrApi::GetTimePointNow();
   target_time.monotonic_system_time_nanos += kPredictionTimeWithoutVsyncNanos;
 
   gvr::Mat4f head_mat =
       gvr_api_->GetHeadSpaceFromStartSpaceRotation(target_time);
   head_mat = gvr_api_->ApplyNeckModel(head_mat, 1.0f);
 
+  target_time.monotonic_system_time_nanos += kAngularVelocityEpsilonNanos;
+  gvr::Mat4f head_mat_2 =
+      gvr_api_->GetHeadSpaceFromStartSpaceRotation(target_time);
+
   webvr_head_pose_[frame_index % kPoseRingBufferSize] = head_mat;
 
-  callback.Run(VrShell::VRPosePtrFromGvrPose(head_mat), time, frame_index,
+  callback.Run(VrShell::VRPosePtrFromGvrPose(head_mat, head_mat_2,
+                                             kAngularVelocityEpsilonNanos),
+               time, frame_index,
                device::mojom::VRVSyncProvider::Status::SUCCESS);
 }
 
 void VrShellGl::ResetPose() {
   // Should never call RecenterTracking when using with Daydream viewers. On
   // those devices recentering should only be done via the controller.
   if (gvr_api_ && gvr_api_->GetViewerType() == GVR_VIEWER_TYPE_CARDBOARD)
     gvr_api_->RecenterTracking();
 }
 
 void VrShellGl::CreateVRDisplayInfo(
     const base::Callback<void(device::mojom::VRDisplayInfoPtr)>& callback,
     uint32_t device_id) {
   // This assumes that the initial webvr_surface_size_ was set to the
   // appropriate recommended render resolution as the default size during
   // InitializeGl. Revisit if the initialization order changes.
   device::mojom::VRDisplayInfoPtr info = VrShell::CreateVRDisplayInfo(
       gvr_api_.get(), webvr_surface_size_, device_id);
   main_thread_task_runner_->PostTask(
       FROM_HERE,
       base::Bind(&RunVRDisplayInfoCallback, callback, base::Passed(&info)));
 }
 
 }  // namespace vr_shell