WebVR: add angular velocity estimate to pose

chrome/browser/android/vr_shell/non_presenting_gvr_delegate.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/non_presenting_gvr_delegate.h"
 
 #include <utility>
 
 #include "base/callback_helpers.h"
 #include "chrome/browser/android/vr_shell/vr_shell.h"
 #include "third_party/gvr-android-sdk/src/libraries/headers/vr/gvr/capi/include/gvr.h"
 
 namespace vr_shell {
 
 namespace {
+// TODO(klausw): These are duplicates from vr_shell_gl.cc, put in header file?

[billorr, 2017/03/27 17:33:53]

any reason not to do this now?

[klausw, 2017/03/27 17:55:42]

Done - though it's annoying that it's now no longer possible to fit a simple "a
+= b" on a single line due to the added "VrShell::" prefix.

 static constexpr int64_t kPredictionTimeWithoutVsyncNanos = 50000000;
+static constexpr int64_t kAngularVelocityEpsilonNanos = 1000000;
 }  // namespace
 
 NonPresentingGvrDelegate::NonPresentingGvrDelegate(gvr_context* context)
     : task_runner_(base::ThreadTaskRunnerHandle::Get()),
       binding_(this),
       weak_ptr_factory_(this) {
   // Context may be null, see VrShellDelegate#createNonPresentingNativeContext
   // for possible reasons a context could fail to be created. For example,
   // the user might uninstall apps or clear data after VR support was detected.
   if (context)
@@ skipping 119 matching lines @@
   target_time.monotonic_system_time_nanos += kPredictionTimeWithoutVsyncNanos;
 
   if (!gvr_api_) {
     callback.Run(device::mojom::VRPosePtr(nullptr), time, -1,
                  device::mojom::VRVSyncProvider::Status::SUCCESS);
     return;
   }
 
   gvr::Mat4f head_mat = gvr_api_->ApplyNeckModel(
       gvr_api_->GetHeadSpaceFromStartSpaceRotation(target_time), 1.0f);
-  callback.Run(VrShell::VRPosePtrFromGvrPose(head_mat), time, -1,
-               device::mojom::VRVSyncProvider::Status::SUCCESS);
+
+  target_time.monotonic_system_time_nanos += kAngularVelocityEpsilonNanos;
+  gvr::Mat4f head_mat_2 =
+      gvr_api_->GetHeadSpaceFromStartSpaceRotation(target_time);
+
+  callback.Run(VrShell::VRPosePtrFromGvrPose(head_mat, head_mat_2,
+                                             kAngularVelocityEpsilonNanos),
+               time, -1, device::mojom::VRVSyncProvider::Status::SUCCESS);
 }
 
 bool NonPresentingGvrDelegate::SupportsPresentation() {
   return false;
 }
 
 void NonPresentingGvrDelegate::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 NonPresentingGvrDelegate::CreateVRDisplayInfo(
     const base::Callback<void(device::mojom::VRDisplayInfoPtr)>& callback,
     uint32_t device_id) {
   if (!gvr_api_) {
     callback.Run(device::mojom::VRDisplayInfoPtr(nullptr));
     return;
   }
 
   gvr::Sizei webvr_size = VrShell::GetRecommendedWebVrSize(gvr_api_.get());
   DVLOG(1) << __FUNCTION__ << ": resize recommended to " << webvr_size.width
            << "x" << webvr_size.height;
   callback.Run(
       VrShell::CreateVRDisplayInfo(gvr_api_.get(), webvr_size, device_id));
 }
 
 }  // namespace vr_shell