Read poses relative to the seated zero pose for OpenVR

device/vr/openvr/openvr_device.cc

 // Copyright (c) 2017 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.
 
 #define _USE_MATH_DEFINES  // for M_PI
 #include "device/vr/openvr/openvr_device.h"
 #include <math.h>
 #include "third_party/openvr/src/headers/openvr.h"
 
 namespace {
@@ skipping 198 matching lines @@
   pose->orientation.value()[3] = 1;
 
   pose->position.emplace(3);
   pose->position.value()[0] = 0;
   pose->position.value()[1] = 0;
   pose->position.value()[2] = 0;
 
   vr::TrackedDevicePose_t poses[vr::k_unMaxTrackedDeviceCount];
 
   vr_system_->GetDeviceToAbsoluteTrackingPose(
-      vr::TrackingUniverseStanding, 0.0f, poses, vr::k_unMaxTrackedDeviceCount);
+      vr::TrackingUniverseSeated, 0.0f, poses, vr::k_unMaxTrackedDeviceCount);
   const auto& hmdPose = poses[vr::k_unTrackedDeviceIndex_Hmd];
   if (hmdPose.bPoseIsValid && hmdPose.bDeviceIsConnected) {
     const auto& transform = hmdPose.mDeviceToAbsoluteTracking;
     const auto& m = transform.m;
     float w = sqrt(1 + m[0][0] + m[1][1] + m[2][2]);
     pose->orientation.value()[0] = (m[2][1] - m[1][2]) / (4 * w);
     pose->orientation.value()[1] = (m[0][2] - m[2][0]) / (4 * w);
     pose->orientation.value()[2] = (m[1][0] - m[0][1]) / (4 * w);
     pose->orientation.value()[3] = w;
 
@@ skipping 19 matching lines @@
   base::TimeDelta time = base::TimeDelta::FromSecondsD(2.0);
 
   device::mojom::VRPosePtr pose = getPose();
   Sleep(11);  // TODO (billorr): Use real vsync timing instead of a sleep (this
               // sleep just throttles vsyncs so we don't fill message queues).
   callback.Run(std::move(pose), time, frame,
                device::mojom::VRVSyncProvider::Status::SUCCESS);
 }
 
 }  // namespace device