gecko-dev/gfx/vr/gfxVROculus.cpp

670 строки
19 KiB
C++
Исходник Обычный вид История

/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include <math.h>
#include "prlink.h"
#include "prmem.h"
#include "prenv.h"
#include "gfxPrefs.h"
#include "nsString.h"
#include "mozilla/Preferences.h"
#include "mozilla/gfx/Quaternion.h"
#ifdef XP_WIN
#include "../layers/d3d11/CompositorD3D11.h"
#endif
#include "gfxVROculus.h"
#include "nsServiceManagerUtils.h"
#include "nsIScreenManager.h"
#ifndef M_PI
# define M_PI 3.14159265358979323846
#endif
using namespace mozilla::gfx;
using namespace mozilla::gfx::impl;
namespace {
#ifdef OVR_CAPI_LIMITED_MOZILLA
static pfn_ovr_Initialize ovr_Initialize = nullptr;
static pfn_ovr_Shutdown ovr_Shutdown = nullptr;
static pfn_ovr_GetTimeInSeconds ovr_GetTimeInSeconds = nullptr;
static pfn_ovrHmd_Detect ovrHmd_Detect = nullptr;
static pfn_ovrHmd_Create ovrHmd_Create = nullptr;
static pfn_ovrHmd_CreateDebug ovrHmd_CreateDebug = nullptr;
static pfn_ovrHmd_Destroy ovrHmd_Destroy = nullptr;
static pfn_ovrHmd_ConfigureTracking ovrHmd_ConfigureTracking = nullptr;
static pfn_ovrHmd_RecenterPose ovrHmd_RecenterPose = nullptr;
static pfn_ovrHmd_GetTrackingState ovrHmd_GetTrackingState = nullptr;
static pfn_ovrHmd_GetFovTextureSize ovrHmd_GetFovTextureSize = nullptr;
static pfn_ovrHmd_GetRenderDesc ovrHmd_GetRenderDesc = nullptr;
static pfn_ovrHmd_DestroySwapTextureSet ovrHmd_DestroySwapTextureSet = nullptr;
static pfn_ovrHmd_SubmitFrame ovrHmd_SubmitFrame = nullptr;
#ifdef XP_WIN
static pfn_ovrHmd_CreateSwapTextureSetD3D11 ovrHmd_CreateSwapTextureSetD3D11 = nullptr;
#endif
static pfn_ovrHmd_CreateSwapTextureSetGL ovrHmd_CreateSwapTextureSetGL = nullptr;
#ifdef HAVE_64BIT_BUILD
#define BUILD_BITS 64
#else
#define BUILD_BITS 32
#endif
#define OVR_PRODUCT_VERSION 0
#define OVR_MAJOR_VERSION 6
#define OVR_MINOR_VERSION 0
static bool
InitializeOculusCAPI()
{
static PRLibrary *ovrlib = nullptr;
if (!ovrlib) {
nsTArray<nsCString> libSearchPaths;
nsCString libName;
nsCString searchPath;
#if defined(_WIN32)
static const char dirSep = '\\';
#else
static const char dirSep = '/';
#endif
#if defined(_WIN32)
static const int pathLen = 260;
searchPath.SetCapacity(pathLen);
int realLen = ::GetSystemDirectoryA(searchPath.BeginWriting(), pathLen);
if (realLen != 0 && realLen < pathLen) {
searchPath.SetLength(realLen);
libSearchPaths.AppendElement(searchPath);
}
libName.AppendPrintf("LibOVRRT%d_%d_%d.dll", BUILD_BITS, OVR_PRODUCT_VERSION, OVR_MAJOR_VERSION);
#elif defined(__APPLE__)
searchPath.Truncate();
searchPath.AppendPrintf("/Library/Frameworks/LibOVRRT_%d.framework/Versions/%d", OVR_PRODUCT_VERSION, OVR_MAJOR_VERSION);
libSearchPaths.AppendElement(searchPath);
if (PR_GetEnv("HOME")) {
searchPath.Truncate();
searchPath.AppendPrintf("%s/Library/Frameworks/LibOVRRT_%d.framework/Versions/%d", PR_GetEnv("HOME"), OVR_PRODUCT_VERSION, OVR_MAJOR_VERSION);
libSearchPaths.AppendElement(searchPath);
}
// The following will match the va_list overload of AppendPrintf if the product version is 0
// That's bad times.
//libName.AppendPrintf("LibOVRRT_%d", OVR_PRODUCT_VERSION);
libName.Append("LibOVRRT_");
libName.AppendInt(OVR_PRODUCT_VERSION);
#else
libSearchPaths.AppendElement(nsCString("/usr/local/lib"));
libSearchPaths.AppendElement(nsCString("/usr/lib"));
libName.AppendPrintf("libOVRRT%d_%d.so.%d", BUILD_BITS, OVR_PRODUCT_VERSION, OVR_MAJOR_VERSION);
#endif
// If the pref is present, we override libName
nsAdoptingCString prefLibPath = mozilla::Preferences::GetCString("dom.vr.ovr_lib_path");
if (prefLibPath && prefLibPath.get()) {
libSearchPaths.InsertElementsAt(0, 1, prefLibPath);
}
nsAdoptingCString prefLibName = mozilla::Preferences::GetCString("dom.vr.ovr_lib_name");
if (prefLibName && prefLibName.get()) {
libName.Assign(prefLibName);
}
// search the path/module dir
libSearchPaths.InsertElementsAt(0, 1, nsCString());
// If the env var is present, we override libName
if (PR_GetEnv("OVR_LIB_PATH")) {
searchPath = PR_GetEnv("OVR_LIB_PATH");
libSearchPaths.InsertElementsAt(0, 1, searchPath);
}
if (PR_GetEnv("OVR_LIB_NAME")) {
libName = PR_GetEnv("OVR_LIB_NAME");
}
for (uint32_t i = 0; i < libSearchPaths.Length(); ++i) {
nsCString& libPath = libSearchPaths[i];
nsCString fullName;
if (libPath.Length() == 0) {
fullName.Assign(libName);
} else {
fullName.AppendPrintf("%s%c%s", libPath.BeginReading(), dirSep, libName.BeginReading());
}
ovrlib = PR_LoadLibrary(fullName.BeginReading());
if (ovrlib)
break;
}
if (!ovrlib) {
printf_stderr("Failed to load Oculus VR library!\n");
return false;
}
}
// was it already initialized?
if (ovr_Initialize)
return true;
#define REQUIRE_FUNCTION(_x) do { \
*(void **)&_x = (void *) PR_FindSymbol(ovrlib, #_x); \
if (!_x) { printf_stderr(#_x " symbol missing\n"); goto fail; } \
} while (0)
REQUIRE_FUNCTION(ovr_Initialize);
REQUIRE_FUNCTION(ovr_Shutdown);
REQUIRE_FUNCTION(ovr_GetTimeInSeconds);
REQUIRE_FUNCTION(ovrHmd_Detect);
REQUIRE_FUNCTION(ovrHmd_Create);
REQUIRE_FUNCTION(ovrHmd_CreateDebug);
REQUIRE_FUNCTION(ovrHmd_Destroy);
REQUIRE_FUNCTION(ovrHmd_ConfigureTracking);
REQUIRE_FUNCTION(ovrHmd_RecenterPose);
REQUIRE_FUNCTION(ovrHmd_GetTrackingState);
REQUIRE_FUNCTION(ovrHmd_GetFovTextureSize);
REQUIRE_FUNCTION(ovrHmd_GetRenderDesc);
REQUIRE_FUNCTION(ovrHmd_DestroySwapTextureSet);
REQUIRE_FUNCTION(ovrHmd_SubmitFrame);
#ifdef XP_WIN
REQUIRE_FUNCTION(ovrHmd_CreateSwapTextureSetD3D11);
#endif
REQUIRE_FUNCTION(ovrHmd_CreateSwapTextureSetGL);
#undef REQUIRE_FUNCTION
return true;
fail:
ovr_Initialize = nullptr;
return false;
}
#else
#include <OVR_Version.h>
// we're statically linked; it's available
static bool InitializeOculusCAPI()
{
return true;
}
#endif
static void
do_CalcEyePoses(ovrPosef headPose,
const ovrVector3f hmdToEyeViewOffset[2],
ovrPosef outEyePoses[2])
{
if (!hmdToEyeViewOffset || !outEyePoses)
return;
for (uint32_t i = 0; i < 2; ++i) {
gfx::Quaternion o(headPose.Orientation.x, headPose.Orientation.y, headPose.Orientation.z, headPose.Orientation.w);
Point3D vo(hmdToEyeViewOffset[i].x, hmdToEyeViewOffset[i].y, hmdToEyeViewOffset[i].z);
Point3D p = o.RotatePoint(vo);
outEyePoses[i].Orientation = headPose.Orientation;
outEyePoses[i].Position.x = p.x + headPose.Position.x;
outEyePoses[i].Position.y = p.y + headPose.Position.y;
outEyePoses[i].Position.z = p.z + headPose.Position.z;
}
}
ovrFovPort
ToFovPort(const VRFieldOfView& aFOV)
{
ovrFovPort fovPort;
fovPort.LeftTan = tan(aFOV.leftDegrees * M_PI / 180.0);
fovPort.RightTan = tan(aFOV.rightDegrees * M_PI / 180.0);
fovPort.UpTan = tan(aFOV.upDegrees * M_PI / 180.0);
fovPort.DownTan = tan(aFOV.downDegrees * M_PI / 180.0);
return fovPort;
}
VRFieldOfView
FromFovPort(const ovrFovPort& aFOV)
{
VRFieldOfView fovInfo;
fovInfo.leftDegrees = atan(aFOV.LeftTan) * 180.0 / M_PI;
fovInfo.rightDegrees = atan(aFOV.RightTan) * 180.0 / M_PI;
fovInfo.upDegrees = atan(aFOV.UpTan) * 180.0 / M_PI;
fovInfo.downDegrees = atan(aFOV.DownTan) * 180.0 / M_PI;
return fovInfo;
}
} // namespace
HMDInfoOculus::HMDInfoOculus(ovrHmd aHMD)
: VRHMDInfo(VRHMDType::Oculus)
, mHMD(aHMD)
, mStartCount(0)
{
MOZ_ASSERT(sizeof(HMDInfoOculus::DistortionVertex) == sizeof(VRDistortionVertex),
"HMDInfoOculus::DistortionVertex must match the size of VRDistortionVertex");
MOZ_COUNT_CTOR_INHERITED(HMDInfoOculus, VRHMDInfo);
mDeviceName.AssignLiteral("Oculus VR HMD");
mSupportedSensorBits = 0;
if (mHMD->TrackingCaps & ovrTrackingCap_Orientation)
mSupportedSensorBits |= State_Orientation;
if (mHMD->TrackingCaps & ovrTrackingCap_Position)
mSupportedSensorBits |= State_Position;
mRecommendedEyeFOV[Eye_Left] = FromFovPort(mHMD->DefaultEyeFov[ovrEye_Left]);
mRecommendedEyeFOV[Eye_Right] = FromFovPort(mHMD->DefaultEyeFov[ovrEye_Right]);
mMaximumEyeFOV[Eye_Left] = FromFovPort(mHMD->MaxEyeFov[ovrEye_Left]);
mMaximumEyeFOV[Eye_Right] = FromFovPort(mHMD->MaxEyeFov[ovrEye_Right]);
SetFOV(mRecommendedEyeFOV[Eye_Left], mRecommendedEyeFOV[Eye_Right], 0.01, 10000.0);
#if 1
int32_t xcoord = 0;
if (getenv("FAKE_OCULUS_SCREEN")) {
const char *env = getenv("FAKE_OCULUS_SCREEN");
nsresult err;
xcoord = nsCString(env).ToInteger(&err);
if (err != NS_OK) xcoord = 0;
}
uint32_t w = mHMD->Resolution.w;
uint32_t h = mHMD->Resolution.h;
mScreen = VRHMDManager::MakeFakeScreen(xcoord, 0, std::max(w, h), std::min(w, h));
#ifdef DEBUG
printf_stderr("OCULUS SCREEN: %d %d %d %d\n", xcoord, 0, std::max(w, h), std::min(w, h));
#endif
#endif
}
void
HMDInfoOculus::Destroy()
{
if (mHMD) {
ovrHmd_Destroy(mHMD);
mHMD = nullptr;
}
}
bool
HMDInfoOculus::SetFOV(const VRFieldOfView& aFOVLeft, const VRFieldOfView& aFOVRight,
double zNear, double zFar)
{
float pixelsPerDisplayPixel = 1.0;
ovrSizei texSize[2];
// get eye parameters and create the mesh
for (uint32_t eye = 0; eye < NumEyes; eye++) {
mEyeFOV[eye] = eye == 0 ? aFOVLeft : aFOVRight;
mFOVPort[eye] = ToFovPort(mEyeFOV[eye]);
ovrEyeRenderDesc renderDesc = ovrHmd_GetRenderDesc(mHMD, (ovrEyeType) eye, mFOVPort[eye]);
// As of Oculus 0.6.0, the HmdToEyeViewOffset values are correct and don't need to be negated.
mEyeTranslation[eye] = Point3D(renderDesc.HmdToEyeViewOffset.x, renderDesc.HmdToEyeViewOffset.y, renderDesc.HmdToEyeViewOffset.z);
// note that we are using a right-handed coordinate system here, to match CSS
mEyeProjectionMatrix[eye] = mEyeFOV[eye].ConstructProjectionMatrix(zNear, zFar, true);
texSize[eye] = ovrHmd_GetFovTextureSize(mHMD, (ovrEyeType) eye, mFOVPort[eye], pixelsPerDisplayPixel);
}
// take the max of both for eye resolution
mEyeResolution.width = std::max(texSize[Eye_Left].w, texSize[Eye_Right].w);
mEyeResolution.height = std::max(texSize[Eye_Left].h, texSize[Eye_Right].h);
mConfiguration.hmdType = mType;
mConfiguration.value = 0;
mConfiguration.fov[0] = aFOVLeft;
mConfiguration.fov[1] = aFOVRight;
return true;
}
void
HMDInfoOculus::FillDistortionConstants(uint32_t whichEye,
const IntSize& textureSize,
const IntRect& eyeViewport,
const Size& destViewport,
const Rect& destRect,
VRDistortionConstants& values)
{
}
bool
HMDInfoOculus::StartSensorTracking()
{
if (mStartCount == 0) {
bool ok = ovrHmd_ConfigureTracking(mHMD, ovrTrackingCap_Orientation | ovrTrackingCap_Position, 0);
if (!ok)
return false;
}
mStartCount++;
return true;
}
void
HMDInfoOculus::StopSensorTracking()
{
if (--mStartCount == 0) {
ovrHmd_ConfigureTracking(mHMD, 0, 0);
}
}
void
HMDInfoOculus::ZeroSensor()
{
ovrHmd_RecenterPose(mHMD);
}
VRHMDSensorState
HMDInfoOculus::GetSensorState(double timeOffset)
{
VRHMDSensorState result;
result.Clear();
// XXX this is the wrong time base for timeOffset; we need to figure out how to synchronize
// the Oculus time base and the browser one.
ovrTrackingState state = ovrHmd_GetTrackingState(mHMD, ovr_GetTimeInSeconds() + timeOffset);
ovrPoseStatef& pose(state.HeadPose);
result.timestamp = pose.TimeInSeconds;
if (state.StatusFlags & ovrStatus_OrientationTracked) {
result.flags |= State_Orientation;
result.orientation[0] = pose.ThePose.Orientation.x;
result.orientation[1] = pose.ThePose.Orientation.y;
result.orientation[2] = pose.ThePose.Orientation.z;
result.orientation[3] = pose.ThePose.Orientation.w;
result.angularVelocity[0] = pose.AngularVelocity.x;
result.angularVelocity[1] = pose.AngularVelocity.y;
result.angularVelocity[2] = pose.AngularVelocity.z;
result.angularAcceleration[0] = pose.AngularAcceleration.x;
result.angularAcceleration[1] = pose.AngularAcceleration.y;
result.angularAcceleration[2] = pose.AngularAcceleration.z;
}
if (state.StatusFlags & ovrStatus_PositionTracked) {
result.flags |= State_Position;
result.position[0] = pose.ThePose.Position.x;
result.position[1] = pose.ThePose.Position.y;
result.position[2] = pose.ThePose.Position.z;
result.linearVelocity[0] = pose.LinearVelocity.x;
result.linearVelocity[1] = pose.LinearVelocity.y;
result.linearVelocity[2] = pose.LinearVelocity.z;
result.linearAcceleration[0] = pose.LinearAcceleration.x;
result.linearAcceleration[1] = pose.LinearAcceleration.y;
result.linearAcceleration[2] = pose.LinearAcceleration.z;
}
mLastTrackingState = state;
return result;
}
struct RenderTargetSetOculus : public VRHMDRenderingSupport::RenderTargetSet
{
RenderTargetSetOculus(const IntSize& aSize,
HMDInfoOculus *aHMD,
ovrSwapTextureSet *aTS)
: hmd(aHMD)
{
textureSet = aTS;
size = aSize;
}
already_AddRefed<layers::CompositingRenderTarget> GetNextRenderTarget() override {
currentRenderTarget = (currentRenderTarget + 1) % renderTargets.Length();
textureSet->CurrentIndex = currentRenderTarget;
renderTargets[currentRenderTarget]->ClearOnBind();
nsRefPtr<layers::CompositingRenderTarget> rt = renderTargets[currentRenderTarget];
return rt.forget();
}
void Destroy() {
if (!hmd)
return;
if (hmd->GetOculusHMD()) {
// If the ovrHmd was already destroyed, so were all associated
// texture sets
ovrHmd_DestroySwapTextureSet(hmd->GetOculusHMD(), textureSet);
}
hmd = nullptr;
textureSet = nullptr;
}
~RenderTargetSetOculus() {
Destroy();
}
nsRefPtr<HMDInfoOculus> hmd;
ovrSwapTextureSet *textureSet;
};
#ifdef XP_WIN
class BasicTextureSourceD3D11 : public layers::TextureSourceD3D11
{
public:
BasicTextureSourceD3D11(ID3D11Texture2D *aTexture, const IntSize& aSize) {
mTexture = aTexture;
mSize = aSize;
}
};
struct RenderTargetSetD3D11 : public RenderTargetSetOculus
{
RenderTargetSetD3D11(layers::CompositorD3D11 *aCompositor,
const IntSize& aSize,
HMDInfoOculus *aHMD,
ovrSwapTextureSet *aTS)
: RenderTargetSetOculus(aSize, aHMD, aTS)
{
compositor = aCompositor;
renderTargets.SetLength(aTS->TextureCount);
currentRenderTarget = aTS->CurrentIndex;
for (int i = 0; i < aTS->TextureCount; ++i) {
ovrD3D11Texture *tex11;
nsRefPtr<layers::CompositingRenderTargetD3D11> rt;
tex11 = (ovrD3D11Texture*)&aTS->Textures[i];
rt = new layers::CompositingRenderTargetD3D11(tex11->D3D11.pTexture, IntPoint(0, 0));
rt->SetSize(size);
renderTargets[i] = rt;
}
}
};
#endif
already_AddRefed<VRHMDRenderingSupport::RenderTargetSet>
HMDInfoOculus::CreateRenderTargetSet(layers::Compositor *aCompositor, const IntSize& aSize)
{
#ifdef XP_WIN
if (aCompositor->GetBackendType() == layers::LayersBackend::LAYERS_D3D11)
{
layers::CompositorD3D11 *comp11 = static_cast<layers::CompositorD3D11*>(aCompositor);
CD3D11_TEXTURE2D_DESC desc(DXGI_FORMAT_B8G8R8A8_UNORM, aSize.width, aSize.height, 1, 1,
D3D11_BIND_SHADER_RESOURCE | D3D11_BIND_RENDER_TARGET);
ovrSwapTextureSet *ts = nullptr;
ovrResult orv = ovrHmd_CreateSwapTextureSetD3D11(mHMD, comp11->GetDevice(), &desc, &ts);
if (orv != ovrSuccess) {
return nullptr;
}
nsRefPtr<RenderTargetSetD3D11> rts = new RenderTargetSetD3D11(comp11, aSize, this, ts);
return rts.forget();
}
#endif
if (aCompositor->GetBackendType() == layers::LayersBackend::LAYERS_OPENGL) {
}
return nullptr;
}
void
HMDInfoOculus::DestroyRenderTargetSet(RenderTargetSet *aRTSet)
{
RenderTargetSetOculus *rts = static_cast<RenderTargetSetOculus*>(aRTSet);
rts->Destroy();
}
void
HMDInfoOculus::SubmitFrame(RenderTargetSet *aRTSet)
{
RenderTargetSetOculus *rts = static_cast<RenderTargetSetOculus*>(aRTSet);
MOZ_ASSERT(rts->hmd != nullptr);
MOZ_ASSERT(rts->textureSet != nullptr);
ovrLayerEyeFov layer;
layer.Header.Type = ovrLayerType_EyeFov;
layer.Header.Flags = 0;
layer.ColorTexture[0] = rts->textureSet;
layer.ColorTexture[1] = nullptr;
layer.Fov[0] = mFOVPort[0];
layer.Fov[1] = mFOVPort[1];
layer.Viewport[0].Pos.x = 0;
layer.Viewport[0].Pos.y = 0;
layer.Viewport[0].Size.w = rts->size.width / 2;
layer.Viewport[0].Size.h = rts->size.height;
layer.Viewport[1].Pos.x = rts->size.width / 2;
layer.Viewport[1].Pos.y = 0;
layer.Viewport[1].Size.w = rts->size.width / 2;
layer.Viewport[1].Size.h = rts->size.height;
const Point3D& l = rts->hmd->mEyeTranslation[0];
const Point3D& r = rts->hmd->mEyeTranslation[1];
const ovrVector3f hmdToEyeViewOffset[2] = { { l.x, l.y, l.z },
{ r.x, r.y, r.z } };
do_CalcEyePoses(rts->hmd->mLastTrackingState.HeadPose.ThePose, hmdToEyeViewOffset, layer.RenderPose);
ovrLayerHeader *layers = &layer.Header;
ovrResult orv = ovrHmd_SubmitFrame(mHMD, 0, nullptr, &layers, 1);
//printf_stderr("Submitted frame %d, result: %d\n", rts->textureSet->CurrentIndex, orv);
if (orv != ovrSuccess) {
// not visible? failed?
}
}
bool
VRHMDManagerOculus::PlatformInit()
{
if (mOculusPlatformInitialized)
return true;
if (!gfxPrefs::VREnabled() ||
!gfxPrefs::VROculusEnabled())
{
return false;
}
if (!InitializeOculusCAPI())
return false;
ovrInitParams params;
params.Flags = ovrInit_RequestVersion;
params.RequestedMinorVersion = OVR_MINOR_VERSION;
params.LogCallback = nullptr;
params.ConnectionTimeoutMS = 0;
ovrResult orv = ovr_Initialize(&params);
if (orv != ovrSuccess)
return false;
mOculusPlatformInitialized = true;
return true;
}
bool
VRHMDManagerOculus::Init()
{
if (mOculusInitialized)
return true;
if (!PlatformInit())
return false;
ovrResult orv;
int count = ovrHmd_Detect();
for (int i = 0; i < count; ++i) {
ovrHmd hmd;
orv = ovrHmd_Create(i, &hmd);
if (orv == ovrSuccess) {
nsRefPtr<HMDInfoOculus> oc = new HMDInfoOculus(hmd);
mOculusHMDs.AppendElement(oc);
}
}
// VRAddTestDevices == 1: add test device only if no real devices present
// VRAddTestDevices == 2: add test device always
if ((count == 0 && gfxPrefs::VRAddTestDevices() == 1) ||
(gfxPrefs::VRAddTestDevices() == 2))
{
ovrHmd hmd;
orv = ovrHmd_CreateDebug(ovrHmd_DK2, &hmd);
if (orv == ovrSuccess) {
nsRefPtr<HMDInfoOculus> oc = new HMDInfoOculus(hmd);
mOculusHMDs.AppendElement(oc);
}
}
mOculusInitialized = true;
return true;
}
void
VRHMDManagerOculus::Destroy()
{
if (!mOculusInitialized)
return;
for (size_t i = 0; i < mOculusHMDs.Length(); ++i) {
mOculusHMDs[i]->Destroy();
}
mOculusHMDs.Clear();
ovr_Shutdown();
mOculusInitialized = false;
}
void
VRHMDManagerOculus::GetHMDs(nsTArray<nsRefPtr<VRHMDInfo>>& aHMDResult)
{
Init();
for (size_t i = 0; i < mOculusHMDs.Length(); ++i) {
aHMDResult.AppendElement(mOculusHMDs[i]);
}
}