/************************************************************************************
Filename : CAPI_FrameTimeManager.h
Content : Manage frame timing and pose prediction for rendering
Created : November 30, 2013
Authors : Volga Aksoy, Michael Antonov
Copyright : Copyright 2014 Oculus VR, Inc. All Rights reserved.
Licensed under the Oculus VR Rift SDK License Version 3.1 (the "License");
you may not use the Oculus VR Rift SDK except in compliance with the License,
which is provided at the time of installation or download, or which
otherwise accompanies this software in either electronic or hard copy form.
You may obtain a copy of the License at
http://www.oculusvr.com/licenses/LICENSE-3.1
Unless required by applicable law or agreed to in writing, the Oculus VR SDK
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
************************************************************************************/
#ifndef OVR_CAPI_FrameTimeManager_h
#define OVR_CAPI_FrameTimeManager_h
#include "../OVR_CAPI.h"
#include "../Kernel/OVR_Timer.h"
#include "../Kernel/OVR_Math.h"
#include "../Util/Util_Render_Stereo.h"
#include "../Util/Util_LatencyTest2.h"
namespace OVR { namespace CAPI {
//-------------------------------------------------------------------------------------
// Helper class to collect median times between frames, so that we know
// how long to wait.
struct TimeDeltaCollector
{
TimeDeltaCollector() : Count(0) { }
void AddTimeDelta(double timeSeconds);
void Clear() { Count = 0; }
double GetMedianTimeDelta() const;
double GetCount() const { return Count; }
enum { Capacity = 12 };
private:
int Count;
double TimeBufferSeconds[Capacity];
};
//-------------------------------------------------------------------------------------
// ***** FrameLatencyTracker
// FrameLatencyTracker tracks frame Present to display Scan-out timing, as reported by
// the DK2 internal latency tester pixel read-back. The computed value is used in
// FrameTimeManager for prediction. View Render and TimeWarp to scan-out latencies are
// also reported for debugging.
//
// The class operates by generating color values from GetNextDrawColor() that must
// be rendered on the back end and then looking for matching values in FrameTimeRecordSet
// structure as reported by HW.
class FrameLatencyTracker
{
public:
enum { FramesTracked = Util::LT2_IncrementCount-1 };
FrameLatencyTracker();
// DrawColor == 0 is special in that it doesn't need saving of timestamp
unsigned char GetNextDrawColor();
void SaveDrawColor(unsigned char drawColor, double endFrameTime,
double renderIMUTime, double timewarpIMUTime );
void MatchRecord(const Util::FrameTimeRecordSet &r);
void GetLatencyTimings(float latencies[3]);
void Reset();
public:
struct FrameTimeRecordEx : public Util::FrameTimeRecord
{
bool MatchedRecord;
double RenderIMUTimeSeconds;
double TimewarpIMUTimeSeconds;
};
// True if rendering read-back is enabled.
bool TrackerEnabled;
enum SampleWaitType {
SampleWait_Zeroes, // We are waiting for a record with all zeros.
SampleWait_Match // We are issuing & matching colors.
};
SampleWaitType WaitMode;
int MatchCount;
// Records of frame timings that we are trying to measure.
FrameTimeRecordEx FrameEndTimes[FramesTracked];
int FrameIndex;
// Median filter for (ScanoutTimeSeconds - PostPresent frame time)
TimeDeltaCollector FrameDeltas;
// Latency reporting results
double RenderLatencySeconds;
double TimewarpLatencySeconds;
double LatencyRecordTime;
};
//-------------------------------------------------------------------------------------
// ***** FrameTimeManager
// FrameTimeManager keeps track of rendered frame timing and handles predictions for
// orientations and time-warp.
class FrameTimeManager
{
public:
FrameTimeManager(bool vsyncEnabled = true);
// Data that affects frame timing computation.
struct TimingInputs
{
// Hard-coded value or dynamic as reported by FrameTimeDeltas.GetMedianTimeDelta().
double FrameDelta;
// Screen delay from present to scan-out, as potentially reported by ScreenLatencyTracker.
double ScreenDelay;
// Negative value of how many seconds before EndFrame we start timewarp. 0.0 if not used.
double TimewarpWaitDelta;
TimingInputs()
: FrameDelta(0), ScreenDelay(0), TimewarpWaitDelta(0)
{ }
};
// Timing values for a specific frame.
struct Timing
{
TimingInputs Inputs;
// Index of a frame that started at ThisFrameTime.
unsigned int FrameIndex;
// Predicted absolute times for when this frame will show up on screen.
// Generally, all values will be >= NextFrameTime, since that's the time we expect next
// vsync to succeed.
double ThisFrameTime;
double TimewarpPointTime;
double NextFrameTime;
double MidpointTime;
double EyeRenderTimes[2];
double TimeWarpStartEndTimes[2][2];
Timing()
{
memset(this, 0, sizeof(Timing));
}
void InitTimingFromInputs(const TimingInputs& inputs, HmdShutterTypeEnum shutterType,
double thisFrameTime, unsigned int frameIndex);
};
// Called on startup to provided data on HMD timing.
void Init(HmdRenderInfo& renderInfo);
// Called with each new ConfigureRendering.
void ResetFrameTiming(unsigned frameIndex,
bool dynamicPrediction, bool sdkRender);
void SetVsync(bool enabled) { VsyncEnabled = enabled; }
// BeginFrame returns time of the call
// TBD: Should this be a predicted time value instead ?
double BeginFrame(unsigned frameIndex);
void EndFrame();
// Thread-safe function to query timing for a future frame
Timing GetFrameTiming(unsigned frameIndex);
double GetEyePredictionTime(ovrEyeType eye);
Transformf GetEyePredictionPose(ovrHmd hmd, ovrEyeType eye);
void GetTimewarpPredictions(ovrEyeType eye, double timewarpStartEnd[2]);
void GetTimewarpMatrices(ovrHmd hmd, ovrEyeType eye, ovrPosef renderPose, ovrMatrix4f twmOut[2]);
// Used by renderer to determine if it should time distortion rendering.
bool NeedDistortionTimeMeasurement() const;
void AddDistortionTimeMeasurement(double distortionTimeSeconds);
// DK2 Lateny test interface
// Get next draw color for DK2 latency tester
unsigned char GetFrameLatencyTestDrawColor()
{ return ScreenLatencyTracker.GetNextDrawColor(); }
// Must be called after EndFrame() to update latency tester timings.
// Must pass color reported by NextFrameColor for this frame.
void UpdateFrameLatencyTrackingAfterEndFrame(unsigned char frameLatencyTestColor,
const Util::FrameTimeRecordSet& rs);
void GetLatencyTimings(float latencies[3])
{ return ScreenLatencyTracker.GetLatencyTimings(latencies); }
const Timing& GetFrameTiming() const { return FrameTiming; }
private:
double calcFrameDelta() const;
double calcScreenDelay() const;
double calcTimewarpWaitDelta() const;
HmdRenderInfo RenderInfo;
// Timings are collected through a median filter, to avoid outliers.
TimeDeltaCollector FrameTimeDeltas;
TimeDeltaCollector DistortionRenderTimes;
FrameLatencyTracker ScreenLatencyTracker;
// Timing changes if we have no Vsync (all prediction is reduced to fixed interval).
bool VsyncEnabled;
// Set if we are rendering via the SDK, so DistortionRenderTimes is valid.
bool DynamicPrediction;
// Set if SDk is doing teh rendering.
bool SdkRender;
// Total frame delay due to VsyncToFirstScanline, persistence and settle time.
// Computed from RenderInfor.Shutter.
double VSyncToScanoutDelay;
double NoVSyncToScanoutDelay;
double ScreenSwitchingDelay;
// Current (or last) frame timing info. Used as a source for LocklessTiming.
Timing FrameTiming;
// TBD: Don't we need NextFrame here as well?
LocklessUpdater<Timing> LocklessTiming;
// IMU Read timings
double RenderIMUTimeSeconds;
double TimewarpIMUTimeSeconds;
};
}} // namespace OVR::CAPI
#endif // OVR_CAPI_FrameTimeManager_h