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Diffstat (limited to 'LibOVR/Src/CAPI/CAPI_FrameTimeManager3.h')
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diff --git a/LibOVR/Src/CAPI/CAPI_FrameTimeManager3.h b/LibOVR/Src/CAPI/CAPI_FrameTimeManager3.h new file mode 100644 index 0000000..1baf5b4 --- /dev/null +++ b/LibOVR/Src/CAPI/CAPI_FrameTimeManager3.h @@ -0,0 +1,228 @@ +/************************************************************************************ + +Filename : CAPI_FrameTimeManager3.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 3.2 (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-3.2 + +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_FrameTimeManager3_h +#define OVR_CAPI_FrameTimeManager3_h + +#include <OVR_CAPI.h> +#include <Kernel/OVR_Timer.h> +#include <Extras/OVR_Math.h> +#include <Util/Util_Render_Stereo.h> + +namespace OVR { namespace CAPI { namespace FTM3 { + +void LogTime(const char* msg); + + +//------------------------------------------------------------------------------------- +// MedianCalculator +// +// Helper class to calculate statistics +class MedianCalculator +{ +public: + MedianCalculator(int capacity); + + void Clear(); + + // This function throws away data larger than 100 milliseconds, + // and it sanitizes negative time deltas replacing them with zero milliseconds. + void Add(double timeDelta); + + int GetCount() const + { + return DataCount; + } + int GetCapacity() const + { + return Capacity; + } + bool AtCapacity() const + { + return DataCount >= Capacity; + } + + double GetMedian(); + bool GetStats(double& minValue, double& maxValue, + double& meanValue, double& medianValue); + +private: + Array<double> Data; + Array<double> SortBuffer; // Buffer for quick select algorithm + + double MinValue, MaxValue, MeanValue, MedianValue; + + int Index; + int DataCount, Capacity; + bool Recalculate; + + // Precondition: Count > 0 + void doRecalculate(); +}; + + +// Helper used to compute AddFrameIndex to DisplayFrameIndex ratio, by tracking +// how much each has advanced over the recent frames. +struct FrameIndexMapper +{ + enum { Capacity = 12 }; + + // Circular buffer starting with StartIndex + unsigned DisplayFrameIndices[Capacity]; + unsigned AppFrameIndices[Capacity]; + unsigned StartIndex; + unsigned Count; + + FrameIndexMapper() : StartIndex(0), Count(0) { } + + void Reset() + { StartIndex = Count = 0; } + + void Add(unsigned displayFrameIndex, unsigned appFrameIndex); + + double GetAppToDisplayFrameRatio() const; +}; + + +//------------------------------------------------------------------------------------- +// ***** FrameTimeManagerCore + +// FrameTimeManager keeps track of rendered frame timing needed for predictions for +// orientations and time-warp. +// +// The following items are not in Core for now +// +// - TimewarpWaitDelta (how many seconds before EndFrame we start timewarp) +// this should be handled externally. +// +// - ScreenDelay (Screen delay from present to scan-out, as potentially reported by ScreenLatencyTracker.) +// this si rendering setup and HW specific +// +// - TimeWarpStartEndTimes (move matrices logic outside for now) +// +// - For now, always assume VSync on + + +class FrameTimeManagerCore +{ +public: + + // Describes last presented frame data. + struct Timing + { + // Hard-coded value or dynamic as reported by FrameTimeDeltas.GetMedianTimeDelta(). + double FrameDelta; + + // Application frame index for which we requested timing. + unsigned AppFrameIndex; + // HW frame index that we expect this will hit, the specified + // frame will start scan-out at ScanoutStartSeconds. Monotonically increasing. + unsigned DisplayFrameIndex; + + // PostPresent & Flush (old approach) or reported scan-out time (new HW-reported approach). + double FrameSubmitSeconds; + + // Ratio of (AppFrames/DisplayFrames) in + double AppToDisplayFrameRatio; + + Timing() + { + memset(this, 0, sizeof(Timing)); + } + + }; + +public: + + FrameTimeManagerCore(bool vsyncEnabled); + + // Called on startup to provided data on HMD timing. DefayltTiming should include FrameDelta + // and other default values. This can also be called to reset timing. + void Initialize(const Timing& defaultTiming); + + // Returns frame timing data for any thread to access, including + // - Simulating thread that may be running ahead + // - Rendering thread, which would treat as BeginFrame data + Timing GetAppFrameTiming(unsigned appFrameIndex); + + // Returns frame timing values for a particular DisplayFrameIndex. + // Maintaining DisplayFrameIndex is the job of the caller, as it may be fied to OS + // VSync frame reporting functionality ad/or system clock. + Timing GetDisplayFrameTiming(unsigned displayFrameIndex); + + // To be called from TW Thread when displayFrame has been submitted for present. + // This call is used to update lock-less timing frame basis. The provided + // values do the following: + // - Establish relationship between App and Display frame index. + // - Track the real frameDelta (difference between VSyncs) + void SubmitDisplayFrame(unsigned displayFrameIndex, + unsigned appFrameIndex, + double scanoutStartSeconds); + + unsigned GetLastDisplayFrameIndex() const + { + return LastTiming.DisplayFrameIndex; + } + double GetLastDisplayFrameTime() const + { + return LastTiming.FrameSubmitSeconds; + } + + double GetFrameDelta() const + { + return calcFrameDelta(); + } + + void SetVsync(bool enabled) { VsyncEnabled = enabled; } + + // ovrFrameTiming ovrFrameTimingFromTiming(const Timing& timing) const; + +private: + + double calcFrameDelta() const; + + + // Timing changes if we have no Vsync (all prediction is reduced to fixed interval). + bool VsyncEnabled; + // Default VsyncToVSync value, received in Initialize. + double DefaultFrameDelta; + // Last timing + Timing LastTiming; + + // Current (or last) frame timing info. Used as a source for LocklessTiming. + LocklessUpdater<Timing, Timing> LocklessTiming; + + // Timings are collected through a median filter, to avoid outliers. + mutable MedianCalculator FrameTimeDeltas; + // Associates AppFrameIndex <-> + FrameIndexMapper FrameIndices; + +}; + + +}}} // namespace OVR::CAPI::FTM3 + +#endif // OVR_CAPI_FrameTimeManager_h |