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64 lines
1.9 KiB
C++
64 lines
1.9 KiB
C++
/*
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* FramerateManager.cpp, part of VCMI engine
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*
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* Authors: listed in file AUTHORS in main folder
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*
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* License: GNU General Public License v2.0 or later
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* Full text of license available in license.txt file, in main folder
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*
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*/
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#include "StdInc.h"
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#include "FramerateManager.h"
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#include "../../lib/CConfigHandler.h"
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#include <SDL_video.h>
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FramerateManager::FramerateManager(int targetFrameRate)
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: targetFrameTime(Duration(boost::chrono::seconds(1)) / targetFrameRate)
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, lastFrameIndex(0)
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, lastFrameTimes({})
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, lastTimePoint(Clock::now())
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, vsyncEnabled(settings["video"]["vsync"].Bool())
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{
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boost::range::fill(lastFrameTimes, targetFrameTime);
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}
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void FramerateManager::framerateDelay()
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{
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Duration timeSpentBusy = Clock::now() - lastTimePoint;
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if(!vsyncEnabled && timeSpentBusy < targetFrameTime)
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{
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// if FPS is higher than it should be, then wait some time
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boost::this_thread::sleep_for(targetFrameTime - timeSpentBusy);
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}
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// compute actual timeElapsed taking into account actual sleep interval
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// limit it to 100 ms to avoid breaking animation in case of huge lag (e.g. triggered breakpoint)
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TimePoint currentTicks = Clock::now();
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Duration timeElapsed = currentTicks - lastTimePoint;
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if(timeElapsed > boost::chrono::milliseconds(100))
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timeElapsed = boost::chrono::milliseconds(100);
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lastTimePoint = currentTicks;
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lastFrameIndex = (lastFrameIndex + 1) % lastFrameTimes.size();
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lastFrameTimes[lastFrameIndex] = timeElapsed;
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}
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ui32 FramerateManager::getElapsedMilliseconds() const
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{
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return lastFrameTimes[lastFrameIndex] / boost::chrono::milliseconds(1);
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}
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ui32 FramerateManager::getFramerate() const
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{
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Duration accumulatedTime = std::accumulate(lastFrameTimes.begin(), lastFrameTimes.end(), Duration());
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auto actualFrameTime = accumulatedTime / lastFrameTimes.size();
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if(actualFrameTime == actualFrameTime.zero())
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return 0;
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return std::round(boost::chrono::duration<double>(1) / actualFrameTime);
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};
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