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1 | sf::Clock frameClock; | |
2 | ||
3 | double desiredRefreshRate = 60.0; | |
4 | double frameSkipPreventionPenalty = desiredRefreshRate / 300; | |
5 | double definiteFramerateTarget = desiredRefreshRate - frameSkipPreventionPenalty; | |
6 | const sf::Time minAdaptiveFrameTimeMicros = sf::microseconds((sf::Int64) (1000000.0f / (definiteFramerateTarget * 2.0))); | |
7 | const sf::Time maxAdaptiveFrameTimeMicros = sf::microseconds((sf::Int64) (1000000.0f / (definiteFramerateTarget * 0.5))); | |
8 | ||
9 | const sf::Time idealFrameTime = sf::microseconds((sf::Int64) (1000000.0 / definiteFramerateTarget)); | |
10 | ||
11 | // Frame time backlog | |
12 | const int frameTimeMemorySize = (int) (desiredRefreshRate * 1.5 + 2); // Adapt within 1.5 seconds | |
13 | sf::Int64* frameTimeMemoryMicros = (sf::Int64*) malloc(sizeof(sf::Int64) * frameTimeMemorySize); | |
14 | ||
15 | // Start filled with ideal frame time | |
16 | std::fill_n(frameTimeMemoryMicros, frameTimeMemorySize, idealFrameTime.asMicroseconds()); | |
17 | sf::Int64 frameTimeMemoryMicrosSum = frameTimeMemorySize * idealFrameTime.asMicroseconds(); | |
18 | ||
19 | int frameTimeOldestMemorySlot = 0; | |
20 | sf::Int64 recentMicros; | |
21 | sf::Int64 oldMicros; | |
22 | ||
23 | sf::Time assumedFrameTime = idealFrameTime; | |
24 | sf::Time elapsedFrameTime; | |
25 | sf::Time frameTime; | |
26 | sf::Time sceneTime; | |
27 | sf::Time previousSceneTime; | |
28 | sf::Time intendedSleepDuration; | |
29 | sf::Time afterSleepTime; | |
30 | sf::Time actualSleepDuration; | |
31 | sf::Time oversleepDuration; | |
32 | sf::Time correctiveFrameTime; | |
33 | ||
34 | while (window->isOpen()) { | |
35 | ||
36 | frameClock.restart(); | |
37 | ||
38 | sceneTime = sceneClock.getElapsedTime(); | |
39 | frameTime = sceneTime - previousSceneTime; | |
40 | ||
41 | if (frameTime < sf::Time::Zero) { // The clock was reset | |
42 | frameTime = sceneTime; | |
43 | previousSceneTime = sf::Time::Zero; | |
44 | } else { | |
45 | previousSceneTime = sceneTime; | |
46 | } | |
47 | ||
48 | if (frameTime > sf::Time::Zero) { | |
49 | parseInput(frameTime); | |
50 | renderScene(sceneTime); | |
51 | window->display(); // Swap buffers | |
52 | glFlush(); | |
53 | } | |
54 | ||
55 | - | //std::cout << "Adaptive FPS target: " << adaptiveFramerateTarget << std::endl; |
55 | + | |
56 | ||
57 | elapsedFrameTime = frameClock.getElapsedTime(); | |
58 | intendedSleepDuration = assumedFrameTime - elapsedFrameTime; | |
59 | ||
60 | // There is time to sleep | |
61 | if (intendedSleepDuration > sf::Time::Zero) { | |
62 | ||
63 | //timeBeginPeriod(1); // Setting this at program start gives better accuracy | |
64 | sf::sleep(intendedSleepDuration); | |
65 | //timeEndPeriod(1); | |
66 | ||
67 | afterSleepTime = frameClock.getElapsedTime(); | |
68 | actualSleepDuration = afterSleepTime - elapsedFrameTime; | |
69 | oversleepDuration = actualSleepDuration - intendedSleepDuration; | |
70 | correctiveFrameTime = idealFrameTime - oversleepDuration; | |
71 | ||
72 | if (correctiveFrameTime < minAdaptiveFrameTimeMicros) { | |
73 | correctiveFrameTime = minAdaptiveFrameTimeMicros; | |
74 | } else if (correctiveFrameTime > maxAdaptiveFrameTimeMicros) { | |
75 | correctiveFrameTime = maxAdaptiveFrameTimeMicros; | |
76 | } | |
77 | ||
78 | recentMicros = correctiveFrameTime.asMicroseconds(); | |
79 | oldMicros = frameTimeMemoryMicros[frameTimeOldestMemorySlot]; | |
80 | ||
81 | frameTimeMemoryMicrosSum += recentMicros - oldMicros; | |
82 | frameTimeMemoryMicros[frameTimeOldestMemorySlot] = recentMicros; | |
83 | frameTimeOldestMemorySlot = (frameTimeOldestMemorySlot + 1) % frameTimeMemorySize; | |
84 | ||
85 | assumedFrameTime = sf::microseconds(frameTimeMemoryMicrosSum / frameTimeMemorySize); | |
86 | } // else don't touch the adaptive FPS we have "learned" so far, and just move on. | |
87 | } | |
88 | ||
89 | glFinish(); // If the frame is still not done rendering, block. | |
90 | } |