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Sleep between frames to save CPU cycles

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GoaLitiuM
2021-05-29 20:15:29 +03:00
parent cc60814334
commit e06200926f
3 changed files with 62 additions and 50 deletions
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37
Source/Engine/Engine/Engine.cpp
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@@ -146,26 +146,22 @@ int32 Engine::Main(const Char* cmdLine)
EngineImpl::IsReady = true;
// Main engine loop
bool canDraw = true; // Prevent drawing 2 or more frames in a row without update or fixed update (nothing will change)
const bool useSleep = true; // TODO: this should probably be a platform setting
while (!ShouldExit())
{
#if 0
// TODO: test it more and maybe use in future to reduce CPU usage
// Reduce CPU usage by introducing idle time if the engine is running very fast and has enough time to spend
{
float tickFps;
auto tick = Time->GetHighestFrequency(tickFps);
double tickTargetStepTime = 1.0 / tickFps;
double nextTick = tick->LastEnd + tickTargetStepTime;
double timeToTick = nextTick - Platform::GetTimeSeconds();
int32 sleepTimeMs = Math::Min(4, Math::FloorToInt(timeToTick * (1000.0 * 0.8))); // Convert seconds to milliseconds and apply adjustment with limit
if (!Device->WasVSyncUsed() && sleepTimeMs > 0)
{
PROFILE_CPU_NAMED("Idle");
Platform::Sleep(sleepTimeMs);
}
}
#endif
// Reduce CPU usage by introducing idle time if the engine is running very fast and has enough time to spend
if ((useSleep && Time::UpdateFPS > 0) || !Platform::GetHasFocus())
{
double nextTick = Time::GetNextTick();
double timeToTick = nextTick - Platform::GetTimeSeconds();
// Sleep less than needed, some platforms may sleep slightly more than requested
if (timeToTick > 0.002)
{
PROFILE_CPU_NAMED("Idle");
Platform::Sleep(1);
}
}
// App paused logic
if (Platform::GetIsPaused())
@@ -187,7 +183,6 @@ int32 Engine::Main(const Char* cmdLine)
OnUpdate();
OnLateUpdate();
Time::OnEndUpdate();
canDraw = true;
}
// Start physics simulation
@@ -195,16 +190,14 @@ int32 Engine::Main(const Char* cmdLine)
{
OnFixedUpdate();
Time::OnEndPhysics();
canDraw = true;
}
// Draw frame
if (canDraw && Time::OnBeginDraw())
if (Time::OnBeginDraw())
{
OnDraw();
Time::OnEndDraw();
FrameMark;
canDraw = false;
}
// Collect physics simulation results (does nothing if Simulate hasn't been called in the previous loop step)