Find a way to bring FPS to exactly 70

soulweaver91 / project-carrot

Project Carrot, an open source spiritual clone of the Jazz Jackrabbit 2 game engine

https://carrot.soulweaver.fi/

MIT License

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Find a way to bring FPS to exactly 70 #45

Open soulweaver91 opened 8 years ago

soulweaver91 commented 8 years ago

Right now, the core timer is based on QTimer. It only supports intervals rounding to whole milliseconds, so effectively there is a new frame every 14 ms instead of the desired ~14.29 ms, resulting in an effective FPS of ~71.43.

There should be a way to bring this to exactly 70 FPS. (Ideally, game logic loop should be separated at some level from the graphics loop anyway – right now they are tied together very closely.)

soulweaver91 commented 7 years ago

Attempted some approaches:

Custom while loop, instead of relying on a QTimer, and sleeping with QThread::usleep with timekeeping by QElapsedTimer::nsecsElapsed(). The loop ended up going from too fast to too slow.
Altering the QTimer between 14 and 15 ms, again keeping time with QElapsedTimer. It managed to slightly drop the FPS to a relatively stable ~71 (14.05 ms/frame), but that still isn't good enough to claim it runs at 70 FPS.