static int oldtime, count, time; count++; if (count >= 10) { time = GetTickCount; FPS = 10000.0f / max(time - oldtime, 1); oldtime = time; count = 0; } Steve ''Sly'' Williams Code Monkey Krome Studios
Frames Per Second (FPS)
Magmai: We use code similar to the following to calculate FPS. I added your filtered framerate calculation alongside it and get a 5 fps difference. That is, your function returns 25 whereas this function returns 30. The game loop is locked into a fixed time step of 30 fps. This code seems to be returning the correct value (I believe), whereas yours is 5 fps lower. Any ideas as to why the difference?
Steve ''Sly'' Williams Code Monkey Krome Studios
Steve ''Sly'' Williams Code Monkey Krome Studios
I thinks it's due to the low accuracy of GetTickCount (+/- 10ms, QueryP... is good to +/-5us)... just a guess.
try this:
the numbers match then - I get a 5fps difference using tickcount as well.
Magmai Kai Holmlor
- The disgruntled & disillusioned
Call CalcFrameRate every frame; you can display the results every frame as well.
Edited by - Magmai Kai Holmlor on March 19, 2001 1:18:38 AM
try this:
static float FPS; static int oldtime, count, time; static LARGE_INTEGER liTime, liOldTime; count++; if (count >= 10) { QueryPerformanceCounter(&liTime); FPS = 10000000.0f / max((liTime.QuadPart - liOldTime.QuadPart), 1); liOldTime.QuadPart = liTime.QuadPart; count = 0; } the numbers match then - I get a 5fps difference using tickcount as well.
Magmai Kai Holmlor
- The disgruntled & disillusioned
Call CalcFrameRate every frame; you can display the results every frame as well.
Edited by - Magmai Kai Holmlor on March 19, 2001 1:18:38 AM
I tried your code and it was giving the same results (unfiltered) as your filtered routine does. So I guess the accuracy of the timers come into play here. On Win95 and possibly 98, GetTickCount is only accurate to 55ms as stated in MSDN.
Steve ''Sly'' Williams Code Monkey Krome Studios
Steve ''Sly'' Williams Code Monkey Krome Studios
Use timeGetTime() instead, it may not be as accurate as QueryPerformanceCounter(), but msdn states that the resolution in W9x is 1ms, in NT or W2k it''s >= 5ms by default, but can be changed by timeBeginPeriod()/timeEndPeriod(). It is also available on all systems.
I use almost the exact same code as you Sly (except for GetTickCount()) and it works pretty ok.
I use almost the exact same code as you Sly (except for GetTickCount()) and it works pretty ok.
Are there any systems out there these days that do not support QueryPerformanceCounter? I have also been told of a few systems that return an incorrect value for QueryPerformanceFrequency. Can anyone confirm this? I found the following KB article about it, and it seems to be fairly rare. There is also this KB article about possible leaps forward in responses from QueryPerformanceCounter due to a design defect in certain chipsets.
Steve ''Sly'' Williams Code Monkey Krome Studios
Steve ''Sly'' Williams Code Monkey Krome Studios
This topic is closed to new replies.
Advertisement
Popular Topics
Advertisement
