calculating fps

[grady]

Hi, i'm calculating my fps with the function in time.h: time( ). But i can only get a difference of seconds for calculating fps. It seems like there should be some way to get time in at least milliseconds. Does anyone know how?

[rts]

gettimeofday() on most BSD based systems (Linux included)

timeGetTime() (or something like that) on Win32

[mcbastian]

If you are on Visual C try:

GetTickCount();

:-)

Gives time in milliseconds...

Greetings,
Sebastian

[Relic]

For most accurate results checkout QueryPerformanceFrequency() and QueryPerformanceCounter() which give time in processor clocks as LARGE_INTEGER (64 bit) values.

[Nutty]

I use this for win32.




//Globals.
LARGE_INTEGER time, last_time, diff, frequency;

GLfloat g_frame_time;

//Initialize the variables with this.
//Get the performance counter metrics.
QueryPerformanceCounter(&last_time);
QueryPerformanceCounter(&time);
QueryPerformanceFrequency(&frequency);
//Set iniitial frame time to 0.
g_frame_time = 0.f;


//Then call this each frame, to setup the current frame time in g_frame_time.

void CalcFrameTime(void)
{
GLfloat frame_time;

last_time = time;
QueryPerformanceCounter(&time);

diff.QuadPart = time.QuadPart - last_time.QuadPart;
frame_time = (GLfloat)diff.QuadPart / (GLfloat)frequency.QuadPart;

g_frame_time = frame_time;

}



Then frame rate is simple 1.0f / g_frame_time.

Use g_frame_time for movements, to make stuff frame rate independant. For example to move something at 1 unit per second, do.

[/CODE]
position += velocity * g_frame_time;

[/CODE]

where velocity has magnitude of 1.

Or something like that.

Nutty

[This message has been edited by Nutty (edited 06-10-2001).]