Besides clock() is there another way to get the clock time?

[Envergure]

Is there a way to get the clock time besides clock()?


Here's my specific problem:

I wrote a little "free camera" application in C++, using OpenGL and SDL.
Its camera was controlled with keyboard & mouse, like in a first-person shooter.
To see where I was going I had it draw a 50x50x50 cube of octahedra:

int i, j, k, l = 500, m = 80;  // l is the radius, m is the side length of the volume
glBegin (GL_QUADS);
for (i=0;  i<m;  i++)
{
    for (j=0;  j<m;  j++)
    {
        for (k=0;  k<m;  k++)
        {
            glColor3f (1, 0.5, 0);  // Draw a quad on the YZ plane
            glVertex3f (i*10000, j*10000+l, k*10000);
            glVertex3f (i*10000, j*10000, k*10000+l);
            glVertex3f (i*10000, j*10000-l, k*10000);
            glVertex3f (i*10000, j*10000, k*10000-l);
            glColor3f (1, 0.6, 0);  // Draw a quad on the XY plane
            glVertex3f (i*10000, j*10000+l, k*10000);
            glVertex3f (i*10000+l, j*10000, k*10000);
            glVertex3f (i*10000, j*10000-l, k*10000);
            glVertex3f (i*10000-l, j*10000, k*10000);
            glColor3f (1, 0.7, 0);  // Draw a quad on the XZ plane.  Together they look look an octahedron
            glVertex3f (i*10000+l, j*10000, k*10000);
            glVertex3f (i*10000, j*10000, k*10000+l);
            glVertex3f (i*10000-l, j*10000, k*10000);
            glVertex3f (i*10000, j*10000, k*10000-l);
        }
    }
}
glEnd();
 

This creates 6.1M verteces, which runs pretty slowly on my computer, so I tried putting it in a display list.

To make the camera move at the same speed regardless of framerate I figured this out: At the end of each frame I take the number of seconds since the last frame frame:

//  double CT is the Current Time
//  double LT is the Last frame's Time
//  double DT is the Difference in Time between this frame and the last
LT = CT;
CT = clock();
if (LT)  DT = CT - LT;  // LT is assigned zero at the beginning of the program.  This way there's no time for the first frame.
DT /= CLOCKS_PER_SEC;
cout << CT << ' ' << DT << '\n';
 

Then I scale the camera movement by that amount:

//  MFore = 1 means the "foreward" key is down
//  Player.Pos is the player's location
//  Player.AimX and AimY indicate where the player is aiming
//  MSpeed is the movement speed in OpenGL units/second
if (MFore)
{
    Player.Pos.X += (int) (sin(Player.AimX) * cos(Player.AimY) * MSpeed * DT);
    Player.Pos.Y += (int) (sin(Player.AimY) * MSpeed * DT);
    Player.Pos.Z += (int) (cos(Player.AimX) * cos(Player.AimY) * MSpeed * DT);
}
 

When I ran it without a display list the console looked like this:

340000 0
590000 0.25
840000 0.25
1.09e+06 0.25
1.34e+06 0.25
 

I get around four frames per second, on average. This is what it's supposed to look like, and everything was drawn and viewed properly.

When I run it using a display list to draw the octahedra it ends up looking like this:

0 0
440000 0
440000 0
440000 0
440000 0
440000 0
440000 0
 

Since it always thinks the frame time is zero, the camera doesn't move.

So I'm looking for a more precise, or just different way to get the framerate or clock time. Any ideas?


Written in C++ under Ubuntu 7.10 running on Intel Pentium 4 at 2.66GHz and ATI Radeon 9550SE (256MB).
Using OpenGL and SDL

[Savage]

So I'm looking for a more precise, or just different way to get the framerate or clock time. Any ideas?

Google for QueryPerformanceFrequency and QueryPerformanceCounter,they together form a very precise counter,which error is about 10e-5 secounds.

[Envergure]

Google for QueryPerformanceFrequency and QueryPerformanceCounter,they together form a very precise counter,which error is about 10e-5 secounds.

I'm running Linux, and according to Answers.com QueryPerformanceCounter is a Windows thing.
I found a function called ftime (timeb*), which is the closest thing for Linux. It offers millisecond timing and is far more reliable than clock().

Thanks anyway, I couldn't have found the Linux equivalent if I didn't have the Windows one in the first place!