CODEWITHSUNDEEP
copenglframe-rategame-development
user10691264
user10691264

Reputation:

Can't limit FPS OpenGL and C

I'm writing my own OpenGL and Win32 library in C, and I'm implementing a function to limit FPS. To do that, I'm firstly writing some code to check if it works and then I will abstract it to functions later. I don't know what's missing but it's not working. Here's my current code and the output

#include "2DM.h"
#include <time.h>

int main(void) {

   WINDOW window = createWindow("WINDOW", 500, 500, WINDOW_NORMAL);

   const int FPS_LIMIT = 60;
   int initialTime = time(NULL), finalTime, frameCount = 0;
   
   while(window.open) {

       if(pollEvents(&window) {

           /*
            * Events handling
            * .........
            */
       }

       /*
        * OpenGL code
        * .........
        */

       display(&window);

       frameCount ++;
       finalTime = time(NULL);
       int ellapsedTime = finalTime - initialTime;

       if(ellapsedTime) {

           int fps = frameCount / ellapsedTime;
           int sleepMs = (1000 / FPS_LIMIT) - ellapsedTime;
           printf("FPS: %i\nMS to Sleep: %i\n", fps, sleepMs);

           frameCount = 0;
           initialTime = finalTime;

           Sleep(sleepMs);
       }

   }
}

The output I get is: FPS:

FPS: 5749
MS to Sleep: 15

Upvotes: 0

Views: 305

Answers (1)

Acorn
Acorn

Reputation: 26066

time() returns the time in integer seconds, which won't work for what you are trying to do.

For instance, at the moment, you only get into the if once every second or so. sleepMs is also wrong, since you are subtracting different units.

Upvotes: 1

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