Frame Per Second Too High

[hentaiw]

#include <sstream>
#include <SDL.h>
#include <SDL_ttf.h>
#include "KD_Surface.h"
#include "KD_Message.h"
#include "KD_Sound.h"
#include "KD_Timer.h"

void event_handler();

KD_TIMER fps;
KD_TIMER update;

int main(int argc,char *argv[])
{
	if( initialization() == false )
	{
		return 1;
	}

	//Frame Calculation
	int frame = 0;

	//Start Update Timer
	update.start();
	//Start FPS Timer
	fps.start();

	//Background Of Game
	SDL_Surface *background = NULL;
	background = load_image("background.jpg");
	
	apply_surface(0,0,background,screen);

	//Update The Screen
	if(SDL_Flip(screen) == -1)
	{
		return false;
	}

	while(quit == false)
	{
		while(SDL_PollEvent(&event))
		{
			if(event.type == SDL_QUIT)
			{
				//Quit the program
				quit = true;
			}
		}

		//Increment Frame
		frame++;

		//If a second has passed since the caption was last updated
		if( update.get_ticks() > 1000 )
		{
			//The frame rate as a string
			std::stringstream caption;

			//Calculate the frames per second and create the string
			caption << "Average Frames Per Second: " << frame / ( fps.get_ticks() / 1000 );

			//Reset the caption
			SDL_WM_SetCaption( caption.str().c_str(), NULL );

			//Restart the update timer
			update.start();    

		}
	}

	clean_up();

	return 0;
}


//The Ultimate Event Handler !
void event_handler()
{

}

Plz check the code,It shows about 1 million fps in the caption,which make me worried.Does the algorithm seem right ?

[Peter87]

The loop doesn't do much so the fps should be pretty high. Try putting a SDL_Delay(100); on line 51 and if you get about 10 fps it is correct.

[hentaiw]

Nice,thanks, but why did it work ?

[zwA4jE8b]

because your computer is iterating through that loop as fast as it can, and that is very very fast

[Disch]

Your original program is running as fast as the computer will let it, which is very very fast.

By adding SDL_Delay(100), you are telling the computer to wait for 100 milliseconds before continuing, thus slowing the framerate.

[hentaiw]

If the frame++ means increasing frame;will it eventually get out of the limitation of an int ?

[zwA4jE8b]

make it an unsigned int. eventually a limit will be reached but not anytime soon
or a Uint64

[hentaiw]

Plz take a look at this :

int main(int argc,char *argv[])
{
	if( initialization() == false )
	{
		return 1;
	}

	//Background Of Game
	SDL_Surface *background = NULL;
	background = load_image("background.jpg");	



	//Apply Background
	apply_surface(0,0,background,screen);

	//Apply Message

	//Update The Screen
	if(SDL_Flip(screen) == -1)
	{
		return false;
	}

	//Start Update Timer
	fps_upd.start();
	//Start FPS_Calc
	fps_calc.start();
	//Start FPS_Reg
	fps_reg.start();

	while(quit == false)
	{
		while(SDL_PollEvent(&event))
		{
			if(event.type == SDL_QUIT)
			{
				//Quit the program
				quit = true;
			}
		}

		//Increment Frame
		frame++;

		//Regulate Frame Rate
		if(fps_reg.get_ticks() < ( 1000 / FRAMES_PER_SECOND ) )
		{
			//Sleep The Remaining Frame Time
			SDL_Delay( ( 1000 / FRAMES_PER_SECOND ) - fps_reg.get_ticks() );
		}

		//If a second has passed since the caption was last updated
		if( fps_upd.get_ticks() > 1000 )
		{
			//The frame rate as a string
			std::stringstream caption;

			//Calculate the frames per second and create the string
			caption << "Average Frames Per Second: " << frame / ( fps_calc.get_ticks() / 1000 );

			//Reset the caption
			SDL_WM_SetCaption( caption.str().c_str(), NULL );

			//Restart the update timer
			fps_upd.start();    

		}

		fps_reg.start();
	}

	clean_up();

	return 0;
}

I've deleted the SDL_Delay above,and now I regulated the frame rate.
I set const int FRAMES_PER_SECOND = 20; and now it's runnning at 20fps (seems fine).
Plz check at the code and check for any error.If everything's fine,I'd go to the next step.

[roberts]

I would recommend using the hi-res timer for your platform, or if you're going for multi-platform, making a wrapper around platform specific hi-res timer functionality.

Windows has QueryPerformanceFrequency and QueryPerformanceCounter you can use to calculate FPS and the time it takes to render a scene.

Linux has clock_getres and clock_gettime.

From either, you should be able to calculate the performance of your app without worrying about rollover on an integer counter.