SDL2_framerate.h File Reference

(986a3bf)

#include "localconsts.h"
#include <SDL.h>

Go to the source code of this file.

Data Structures
struct	FPSmanager
	Structure holding the state and timing information of the framerate controller. More...

Macros
#define	FPS_UPPER_LIMIT   200
	Highest possible rate supported by framerate controller in Hz (1/s). More...
#define	FPS_LOWER_LIMIT   1
	Lowest possible rate supported by framerate controller in Hz (1/s). More...
#define	FPS_DEFAULT   30
	Default rate of framerate controller in Hz (1/s). More...
#define	SDL2_FRAMERATE_SCOPE   extern

Functions
void	SDL_initFramerate (FPSmanager *manager)
	Initialize the framerate manager. More...
int	SDL_setFramerate (FPSmanager *manager, Uint32 rate)
	Set the framerate in Hz. More...
int	SDL_getFramerate (FPSmanager *manager)
	Return the current target framerate in Hz. More...
int	SDL_getFramecount (FPSmanager *manager)
	Return the current framecount. More...
Uint32	SDL_framerateDelay (FPSmanager *manager)
	Delay execution to maintain a constant framerate and calculate fps. More...

Macro Definition Documentation

FPS_DEFAULT

#define FPS_DEFAULT   30

Default rate of framerate controller in Hz (1/s).

Definition at line 65 of file SDL2_framerate.h.

FPS_LOWER_LIMIT

#define FPS_LOWER_LIMIT   1

Lowest possible rate supported by framerate controller in Hz (1/s).

Definition at line 60 of file SDL2_framerate.h.

FPS_UPPER_LIMIT

#define FPS_UPPER_LIMIT   200

Highest possible rate supported by framerate controller in Hz (1/s).

Definition at line 55 of file SDL2_framerate.h.

SDL2_FRAMERATE_SCOPE

#define SDL2_FRAMERATE_SCOPE   extern

Definition at line 91 of file SDL2_framerate.h.

Function Documentation

SDL_framerateDelay()

Uint32 SDL_framerateDelay

(

FPSmanager *

manager

)

Delay execution to maintain a constant framerate and calculate fps.

Generate a delay to accomodate currently set framerate. Call once in the graphics/rendering loop. If the computer cannot keep up with the rate (i.e. drawing too slow), the delay is zero and the delay interpolation is reset.

Parameters

manager

Pointer to the framerate manager.

Returns

The time that passed since the last call to the function in ms. May return 0.

Definition at line 162 of file SDL2_framerate.cpp.

{
    Uint32 current_ticks;
    Uint32 target_ticks;
    Uint32 the_delay;
    Uint32 time_passed = 0;
 
    /*
    * No manager, no delay
    */
    if (manager == nullptr)
    {
        return 0;
    }
 
    /*
    * Initialize uninitialized manager
    */
    if (manager->baseticks == 0)
    {
        SDL_initFramerate(manager);
    }
 
    /*
    * Next frame
    */
    manager->framecount++;
 
    /*
    * Get/calc ticks
    */
    current_ticks = _getTicks();
    time_passed = current_ticks - manager->lastticks;
    manager->lastticks = current_ticks;
    target_ticks = manager->baseticks + static_cast<Uint32>(static_cast<float>(
        manager->framecount) * manager->rateticks);
 
    if (current_ticks <= target_ticks)
    {
        the_delay = target_ticks - current_ticks;
        SDL_Delay(the_delay);
    }
    else
    {
        manager->framecount = 0;
        manager->baseticks = _getTicks();
    }
 
    return time_passed;
}

References _getTicks(), FPSmanager::baseticks, FPSmanager::framecount, FPSmanager::lastticks, FPSmanager::rateticks, and SDL_initFramerate().

Referenced by Client::gameExec().

SDL_getFramecount()

int SDL_getFramecount

(

FPSmanager *

manager

)

Return the current framecount.

Get the current framecount from the framerate manager. A frame is counted each time SDL_framerateDelay is called.

Parameters

manager

Pointer to the framerate manager.

Returns

Current frame count or -1 for error.

Definition at line 139 of file SDL2_framerate.cpp.

{
    if (manager == nullptr)
    {
        return (-1);
    }
    else
    {
        return (static_cast<int>(manager->framecount));
    }
}

References FPSmanager::framecount.

SDL_getFramerate()

int SDL_getFramerate

(

FPSmanager *

manager

)

Return the current target framerate in Hz.

Get the currently set framerate of the manager.

Parameters

manager

Pointer to the framerate manager.

Returns

Current framerate in Hz or -1 for error.

Definition at line 117 of file SDL2_framerate.cpp.

{
    if (manager == nullptr)
    {
        return (-1);
    }
    else
    {
        return (static_cast<int>(manager->rate));
    }
}

References FPSmanager::rate.

Referenced by WindowManager::getFramerate().

SDL_initFramerate()

void SDL_initFramerate

(

FPSmanager *

manager

)

Initialize the framerate manager.

Initialize the framerate manager, set default framerate of 30Hz and reset delay interpolation.

Parameters

manager

Pointer to the framerate manager.

Definition at line 69 of file SDL2_framerate.cpp.

{
    /*
    * Store some sane values
    */
    manager->framecount = 0;
    manager->rate = FPS_DEFAULT;
    manager->rateticks = (1000.0F / static_cast<float>(FPS_DEFAULT));
    manager->baseticks = _getTicks();
    manager->lastticks = manager->baseticks;
 
}

References _getTicks(), FPSmanager::baseticks, FPS_DEFAULT, FPSmanager::framecount, FPSmanager::lastticks, FPSmanager::rate, and FPSmanager::rateticks.

Referenced by Client::gameInit(), and SDL_framerateDelay().

SDL_setFramerate()

int SDL_setFramerate	(	FPSmanager *	manager,
		Uint32	rate
	)

Set the framerate in Hz.

Sets a new framerate for the manager and reset delay interpolation. Rate values must be between FPS_LOWER_LIMIT and FPS_UPPER_LIMIT inclusive to be accepted.

Parameters

manager	Pointer to the framerate manager.
rate	The new framerate in Hz (frames per second).

Returns

0 for sucess and -1 for error.

Definition at line 93 of file SDL2_framerate.cpp.

{
    if ((rate >= FPS_LOWER_LIMIT) && (rate <= FPS_UPPER_LIMIT))
    {
        manager->framecount = 0;
        manager->rate = rate;
        manager->rateticks = (1000.0F / static_cast<float>(rate));
        return (0);
    }
    else
    {
        return (-1);
    }
}

References FPS_LOWER_LIMIT, FPS_UPPER_LIMIT, FPSmanager::framecount, FPSmanager::rate, and FPSmanager::rateticks.

Referenced by WindowManager::setFramerate().