SDL2_framerate.cpp File Reference

(986a3bf)

#include "sdl2gfx/SDL2_framerate.h"
#include "debug.h"

Go to the source code of this file.

Functions
static Uint32	_getTicks ()
	Internal wrapper to SDL_GetTicks that ensures a non-zero return value. More...
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...

Function Documentation

_getTicks()

static Uint32 _getTicks ( )

static

Internal wrapper to SDL_GetTicks that ensures a non-zero return value.

Returns

The tick count.

Definition at line 41 of file SDL2_framerate.cpp.

{
    Uint32 ticks = SDL_GetTicks();
 
    /*
    * Since baseticks!=0 is used to track initialization
    * we need to ensure that the tick count is always >0
    * since SDL_GetTicks may not have incremented yet and
    * return 0 depending on the timing of the calls.
    */
    if (ticks == 0)
    {
        return 1;
    }
    else
    {
        return ticks;
    }
}

Referenced by SDL_framerateDelay(), and SDL_initFramerate().

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().