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85 lines
1.5 KiB
C++
85 lines
1.5 KiB
C++
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/*
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SDL_framerate: framerate manager
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LGPL (c) A. Schiffler
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*/
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#include "../stdafx.h"
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#include "SDL_framerate.h"
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/*
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Initialize the framerate manager
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*/
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void SDL_initFramerate(FPSmanager * manager)
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{
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/*
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* Store some sane values
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*/
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manager->framecount = 0;
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manager->rate = FPS_DEFAULT;
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manager->rateticks = (1000.0 / (float) FPS_DEFAULT);
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manager->lastticks = SDL_GetTicks();
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}
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/*
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Set the framerate in Hz
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*/
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int SDL_setFramerate(FPSmanager * manager, int rate)
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{
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if ((rate >= FPS_LOWER_LIMIT) && (rate <= FPS_UPPER_LIMIT)) {
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manager->framecount = 0;
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manager->rate = rate;
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manager->rateticks = (1000.0 / (float) rate);
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return (0);
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} else {
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return (-1);
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}
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}
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/*
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Return the current target framerate in Hz
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*/
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int SDL_getFramerate(FPSmanager * manager)
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{
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if (manager == NULL) {
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return (-1);
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} else {
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return (manager->rate);
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}
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}
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/*
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Delay execution to maintain a constant framerate. Calculate fps.
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*/
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void SDL_framerateDelay(FPSmanager * manager)
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{
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Uint32 current_ticks;
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Uint32 target_ticks;
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Uint32 the_delay;
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/*
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* Next frame
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*/
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manager->framecount++;
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/*
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* Get/calc ticks
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*/
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current_ticks = SDL_GetTicks();
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target_ticks = manager->lastticks + (Uint32) ((float) manager->framecount * manager->rateticks);
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if (current_ticks <= target_ticks) {
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the_delay = target_ticks - current_ticks;
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SDL_Delay(the_delay);
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} else {
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manager->framecount = 0;
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manager->lastticks = SDL_GetTicks();
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}
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}
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