libsegl/fpsmanager.cpp

/* libsegl - Sebas Extended GL Library
 *           Collection of Opengl/3D-Math helpers
 *
 *      Copyright (c) 2008 by Sebastian Lohff, seba@seba-geek.de
 *      http://www.seba-geek.de
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 * 
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
 * Boston, MA  02110-1301, USA.
 */

#include "fpsmanager.h"

namespace segl {

FPSManager::FPSManager(int _fps) {
	setFPS(_fps);
	frames = 0;
	framerate = 0;
	lastticks = SDL_GetTicks();
}

void FPSManager::setFPS(int _fps) {
	if(_fps<1 || _fps > 500)
		return;
	tickrate = 1000.0f/(float)_fps;
}

void FPSManager::delay() {
	frames++;
	
	Uint32 now    = SDL_GetTicks();
	Uint32 target = lastticks + (Uint32)(tickrate * (float)frames);
	
	if(now <= target) {
		SDL_Delay(target-now);
	} else {
		framerate = frames/((now-lastticks)/1000.0f);
		frames = 0;
		lastticks = SDL_GetTicks();
	}
}

float FPSManager::getFPS() {
	return framerate;
}

} // namespace segl