added GPL copyrights

[physics.git] / src / main.cpp

/*
 *  Copyright (C) 2008 Patrik Gornicz, Gornicz_P (at) hotmail (dot) com.
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program 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 General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <GL/gl.h>
#include <GL/glu.h>
#include <SDL/SDL.h>

#include "debug.h"
#include "handleSignal.h"

#include "game.h"
#include "ticks.h"

#include "graphics/graphics.h"
#include "input/inputManager.h"

/// ***** Private Method Headers *****

void init();

void sighandler( int sig );

void run();
void clean();

void blockUpdate();
void updateFPSCounters();

void handleInput();
void update(float);
void draw();

/// ***** Private Variables *****

// variable used to determine if it is time to shutdown
bool is_Running;

/* Values for the main game loop
 * target_UPS := the amount of updates that is wanted in one second
 * last_Update := stores the time of the last update
 * update_Sum := used to determine the updates needs for this run

 * ups := updates per second for the last second
 * fps := frames per second for the last second
 * update_Count := counts this seconds updates
 * draw_Count  := counts this seconds draws
 * last_Second := stores the time of the last second, used for ups and fps
 */
int target_UPS = 250;
long int last_Block_Update;
float update_Sum = 0;

int ups, fps;
int update_Count, draw_Count;
long int last_Second;


/// ***** MAIN Method *****
int main()
{
    init();
    run();
    clean();
    return 0;
}

/// ***** Initializers/Cleaners *****

void init()
{
    installSignal();

    graphics::init();

    game::init();

    input::init();

#ifdef DEBUGGING
    cout << "Initialization Complete" << endl;
#endif
}

void clean()
{
#ifdef DEBUGGING
    cout << "Cleaning up" << endl;
#endif

    input::clean();

    game::clean();

    graphics::clean();
}

/// ***** Private Methods *****

void run()
{
    is_Running = true;
    last_Block_Update = tickCountMicro();
    last_Second = tickCountMicro();

    while(is_Running)
    {
        blockUpdate();
        updateFPSCounters();
        draw();
    }
}

void blockUpdate()
{
    long int start = tickCountMicro();

    // Calculate the updates that should be run for the next draw
    update_Sum += (start - last_Block_Update) / (1000000 / (float)target_UPS);

    // insures the float to int cast is done once.
    int iupdate_sum = (int)update_Sum;

    // TODO the main run loop needs to be tested and pruned
    if (iupdate_sum > 0)
    {
        // Calculate a time step that spreads the updates out as much as possible
        // used because really quick updates are nearly wasted
        float time_step = ((float)(start - last_Block_Update)) / iupdate_sum;

        // run the updates
        for (int i = 1; i <= iupdate_sum; i++)
        {
            handleInput();
            update(time_step*i / 1000);
        }
        // remove the updates that where run from the sum
        update_Sum -= iupdate_sum;
        last_Block_Update = tickCountMicro();
    }
}

void updateFPSCounters()
{
    // Check if a second has passed to recalculate UPS and FPS
    if (tickCountMicro() - last_Second >= 1000000)
    {
        ups = update_Count;
        fps = draw_Count;
        update_Count = 0;
        draw_Count = 0;

        last_Second = tickCountMicro();

#ifdef FPSUPS
        cout << "ups:\t" << ups << endl;
        cout << "fps:\t" << fps << endl;
#endif
    }
}

void handleInput()
{
    input::update();

    game::input();

    if(input::wasReleased(SDLK_ESCAPE))
        is_Running = false;
}

void update(float time_step)
{
    update_Count++;

    game::update(time_step);
}

void draw()
{
    draw_Count++;

    game::draw();

    SDL_GL_SwapBuffers();

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
}