set to ignore *.o files

[physics.git] / src / main.cpp

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

#include <iostream>
using std::cerr;
using std::cout;
using std::endl;

#include <vector>
using std::vector;

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


/// ***** Private Method Headers *****
void init();

void run();
void cleanUp();

void blockUpdate();
void updateFPSCounters();

void input();
void update(float);
void draw();


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


/// ***** 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;


/// ***** Private Methods *****
void init()
{
    graphicsInit();

    gameInit();

    // TODO
    // add a game state

    cout << "Initialization Complete" << endl;

    // create starting entities

    cout << "World Created" << endl;
}

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

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

void cleanUp()
{
    gameClean();
}

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++)
        {
            input();
            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();
    }
}

void input()
{
    gameInput();

    /*
    if(key[KEY_ESC])
        is_Running = false;
    */
}

void update(float time_step)
{
    update_Count++;

    gameUpdate(time_step);
}

void draw()
{
    draw_Count++;

    gameDraw();

    SDL_GL_SwapBuffers();

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
}