Simple OpenGL (SDL) 3D FPS camera - main.cpp

//This example program is created by thecplusplusuy for demonstration purposes. It's a simple 3D FPS camera:
//http://www.youtube.com/user/thecplusplusguy
//Free source, modify if you want, LGPL licence (I guess), I would be happy, if you would not delete the link
//so other people can see the tutorial
//this file is main.cpp, the entry point of the program, and we load the model here, and use the 3D camera in here.
//You need the objloader.h and objloader.cpp file for that (earlier I uploaded the source, so I don't again), and you need an object (test10.obj) which you load (obviously you could use just simple primitives (triangle, quad) for that too, but object are looks better)
#include "functions.h"
#include "objloader.h"

float angle=0.0;

int cube;
objloader obj;
bool mousein=false;
void init()
{
    glClearColor(0.5,0.5,0.5,1.0);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(45,640.0/480.0,1.0,500.0);
    glMatrixMode(GL_MODELVIEW);
    glEnable(GL_DEPTH_TEST);
    cube=obj.load("test10.obj");
    glEnable(GL_LIGHTING);
    glEnable(GL_LIGHT0);
    float col[]={1.0,1.0,1.0,1.0};
    glLightfv(GL_LIGHT0,GL_DIFFUSE,col);
    initskybox();
}

void display()
{
    glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
    glLoadIdentity();
    Control(0.2,0.2,mousein);   //calculate the position, and rotate the camera
    UpdateCamera(); //move the camera to the new location
    float pos[]={-1.0,1.0,-2.0,1.0};
    glLightfv(GL_LIGHT0,GL_POSITION,pos);
    glCallList(cube);
}


int main()
{
    SDL_Init(SDL_INIT_EVERYTHING);
    SDL_Surface* screen=SDL_SetVideoMode(640,480,32,SDL_SWSURFACE|SDL_OPENGL);
    bool running=true;
    Uint32 start;
    SDL_Event event;
    init();
    while(running)
    {
        start=SDL_GetTicks();
        while(SDL_PollEvent(&event))
        {
            switch(event.type)
            {
                case SDL_QUIT:
                    running=false;
                    break;
                case SDL_MOUSEBUTTONDOWN:
                    mousein=true;
                    SDL_ShowCursor(SDL_DISABLE);
                    break;
                case SDL_KEYDOWN:
                    if(event.key.keysym.sym==SDLK_p)
                    {
                        mousein=false;
                        SDL_ShowCursor(SDL_ENABLE);
                        break;
                    }
                    if(event.key.keysym.sym==SDLK_ESCAPE)
                    {
                        running=false;
                        break;
                    }
            }
        }
        display();
        SDL_GL_SwapBuffers();
        angle+=0.5;
        if(angle>360)
            angle-=360;
        if(1000/30>(SDL_GetTicks()-start))
            SDL_Delay(1000/30-(SDL_GetTicks()-start));
    }
    SDL_Quit();
    killskybox();
    return 0;
}