Game code

#include"SDL/SDL.h"
#include"SDL/SDL_ttf.h"
#include"SDL/SDL_image.h"
#include<sstream>
#include"SDL/SDL_mixer.h"
#include<string>
#include<vector>
#include<iostream>

//Dimensions
const int SCREEN_WIDTH = 1000;
const int SCREEN_HEIGHT = 450;
const int BPP = 32;

//Screen, event and font
SDL_Surface* screen = NULL;
SDL_Event event;
TTF_Font* font;

class projectile;

std::vector<projectile> allProjectiles;

//Background camera (allows me to change the position of the background)
SDL_Rect backgroundCam = {0, 50, 1000, 500};

//Music
Mix_Music* songs[1];

void handleMusic()
{
     static int time = SDL_GetTicks();
     static int playing = 0;

     if( SDL_GetTicks() - time >= 100000 && (!playing) )
     {
         Mix_PlayMusic( songs[1], 0 );
         time = SDL_GetTicks();
         playing = 1;
     }

     if( (SDL_GetTicks() - time >= 18000) && (playing) )
     {
         Mix_PlayMusic( songs[0], 0 );
         time = SDL_GetTicks();
         playing = 0;
     }
}

void blitSurface( int srcX, int srcY, SDL_Surface* source, SDL_Rect* clip = NULL )
{

     SDL_Rect offsets;
     offsets.x = srcX;
     offsets.y = srcY;

     SDL_BlitSurface( source, clip, screen, &offsets );
}

int init( std::string caption )
{
    if( SDL_Init(SDL_INIT_EVERYTHING) == -1 )
    {
        return -1;
    }

    if( Mix_OpenAudio( 22050, MIX_DEFAULT_FORMAT, 2, 4096 ) == -1 )
    {
        return -1;
    }

    if( TTF_Init() == -1 )
    {
        return -1;
    }

    if( (screen = SDL_SetVideoMode( SCREEN_WIDTH, SCREEN_HEIGHT, BPP, SDL_SWSURFACE )) == NULL )
    {
        return -1;
    }

    SDL_WM_SetCaption( caption.c_str(), NULL );

    return 0;
}

void clearUp()
{
     TTF_CloseFont( font );
     Mix_FreeMusic( songs[0] );
     Mix_FreeMusic( songs[1] );

     SDL_Quit();
     TTF_Quit();
     Mix_CloseAudio();
}

void clearScreen()
{
      SDL_FillRect( screen, &screen->clip_rect, SDL_MapRGB( screen->format, 255, 255, 255 ) );
}

SDL_Surface* loadImage( std::string path )
{
      SDL_Surface* loadedImage = NULL;

      SDL_Surface* optimizedImage = NULL;

      loadedImage = IMG_Load( path.c_str() );

      if( loadedImage != NULL )
      {
          optimizedImage = SDL_DisplayFormat( loadedImage );
          SDL_FreeSurface( loadedImage );
      }

       if( optimizedImage != NULL )
       {
           Uint32 colorkey = SDL_MapRGB( optimizedImage->format, 255, 0, 255 );
           SDL_SetColorKey( optimizedImage, SDL_SRCCOLORKEY, colorkey );
       }

       return optimizedImage;
}

int checkCollison( SDL_Rect* rect1, SDL_Rect* rect2 )
{
     if(rect1->y >= rect2->y + rect2->h)
        return 0;

     if(rect1->x >= rect2->x + rect2->w)
        return 0;

     if(rect1->y + rect1->h <= rect2->y)
        return 0;

     if(rect1->x + rect1->w <= rect2->x)
        return 0;

     return 1;
}

void displayTTF( std::string text, int x, int y, int red = 0, int green = 0, int blue = 0 )
{

     SDL_Color colour = { red, green, blue };
     SDL_Surface* temp = TTF_RenderText_Solid( font, text.c_str(), colour );
     blitSurface( x, y, temp );

     SDL_FreeSurface( temp );
     temp = NULL;
}

void displayTTF( int num, int x, int y, int red = 0, int green = 0, int blue = 0 )
{
      SDL_Color colour = { red, green, blue };

      std::stringstream stream;
      stream << num;

      SDL_Surface* temp = TTF_RenderText_Solid( font, stream.str().c_str(), colour );

      blitSurface( x, y, temp );

      SDL_FreeSurface( temp );
      temp = NULL;
}

class projectile
{
      public:

      int x, y, w, h, velocity;

      std::string filePath;

      SDL_Surface* sprite;

      projectile( int X, int Y, int VEL, int W, int H, std::string path ): x(X), y(Y), w(W), h(H), velocity(VEL), filePath(path) { sprite = loadImage( path.c_str() ); }

      projectile( const projectile& proj )
      {
                  this->x = proj.x;
                  this->y = proj.y;
                  this->w = proj.w;
                  this->h = proj.h;
                  this->velocity = proj.velocity;
                  this->filePath = proj.filePath;

                  this->sprite = loadImage( filePath.c_str() );
      }

     ~projectile(){ SDL_FreeSurface(sprite); }

      void show(){ blitSurface( x, y, sprite ); }
};

projectile spawnProjectile( int x, int y, int w, int h, int velocity, std::string path )
{
           projectile proj( x, y, velocity, w, h, path );
           return proj;
}

class player;

class enemy
{
      protected:

      SDL_Surface* spriteSheet;

      SDL_Rect walk_left[3];

      int x, y, w, h, xVel, hitDamage, frame;

      virtual void setClips();

      void handle_animation();

      public:

      enemy( std::string path, int X, int Y, int W, int H, int damage = 5, int VEL = -2 );
      ~enemy();

      void move();

      void show();

      void shootBullet();

      int getDamage() const { return hitDamage; }

      SDL_Rect getStats();
};

void enemy::shootBullet()
{
     static int counter = SDL_GetTicks();

     if( SDL_GetTicks() - counter >= 1000 )
     {
         allProjectiles.push_back( spawnProjectile( x - 10, y, 10, 10, -3, "Lazer.png" ) );
         counter = SDL_GetTicks();
     }
}

SDL_Rect enemy::getStats()
{
         SDL_Rect temp = {x, y, w, h};
         return temp;
}

void enemy::show()
{
     blitSurface( x, y, spriteSheet, &walk_left[frame] );
}

void enemy::setClips()
{
}

void enemy::move()
{
     x += xVel;

     if( x + w < 0 )
     {
         x = SCREEN_WIDTH;
         y = rand() % SCREEN_HEIGHT;
     }

     handle_animation();
}

void enemy::handle_animation()
{
     frame  = (SDL_GetTicks() / 150) % 3;

     if( frame > 3 )
     {
         frame = 0;
     }
}

enemy::enemy( std::string path, int X, int Y, int W, int H, int damage, int VEL ):

x(X),
y(Y),
w(W),
h(H),
xVel(VEL),
hitDamage(damage),
frame(0)

{
         setClips();
         spriteSheet = loadImage( path.c_str() );
}

enemy::~enemy()
{
               SDL_FreeSurface( spriteSheet );
}


class bunny : public enemy
{
      private:

     void setClips();

      public:

      bunny( std::string path, int X, int Y, int W, int H, int damage, int VEL ):
             enemy::enemy( path, X, Y, W, H, damage, VEL )
      {
         setClips();
      }
};

void bunny::setClips()
{
     walk_left[0].x = 0;
     walk_left[0].y = 0;
     walk_left[0].w = 39;
     walk_left[0].h = 44;

     walk_left[1].x = 43;
     walk_left[1].y = 2;
     walk_left[1].w = 39;
     walk_left[1].h = 44;

     walk_left[2].x = 87;
     walk_left[2].y = 5;
     walk_left[2].w = 39;
     walk_left[2].h = 44;
}

bunny createBunny( int x, int y )
{
      bunny bunny( "Bunny.png", x, y, 39, 44, 5, -1 );
      return bunny;
}

class player
{
      private:

      int x, y, w, h, yVel;

      SDL_Surface* sprite;

      public:

      void move();

      void show();

      void handle_events();

      player( int X, int Y, int W, int H, std::string path );

      ~player();
};

player::player( int X, int Y, int W, int H, std::string path ):

x(X),
y(W),
w(W),
h(H),
yVel(0)

{
       sprite = loadImage( path.c_str() );
}

player::~player()
{
                 SDL_FreeSurface( sprite );
}

void player::handle_events()
{

     if( event.type == SDL_KEYDOWN )
     {
         switch( event.key.keysym.sym )
         {
                 case(SDLK_w): yVel-= 3; break;
                 case(SDLK_s): yVel+= 3; break;
         }
     }

     if( event.type == SDL_KEYUP )
     {
         switch( event.key.keysym.sym )
         {
                 case(SDLK_w): yVel+= 3; break;
                 case(SDLK_s): yVel-= 3; break;
         }
     }
}

void player::move()
{
     y += yVel;

     if( (y + h) > SCREEN_HEIGHT - 10 )
     {
         y -= yVel;
         backgroundCam.y++;
     }

     if( backgroundCam.y + SCREEN_HEIGHT > backgroundCam.h )
     {
         backgroundCam.y--;
     }

     if( y < 10 )
     {
         y -= yVel;
         backgroundCam.y-=2;
     }

     if( backgroundCam.y < 0 )
     {
         backgroundCam.y+=2;
     }

}

void player::show()
{
     SDL_Rect clip;
     clip.x = 385;
     clip.y = 11;

     blitSurface( x, y, sprite, &clip );
}
//THIS DELETES THE REDUNDANT BULLETS
void handleProjectiles()
{
   if( !allProjectiles.empty() )
   {
      std::vector<projectile>::iterator it = allProjectiles.begin();

      for( ; it != allProjectiles.end(); it++ )
      {
           it->x += it->velocity;
           it->show();

           if( it->x + it->w < 0 )
           {
               allProjectiles.erase( allProjectiles.begin(), it );
           }
      }
   }
}

int main( int argv, char* argc[] )
{
       //Initialisation stage
       init( "Space Game!" );

       font = TTF_OpenFont( "arial.ttf", 15 );

       songs[0] = Mix_LoadMUS( "music.ogg" );
       songs[1] = Mix_LoadMUS( "music3.ogg" );

       Mix_PlayMusic( songs[0], 0 );
       Mix_VolumeMusic( 20 );

       //Determines whether the game will run
       bool quit = false;

       player player(  50, 0, 153, 36, "Superman.png" );

       SDL_Surface* background = loadImage( "Background.JPG" );

       bunny bun = createBunny( 800, 20 );

       while( !quit )
       {
              //Event handling
              while( SDL_PollEvent(&event) )
              {
                     if( event.type == SDL_QUIT )
                     {
                         quit = true;
                     }

                     player.handle_events();
              }

              player.move();
              bun.move();

              //Clears the previous frame
              clearScreen();

              //Rendering
              //blitSurface( 0, 0, background, &backgroundCam );
              player.show();
              bun.show();
              bun.shootBullet();
              handleProjectiles();

              SDL_Flip( screen );
              SDL_Delay(20);

              handleMusic();
       }

       SDL_FreeSurface( background );

       clearUp();

       return 0;
}