BirdGame.cpp

/*
 * Copyright (c) 2014, Wei Mingzhi <whistler_wmz@users.sf.net>.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author and contributors may not be used to endorse
 *    or promote products derived from this software without specific prior
 *    written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL WASABI SYSTEMS, INC
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <SDL.h>

#include "BirdGame.h"
#include "Sprite.h"
#include "Video.h"
#include "Audio.h"

#include <algorithm>
#include <math.h>
#include <stdlib.h>
#include <time.h>

static CSprite *gpSprite = NULL;

typedef enum tagGameState
  {
    GAMESTATE_INITIAL = 0,
    GAMESTATE_GAMESTART,
    GAMESTATE_GAME,
    GAMESTATE_GAMEOVER,
  } GameState;

static GameState g_GameState = GAMESTATE_INITIAL;
static bool g_bMouseDown = false;
static bool g_bNight = false;
static int g_iBirdPic = 0;
static int g_iMouseX = 0;
static int g_iMouseY = 0;
static int g_iScore = 0;
static int g_iHighScore = 0;
static float g_flBirdVelocity = 0;
static float g_flBirdHeight = 0;
static float g_flBirdAngle = 0;
static int g_iPipePosX[3] = { 0, 0, 0 };
static int g_iPipePosY[3] = { 0, 0, 0 };

static void *g_pSfxDie = NULL;
static void *g_pSfxHit = NULL;
static void *g_pSfxPoint = NULL;
static void *g_pSfxSwooshing = NULL;
static void *g_pSfxWing = NULL;

static bool g_bPauseGame = false;

#define GRAVITY      0.32f
#define WINGPOWER    5.2f
#define ROTATION     2.7f
#define PIPEDISTANCE 150
#define PIPEWIDTH    50
#define BIRDWIDTH    48
#define BIRDMARGIN   12

#ifdef __WINPHONE__
extern "C" const char *GetRootPath();
extern "C" const char *GetInstallPath();
extern "C" void RateApp();
#define fopen(a,b) _fsopen((a), (b), 0x40)
#endif

static const char *MakeFileName(const char *path, bool bUserDir = false)
{
#if defined __WINPHONE__
  static char buf[2][4096];
  static int current = 0;
  current ^= 1;
  strcpy(buf[current], bUserDir ? GetRootPath() : GetInstallPath());
  strcat(buf[current], "\\");
  const char *mypath = path + strlen(path) - 1;
  while (mypath >= path && (*mypath != '/' && *mypath != '\\'))
    {
      mypath--;
    }
  mypath++;
  strcat(buf[current], mypath);
  return buf[current];
#elif defined __IPHONEOS__
  static char buf[2][4096];
  static int current = 0;
  current ^= 1;
  if (bUserDir)
    {
      char *p = SDL_GetPrefPath("", "");
      strcpy(buf[current], p);
      strcat(buf[current], path);
      SDL_free(p);
    }
  else
    {
      char *p = SDL_GetBasePath();
      strcpy(buf[current], p);
      strcat(buf[current], "/");
      strcat(buf[current], path);
    }
  return buf[current];
#else
  return path;
#endif
}

static void LoadBestScore()
{
  g_iHighScore = 0;
  FILE *fp = fopen(MakeFileName("sdlbird.ini", true), "r");
  if (fp != NULL)
    {
      fscanf(fp, "%d", &g_iHighScore);
      fclose(fp);
    }
}

static void SaveBestScore()
{
  FILE *fp = fopen(MakeFileName("sdlbird.ini", true), "w");
  if (fp != NULL)
    {
      fprintf(fp, "%d", g_iHighScore);
      fclose(fp);
    }
}

static void LoadWav()
{
  g_pSfxDie = SOUND_LoadWAV(MakeFileName("res/sfx_die.wav"));
  g_pSfxHit = SOUND_LoadWAV(MakeFileName("res/sfx_hit.wav"));
  g_pSfxPoint = SOUND_LoadWAV(MakeFileName("res/sfx_point.wav"));
  g_pSfxSwooshing = SOUND_LoadWAV(MakeFileName("res/sfx_swooshing.wav"));
  g_pSfxWing = SOUND_LoadWAV(MakeFileName("res/sfx_wing.wav"));
}

static void FreeWav()
{
  SDL_PauseAudio(1);

  if (g_pSfxDie != NULL)
    {
      SOUND_FreeWAV(g_pSfxDie);
      g_pSfxDie = NULL;
    }
  if (g_pSfxHit != NULL)
    {
      SOUND_FreeWAV(g_pSfxHit);
      g_pSfxHit = NULL;
    }
  if (g_pSfxPoint != NULL)
    {
      SOUND_FreeWAV(g_pSfxPoint);
      g_pSfxPoint = NULL;
    }
  if (g_pSfxSwooshing != NULL)
    {
      SOUND_FreeWAV(g_pSfxSwooshing);
      g_pSfxSwooshing = NULL;
    }
  if (g_pSfxWing != NULL)
    {
      SOUND_FreeWAV(g_pSfxWing);
      g_pSfxWing = NULL;
    }
}

static void UpdateEvents()
{
  SDL_Event evt;

  while (SDL_PollEvent(&evt))
    {
      switch (evt.type)
	{
	case SDL_QUIT:
	  exit(0);
	  break;

	case SDL_MOUSEBUTTONDOWN:
	  g_bMouseDown = true;
	  g_iMouseX = evt.button.x;
	  g_iMouseY = evt.button.y;
	  break;

	case SDL_MOUSEBUTTONUP:
	  g_bMouseDown = false;
	  break;

	case SDL_FINGERDOWN:
	  g_bMouseDown = true;
	  g_iMouseX = (int)(evt.tfinger.x * SCREEN_WIDTH);
	  g_iMouseY = (int)(evt.tfinger.y * SCREEN_HEIGHT);
	  break;

	case SDL_FINGERUP:
	  g_bMouseDown = false;
	  break;

	case SDL_KEYDOWN:
	  if (evt.key.keysym.sym == SDLK_AC_BACK)
	    {
	      exit(0);
	    }
	  break;
            
#ifdef __IPHONEOS__
        case SDL_APP_WILLENTERBACKGROUND:
	  g_bPauseGame = true;
	  break;
            
        case SDL_APP_DIDENTERFOREGROUND:
	  g_bPauseGame = false;
	  break;
#endif
	}
    }
}

static void ShowTitle()
{
  SDL_Surface *pSurfaceTitle = SDL_LoadBMP(MakeFileName("res/splash.bmp"));
  if (pSurfaceTitle == NULL)
    {
      fprintf(stderr, "cannot load res/splash.bmp\n");
      return;
    }

  SDL_Texture *pTextureTitle = SDL_CreateTextureFromSurface(gpRenderer, pSurfaceTitle);
  SDL_FreeSurface(pSurfaceTitle);

  if (pTextureTitle == NULL)
    {
      fprintf(stderr, "cannot create texture from splash.png\n");
      return;
    }

  unsigned int uiStartTime = SDL_GetTicks();

  while (SDL_GetTicks() - uiStartTime < 3000)
    {
      SDL_RenderCopy(gpRenderer, pTextureTitle, NULL, NULL);
      SDL_RenderPresent(gpRenderer);

      UpdateEvents();
      SDL_Delay(100);
    }

  SDL_DestroyTexture(pTextureTitle);
}

static void DrawBackground()
{
  gpSprite->Draw(gpRenderer, g_bNight ? "bg_night" : "bg_day", 0, 0);
}

static void DrawLand(bool bStatic)
{
  static unsigned int time = 0;
  if (!bStatic)
    {
      time++;
    }

  gpSprite->Draw(gpRenderer, "land", -(int)((time * 2) % SCREEN_WIDTH), SCREEN_HEIGHT - 110);
  gpSprite->Draw(gpRenderer, "land", 287 - ((time * 2) % SCREEN_WIDTH), SCREEN_HEIGHT - 110);
}

static void DrawScore(int score)
{
  int iScoreLen = 0;
  int iBeginX = SCREEN_WIDTH / 2;
  int iReverseScore = 0;

  do
    {
      if (score % 10 == 1)
	{
	  iBeginX -= 16 / 2 + 1;
	}
      else
	{
	  iBeginX -= 24 / 2 + 1;
	}

      iReverseScore *= 10;
      iReverseScore += score % 10;

      score /= 10;
      iScoreLen++;
    } while (score > 0);

  do
    {
      char buf[256];
      sprintf(buf, "font_%.3d", 48 + (iReverseScore % 10));

      gpSprite->Draw(gpRenderer, buf, iBeginX, 60);
      if (iReverseScore % 10 == 1)
	{
	  iBeginX += 16 + 2;
	}
      else
	{
	  iBeginX += 24 + 2;
	}
      
      iReverseScore /= 10;
      iScoreLen--;
    } while (iScoreLen > 0);
}

static void DrawScoreOnBoard(int score, int x, int y)
{
  int iScoreLen = 0;
  int iBeginX = x;
  int iReverseScore = 0;

  do
    {
      iBeginX -= 16;
      iReverseScore *= 10;
      iReverseScore += score % 10;

      score /= 10;
      iScoreLen++;
    } while (score > 0);

  do
    {
      char buf[256];
      sprintf(buf, "number_score_%.2d", iReverseScore % 10);

      gpSprite->Draw(gpRenderer, buf, iBeginX, y);
      iBeginX += 16;

      iReverseScore /= 10;
      iScoreLen--;
    } while (iScoreLen > 0);
}

static void GameThink_Initial()
{
  static unsigned int fading_start_time = 0;
  static GameState enNextGameState;

  if (fading_start_time > 0)
    {
      unsigned int elapsed = SDL_GetTicks() - fading_start_time;

      if (elapsed > 500)
	{
	  g_GameState = enNextGameState;
	  gpSprite->SetColorMod(255, 255, 255);
	  fading_start_time = 0;
	  g_bNight = ((rand() % 2) == 1);
	  g_iBirdPic = rand() % 3;
	  for (int i = 0; i < 3; i++)
	    {
	      g_iPipePosX[i] = SCREEN_WIDTH + 200 + i * PIPEDISTANCE;
	      g_iPipePosY[i] = rand() % 200;
	    }
	  return;
	}

      elapsed *= 255;
      elapsed /= 500;

      elapsed = 255 - elapsed;

      gpSprite->SetColorMod(elapsed, elapsed, elapsed);
    }

  DrawBackground();
  DrawLand(false);

  gpSprite->Draw(gpRenderer, "title", 55, 110);

  char buf[256];
  sprintf(buf, "bird0_%d", (SDL_GetTicks() / 200) % 3);
  gpSprite->Draw(gpRenderer, buf, 118, 180 + (int)(cos(SDL_GetTicks() / 2 * 3.14 / 180) * 5));

  gpSprite->Draw(gpRenderer, "button_rate", 105, 275);
  gpSprite->Draw(gpRenderer, "button_play", 25, 340);
  gpSprite->Draw(gpRenderer, "button_score", 145, 340);

  gpSprite->Draw(gpRenderer, "brand_copyright", 80, 450);

  if (g_bMouseDown)
    {
      if (g_iMouseX > 25 && g_iMouseY > 340 && g_iMouseX < 25 + 100 && g_iMouseY < 340 + 55)
	{
	  // user clicked "play" button
	  fading_start_time = SDL_GetTicks();
	  enNextGameState = GAMESTATE_GAMESTART;
	}
      else if (g_iMouseX > 145 && g_iMouseY > 340 && g_iMouseX < 145 + 100 && g_iMouseY < 340 + 55)
	{
	  // user clicked "score" button
	  // TODO
	}
      else if (g_iMouseX > 105 && g_iMouseY > 275 && g_iMouseX < 105 + 64 && g_iMouseY < 275 + 32)
	{
	  // user clicked "rate" button
#ifdef __WINPHONE__
	  RateApp();
#endif
	}
    }
}

static void BirdFly()
{
  g_flBirdVelocity = WINGPOWER;
  g_flBirdAngle = -45;
  SOUND_PlayWAV(1, g_pSfxWing);
}

static void GameThink_GameStart()
{
  static unsigned int fading_start_time = 0;

  if (fading_start_time == 0)
    {
      fading_start_time = SDL_GetTicks();
    }

  unsigned int elapsed = SDL_GetTicks() - fading_start_time;

  if (elapsed < 500)
    {
      elapsed *= 255;
      elapsed /= 500;

      gpSprite->SetColorMod(elapsed, elapsed, elapsed);
    }
  else
    {
      gpSprite->SetColorMod(255, 255, 255);
    }

  DrawBackground();
  DrawLand(false);

  char buf[256];
  sprintf(buf, "bird%d_%d", g_iBirdPic, (SDL_GetTicks() / 200) % 3);
  g_flBirdHeight = 230 + (float)(cos(SDL_GetTicks() / 2 * 3.14 / 180) * 5);
  gpSprite->Draw(gpRenderer, buf, 60, (int)g_flBirdHeight);

  // draw score
  DrawScore(0);

  // draw "get ready" notice
  gpSprite->Draw(gpRenderer, "text_ready", 50, 130);

  // draw hint picture
  gpSprite->Draw(gpRenderer, "tutorial", 90, 220);

  if (g_bMouseDown)
    {
      g_GameState = GAMESTATE_GAME;
      gpSprite->SetColorMod(255, 255, 255);
      fading_start_time = 0;
      g_iScore = 0;
      BirdFly();
    }
}

static void GameThink_Game()
{
  static bool bPrevMouseDown = false;
  bool bGameOver = false;
	
  static bool bPrevInRange = false;

  int i;

  g_flBirdHeight -= g_flBirdVelocity;
  g_flBirdVelocity -= GRAVITY;

  g_flBirdAngle += ROTATION;
  if (g_flBirdAngle > 85)
    {
      g_flBirdAngle = 85;
    }

  if (g_flBirdHeight < -50)
    {
      g_flBirdHeight = -50;
    }
  else if (g_flBirdHeight > SCREEN_HEIGHT - 150)
    {
      // bird has hit the ground
      g_flBirdHeight = SCREEN_HEIGHT - 150;
      bGameOver = true;
    }

  DrawBackground();

  // move pipes
  for (i = 0; i < 3; i++)
    {
      g_iPipePosX[i] -= 2;
    }

  if (g_iPipePosX[0] < -PIPEWIDTH)
    {
      g_iPipePosX[0] = g_iPipePosX[1];
      g_iPipePosX[1] = g_iPipePosX[2];
      g_iPipePosX[2] = g_iPipePosX[1] + PIPEDISTANCE;

      g_iPipePosY[0] = g_iPipePosY[1];
      g_iPipePosY[1] = g_iPipePosY[2];
      g_iPipePosY[2] = rand() % 200;
    }

  // draw pipes
  for (i = 0; i < 3; i++)
    {
      gpSprite->Draw(gpRenderer, "pipe_down", g_iPipePosX[i], -320 + 60 + g_iPipePosY[i]);
      gpSprite->Draw(gpRenderer, "pipe_up", g_iPipePosX[i], SCREEN_HEIGHT - 110 - 250 + g_iPipePosY[i]);
    }

  DrawScore(g_iScore);
  DrawLand(false);

  // draw bird
  char buf[256];
  sprintf(buf, "bird%d_%d", g_iBirdPic, (SDL_GetTicks() / 200) % 3);
  gpSprite->DrawEx(gpRenderer, buf, 60, (int)g_flBirdHeight, g_flBirdAngle, SDL_FLIP_NONE);

  // check if bird is in the range of a pipe
  if (g_iPipePosX[0] < 60 + BIRDWIDTH - BIRDMARGIN && g_iPipePosX[0] + PIPEWIDTH > 60 + BIRDMARGIN)
    {
      if (!bPrevInRange && g_iPipePosX[0] + PIPEWIDTH / 2 < 60 + BIRDMARGIN)
	{
	  g_iScore++;
	  SOUND_PlayWAV(0, g_pSfxPoint);
	  bPrevInRange = true;
	}

      // check if the bird hits the pipe
      if (g_flBirdHeight + BIRDMARGIN < 60 + g_iPipePosY[0] ||
	  g_flBirdHeight + BIRDWIDTH - BIRDMARGIN > SCREEN_HEIGHT - 110 - 250 + g_iPipePosY[0])
	{
	  bGameOver = true;
	}
    }
  else
    {
      bPrevInRange = false;
    }

  if (bGameOver)
    {
      bPrevMouseDown = false;
      bPrevInRange = false;
      g_GameState = GAMESTATE_GAMEOVER;
      return;
    }

  if (g_bMouseDown && !bPrevMouseDown)
    {
      BirdFly();
    }

  bPrevMouseDown = g_bMouseDown;
}

static void GameThink_GameOver()
{
  static enum { FLASH, DROP, SHOWTITLE, SHOWSCORE } gameoverState = FLASH;
  static int time = 0;
  static bool bIsHighscore = false;
  static int fading_start_time = 0;

  if (gameoverState == FLASH)
    {
      SDL_Surface *surface = SDL_CreateRGBSurface(0, 1, 1, 32, 0x00FF0000, 0x0000FF00, 0x000000FF, 0xFF000000);
      SDL_FillRect(surface, NULL, 0xFFFFFFFF);

      SDL_Texture *texture = SDL_CreateTextureFromSurface(gpRenderer, surface);
      SDL_FreeSurface(surface);

      SDL_RenderCopy(gpRenderer, texture, NULL, NULL);
      SDL_DestroyTexture(texture);

      if (time == 0)
	{
	  SOUND_PlayWAV(0, g_pSfxHit);
	}
      else if (time > 2)
	{
	  gameoverState = DROP;
	  time = 0;
	  return;
	}
      time++;
    }
  else if (gameoverState == DROP)
    {
      if (g_flBirdHeight < SCREEN_HEIGHT - 150 || !time)
	{
	  if (time == 15)
	    {
	      SOUND_PlayWAV(1, g_pSfxDie);
	    }
	  g_flBirdAngle = 85;
	  g_flBirdHeight += 8;

	  if (g_flBirdHeight > SCREEN_HEIGHT - 150)
	    {
	      g_flBirdHeight = SCREEN_HEIGHT - 150;
	    }

	  DrawBackground();

	  // draw pipes
	  for (int i = 0; i < 3; i++)
	    {
	      gpSprite->Draw(gpRenderer, "pipe_down", g_iPipePosX[i], -320 + 60 + g_iPipePosY[i]);
	      gpSprite->Draw(gpRenderer, "pipe_up", g_iPipePosX[i], SCREEN_HEIGHT - 110 - 250 + g_iPipePosY[i]);
	    }

	  DrawLand(true);

	  // draw bird
	  char buf[256];
	  sprintf(buf, "bird%d_%d", g_iBirdPic, (SDL_GetTicks() / 200) % 3);
	  gpSprite->DrawEx(gpRenderer, buf, 60, (int)g_flBirdHeight, g_flBirdAngle, SDL_FLIP_NONE);

	  DrawScore(g_iScore);
	  time++;
	}
      else
	{
	  gameoverState = SHOWTITLE;
	  time = 0;
	}
    }
  else if (gameoverState == SHOWTITLE)
    {
      DrawBackground();

      // draw pipes
      for (int i = 0; i < 3; i++)
	{
	  gpSprite->Draw(gpRenderer, "pipe_down", g_iPipePosX[i], -320 + 60 + g_iPipePosY[i]);
	  gpSprite->Draw(gpRenderer, "pipe_up", g_iPipePosX[i], SCREEN_HEIGHT - 110 - 250 + g_iPipePosY[i]);
	}

      DrawLand(true);

      // draw bird
      char buf[256];
      sprintf(buf, "bird%d_0", g_iBirdPic);
      gpSprite->DrawEx(gpRenderer, buf, 60, (int)g_flBirdHeight, g_flBirdAngle, SDL_FLIP_NONE);

      if (time > 30)
	{
	  if (time < 30 + 5)
	    {
	      if (time == 30 + 1)
		{
		  SOUND_PlayWAV(0, g_pSfxSwooshing);
		}
	      gpSprite->Draw(gpRenderer, "text_game_over", 45, 110 - (time - 30) * 6);
	      time++;
	    }
	  else if (time < 30 + 15)
	    {
	      gpSprite->Draw(gpRenderer, "text_game_over", 45, 80 + (time - 30) * 3);
	      time++;
	    }
	  else if (time < 30 + 25)
	    {
	      gpSprite->Draw(gpRenderer, "text_game_over", 45, 80 + 15 * 3);
	      time++;
	    }
	  else
	    {
	      gpSprite->Draw(gpRenderer, "text_game_over", 45, 80 + 15 * 3);
	      gameoverState = SHOWSCORE;
	      time = 0;

	      if (g_iScore > g_iHighScore)
		{
		  g_iHighScore = g_iScore;
		  bIsHighscore = true;
		  SaveBestScore();
		}
	    }
	}
      else
	{
	  DrawScore(g_iScore);
	  time++;
	}
    }
  else if (gameoverState == SHOWSCORE)
    {
      if (fading_start_time > 0)
	{
	  unsigned int elapsed = SDL_GetTicks() - fading_start_time;

	  if (elapsed > 500)
	    {
	      g_GameState = GAMESTATE_GAMESTART;
	      gpSprite->SetColorMod(255, 255, 255);
	      fading_start_time = 0;
	      gameoverState = FLASH;
	      time = 0;
	      bIsHighscore = false;
	      g_bNight = ((rand() % 2) == 1);
	      g_iBirdPic = rand() % 3;
	      for (int i = 0; i < 3; i++)
		{
		  g_iPipePosX[i] = SCREEN_WIDTH + 200 + i * PIPEDISTANCE;
		  g_iPipePosY[i] = rand() % 200;
		}
	      return;
	    }

	  elapsed *= 255;
	  elapsed /= 500;

	  elapsed = 255 - elapsed;

	  gpSprite->SetColorMod(elapsed, elapsed, elapsed);
	}

      DrawBackground();

      // draw pipes
      for (int i = 0; i < 3; i++)
	{
	  gpSprite->Draw(gpRenderer, "pipe_down", g_iPipePosX[i], -320 + 60 + g_iPipePosY[i]);
	  gpSprite->Draw(gpRenderer, "pipe_up", g_iPipePosX[i], SCREEN_HEIGHT - 110 - 250 + g_iPipePosY[i]);
	}

      DrawLand(true);

      // draw bird
      char buf[256];
      sprintf(buf, "bird%d_0", g_iBirdPic);
      gpSprite->DrawEx(gpRenderer, buf, 60, (int)g_flBirdHeight, g_flBirdAngle, SDL_FLIP_NONE);

      gpSprite->Draw(gpRenderer, "text_game_over", 45, 80 + 15 * 3);

      if (time < 15)
	{
	  if (time == 0)
	    {
	      SOUND_PlayWAV(0, g_pSfxSwooshing);
	    }
	  gpSprite->Draw(gpRenderer, "score_panel", 31, 190 + (15 - time) * 20);
	}
      else
	{
	  gpSprite->Draw(gpRenderer, "score_panel", 31, 190);
	  DrawScoreOnBoard(std::min<int>(g_iScore, (time - 15) / 2), 240, 225);
	  DrawScoreOnBoard(g_iHighScore, 240, 265);

	  if (bIsHighscore)
	    {
	      gpSprite->Draw(gpRenderer, "new", 170, 250);
	    }

	  if (g_iScore >= 40)
	    {
	      gpSprite->Draw(gpRenderer, "medals_0", 62, 235);
	    }
	  else if (g_iScore >= 30)
	    {
	      gpSprite->Draw(gpRenderer, "medals_1", 62, 235);
	    }
	  else if (g_iScore >= 20)
	    {
	      gpSprite->Draw(gpRenderer, "medals_2", 62, 235);
	    }
	  else if (g_iScore >= 10)
	    {
	      gpSprite->Draw(gpRenderer, "medals_3", 62, 235);
	    }
		  
	  gpSprite->Draw(gpRenderer, "button_play", 30, 340);
	  gpSprite->Draw(gpRenderer, "button_score", 150, 340);

	  if (fading_start_time == 0 && g_bMouseDown)
	    {
	      if (g_iMouseX > 30 && g_iMouseY > 340 && g_iMouseX < 30 + 100 && g_iMouseY < 340 + 55)
		{
		  // user clicked "play" button
		  fading_start_time = SDL_GetTicks();
		}
	      else if (g_iMouseX > 150 && g_iMouseY > 340 && g_iMouseX < 150 + 100 && g_iMouseY < 340 + 55)
		{
		  // user clicked "score" button
		  // TODO
		}
	    }

	}

      time++;
    }
}

int GameMain()
{
  srand((unsigned int)time(NULL));
  LoadBestScore();

  gpSprite = new CSprite(gpRenderer, MakeFileName("res/atlas.bmp"), MakeFileName("res/atlas.txt"));

  atexit([](void) { delete gpSprite; });

  LoadWav();

  atexit(FreeWav);
  atexit(SOUND_CloseAudio);

  ShowTitle();

  g_GameState = GAMESTATE_INITIAL;

  unsigned int uiNextFrameTime = SDL_GetTicks();
  unsigned int uiCurrentTime = SDL_GetTicks();

  while (1)
    {
      // 60fps
      do
	{
	  uiCurrentTime = SDL_GetTicks();
	  UpdateEvents();
	  SDL_Delay(1);
	} while (uiCurrentTime < uiNextFrameTime);

      if ((int)(uiCurrentTime - uiNextFrameTime) > 1000)
	{
	  uiNextFrameTime = uiCurrentTime + 1000 / 60;
	}
      else
	{
	  uiNextFrameTime += 1000 / 60;
	}

      if (g_bPauseGame)
        {
	  continue;
        }

      FrameBegin();
      switch (g_GameState)
	{
	case GAMESTATE_INITIAL:
	  GameThink_Initial();
	  break;

	case GAMESTATE_GAMESTART:
	  GameThink_GameStart();
	  break;

	case GAMESTATE_GAME:
	  GameThink_Game();
	  break;

	case GAMESTATE_GAMEOVER:
	  GameThink_GameOver();
	  break;

	default:
	  fprintf(stderr, "invalid game state: %d\n", (int)g_GameState);
	  exit(255);
	}

      FrameEnd();
    }

  return 255; // shouldn't really reach here
}