roids.cpp

来自「《24小时教会你游戏编程》上的源码」· C++ 代码 · 共 228 行

//-----------------------------------------------------------------
// Roids 2 Application
// C++ Source - Roids.cpp
//-----------------------------------------------------------------

//-----------------------------------------------------------------
// Include Files
//-----------------------------------------------------------------
#include "Roids.h"

//-----------------------------------------------------------------
// Game Engine Functions
//-----------------------------------------------------------------
BOOL GameInitialize(HINSTANCE hInstance)
{
  // Create the game engine
  _pGame = new GameEngine(hInstance, TEXT("Roids 2"),
    TEXT("Roids 2"), IDI_ROIDS, IDI_ROIDS_SM, 500, 400);
  if (_pGame == NULL)
    return FALSE;

  // Set the frame rate
  _pGame->SetFrameRate(30);

  // Store the instance handle
  _hInstance = hInstance;

  return TRUE;
}

void GameStart(HWND hWindow)
{
  // Seed the random number generator
  srand(GetTickCount());

  // Create the offscreen device context and bitmap
  _hOffscreenDC = CreateCompatibleDC(GetDC(hWindow));
  _hOffscreenBitmap = CreateCompatibleBitmap(GetDC(hWindow),
    _pGame->GetWidth(), _pGame->GetHeight());
  SelectObject(_hOffscreenDC, _hOffscreenBitmap);

  // Create and load the asteroid and saucer bitmaps
  HDC hDC = GetDC(hWindow);
  _pAsteroidBitmap = new Bitmap(hDC, IDB_ASTEROID, _hInstance);
  _pSaucerBitmap = new Bitmap(hDC, IDB_SAUCER, _hInstance);

  // Create the starry background
  _pBackground = new StarryBackground(500, 400);

  // Create the asteroid sprites
  RECT    rcBounds = { 0, 0, 500, 400 };
  _pAsteroids[0] = new Sprite(_pAsteroidBitmap, rcBounds, BA_WRAP);
  _pAsteroids[0]->SetNumFrames(14);
  _pAsteroids[0]->SetFrameDelay(1);
  _pAsteroids[0]->SetPosition(250, 200);
  _pAsteroids[0]->SetVelocity(-3, 1);
  _pGame->AddSprite(_pAsteroids[0]);
  _pAsteroids[1] = new Sprite(_pAsteroidBitmap, rcBounds, BA_WRAP);
  _pAsteroids[1]->SetNumFrames(14);
  _pAsteroids[1]->SetFrameDelay(2);
  _pAsteroids[1]->SetPosition(250, 200);
  _pAsteroids[1]->SetVelocity(3, -2);
  _pGame->AddSprite(_pAsteroids[1]);
  _pAsteroids[2] = new Sprite(_pAsteroidBitmap, rcBounds, BA_WRAP);
  _pAsteroids[2]->SetNumFrames(14);
  _pAsteroids[2]->SetFrameDelay(3);
  _pAsteroids[2]->SetPosition(250, 200);
  _pAsteroids[2]->SetVelocity(-2, -4);
  _pGame->AddSprite(_pAsteroids[2]);

  // Create the saucer sprite
  _pSaucer = new Sprite(_pSaucerBitmap, rcBounds, BA_WRAP);
  _pSaucer->SetPosition(0, 0);
  _pSaucer->SetVelocity(3, 1);
  _pGame->AddSprite(_pSaucer);
}

void GameEnd()
{
  // Cleanup the offscreen device context and bitmap
  DeleteObject(_hOffscreenBitmap);
  DeleteDC(_hOffscreenDC);  

  // Cleanup the asteroid and saucer bitmaps
  delete _pAsteroidBitmap;
  delete _pSaucerBitmap;

  // Cleanup the background
  delete _pBackground;

  // Cleanup the sprites
  _pGame->CleanupSprites();

  // Cleanup the game engine
  delete _pGame;
}

void GameActivate(HWND hWindow)
{
}

void GameDeactivate(HWND hWindow)
{
}

void GamePaint(HDC hDC)
{
  // Draw the background
  _pBackground->Draw(hDC);

  // Draw the sprites
  _pGame->DrawSprites(hDC);
}

void GameCycle()
{
  // Update the background
  _pBackground->Update();

  // Update the sprites
  _pGame->UpdateSprites();

  // Update the saucer to help it dodge the asteroids
  UpdateSaucer();

  // Obtain a device context for repainting the game
  HWND  hWindow = _pGame->GetWindow();
  HDC   hDC = GetDC(hWindow);

  // Paint the game to the offscreen device context
  GamePaint(_hOffscreenDC);

  // Blit the offscreen bitmap to the game screen
  BitBlt(hDC, 0, 0, _pGame->GetWidth(), _pGame->GetHeight(),
    _hOffscreenDC, 0, 0, SRCCOPY);

  // Cleanup
  ReleaseDC(hWindow, hDC);
}

void HandleKeys()
{
}

void MouseButtonDown(int x, int y, BOOL bLeft)
{
}

void MouseButtonUp(int x, int y, BOOL bLeft)
{
}

void MouseMove(int x, int y)
{
}

void HandleJoystick(JOYSTATE jsJoystickState)
{
}

BOOL SpriteCollision(Sprite* pSpriteHitter, Sprite* pSpriteHittee)
{
  return FALSE;
}

void SpriteDying(Sprite* pSprite)
{
}

//-----------------------------------------------------------------
// Functions
//-----------------------------------------------------------------
void UpdateSaucer()
{
  // Obtain the saucer's position
  RECT rcSaucer, rcRoid;
  rcSaucer = _pSaucer->GetPosition();

  // Find out which asteroid is closest to the saucer
  int iXCollision = 500, iYCollision = 400, iXYCollision = 900;
  for (int i = 0; i < 3; i++)
  {
    // Get the asteroid position
    rcRoid = _pAsteroids[i]->GetPosition();

    // Calculate the minimum XY collision distance
    int iXCollisionDist = (rcSaucer.left +
      (rcSaucer.right - rcSaucer.left) / 2) -
      (rcRoid.left +
      (rcRoid.right - rcRoid.left) / 2);
    int iYCollisionDist = (rcSaucer.top +
      (rcSaucer.bottom - rcSaucer.top) / 2) -
      (rcRoid.top +
      (rcRoid.bottom - rcRoid.top) / 2);
    if ((abs(iXCollisionDist) < abs(iXCollision)) ||
      (abs(iYCollisionDist) < abs(iYCollision)))
      if ((abs(iXCollisionDist) + abs(iYCollisionDist)) < iXYCollision)
      {
        iXYCollision = abs(iXCollision) + abs(iYCollision);
        iXCollision = iXCollisionDist;
        iYCollision = iYCollisionDist;
      }
  }

  // Move to dodge the asteroids, if necessary
  POINT ptVelocity;
  ptVelocity = _pSaucer->GetVelocity();
  if (abs(iXCollision) < 60)
  {
    // Adjust the X velocity
    if (iXCollision < 0)
      ptVelocity.x = max(ptVelocity.x - 1, -8);
    else
      ptVelocity.x = min(ptVelocity.x + 1, 8);
  }
  if (abs(iYCollision) < 60)
  {
    // Adjust the Y velocity
    if (iYCollision < 0)
      ptVelocity.y = max(ptVelocity.y - 1, -8);
    else
      ptVelocity.y = min(ptVelocity.y + 1, 8);
  }

  // Update the saucer to the new position
  _pSaucer->SetVelocity(ptVelocity);
}