//=============================================================================
  // RainDemo.cpp by Frank Luna (C) 2005 All Rights Reserved.
  //
  // Demonstrates a rain particle system.
  //
  // Controls: Use mouse to look and 'W', 'S', 'A', and 'D' keys to move.
  //=============================================================================
  
  include <d3dApp.h>
  include <DirectInput.h>
  include <crtdbg.h>
  include <GfxStats.h>
  include <list>
  include <ctime>
  include <Terrain.h>
  include <Camera.h>
  include <PSystem.h>
  
  class Rain : public PSystem
  {
  public:
          Rain(const std::string& fxName, 
                  const std::string& techName, 
                  const std::string& texName, 
                  const D3DXVECTOR3& accel, 
                  const AABB& box,
                  int maxNumParticles,
                  float timePerParticle)
                  : PSystem(fxName, techName, texName, accel, box, maxNumParticles,
                  timePerParticle)
          {
          }
  
          void initParticle(Particle& out)
          {
                  // Generate about the camera.
                  out.initialPos = gCamera->pos();
  
                  // Spread the particles out on xz-plane.
                  out.initialPos.x += GetRandomFloat(-100.0f, 100.0f);
                  out.initialPos.z += GetRandomFloat(-100.0f, 100.0f);
  
                  // Generate above the camera.
                  out.initialPos.y += GetRandomFloat(50.0f, 55.0f);
  
                  out.initialTime      = mTime;
                  out.lifeTime        = GetRandomFloat(2.0f, 2.5f);
                  out.initialColor    = WHITE;
                  out.initialSize     = GetRandomFloat(6.0f, 7.0f);
  
                  // Give them an initial falling down velocity.
                  out.initialVelocity.x = GetRandomFloat(-1.5f, 0.0f);
                  out.initialVelocity.y = GetRandomFloat(-50.0f, -45.0f);
                  out.initialVelocity.z = GetRandomFloat(-0.5f, 0.5f);
          }
  };
  
  class RainDemo : public D3DApp
  {
  public:
          RainDemo(HINSTANCE hInstance, std::string winCaption, D3DDEVTYPE devType, DWORD requestedVP);
          ~RainDemo();
  
          bool checkDeviceCaps();
          void onLostDevice();
          void onResetDevice();
          void updateScene(float dt);
          void drawScene();
  
  private:
          GfxStats* mGfxStats;
          Terrain*  mTerrain;
          PSystem*  mPSys;
  };
  
  int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE prevInstance,
                                     PSTR cmdLine, int showCmd)
  {
          // Enable run-time memory check for debug builds.
          #if defined(DEBUG) | defined(_DEBUG)
                  _CrtSetDbgFlag( _CRTDBG_ALLOC_MEM_DF | _CRTDBG_LEAK_CHECK_DF );
          #endif
  
          srand(time(0));
  
          // Construct camera before application, since the application uses the camera.
          Camera camera;
          gCamera = &camera;
  
          RainDemo app(hInstance, "Rain Demo", D3DDEVTYPE_HAL, D3DCREATE_HARDWARE_VERTEXPROCESSING);
          gd3dApp = &app;
  
          DirectInput di(DISCL_NONEXCLUSIVE|DISCL_FOREGROUND, DISCL_NONEXCLUSIVE|DISCL_FOREGROUND);
          gDInput = &di;
  
      return gd3dApp->run();
  }
  
  RainDemo::RainDemo(HINSTANCE hInstance, std::string winCaption, D3DDEVTYPE devType, DWORD requestedVP)
  : D3DApp(hInstance, winCaption, devType, requestedVP)
  {
          if(!checkDeviceCaps())
          {
                  MessageBox(0, "checkDeviceCaps() Failed", 0, 0);
                  PostQuitMessage(0);
          }
  
          InitAllVertexDeclarations();
  
          mGfxStats = new GfxStats();
          
          // World space units are meters.  
          mTerrain = new Terrain(257, 257, 2.0f, 2.0f, 
                  "heightmap1_257.raw",  
                  "mud.dds",
                  "stone.dds",
                  "snow.dds",
                  "blend_hm1.dds",
                  0.4f, 0.0f);
  
          D3DXVECTOR3 toSun(1.0f, 1.0f, 1.0f);
          D3DXVec3Normalize(&toSun, &toSun);
          mTerrain->setDirToSunW(toSun);
  
          // Initialize camera.
          gCamera->pos() = D3DXVECTOR3(55.0f, 50.0f, 25.0f);
          gCamera->setSpeed(40.0f);
  
          // Initialize the particle system.
          D3DXMATRIX psysWorld;
          D3DXMatrixIdentity(&psysWorld);
  
          // Rain always visible, so make infinitely huge bounding box
          // so that it is always seen.
          AABB psysBox; 
          psysBox.maxPt = D3DXVECTOR3(INFINITY, INFINITY, INFINITY);
          psysBox.minPt = D3DXVECTOR3(-INFINITY, -INFINITY, -INFINITY);
  
          // Accelerate due to wind and gravity.
          mPSys = new Rain("rain.fx", "RainTech", "raindrop.dds", 
                  D3DXVECTOR3(-1.0f, -9.8f, 0.0f), psysBox, 4000, 0.001f);
          mPSys->setWorldMtx(psysWorld);
  
          mGfxStats->addVertices(mTerrain->getNumVertices());
          mGfxStats->addTriangles(mTerrain->getNumTriangles());
  
          onResetDevice();
  }
  
  RainDemo::~RainDemo()
  {
          delete mGfxStats;
          delete mTerrain;
          delete mPSys;
  
          DestroyAllVertexDeclarations();
  }
  
  bool RainDemo::checkDeviceCaps()
  {
          D3DCAPS9 caps;
          HR(gd3dDevice->GetDeviceCaps(&caps));
  
          // Check for vertex shader version 2.0 support.
          if( caps.VertexShaderVersion < D3DVS_VERSION(2, 0) )
                  return false;
  
          // Check for pixel shader version 2.0 support.
          if( caps.PixelShaderVersion < D3DPS_VERSION(2, 0) )
                  return false;
  
          return true;
  }
  
  void RainDemo::onLostDevice()
  {
          mGfxStats->onLostDevice();
          mTerrain->onLostDevice();
          mPSys->onLostDevice();
  }
  
  void RainDemo::onResetDevice()
  {
          mGfxStats->onResetDevice();
          mTerrain->onResetDevice();
          mPSys->onResetDevice();
  
          // The aspect ratio depends on the backbuffer dimensions, which can 
          // possibly change after a reset.  So rebuild the projection matrix.
          float w = (float)md3dPP.BackBufferWidth;
          float h = (float)md3dPP.BackBufferHeight;
          gCamera->setLens(D3DX_PI * 0.25f, w/h, 0.01f, 5000.0f);
  }
  
  void RainDemo::updateScene(float dt)
  {
          mGfxStats->update(dt);
  
          gDInput->poll();
  
          gCamera->update(dt, 0, 0);
  
          mPSys->update(dt);
  }
  
  void RainDemo::drawScene()
  {
          // Clear the backbuffer and depth buffer.
          HR(gd3dDevice->Clear(0, 0, D3DCLEAR_TARGET | D3DCLEAR_ZBUFFER, 0xff666666, 1.0f, 0));
  
          HR(gd3dDevice->BeginScene());
  
          mTerrain->draw();
          mPSys->draw();
  
          mGfxStats->display();
  
          HR(gd3dDevice->EndScene());
  
          // Present the backbuffer.
          HR(gd3dDevice->Present(0, 0, 0, 0));
  }