//=============================================================================
  // Sky.cpp by Frank Luna (C) 2004 All Rights Reserved.
  //=============================================================================
  
  include <Sky.h>
  include <Camera.h>
  include <d3dUtil.h>
  
  Sky::Sky(const std::string& envmapFilename, float skyRadius)
  : mRadius(skyRadius)
  {
          HR(D3DXCreateSphere(gd3dDevice, skyRadius, 30, 30, &mSphere, 0));
          HR(D3DXCreateCubeTextureFromFile(gd3dDevice, envmapFilename.c_str(), &mEnvMap));
  
          ID3DXBuffer* errors = 0;
          HR(D3DXCreateEffectFromFile(gd3dDevice, "sky.fx", 0, 0, 0, 
                  0, &mFX, &errors));
          if( errors )
                  MessageBox(0, (char*)errors->GetBufferPointer(), 0, 0);
  
          mhTech   = mFX->GetTechniqueByName("SkyTech");
          mhWVP    = mFX->GetParameterByName(0, "gWVP");
          mhEnvMap = mFX->GetParameterByName(0, "gEnvMap");
  
          // Set effect parameters that do not vary.
          HR(mFX->SetTechnique(mhTech));
          HR(mFX->SetTexture(mhEnvMap, mEnvMap));
  }
  
  Sky::~Sky()
  {
          ReleaseCOM(mSphere);
          ReleaseCOM(mEnvMap);
          ReleaseCOM(mFX);
  }
  
  DWORD Sky::getNumTriangles()
  {
          return mSphere->GetNumFaces();
  }
  
  DWORD Sky::getNumVertices()
  {
          return mSphere->GetNumVertices();
  }
  
  IDirect3DCubeTexture9* Sky::getEnvMap()
  {
          return mEnvMap;
  }
  
  float Sky::getRadius()
  {
          return mRadius;
  }
  
  void Sky::onLostDevice()
  {
          HR(mFX->OnLostDevice());
  }
  
  void Sky::onResetDevice()
  {
          HR(mFX->OnResetDevice());
  }
  
  void Sky::draw()
  {
          // Sky always centered about camera's position.
          D3DXMATRIX W;
          D3DXVECTOR3 p = gCamera->pos();
          D3DXMatrixTranslation(&W, p.x, p.y, p.z);
          HR(mFX->SetMatrix(mhWVP, &(W*gCamera->viewProj())));
          
          UINT numPasses = 0;
          HR(mFX->Begin(&numPasses, 0));
          HR(mFX->BeginPass(0));
          HR(mSphere->DrawSubset(0));
          HR(mFX->EndPass());
          HR(mFX->End());
  }