//=============================================================================
  // BasicTerrainDemo.cpp by Frank Luna (C) 2005 All Rights Reserved.
  //
  // Builds off the Multi-Tex demo from chapter 10 by using a heightmap
  // to adjust the grid heights to create hills and valleys.
  //
  // Controls: Use mouse to orbit and zoom; use the 'W' and 'S' keys to 
  //           alter the height of the camera.
  //=============================================================================
  
  include <d3dApp.h>
  include <DirectInput.h>
  include <crtdbg.h>
  include <GfxStats.h>
  include <list>
  include <Vertex.h>
  include <Heightmap.h>
  
  class BasicTerrainDemo : public D3DApp
  {
  public:
          BasicTerrainDemo(HINSTANCE hInstance, std::string winCaption, D3DDEVTYPE devType, DWORD requestedVP);
          ~BasicTerrainDemo();
  
          bool checkDeviceCaps();
          void onLostDevice();
          void onResetDevice();
          void updateScene(float dt);
          void drawScene();
  
          // Helper methods
          void buildGridGeometry();
          void buildFX();
          void buildViewMtx();
          void buildProjMtx();
  
  private:
          GfxStats* mGfxStats;
  
          Heightmap mHeightmap;
  
          ID3DXMesh* mTerrainMesh;
  
          IDirect3DTexture9* mTex0;
          IDirect3DTexture9* mTex1;
          IDirect3DTexture9* mTex2;
          IDirect3DTexture9* mBlendMap;
  
          ID3DXEffect* mFX;
          D3DXHANDLE   mhTech;
          D3DXHANDLE   mhViewProj;
          D3DXHANDLE   mhDirToSunW;
          D3DXHANDLE   mhTex0;
          D3DXHANDLE   mhTex1;
          D3DXHANDLE   mhTex2;
          D3DXHANDLE   mhBlendMap;
  
          float mCameraRotationY;
          float mCameraRadius;
          float mCameraHeight;
  
          D3DXMATRIX mWorld;
          D3DXMATRIX mView;
          D3DXMATRIX mProj;
  };
  
  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
  
          BasicTerrainDemo app(hInstance, "Basic Terrain Demo", D3DDEVTYPE_HAL, D3DCREATE_HARDWARE_VERTEXPROCESSING);
          gd3dApp = &app;
  
          DirectInput di(DISCL_NONEXCLUSIVE|DISCL_FOREGROUND, DISCL_NONEXCLUSIVE|DISCL_FOREGROUND);
          gDInput = &di;
  
      return gd3dApp->run();
  }
  
  BasicTerrainDemo::BasicTerrainDemo(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();
  
          mCameraRadius    = 80.0f;
          mCameraRotationY = 1.2 * D3DX_PI;
          mCameraHeight    = 40.0f;
  
          D3DXMatrixIdentity(&mWorld);
  
          mHeightmap.loadRAW(129, 129, "heightmap17_129.raw", 0.25f, 0.0f);
  
          // Load textures from file.
          HR(D3DXCreateTextureFromFile(gd3dDevice, "grass.dds", &mTex0));
          HR(D3DXCreateTextureFromFile(gd3dDevice, "dirt.dds", &mTex1));
          HR(D3DXCreateTextureFromFile(gd3dDevice, "stone.dds", &mTex2));
          HR(D3DXCreateTextureFromFile(gd3dDevice, "blend_hm17.dds", &mBlendMap));
          
          buildGridGeometry();
          mGfxStats->addVertices(mTerrainMesh->GetNumVertices());
          mGfxStats->addTriangles(mTerrainMesh->GetNumFaces());
  
          buildFX();
  
          onResetDevice();
  }
  
  BasicTerrainDemo::~BasicTerrainDemo()
  {
          delete mGfxStats;
          ReleaseCOM(mTerrainMesh);
          ReleaseCOM(mTex0);
          ReleaseCOM(mTex1);
          ReleaseCOM(mTex2);
          ReleaseCOM(mBlendMap);
          ReleaseCOM(mFX);
  
          DestroyAllVertexDeclarations();
  }
  
  bool BasicTerrainDemo::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 BasicTerrainDemo::onLostDevice()
  {
          mGfxStats->onLostDevice();
          HR(mFX->OnLostDevice());
  }
  
  void BasicTerrainDemo::onResetDevice()
  {
          mGfxStats->onResetDevice();
          HR(mFX->OnResetDevice());
  
          // The aspect ratio depends on the backbuffer dimensions, which can 
          // possibly change after a reset.  So rebuild the projection matrix.
          buildProjMtx();
  }
  
  void BasicTerrainDemo::updateScene(float dt)
  {
          mGfxStats->update(dt);
  
          // Get snapshot of input devices.
          gDInput->poll();
  
          // Check input.
          if( gDInput->keyDown(DIK_W) )         
                  mCameraHeight   += 25.0f * dt;
          if( gDInput->keyDown(DIK_S) )         
                  mCameraHeight   -= 25.0f * dt;
  
          // Divide by 50 to make mouse less sensitive. 
          mCameraRotationY += gDInput->mouseDX() / 100.0f;
          mCameraRadius    += gDInput->mouseDY() / 25.0f;
  
          // If we rotate over 360 degrees, just roll back to 0
          if( fabsf(mCameraRotationY) >= 2.0f * D3DX_PI ) 
                  mCameraRotationY = 0.0f;
  
          // Don't let radius get too small.
          if( mCameraRadius < 5.0f )
                  mCameraRadius = 5.0f;
  
          // The camera position/orientation relative to world space can 
          // change every frame based on input, so we need to rebuild the
          // view matrix every frame with the latest changes.
          buildViewMtx();
  }
  
  void BasicTerrainDemo::drawScene()
  {
          // Clear the backbuffer and depth buffer.
          HR(gd3dDevice->Clear(0, 0, D3DCLEAR_TARGET | D3DCLEAR_ZBUFFER, 0xffeeeeee, 1.0f, 0));
  
          HR(gd3dDevice->BeginScene());
  
          // Setup the rendering FX
          HR(mFX->SetMatrix(mhViewProj, &(mView*mProj)));
          HR(mFX->SetTechnique(mhTech));
          UINT numPasses = 0;
          HR(mFX->Begin(&numPasses, 0));
          HR(mFX->BeginPass(0));
  
          HR(mTerrainMesh->DrawSubset(0));
  
          HR(mFX->EndPass());
          HR(mFX->End());
          
          mGfxStats->display();
  
          HR(gd3dDevice->EndScene());
  
          // Present the backbuffer.
          HR(gd3dDevice->Present(0, 0, 0, 0));
  }
  
  void BasicTerrainDemo::buildGridGeometry()
  {
          std::vector<D3DXVECTOR3> verts;
          std::vector<DWORD> indices;
  
          int vertRows = 129;
          int vertCols = 129;
          float dx = 1.0f;
          float dz = 1.0f;
  
          GenTriGrid(vertRows, vertCols, dx, dz, 
                  D3DXVECTOR3(0.0f, 0.0f, 0.0f), verts, indices);
  
          int numVerts = vertRows*vertCols;
          int numTris  = (vertRows-1)*(vertCols-1)*2;
  
          // Create the mesh.
          D3DVERTEXELEMENT9 elems[MAX_FVF_DECL_SIZE];
          UINT numElems = 0;
          HR(VertexPNT::Decl->GetDeclaration(elems, &numElems));
          HR(D3DXCreateMesh(numTris, numVerts, 
                  D3DXMESH_MANAGED, elems, gd3dDevice, &mTerrainMesh));
  
          // Write the vertices.
          VertexPNT* v = 0;
          HR(mTerrainMesh->LockVertexBuffer(0,(void**)&v));
  
          // width/depth
          float w = (vertCols-1) * dx; 
          float d = (vertRows-1) * dz;
          for(int i = 0; i < vertRows; ++i)
          {
                  for(int j = 0; j < vertCols; ++j)
                  {
                          DWORD index = i * vertCols + j;
                          v[index].pos    = verts[index];
                          v[index].pos.y  = mHeightmap(i, j);
                          v[index].normal = D3DXVECTOR3(0.0f, 1.0f, 0.0f);
                          v[index].tex0.x = (v[index].pos.x + (0.5f*w)) / w;
                          v[index].tex0.y = (v[index].pos.z - (0.5f*d)) / -d;
                  }
          }
  
          HR(mTerrainMesh->UnlockVertexBuffer());
  
          // Write the indices and attribute buffer.
          WORD* k = 0;
          HR(mTerrainMesh->LockIndexBuffer(0, (void**)&k));
          DWORD* attBuffer = 0;
          HR(mTerrainMesh->LockAttributeBuffer(0, &attBuffer));
  
          // Compute the indices for each triangle.
          for(int i = 0; i < numTris; ++i)
          {
                  k[i*3+0] = (WORD)indices[i*3+0];
                  k[i*3+1] = (WORD)indices[i*3+1];
                  k[i*3+2] = (WORD)indices[i*3+2];
  
                  attBuffer[i] = 0; // Always subset 0
          }
  
          HR(mTerrainMesh->UnlockIndexBuffer());
          HR(mTerrainMesh->UnlockAttributeBuffer());
  
          // Generate normals and then optimize the mesh.
          HR(D3DXComputeNormals(mTerrainMesh, 0));
  
          DWORD* adj = new DWORD[mTerrainMesh->GetNumFaces()*3];
          HR(mTerrainMesh->GenerateAdjacency(EPSILON, adj));
          HR(mTerrainMesh->OptimizeInplace(D3DXMESHOPT_VERTEXCACHE|D3DXMESHOPT_ATTRSORT,
                  adj, 0, 0, 0));
          delete[] adj;
  }
  
  void BasicTerrainDemo::buildFX()
  {
          ID3DXBuffer* errors = 0;
          HR(D3DXCreateEffectFromFile(gd3dDevice, "Terrain.fx",
                  0, 0, D3DXSHADER_DEBUG, 0, &mFX, &errors));
          if( errors )
                  MessageBox(0, (char*)errors->GetBufferPointer(), 0, 0);
  
          mhTech      = mFX->GetTechniqueByName("TerrainTech");
          mhViewProj  = mFX->GetParameterByName(0, "gViewProj");
          mhDirToSunW = mFX->GetParameterByName(0, "gDirToSunW");
          mhTex0      = mFX->GetParameterByName(0, "gTex0");
          mhTex1      = mFX->GetParameterByName(0, "gTex1");
          mhTex2      = mFX->GetParameterByName(0, "gTex2");
          mhBlendMap  = mFX->GetParameterByName(0, "gBlendMap");
  
          HR(mFX->SetTexture(mhTex0, mTex0));
          HR(mFX->SetTexture(mhTex1, mTex1));
          HR(mFX->SetTexture(mhTex2, mTex2));
          HR(mFX->SetTexture(mhBlendMap, mBlendMap));
  
          D3DXVECTOR3 d(0.0f, 1.0f, 0.0f);
          HR(mFX->SetValue(mhDirToSunW, &d, sizeof(D3DXVECTOR3)));
  }
  
  void BasicTerrainDemo::buildViewMtx()
  {
          float x = mCameraRadius * cosf(mCameraRotationY);
          float z = mCameraRadius * sinf(mCameraRotationY);
          D3DXVECTOR3 pos(x, mCameraHeight, z);
          D3DXVECTOR3 target(0.0f, 0.0f, 0.0f);
          D3DXVECTOR3 up(0.0f, 1.0f, 0.0f);
          D3DXMatrixLookAtLH(&mView, &pos, &target, &up);
  }
  
  void BasicTerrainDemo::buildProjMtx()
  {
          float w = (float)md3dPP.BackBufferWidth;
          float h = (float)md3dPP.BackBufferHeight;
          D3DXMatrixPerspectiveFovLH(&mProj, D3DX_PI * 0.25f, w/h, 1.0f, 5000.0f);
  }