//=============================================================================
  // RobotArmDemo.cpp by Frank Luna (C) 2005 All Rights Reserved.
  //
  // Demonstrates how to animate mesh hierarchies.
  //
  // Controls: Use mouse to orbit and zoom; use the 'W' and 'S' keys to 
  //           alter the height of the camera.
  //           Use '1', '2', '3', '4', and '5' keys to select the bone
  //           to rotate.  Use the 'A' and 'D' keys to rotate the bone.
  //=============================================================================
  
  include <d3dApp.h>
  include <DirectInput.h>
  include <crtdbg.h>
  include <GfxStats.h>
  include <list>
  include <Vertex.h>
  
  struct BoneFrame
  {
          // Note: The root bone's "parent" frame is the world space.
  
          D3DXVECTOR3 pos; // Relative to parent frame.
          float zAngle;    // Relative to parent frame.
  
          D3DXMATRIX toParentXForm;
          D3DXMATRIX toWorldXForm;
  };
  
  class RobotArmDemo : public D3DApp
  {
  public:
          RobotArmDemo(HINSTANCE hInstance, std::string winCaption, D3DDEVTYPE devType, DWORD requestedVP);
          ~RobotArmDemo();
  
          bool checkDeviceCaps();
          void onLostDevice();
          void onResetDevice();
          void updateScene(float dt);
          void drawScene();
  
          // Helper methods
          void buildFX();
          void buildViewMtx();
          void buildProjMtx();
  
          void buildBoneWorldTransforms();
  
  private:
          GfxStats* mGfxStats;
          
          // We only need one bone mesh.  To draw several bones we just draw the
          // same mesh several times, but with a different transformation
          // applied so that it is drawn in a different place.
          ID3DXMesh* mBoneMesh;
          std::vector<Mtrl> mMtrl;
          std::vector<IDirect3DTexture9*> mTex;
  
          // Our robot arm has five bones.
          static const int NUM_BONES = 5;
          BoneFrame mBones[NUM_BONES];
          
          // Index into the bone array to the currently selected bone.
          // The user can select a bone and rotate it.
          int mBoneSelected;
  
          IDirect3DTexture9* mWhiteTex;
  
          ID3DXEffect* mFX;
          D3DXHANDLE   mhTech;
          D3DXHANDLE   mhWVP;
          D3DXHANDLE   mhWorldInvTrans;
          D3DXHANDLE   mhEyePos;
          D3DXHANDLE   mhWorld;
          D3DXHANDLE   mhTex;
          D3DXHANDLE   mhMtrl;
          D3DXHANDLE   mhLight;
  
          DirLight mLight;
  
          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
  
          RobotArmDemo app(hInstance, "Robot Arm Demo", D3DDEVTYPE_HAL, D3DCREATE_HARDWARE_VERTEXPROCESSING);
          gd3dApp = &app;
  
          DirectInput di(DISCL_NONEXCLUSIVE|DISCL_FOREGROUND, DISCL_NONEXCLUSIVE|DISCL_FOREGROUND);
          gDInput = &di;
  
      return gd3dApp->run();
  }
  
  RobotArmDemo::RobotArmDemo(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();
          
          // Initialize Camera Settings
          mCameraRadius    = 9.0f;
          mCameraRotationY = 1.5f * D3DX_PI;
          mCameraHeight    = 0.0f;
  
          // Setup a directional light.
          mLight.dirW    = D3DXVECTOR3(0.0f, 1.0f, 2.0f);
          D3DXVec3Normalize(&mLight.dirW, &mLight.dirW);
          mLight.ambient = D3DXCOLOR(0.8f, 0.8f, 0.8f, 1.0f);
          mLight.diffuse = D3DXCOLOR(0.8f, 0.8f, 0.8f, 1.0f);
          mLight.spec    = D3DXCOLOR(0.8f, 0.8f, 0.8f, 1.0f);
  
          // Load the bone .X file mesh.
          LoadXFile(<bone.x>, &mBoneMesh, mMtrl, mTex);
          D3DXMatrixIdentity(&mWorld);
  
          // Create the white dummy texture.
          HR(D3DXCreateTextureFromFile(gd3dDevice, "whitetex.dds", &mWhiteTex));
  
          // Initialize the bones relative to their parent frame.
          // The root is special--its parent frame is the world space.
          // As such, its position and angle are ignored--its 
          // toWorldXForm should be set explicitly (that is, the world
          // transform of the entire skeleton).
          //
          // *------*------*------*------
          //    0      1      2      3
  
          for(int i = 1; i < NUM_BONES; ++i) // Ignore root.
          {
                  // Describe each bone frame relative to its parent frame.
                  mBones[i].pos    = D3DXVECTOR3(2.0f, 0.0f, 0.0f);
                  mBones[i].zAngle = 0.0f;
          }
          // Root frame at center of world.
          mBones[0].pos    = D3DXVECTOR3(0.0f, 0.0f, 0.0f);
          mBones[0].zAngle = 0.0f;
  
          // Start off with the last (leaf) bone:
          mBoneSelected = NUM_BONES-1;
  
          mGfxStats->addVertices(mBoneMesh->GetNumVertices() * NUM_BONES);
          mGfxStats->addTriangles(mBoneMesh->GetNumFaces() * NUM_BONES);
  
          buildFX();
  
          onResetDevice();
  }
  
  RobotArmDemo::~RobotArmDemo()
  {
          delete mGfxStats;
          
          ReleaseCOM(mFX);
  
          ReleaseCOM(mBoneMesh);
          for(int i = 0; i < mTex.size(); ++i)
                  ReleaseCOM(mTex[i]);
  
          ReleaseCOM(mWhiteTex);
  
          DestroyAllVertexDeclarations();
  }
  
  bool RobotArmDemo::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 RobotArmDemo::onLostDevice()
  {
          mGfxStats->onLostDevice();
          HR(mFX->OnLostDevice());
  }
  
  void RobotArmDemo::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 RobotArmDemo::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;
  
          // Allow the user to select a bone (zero based index)
          if( gDInput->keyDown(DIK_1) )        mBoneSelected = 0; 
          if( gDInput->keyDown(DIK_2) )        mBoneSelected = 1;  
          if( gDInput->keyDown(DIK_3) )        mBoneSelected = 2; 
          if( gDInput->keyDown(DIK_4) )        mBoneSelected = 3; 
          if( gDInput->keyDown(DIK_5) )        mBoneSelected = 4; 
          
          // Allow the user to rotate a bone.
          if( gDInput->keyDown(DIK_A) )         
                  mBones[mBoneSelected].zAngle += 1.0f * dt;
          if( gDInput->keyDown(DIK_D) )         
                  mBones[mBoneSelected].zAngle -= 1.0f * dt;
  
          // If we rotate over 360 degrees, just roll back to 0
          if( fabsf(mBones[mBoneSelected].zAngle) >= 2.0f*D3DX_PI)
                  mBones[mBoneSelected].zAngle = 0.0f;
  
          // 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 < 2.0f )
                  mCameraRadius = 2.0f;
  
          // 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 RobotArmDemo::drawScene()
  {
          // Clear the backbuffer and depth buffer.
          HR(gd3dDevice->Clear(0, 0, D3DCLEAR_TARGET | D3DCLEAR_ZBUFFER, 0xffffffff, 1.0f, 0));
  
          HR(gd3dDevice->BeginScene());
  
          HR(mFX->SetValue(mhLight, &mLight, sizeof(DirLight)));
          
          HR(mFX->SetTechnique(mhTech));
          UINT numPasses = 0;
          HR(mFX->Begin(&numPasses, 0));
          HR(mFX->BeginPass(0));
  
          // Build the world transforms for each bone, then render them.
          buildBoneWorldTransforms();
          D3DXMATRIX T;
          D3DXMatrixTranslation(&T, -NUM_BONES, 0.0f, 0.0f);
          for(int i = 0; i < NUM_BONES; ++i)
          {
                  // Append the transformation with a slight translation to better
                  // center the skeleton at the center of the scene.
                  mWorld = mBones[i].toWorldXForm * T;
                  HR(mFX->SetMatrix(mhWVP, &(mWorld*mView*mProj)));
                  D3DXMATRIX worldInvTrans;
                  D3DXMatrixInverse(&worldInvTrans, 0, &mWorld);
                  D3DXMatrixTranspose(&worldInvTrans, &worldInvTrans);
                  HR(mFX->SetMatrix(mhWorldInvTrans, &worldInvTrans));
                  HR(mFX->SetMatrix(mhWorld, &mWorld));
                  for(int j = 0; j < mMtrl.size(); ++j)
                  {
                          HR(mFX->SetValue(mhMtrl, &mMtrl[j], sizeof(Mtrl)));
                  
                          // If there is a texture, then use.
                          if(mTex[j] != 0)
                          {
                                  HR(mFX->SetTexture(mhTex, mTex[j]));
                          }
  
                          // But if not, then set a pure white texture.  When the texture color
                          // is multiplied by the color from lighting, it is like multiplying by
                          // 1 and won't change the color from lighting.
                          else
                          {
                                  HR(mFX->SetTexture(mhTex, mWhiteTex));
                          }
                  
                          HR(mFX->CommitChanges());
                          HR(mBoneMesh->DrawSubset(j));
                  }
          }
  
          HR(mFX->EndPass());
          HR(mFX->End());
          
          mGfxStats->display();
  
          HR(gd3dDevice->EndScene());
  
          // Present the backbuffer.
          HR(gd3dDevice->Present(0, 0, 0, 0));
  }
  
  void RobotArmDemo::buildFX()
  {
          // Create the FX from a .fx file.
          ID3DXBuffer* errors = 0;
          HR(D3DXCreateEffectFromFile(gd3dDevice, "PhongDirLtTex.fx", 
                  0, 0, D3DXSHADER_DEBUG, 0, &mFX, &errors));
          if( errors )
                  MessageBox(0, (char*)errors->GetBufferPointer(), 0, 0);
  
          // Obtain handles.
          mhTech            = mFX->GetTechniqueByName("PhongDirLtTexTech");
          mhWVP             = mFX->GetParameterByName(0, "gWVP");
          mhWorldInvTrans   = mFX->GetParameterByName(0, "gWorldInvTrans");
          mhMtrl            = mFX->GetParameterByName(0, "gMtrl");
          mhLight           = mFX->GetParameterByName(0, "gLight");
          mhEyePos          = mFX->GetParameterByName(0, "gEyePosW");
          mhWorld           = mFX->GetParameterByName(0, "gWorld");
          mhTex             = mFX->GetParameterByName(0, "gTex");
  }
  
  void RobotArmDemo::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);
  
          HR(mFX->SetValue(mhEyePos, &pos, sizeof(D3DXVECTOR3)));
  }
  
  void RobotArmDemo::buildProjMtx()
  {
          float w = (float)md3dPP.BackBufferWidth;
          float h = (float)md3dPP.BackBufferHeight;
          D3DXMatrixPerspectiveFovLH(&mProj, D3DX_PI * 0.25f, w/h, 1.0f, 5000.0f);
  }
  
  void RobotArmDemo::buildBoneWorldTransforms()
  {
          // First, construct the transformation matrix that transforms
          // the ith bone into the coordinate system of its parent.
  
          D3DXMATRIX R, T;
          D3DXVECTOR3 p;
          for(int i = 0; i < NUM_BONES; ++i) 
          {
                  p = mBones[i].pos;
                  D3DXMatrixRotationZ(&R, mBones[i].zAngle);
                  D3DXMatrixTranslation(&T, p.x, p.y, p.z);
                  mBones[i].toParentXForm = R * T;
          }
  
          // Now, the ith object's world transform is given by its 
          // to-parent transform, followed by its parent's to-parent transform, 
          // followed by its grandparent's to-parent transform, and
          // so on, up to the root's to-parent transform.
  
          // For each bone...
          for(int i = 0; i < NUM_BONES; ++i)
          {
                  // Initialize to identity matrix.
                  D3DXMatrixIdentity(&mBones[i].toWorldXForm);
  
                  // Combine  W[i] = W[i]*W[i-1]*...*W[0].
                  for(int j = i; j >= 0; --j)
                  {
                          mBones[i].toWorldXForm *= mBones[j].toParentXForm;
                  }
          }
  }