//=============================================================================
  // Camera.h by Frank Luna (C) 2004 All Rights Reserved.
  //=============================================================================
  
  ifndef CAMERA_H
  define CAMERA_H
  
  include <d3dx9.h>
  
  class Camera
  {
  public:
          // By default, the camera starts out with its basis vectors 
          // aligned with the world space axes, and its origin positioned
          // at the world space origin.
          Camera();
  
          // Read only accessor functions.
          const D3DXMATRIX& view() const;
          const D3DXMATRIX& proj() const;
          const D3DXMATRIX& viewProj() const;
  
          const D3DXVECTOR3& right() const;
          const D3DXVECTOR3& up() const;
          const D3DXVECTOR3& look() const;
  
          // Read/write access to the camera position.
          D3DXVECTOR3& pos();
  
          // Our implementation of D3DXMatrixLookAtLH
          void lookAt(D3DXVECTOR3& pos, D3DXVECTOR3& target, D3DXVECTOR3& up);
  
          // Perspective projection parameters.
          void setLens(float fov, float aspect, float nearZ, float farZ);
  
          // Sets the camera speed.
          void setSpeed(float s);
  
          // Updates the camera's basis vectors and origin, relative to 
          // the world space, based in user input.
          void update(float dt);
  
  protected:
          // Constructs the view matrix based on the camera's basis
          // vectors and origin, relative to the world space
          void buildView();
  
  protected:
          // Save camera related matrices.
          D3DXMATRIX mView;
          D3DXMATRIX mProj;
          D3DXMATRIX mViewProj;
  
          // Relative to world space.
          D3DXVECTOR3 mPosW;
          D3DXVECTOR3 mRightW;
          D3DXVECTOR3 mUpW;
          D3DXVECTOR3 mLookW;
  
          // Camera speed.
          float mSpeed;
  };
  
  endif // CAMERA_H