The following figure shows a free viewing camera. When we rotate the camera, it rotates at its position. When we move the camera, it keeps looking in the same direction.

The source code for this recipe is in the Chapter2/FreeCamera directory. The CFreeCamera class is defined in the Chapter2/src/FreeCamera.[h/cpp] files. The class interface is as follows:

class CFreeCamera : public CAbstractCamera
{
public:
  CFreeCamera(void);
  ~CFreeCamera(void);
  void Update();
  void Walk(const float dt);
  void Strafe(const float dt);
  void Lift(const float dt);
  void SetTranslation(const glm::vec3& t);
  glm::vec3 GetTranslation() const;
  void SetSpeed(const float speed);
  const float GetSpeed() const;
protected:
  float speed; //move speed of camera in m/s
  glm::vec3 translation;
};

The steps needed to implement the free camera are as follows:

The Walk function simply translates the camera in the look direction:

void CFreeCamera::Walk(const float dt) {
  translation += (look*dt);
}

The Strafe function translates the camera in the right direction:

void CFreeCamera::Strafe(const float dt) {
  translation += (right*dt);
}

The Lift function translates the camera in the up direction:

void CFreeCamera::Lift(const float dt) {
  translation += (up*dt);
}

Running the demo application renders an infinite checkered plane as shown in the following figure. The free camera can be moved around by pressing the keys W, S, A, D, Q, and Z. Left-clicking the mouse rotates the camera at the current position to change the look direction. Middle-click zooms the camera in the look direction.