text: #ifndef CAMERA_HPP_
  #define CAMERA_HPP_
  
  #include <glm/mat4x4.hpp>
  #include <glm/vec3.hpp>
  
  class OpenGLWindow;
  
  class Camera {
   public:
    void computeViewMatrix();
    void computeProjectionMatrix(int width, int height);
  
    void dolly(float speed);
    void truck(float speed);
    void pan(float speed);
  
   private:
    friend OpenGLWindow;
  
    glm::vec3 m_eye{glm::vec3(0.0f, 0.5f, 2.5f)};
    glm::vec3 m_at{glm::vec3(0.0f, 0.5f, 0.0f)};
    glm::vec3 m_up{glm::vec3(0.0f, 1.0f, 0.0f)};
  
    glm::mat4 m_viewMatrix;
  
    glm::mat4 m_projMatrix;
  };
  
  #endif