text: #ifndef PERSPECTIVE_CAMERA_H_
  #define PERSPECTIVE_CAMERA_H_
  
  #include "camera.h"
  #include "ray.h"
  
  class PerspectiveCamera : public Camera
  {
  public:
  
      PerspectiveCamera( void );
  
      PerspectiveCamera( const float min_x,
                          const float max_x,
                          const float min_y,
                          const float max_y,
  			const float s,
                          const glm::ivec2 &resolution,
                          const glm::vec3 &position,
                          const glm::vec3 &up_vector,
                          const glm::vec3 &look_at );
  
      Ray getWorldSpaceRay( const glm::vec2 &pixel_coord ) const;
  
      float min_x_;
  
      float max_x_;
  
      float min_y_;
  
      float max_y_;
  
      float s_;
  
  };
  
  #endif /* PERSPECTIVE_CAMERA_H_ */
  