(in-package :2d-geometry)
(defclass bounding-box ()
((x-min :accessor x-min :initarg :x-min)
(x-max :accessor x-max :initarg :x-max)
(y-min :accessor y-min :initarg :y-min)
(y-max :accessor y-max :initarg :y-max))
(:documentation "A bounding box."))
(defmethod print-object ((object bounding-box) stream)
(print-unreadable-object (object stream :type t)
(format stream "~a-~a:~a-~a" (x-min object)(x-max object)(y-min object)(y-max object))))
(defgeneric construct-bounding-box (object)
(:documentation "Construct a bounding box of a given object."))
(defun bounding-boxes-intersect-p (box1 box2)
"Check if two bounding boxes intersect."
(not (or (< (x-max box1)(x-min box2))
(< (x-max box2)(x-min box1))
(< (y-max box1)(y-min box2))
(< (y-max box2)(y-min box1)))))
(defun point-in-box-exclusive (point box &key (include-in-degenerate-dimension nil))
"Check if point is contained inside a bounding box."
(or (and (> (x point)(x-min box))
(> (y point)(y-min box))
(< (x point)(x-max box))
(< (y point)(y-max box)))
(when include-in-degenerate-dimension
(or (and (= (x-min box)(x-max box)(x point))
(> (y point)(y-min box))
(< (y point)(y-max box)))
(and (= (y-min box)(y-max box)(y point))
(> (x point)(x-min box))
(< (x point)(x-max box)))))))
(defun point-in-box-inclusive (point box)
"Check if point is contained inside or directly on a bounding box."
(and (>= (x point)(x-min box))
(>= (y point)(y-min box))
(<= (x point)(x-max box))
(<= (y point)(y-max box))))
(defun intersect-boxes (box1 box2)
"Return bounding box common to both boxes."
(when (bounding-boxes-intersect-p box1 box2)
(make-instance 'bounding-box
:x-min (max (x-min box1)
(x-min box2))
:x-max (min (x-max box1)
(x-max box2))
:y-min (max (y-min box1)
(y-min box2))
:y-max (min (y-max box1)
(y-max box2)))))
