;;;; -*- Mode: LISP; Syntax: ANSI-Common-Lisp; Base: 10; Package: photo -*-
;;;; *************************************************************************
;;;; FILE IDENTIFICATION
;;;;
;;;; Name:          dof.lisp
;;;; Purpose:       Depth of field functions for cl-photo
;;;; Programmer:    Kevin M. Rosenberg
;;;; Date Started:  April 2005
;;;;
;;;; $Id: package.lisp 8596 2004-02-03 18:32:50Z kevin $
;;;;
;;;; This file, part of cl-photo, is Copyright (c) 2005 by Kevin Rosenberg.
;;;; Rights of modification and redistribution are in the LICENSE file.
;;;;
;;;; *************************************************************************

(in-package #:photo)

;; Based on http://www.photostuff.co.uk/dofmstr.htm

(defun dof (focal-length f-stop distance coc)
  "Returns depth of field as fives values: 
near dof, far dof, total dof, near point, far point"
  (let* ((aperature (/ focal-length f-stop))
         (numerator (* distance coc (- distance focal-length)))
         (factor-1 (* focal-length aperature))
         (factor-2 (* coc (- distance focal-length)))
         (near (/ numerator (+ factor-1 factor-2)))
         (far (/ numerator (- factor-1 factor-2)))
         (depth (+ far near)))
    (values near far depth (- distance near) (+ distance far))))

(defun dof-feet (focal-length f-stop distance coc)
  (multiple-value-bind (near-dof far-dof total-dof near-point far-point)
      (dof focal-length f-stop (feet->mm distance) coc)
    (values (mm->feet near-dof) (mm->feet far-dof) (mm->feet total-dof)
            (mm->feet near-point) (mm->feet far-point))))

(defun dof-meters (focal-length f-stop distance coc)
  (multiple-value-bind (near-dof far-dof total-dof near-point far-point)
      (dof focal-length f-stop (* 1000 distance) coc)
    (values (* 0.001 near-dof) (* 0.001 far-dof) (* 0.001 total-dof)
            (* 0.001 near-point) (* 0.001 far-point))))


(defun hyperfocal (focal-length f-stop coc)
  (+ focal-length (/ (* focal-length focal-length) (* f-stop coc))))

(defun hyperfocal-feet (focal-length f-stop coc)
  (mm->feet (hyperfocal focal-length f-stop coc)))