Create an alpha map png from a png file

create-alpha-map.ros

#!/bin/sh
#|-*- mode:lisp -*-|#
#| <Put a one-line description here>
exec ros -Q -- $0 "$@"
|#
(progn ;;init forms
  (ros:ensure-asdf)
  #+quicklisp (ql:quickload '(opticl cl-cli) :silent t))

(defpackage :ros.script.create-alpha-map.lisp.3711282690
  (:use :cl
        :opticl))
(in-package :ros.script.create-alpha-map.lisp.3711282690)

(defparameter *input-path* nil)
(defparameter *output-path* nil)

(defparameter *options*
  '((*input-path* nil "[Required] Input image file path" :alias ("-i") :params ("FILE"))
    (*output-path* "/tmp/temp.png" "Input image file path" :alias ("-o") :params ("FILE"))))

(defun run (input-path output-path)
  (let ((img (read-png-file input-path)))
    (typecase img
      (8-bit-rgba-image
       (with-image-bounds (height width) img
         (loop for y below height do
              (loop for x below width do
                   (multiple-value-bind (r g b a) (pixel img y x)
                     (declare (ignore r g b))
                     (setf (pixel img y x)
                           (values a a a #xff)))))))
      (t (error "The png file is not 8-bit-rgba-image")))
    (write-png-file output-path img)))

(defun main (&rest argv)
  (print argv)
  (multiple-value-bind (vars values)
      (cl-cli:parse-cli (cons "" argv) *options*)
    (cl-cli:with-environment vars values
      (unless *input-path*
        (cl-cli:help *options* nil)
        (return-from main 1))
      (run *input-path* *output-path*))))
;;; vim: set ft=lisp lisp: