My previous post understandably prompted a request or two for what I believe are good examples of the type of code that I'm looking for. Here is one piece of code that I had in mind. This is a Lisp version of an example program that was originally written in C. The C version is quite good. The Lisp version is nearly perfect, in my opinion.
;;;; -*- Mode: lisp; indent-tabs-mode: nil -*- ;;; planet.lisp --- Lisp version of planet.c (Red Book examples) ;;; ;;; Original C version contains the following copyright notice: ;;; Copyright (c) 1993-1997, Silicon Graphics, Inc. ;;; ALL RIGHTS RESERVED ;;; This program shows how to composite modeling transformations ;;; to draw translated and rotated models. ;;; Interaction: pressing the d and y keys (day and year) ;;; alters the rotation of the planet around the sun. (in-package #:cl-glut-examples) (defclass planet-window (glut:window) ((year :accessor year :initform 0) (day :accessor day :initform 0)) (:default-initargs :pos-x 100 :pos-y 100 :width 500 :height 500 :mode '(:double :rgb) :title "planet.lisp")) (defmethod glut:display-window :before ((w planet-window)) (gl:clear-color 0 0 0 0) (gl:shade-model :flat)) (defmethod glut:display ((w planet-window)) (gl:clear :color-buffer) (gl:color 1 1 1) (gl:with-pushed-matrix ;; draw sun (glut:wire-sphere 1 20 16) ;; draw smaller planet (gl:rotate (year w) 0 1 0) (gl:translate 2 0 0) (gl:rotate (day w) 0 1 0) (glut:wire-sphere 0.2 10 8)) (glut:swap-buffers)) (defmethod glut:reshape ((w planet-window) width height) (gl:viewport 0 0 width height) (gl:matrix-mode :projection) (gl:load-identity) (glu:perspective 60 (/ width height) 1 20) (gl:matrix-mode :modelview) (gl:load-identity) (glu:look-at 0 0 5 0 0 0 0 1 0)) (defmethod glut:keyboard ((w planet-window) key x y) (declare (ignore x y)) (flet ((update (slot n) (setf (slot-value w slot) (mod (+ (slot-value w slot) n) 360)) (glut:post-redisplay))) (case key (#\d (update 'day 10)) (#\D (update 'day -10)) (#\y (update 'year 5)) (#\Y (update 'year -5)) (#\Esc (glut:destroy-current-window))))) (defun rb-planet () (glut:display-window (make-instance 'planet-window)))
This code still has some issues (all issues shared with the C version).
- In this code, years and days are entirely independent.
- It is not obvious from this code what the arguments to
- It is not obvious what the arguments to
Almost everything else is completely transparent to one who
knows enough Lisp. Even without knowing Lisp,
is the only thing that may not be readily obvious from the formatting
and naming conventions.
Copyright (c) 2004, Oliver Markovic <email@example.com> All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: o Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. o Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. o Neither the name of the author nor the names of the contributors may be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
From the original C code:
Copyright (c) 1993-1997, Silicon Graphics, Inc. ALL RIGHTS RESERVED Permission to use, copy, modify, and distribute this software for any purpose and without fee is hereby granted, provided that the above copyright notice appear in all copies and that both the copyright notice and this permission notice appear in supporting documentation, and that the name of Silicon Graphics, Inc. not be used in advertising or publicity pertaining to distribution of the software without specific, written prior permission. THE MATERIAL EMBODIED ON THIS SOFTWARE IS PROVIDED TO YOU "AS-IS" AND WITHOUT WARRANTY OF ANY KIND, EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL SILICON GRAPHICS, INC. BE LIABLE TO YOU OR ANYONE ELSE FOR ANY DIRECT, SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND, OR ANY DAMAGES WHATSOEVER, INCLUDING WITHOUT LIMITATION, LOSS OF PROFIT, LOSS OF USE, SAVINGS OR REVENUE, OR THE CLAIMS OF THIRD PARTIES, WHETHER OR NOT SILICON GRAPHICS, INC. HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH LOSS, HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE POSSESSION, USE OR PERFORMANCE OF THIS SOFTWARE. US Government Users Restricted Rights Use, duplication, or disclosure by the Government is subject to restrictions set forth in FAR 52.227.19(c)(2) or subparagraph (c)(1)(ii) of the Rights in Technical Data and Computer Software clause at DFARS 252.227-7013 and/or in similar or successor clauses in the FAR or the DOD or NASA FAR Supplement. Unpublished-- rights reserved under the copyright laws of the United States. Contractor/manufacturer is Silicon Graphics, Inc., 2011 N. Shoreline Blvd., Mountain View, CA 94039-7311. OpenGL(R) is a registered trademark of Silicon Graphics, Inc.