| 1 | .\" Copyright (c) 1980 The Regents of the University of California. |
| 2 | .\" All rights reserved. |
| 3 | .\" |
| 4 | .\" Redistribution and use in source and binary forms, with or without |
| 5 | .\" modification, are permitted provided that the following conditions |
| 6 | .\" are met: |
| 7 | .\" 1. Redistributions of source code must retain the above copyright |
| 8 | .\" notice, this list of conditions and the following disclaimer. |
| 9 | .\" 2. Redistributions in binary form must reproduce the above copyright |
| 10 | .\" notice, this list of conditions and the following disclaimer in the |
| 11 | .\" documentation and/or other materials provided with the distribution. |
| 12 | .\" 3. All advertising materials mentioning features or use of this software |
| 13 | .\" must display the following acknowledgement: |
| 14 | .\" This product includes software developed by the University of |
| 15 | .\" California, Berkeley and its contributors. |
| 16 | .\" 4. Neither the name of the University nor the names of its contributors |
| 17 | .\" may be used to endorse or promote products derived from this software |
| 18 | .\" without specific prior written permission. |
| 19 | .\" |
| 20 | .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
| 21 | .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| 22 | .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| 23 | .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
| 24 | .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| 25 | .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| 26 | .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| 27 | .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| 28 | .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| 29 | .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| 30 | .\" SUCH DAMAGE. |
| 31 | .\" |
| 32 | .\" @(#)appen.C 6.3 (Berkeley) 4/17/91 |
| 33 | .\" |
| 34 | .ie t .oh '\*(Ln Appendix C''PS1:18-%' |
| 35 | .eh 'PS1:18-%''\*(Ln Appendix C' |
| 36 | .el .he ''\fIAppendix C\fR'' |
| 37 | .bp |
| 38 | .(x |
| 39 | .ti 0 |
| 40 | .b "Appendix C" |
| 41 | .)x |
| 42 | .sh 1 "Examples" 1 |
| 43 | .pp |
| 44 | Here we present a few examples |
| 45 | of how to use the package. |
| 46 | They attempt to be representative, |
| 47 | though not comprehensive. |
| 48 | .sh 1 "Screen Updating" |
| 49 | .pp |
| 50 | The following examples are intended to demonstrate |
| 51 | the basic structure of a program |
| 52 | using the screen updating sections of the package. |
| 53 | Several of the programs require calculational sections |
| 54 | which are irrelevant of to the example, |
| 55 | and are therefore usually not included. |
| 56 | It is hoped that the data structure definitions |
| 57 | give enough of an idea to allow understanding |
| 58 | of what the relevant portions do. |
| 59 | The rest is left as an exercise to the reader, |
| 60 | and will not be on the final. |
| 61 | .sh 2 "Twinkle" |
| 62 | .pp |
| 63 | This is a moderately simple program which prints |
| 64 | pretty patterns on the screen |
| 65 | that might even hold your interest for 30 seconds or more. |
| 66 | It switches between patterns of asterisks, |
| 67 | putting them on one by one in random order, |
| 68 | and then taking them off in the same fashion. |
| 69 | It is more efficient to write this |
| 70 | using only the motion optimization, |
| 71 | as is demonstrated below. |
| 72 | .(l I |
| 73 | .so twinkle1.gr |
| 74 | .)l |
| 75 | .sh 2 "Life" |
| 76 | .pp |
| 77 | This program fragment models the famous computer pattern game of life |
| 78 | (Scientific American, May, 1974). |
| 79 | The calculational routines create a linked list of structures |
| 80 | defining where each piece is. |
| 81 | Nothing here claims to be optimal, |
| 82 | merely demonstrative. |
| 83 | This code, however, |
| 84 | is a very good place to use the screen updating routines, |
| 85 | as it allows them to worry about what the last position looked like, |
| 86 | so you don't have to. |
| 87 | It also demonstrates some of the input routines. |
| 88 | .(l I |
| 89 | .so life.gr |
| 90 | .)l |
| 91 | .sh 1 "Motion optimization" |
| 92 | .pp |
| 93 | The following example shows how motion optimization |
| 94 | is written on its own. |
| 95 | Programs which flit from one place to another without |
| 96 | regard for what is already there |
| 97 | usually do not need the overhead of both space and time |
| 98 | associated with screen updating. |
| 99 | They should instead use motion optimization. |
| 100 | .sh 2 "Twinkle" |
| 101 | .pp |
| 102 | The |
| 103 | .b twinkle |
| 104 | program |
| 105 | is a good candidate for simple motion optimization. |
| 106 | Here is how it could be written |
| 107 | (only the routines that have been changed are shown): |
| 108 | .(l |
| 109 | .so twinkle2.gr |
| 110 | .)l |