1 .\" Copyright (c) 1980 The Regents of the University of California. 2 .\" All rights reserved. 3 .\" 4 .\" %sccs.include.redist.roff% 5 .\" 6 .\" @(#)appen.C 6.3 (Berkeley) 04/17/91 7 .\" 8 .ie t .oh '\*(Ln Appendix C''PS1:18-%' 9 .eh 'PS1:18-%''\*(Ln Appendix C' 10 .el .he ''\fIAppendix C\fR'' 11 .bp 12 .(x 13 .ti 0 14 .b "Appendix C" 15 .)x 16 .sh 1 "Examples" 1 17 .pp 18 Here we present a few examples 19 of how to use the package. 20 They attempt to be representative, 21 though not comprehensive. 22 .sh 1 "Screen Updating" 23 .pp 24 The following examples are intended to demonstrate 25 the basic structure of a program 26 using the screen updating sections of the package. 27 Several of the programs require calculational sections 28 which are irrelevant of to the example, 29 and are therefore usually not included. 30 It is hoped that the data structure definitions 31 give enough of an idea to allow understanding 32 of what the relevant portions do. 33 The rest is left as an exercise to the reader, 34 and will not be on the final. 35 .sh 2 "Twinkle" 36 .pp 37 This is a moderately simple program which prints 38 pretty patterns on the screen 39 that might even hold your interest for 30 seconds or more. 40 It switches between patterns of asterisks, 41 putting them on one by one in random order, 42 and then taking them off in the same fashion. 43 It is more efficient to write this 44 using only the motion optimization, 45 as is demonstrated below. 46 .(l I 47 .so twinkle1.gr 48 .)l 49 .sh 2 "Life" 50 .pp 51 This program fragment models the famous computer pattern game of life 52 (Scientific American, May, 1974). 53 The calculational routines create a linked list of structures 54 defining where each piece is. 55 Nothing here claims to be optimal, 56 merely demonstrative. 57 This code, however, 58 is a very good place to use the screen updating routines, 59 as it allows them to worry about what the last position looked like, 60 so you don't have to. 61 It also demonstrates some of the input routines. 62 .(l I 63 .so life.gr 64 .)l 65 .sh 1 "Motion optimization" 66 .pp 67 The following example shows how motion optimization 68 is written on its own. 69 Programs which flit from one place to another without 70 regard for what is already there 71 usually do not need the overhead of both space and time 72 associated with screen updating. 73 They should instead use motion optimization. 74 .sh 2 "Twinkle" 75 .pp 76 The 77 .b twinkle 78 program 79 is a good candidate for simple motion optimization. 80 Here is how it could be written 81 (only the routines that have been changed are shown): 82 .(l 83 .so twinkle2.gr 84 .)l 85