1 | /* |
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2 | * libee ASCII-Art library |
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3 | * Copyright (c) 2002, 2003 Sam Hocevar <sam@zoy.org> |
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4 | * All Rights Reserved |
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5 | * |
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6 | * $Id: conic.c 147 2003-11-10 23:38:50Z sam $ |
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7 | * |
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8 | * This program is free software; you can redistribute it and/or modify |
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9 | * it under the terms of the GNU General Public License as published by |
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10 | * the Free Software Foundation; either version 2 of the License, or |
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11 | * (at your option) any later version. |
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12 | * |
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13 | * This program is distributed in the hope that it will be useful, |
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14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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16 | * GNU General Public License for more details. |
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17 | * |
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18 | * You should have received a copy of the GNU General Public License |
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19 | * along with this program; if not, write to the Free Software |
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20 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. |
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21 | */ |
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22 | |
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23 | #include "config.h" |
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24 | |
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25 | #ifdef USE_SLANG |
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26 | # include <slang.h> |
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27 | #elif USE_NCURSES |
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28 | # include <curses.h> |
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29 | #endif |
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30 | |
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31 | #include <stdlib.h> |
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32 | #include <inttypes.h> |
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33 | |
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34 | #include "ee.h" |
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35 | |
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36 | static void ellipsepoints(int, int, int, int, char); |
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37 | |
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38 | void ee_draw_circle(int x, int y, int r, char c) |
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39 | { |
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40 | int test, dx, dy; |
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41 | |
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42 | /* Optimized Bresenham. Kick ass. */ |
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43 | for(test = 0, dx = 0, dy = r ; dx <= dy ; dx++) |
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44 | { |
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45 | ellipsepoints(x, y, dx, dy, c); |
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46 | ellipsepoints(x, y, dy, dx, c); |
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47 | |
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48 | test += test > 0 ? dx - dy-- : dx; |
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49 | } |
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50 | } |
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51 | |
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52 | void ee_draw_ellipse(int xo, int yo, int a, int b, char c) |
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53 | { |
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54 | int d2; |
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55 | int x = 0; |
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56 | int y = b; |
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57 | int d1 = b*b - (a*a*b) + (a*a/4); |
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58 | |
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59 | ellipsepoints(xo, yo, x, y, c); |
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60 | |
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61 | while( a*a*y - a*a/2 > b*b*(x+1)) |
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62 | { |
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63 | if(d1 < 0) |
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64 | { |
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65 | d1 += b*b*(2*x+1); /* XXX: "Computer Graphics" has + 3 here. */ |
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66 | } |
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67 | else |
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68 | { |
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69 | d1 += b*b*(2*x*1) + a*a*(-2*y+2); |
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70 | y--; |
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71 | } |
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72 | x++; |
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73 | ellipsepoints(xo, yo, x, y, c); |
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74 | } |
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75 | |
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76 | d2 = b*b*(x+0.5)*(x+0.5) + a*a*(y-1)*(y-1) - a*a*b*b; |
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77 | while(y > 0) |
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78 | { |
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79 | if(d2 < 0) |
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80 | { |
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81 | d2 += b*b*(2*x+2) + a*a*(-2*y+3); |
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82 | x++; |
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83 | } |
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84 | else |
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85 | { |
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86 | d2 += a*a*(-2*y+3); |
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87 | } |
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88 | |
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89 | y--; |
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90 | ellipsepoints(xo, yo, x, y, c); |
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91 | } |
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92 | } |
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93 | |
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94 | static void ellipsepoints(int xo, int yo, int x, int y, char c) |
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95 | { |
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96 | uint8_t b = 0; |
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97 | |
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98 | if(xo + x >= 0 && xo + x < ee_get_width()) |
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99 | b |= 0x1; |
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100 | if(xo - x >= 0 && xo - x < ee_get_width()) |
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101 | b |= 0x2; |
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102 | if(yo + y >= 0 && yo + y < ee_get_height()) |
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103 | b |= 0x4; |
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104 | if(yo - y >= 0 && yo - y < ee_get_height()) |
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105 | b |= 0x8; |
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106 | |
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107 | if((b & (0x1|0x4)) == (0x1|0x4)) |
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108 | ee_putchar(xo + x, yo + y, c); |
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109 | |
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110 | if((b & (0x2|0x4)) == (0x2|0x4)) |
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111 | ee_putchar(xo - x, yo + y, c); |
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112 | |
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113 | if((b & (0x1|0x8)) == (0x1|0x8)) |
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114 | ee_putchar(xo + x, yo - y, c); |
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115 | |
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116 | if((b & (0x2|0x8)) == (0x2|0x8)) |
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117 | ee_putchar(xo - x, yo - y, c); |
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118 | } |
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119 | |
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