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| 1 | pmbaty | 1 | /* |
| 2 | * Portions of this file are copyright Rebirth contributors and licensed as |
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| 3 | * described in COPYING.txt. |
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| 4 | * Portions of this file are copyright Parallax Software and licensed |
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| 5 | * according to the Parallax license below. |
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| 6 | * See COPYING.txt for license details. |
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| 7 | |||
| 8 | THE COMPUTER CODE CONTAINED HEREIN IS THE SOLE PROPERTY OF PARALLAX |
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| 9 | SOFTWARE CORPORATION ("PARALLAX"). PARALLAX, IN DISTRIBUTING THE CODE TO |
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| 10 | END-USERS, AND SUBJECT TO ALL OF THE TERMS AND CONDITIONS HEREIN, GRANTS A |
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| 11 | ROYALTY-FREE, PERPETUAL LICENSE TO SUCH END-USERS FOR USE BY SUCH END-USERS |
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| 12 | IN USING, DISPLAYING, AND CREATING DERIVATIVE WORKS THEREOF, SO LONG AS |
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| 13 | SUCH USE, DISPLAY OR CREATION IS FOR NON-COMMERCIAL, ROYALTY OR REVENUE |
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| 14 | FREE PURPOSES. IN NO EVENT SHALL THE END-USER USE THE COMPUTER CODE |
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| 15 | CONTAINED HEREIN FOR REVENUE-BEARING PURPOSES. THE END-USER UNDERSTANDS |
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| 16 | AND AGREES TO THE TERMS HEREIN AND ACCEPTS THE SAME BY USE OF THIS FILE. |
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| 17 | COPYRIGHT 1993-1998 PARALLAX SOFTWARE CORPORATION. ALL RIGHTS RESERVED. |
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| 18 | */ |
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| 19 | |||
| 20 | /* |
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| 21 | * |
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| 22 | * Graphical routines for drawing lines. |
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| 23 | * |
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| 24 | */ |
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| 25 | |||
| 26 | #include <stdlib.h> |
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| 27 | #include "u_mem.h" |
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| 28 | #include "gr.h" |
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| 29 | #include "grdef.h" |
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| 30 | #include "maths.h" |
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| 31 | #include "clip.h" |
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| 32 | #if DXX_USE_OGL |
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| 33 | #include "ogl_init.h" |
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| 34 | #endif |
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| 35 | |||
| 36 | namespace dcx { |
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| 37 | |||
| 38 | /* |
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| 39 | Symmetric Double Step Line Algorithm |
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| 40 | by Brian Wyvill |
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| 41 | from "Graphics Gems", Academic Press, 1990 |
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| 42 | */ |
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| 43 | |||
| 44 | /* non-zero flag indicates the pixels needing EXCHG back. */ |
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| 45 | static void plot(grs_canvas &canvas, int x, int y, int flag, const color_palette_index color) |
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| 46 | #define plot(x,y,f) plot(canvas,x,y,f,color) |
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| 47 | { |
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| 48 | if (flag) |
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| 49 | std::swap(x, y); |
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| 50 | gr_upixel(canvas.cv_bitmap, x, y, color); |
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| 51 | } |
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| 52 | |||
| 53 | static void gr_hline(grs_canvas &canvas, int x1, int x2, const int y, const color_palette_index color) |
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| 54 | { |
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| 55 | using std::swap; |
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| 56 | if (x1 > x2) |
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| 57 | swap(x1,x2); |
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| 58 | for (int i=x1; i<=x2; i++ ) |
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| 59 | gr_upixel(canvas.cv_bitmap, i, y, color); |
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| 60 | } |
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| 61 | |||
| 62 | static void gr_vline(grs_canvas &canvas, int y1, int y2, const int x, const color_palette_index color) |
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| 63 | { |
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| 64 | using std::swap; |
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| 65 | if (y1 > y2) swap(y1,y2); |
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| 66 | for (int i=y1; i<=y2; i++ ) |
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| 67 | gr_upixel(canvas.cv_bitmap, x, i, color); |
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| 68 | } |
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| 69 | |||
| 70 | static void gr_universal_uline(grs_canvas &canvas, int a1, int b1, int a2, int b2, const color_palette_index color) |
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| 71 | { |
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| 72 | int dx, dy, incr1, incr2, D, x, y, xend, c, pixels_left; |
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| 73 | int x1, y1; |
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| 74 | int sign_x = 1, sign_y = 1, step, reverse; |
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| 75 | |||
| 76 | if (a1==a2) { |
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| 77 | gr_vline(canvas, b1, b2, a1, color); |
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| 78 | return; |
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| 79 | } |
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| 80 | |||
| 81 | if (b1==b2) { |
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| 82 | gr_hline(canvas, a1, a2, b1, color); |
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| 83 | return; |
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| 84 | } |
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| 85 | |||
| 86 | dx = a2 - a1; |
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| 87 | dy = b2 - b1; |
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| 88 | |||
| 89 | if (dx < 0) { |
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| 90 | sign_x = -1; |
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| 91 | dx *= -1; |
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| 92 | } |
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| 93 | if (dy < 0) { |
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| 94 | sign_y = -1; |
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| 95 | dy *= -1; |
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| 96 | } |
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| 97 | |||
| 98 | /* decide increment sign by the slope sign */ |
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| 99 | if (sign_x == sign_y) |
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| 100 | step = 1; |
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| 101 | else |
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| 102 | step = -1; |
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| 103 | |||
| 104 | if (dy > dx) { /* chooses axis of greatest movement (make * dx) */ |
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| 105 | using std::swap; |
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| 106 | swap(a1, b1); |
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| 107 | swap(a2, b2); |
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| 108 | swap(dx, dy); |
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| 109 | reverse = 1; |
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| 110 | } else |
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| 111 | reverse = 0; |
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| 112 | /* note error check for dx==0 should be included here */ |
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| 113 | if (a1 > a2) { /* start from the smaller coordinate */ |
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| 114 | x = a2; |
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| 115 | y = b2; |
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| 116 | x1 = a1; |
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| 117 | y1 = b1; |
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| 118 | } else { |
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| 119 | x = a1; |
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| 120 | y = b1; |
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| 121 | x1 = a2; |
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| 122 | y1 = b2; |
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| 123 | } |
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| 124 | |||
| 125 | |||
| 126 | /* Note dx=n implies 0 - n or (dx+1) pixels to be set */ |
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| 127 | /* Go round loop dx/4 times then plot last 0,1,2 or 3 pixels */ |
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| 128 | /* In fact (dx-1)/4 as 2 pixels are already plottted */ |
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| 129 | xend = (dx - 1) / 4; |
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| 130 | pixels_left = (dx - 1) % 4; /* number of pixels left over at the |
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| 131 | * end */ |
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| 132 | plot(x, y, reverse); |
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| 133 | plot(x1, y1, reverse); /* plot first two points */ |
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| 134 | incr2 = 4 * dy - 2 * dx; |
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| 135 | if (incr2 < 0) { /* slope less than 1/2 */ |
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| 136 | c = 2 * dy; |
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| 137 | incr1 = 2 * c; |
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| 138 | D = incr1 - dx; |
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| 139 | |||
| 140 | for (uint_fast32_t i = xend; i--;) |
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| 141 | { /* plotting loop */ |
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| 142 | ++x; |
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| 143 | --x1; |
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| 144 | if (D < 0) { |
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| 145 | /* pattern 1 forwards */ |
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| 146 | plot(x, y, reverse); |
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| 147 | plot(++x, y, reverse); |
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| 148 | /* pattern 1 backwards */ |
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| 149 | plot(x1, y1, reverse); |
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| 150 | plot(--x1, y1, reverse); |
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| 151 | D += incr1; |
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| 152 | } else { |
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| 153 | if (D < c) { |
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| 154 | /* pattern 2 forwards */ |
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| 155 | plot(x, y, reverse); |
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| 156 | plot(++x, y += step, reverse); |
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| 157 | /* pattern 2 backwards */ |
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| 158 | plot(x1, y1, reverse); |
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| 159 | plot(--x1, y1 -= step, reverse); |
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| 160 | } else { |
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| 161 | /* pattern 3 forwards */ |
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| 162 | plot(x, y += step, reverse); |
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| 163 | plot(++x, y, reverse); |
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| 164 | /* pattern 3 backwards */ |
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| 165 | plot(x1, y1 -= step, reverse); |
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| 166 | plot(--x1, y1, reverse); |
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| 167 | } |
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| 168 | D += incr2; |
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| 169 | } |
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| 170 | } /* end for */ |
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| 171 | |||
| 172 | /* plot last pattern */ |
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| 173 | if (pixels_left) { |
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| 174 | if (D < 0) { |
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| 175 | plot(++x, y, reverse); /* pattern 1 */ |
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| 176 | if (pixels_left > 1) |
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| 177 | plot(++x, y, reverse); |
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| 178 | if (pixels_left > 2) |
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| 179 | plot(--x1, y1, reverse); |
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| 180 | } else { |
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| 181 | if (D < c) { |
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| 182 | plot(++x, y, reverse); /* pattern 2 */ |
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| 183 | if (pixels_left > 1) |
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| 184 | plot(++x, y += step, reverse); |
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| 185 | if (pixels_left > 2) |
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| 186 | plot(--x1, y1, reverse); |
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| 187 | } else { |
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| 188 | /* pattern 3 */ |
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| 189 | plot(++x, y += step, reverse); |
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| 190 | if (pixels_left > 1) |
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| 191 | plot(++x, y, reverse); |
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| 192 | if (pixels_left > 2) |
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| 193 | plot(--x1, y1 -= step, reverse); |
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| 194 | } |
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| 195 | } |
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| 196 | } /* end if pixels_left */ |
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| 197 | } |
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| 198 | /* end slope < 1/2 */ |
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| 199 | else { /* slope greater than 1/2 */ |
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| 200 | c = 2 * (dy - dx); |
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| 201 | incr1 = 2 * c; |
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| 202 | D = incr1 + dx; |
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| 203 | for (uint_fast32_t i = xend; i--;) |
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| 204 | { |
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| 205 | ++x; |
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| 206 | --x1; |
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| 207 | if (D > 0) { |
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| 208 | /* pattern 4 forwards */ |
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| 209 | plot(x, y += step, reverse); |
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| 210 | plot(++x, y += step, reverse); |
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| 211 | /* pattern 4 backwards */ |
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| 212 | plot(x1, y1 -= step, reverse); |
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| 213 | plot(--x1, y1 -= step, reverse); |
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| 214 | D += incr1; |
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| 215 | } else { |
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| 216 | if (D < c) { |
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| 217 | /* pattern 2 forwards */ |
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| 218 | plot(x, y, reverse); |
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| 219 | plot(++x, y += step, reverse); |
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| 220 | |||
| 221 | /* pattern 2 backwards */ |
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| 222 | plot(x1, y1, reverse); |
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| 223 | plot(--x1, y1 -= step, reverse); |
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| 224 | } else { |
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| 225 | /* pattern 3 forwards */ |
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| 226 | plot(x, y += step, reverse); |
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| 227 | plot(++x, y, reverse); |
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| 228 | /* pattern 3 backwards */ |
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| 229 | plot(x1, y1 -= step, reverse); |
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| 230 | plot(--x1, y1, reverse); |
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| 231 | } |
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| 232 | D += incr2; |
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| 233 | } |
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| 234 | } /* end for */ |
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| 235 | /* plot last pattern */ |
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| 236 | if (pixels_left) { |
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| 237 | if (D > 0) { |
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| 238 | plot(++x, y += step, reverse); /* pattern 4 */ |
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| 239 | if (pixels_left > 1) |
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| 240 | plot(++x, y += step, reverse); |
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| 241 | if (pixels_left > 2) |
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| 242 | plot(--x1, y1 -= step, reverse); |
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| 243 | } else { |
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| 244 | if (D < c) { |
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| 245 | plot(++x, y, reverse); /* pattern 2 */ |
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| 246 | if (pixels_left > 1) |
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| 247 | plot(++x, y += step, reverse); |
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| 248 | if (pixels_left > 2) |
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| 249 | plot(--x1, y1, reverse); |
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| 250 | } else { |
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| 251 | /* pattern 3 */ |
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| 252 | plot(++x, y += step, reverse); |
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| 253 | if (pixels_left > 1) |
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| 254 | plot(++x, y, reverse); |
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| 255 | if (pixels_left > 2) { |
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| 256 | if (D > c) /* step 3 */ |
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| 257 | plot(--x1, y1 -= step, reverse); |
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| 258 | else /* step 2 */ |
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| 259 | plot(--x1, y1, reverse); |
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| 260 | } |
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| 261 | } |
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| 262 | } |
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| 263 | } |
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| 264 | } |
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| 265 | } |
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| 266 | |||
| 267 | |||
| 268 | //unclipped version just calls clipping version for now |
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| 269 | void gr_uline(grs_canvas &canvas, const fix _a1, const fix _b1, const fix _a2, const fix _b2, const color_palette_index color) |
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| 270 | { |
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| 271 | int a1,b1,a2,b2; |
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| 272 | a1 = f2i(_a1); b1 = f2i(_b1); a2 = f2i(_a2); b2 = f2i(_b2); |
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| 273 | switch(canvas.cv_bitmap.get_type()) |
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| 274 | { |
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| 275 | #if DXX_USE_OGL |
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| 276 | case bm_mode::ogl: |
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| 277 | ogl_ulinec(canvas, a1, b1, a2, b2, color); |
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| 278 | return; |
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| 279 | #endif |
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| 280 | case bm_mode::linear: |
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| 281 | gr_universal_uline(canvas, a1, b1, a2, b2, color); |
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| 282 | return; |
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| 283 | } |
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| 284 | return; |
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| 285 | } |
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| 286 | |||
| 287 | // Returns 0 if drawn with no clipping, 1 if drawn but clipped, and |
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| 288 | // 2 if not drawn at all. |
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| 289 | |||
| 290 | void gr_line(grs_canvas &canvas, fix a1, fix b1, fix a2, fix b2, const color_palette_index color) |
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| 291 | { |
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| 292 | int x1, y1, x2, y2; |
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| 293 | x1 = i2f(MINX); |
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| 294 | y1 = i2f(MINY); |
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| 295 | x2 = i2f(canvas.cv_bitmap.bm_w - 1); |
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| 296 | y2 = i2f(canvas.cv_bitmap.bm_h - 1); |
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| 297 | |||
| 298 | CLIPLINE(a1,b1,a2,b2,x1,y1,x2,y2,return,, FIXSCALE ); |
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| 299 | gr_uline(canvas, a1, b1, a2, b2, color); |
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| 300 | } |
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| 301 | |||
| 302 | } |