source: ttyvaders/trunk/libee/line.c @ 148

Last change on this file since 148 was 148, checked in by Sam Hocevar, 17 years ago
  • libee/graphics.c: + Moved ee_putstr() and ee_putchar() in here.
  • libee/ee.h: + Got rid of ee_goto(). + Moved <slang.h> or <curses.h> into libee.
  • Replaced ee_goto()/ee_putstr() pairs with ee_putstr().
  • Ditto for ee_putchar().
  • Property svn:keywords set to Id
File size: 7.3 KB
Line 
1/*
2 *   libee         ASCII-Art library
3 *   Copyright (c) 2002, 2003 Sam Hocevar <sam@zoy.org>
4 *                 All Rights Reserved
5 *
6 *   $Id: line.c 148 2003-11-10 23:38:50Z sam $
7 *
8 *   This program is free software; you can redistribute it and/or modify
9 *   it under the terms of the GNU General Public License as published by
10 *   the Free Software Foundation; either version 2 of the License, or
11 *   (at your option) any later version.
12 *
13 *   This program is distributed in the hope that it will be useful,
14 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
15 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16 *   GNU General Public License for more details.
17 *
18 *   You should have received a copy of the GNU General Public License
19 *   along with this program; if not, write to the Free Software
20 *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
21 */
22
23#include "config.h"
24
25#ifdef USE_SLANG
26#   include <slang.h>
27#elif USE_NCURSES
28#   include <curses.h>
29#endif
30
31#include <inttypes.h>
32#include <stdlib.h>
33
34#include "ee.h"
35
36struct line
37{
38    int x1, y1;
39    int x2, y2;
40    char c;
41    void (*draw) (struct line*);
42};
43
44static void clip_line(struct line*);
45static uint8_t clip_bits(int, int);
46static void draw_solid_line(struct line*);
47static void draw_thin_line(struct line*);
48
49/**
50 * \brief Draw a line on the screen using the given character.
51 *
52 * \param x1 X coordinate of the first point.
53 * \param y1 Y coordinate of the first point.
54 * \param x2 X coordinate of the second point.
55 * \param y2 Y coordinate of the second point.
56 * \param c Character to draw the line with.
57 * \return nothing
58 */
59void ee_draw_line(int x1, int y1, int x2, int y2, char c)
60{
61    struct line s;
62    s.x1 = x1;
63    s.y1 = y1;
64    s.x2 = x2;
65    s.y2 = y2;
66    s.c = c;
67    s.draw = draw_solid_line;
68    clip_line(&s);
69}
70
71/**
72 * \brief Draw a thin line on the screen, using ASCII art.
73 *
74 * \param x1 X coordinate of the first point.
75 * \param y1 Y coordinate of the first point.
76 * \param x2 X coordinate of the second point.
77 * \param y2 Y coordinate of the second point.
78 * \return nothing
79 */
80void ee_draw_thin_line(int x1, int y1, int x2, int y2)
81{
82    struct line s;
83    s.x1 = x1;
84    s.y1 = y1;
85    s.x2 = x2;
86    s.y2 = y2;
87    s.draw = draw_thin_line;
88    clip_line(&s);
89}
90
91/*
92 * XXX: The following functions are local.
93 */
94
95/**
96 * \brief Generic Cohen-Sutherland line clipping function.
97 *
98 * \param s a line structure
99 * \return nothing
100 */
101static void clip_line(struct line* s)
102{
103    uint8_t bits1, bits2;
104
105    bits1 = clip_bits(s->x1, s->y1);
106    bits2 = clip_bits(s->x2, s->y2);
107
108    if(bits1 & bits2)
109        return;
110
111    if(bits1 == 0)
112    {
113        if(bits2 == 0)
114            s->draw(s);
115        else
116        {
117            int tmp;
118            tmp = s->x1; s->x1 = s->x2; s->x2 = tmp;
119            tmp = s->y1; s->y1 = s->y2; s->y2 = tmp;
120            clip_line(s);
121        }
122
123        return;
124    }
125
126    if(bits1 & (1<<0))
127    {
128        s->y1 = s->y2 - (s->x2 - 0) * (s->y2 - s->y1) / (s->x2 - s->x1);
129        s->x1 = 0;
130    }
131    else if( bits1 & (1<<1) )
132    {
133        int xmax = ee_get_width() - 1;
134        s->y1 = s->y2 - (s->x2 - xmax) * (s->y2 - s->y1) / (s->x2 - s->x1);
135        s->x1 = xmax;
136    }
137    else if( bits1 & (1<<2) )
138    {
139        s->x1 = s->x2 - (s->y2 - 0) * (s->x2 - s->x1) / (s->y2 - s->y1);
140        s->y1 = 0;
141    }
142    else if( bits1 & (1<<3) )
143    {
144        int ymax = ee_get_height() - 1;
145        s->x1 = s->x2 - (s->y2 - ymax) * (s->x2 - s->x1) / (s->y2 - s->y1);
146        s->y1 = ymax;
147    }
148
149    clip_line(s);
150}
151
152/**
153 * \brief Helper function for clip_line().
154 *
155 * \param x X coordinate of the point.
156 * \param y Y coordinate of the point.
157 * \return b The clipping bits for the given point.
158 */
159static uint8_t clip_bits(int x, int y)
160{
161    uint8_t b = 0;
162
163    if(x < 0)
164        b |= (1<<0);
165    else if(x >= ee_get_width())
166        b |= (1<<1);
167
168    if(y < 0)
169        b |= (1<<2);
170    else if(y >= ee_get_height())
171        b |= (1<<3);
172
173    return b;
174}
175
176/**
177 * \brief Solid line drawing function, using Bresenham's mid-point line
178 *        scan-conversion algorithm.
179 *
180 * \param s a line structure
181 * \return nothing
182 */
183static void draw_solid_line(struct line* s)
184{
185    int x1, y1, x2, y2;
186    int dx, dy;
187    int xinc, yinc;
188
189    x1 = s->x1; y1 = s->y1; x2 = s->x2; y2 = s->y2;
190
191    dx = abs(x2 - x1);
192    dy = abs(y2 - y1);
193
194    xinc = (x1 > x2) ? -1 : 1;
195    yinc = (y1 > y2) ? -1 : 1;
196
197    if(dx >= dy)
198    {
199        int dpr = dy << 1;
200        int dpru = dpr - (dx << 1);
201        int delta = dpr - dx;
202
203        for(; dx>=0; dx--)
204        {
205            ee_putchar(x1, y1, s->c);
206            if(delta > 0)
207            {
208                x1 += xinc;
209                y1 += yinc;
210                delta += dpru;
211            }
212            else
213            {
214                x1 += xinc;
215                delta += dpr;
216            }
217        }
218    }
219    else
220    {
221        int dpr = dx << 1;
222        int dpru = dpr - (dy << 1);
223        int delta = dpr - dy;
224
225        for(; dy >= 0; dy--)
226        {
227            ee_putchar(x1, y1, s->c);
228            if(delta > 0)
229            {
230                x1 += xinc;
231                y1 += yinc;
232                delta += dpru;
233            }
234            else
235            {
236                y1 += yinc;
237                delta += dpr;
238            }
239        }
240    }
241}
242
243/**
244 * \brief Thin line drawing function, using Bresenham's mid-point line
245 *        scan-conversion algorithm and ASCII art graphics.
246 *
247 * \param s a line structure
248 * \return nothing
249 */
250static void draw_thin_line(struct line* s)
251{
252    char *charmapx, *charmapy;
253    int x1, y1, x2, y2;
254    int dx, dy;
255    int yinc;
256
257    if(s->x2 >= s->x1)
258    {
259        if(s->y1 > s->y2)
260            charmapx = ",'";
261        else
262            charmapx = "`.";
263        x1 = s->x1; y1 = s->y1; x2 = s->x2; y2 = s->y2;
264    }
265    else
266    {
267        if(s->y1 > s->y2)
268            charmapx = "`.";
269        else
270            charmapx = ",'";
271        x2 = s->x1; y2 = s->y1; x1 = s->x2; y1 = s->y2;
272    }
273
274    dx = abs(x2 - x1);
275    dy = abs(y2 - y1);
276
277    if(y1 > y2)
278    {
279        charmapy = ",'";
280        yinc = -1;
281    }
282    else
283    {
284        yinc = 1;
285        charmapy = "`.";
286    }
287
288    if(dx >= dy)
289    {
290        int dpr = dy << 1;
291        int dpru = dpr - (dx << 1);
292        int delta = dpr - dx;
293        int prev = 0;
294
295        for(; dx>=0; dx--)
296        {
297            if(delta > 0)
298            {
299                ee_putchar(x1, y1, charmapy[1]);
300                x1++;
301                y1 += yinc;
302                delta += dpru;
303                prev = 1;
304            }
305            else
306            {
307                if(prev)
308                    ee_putchar(x1, y1, charmapy[0]);
309                else
310                    ee_putchar(x1, y1, '-');
311                x1++;
312                delta += dpr;
313                prev = 0;
314            }
315        }
316    }
317    else
318    {
319        int dpr = dx << 1;
320        int dpru = dpr - (dy << 1);
321        int delta = dpr - dy;
322
323        for(; dy >= 0; dy--)
324        {
325            if(delta > 0)
326            {
327                ee_putchar(x1, y1, charmapx[0]);
328                ee_putchar(x1 + 1, y1, charmapx[1]);
329                x1++;
330                y1 += yinc;
331                delta += dpru;
332            }
333            else
334            {
335                ee_putchar(x1, y1, '|');
336                y1 += yinc;
337                delta += dpr;
338            }
339        }
340    }
341}
342
Note: See TracBrowser for help on using the repository browser.