source: libcaca/trunk/src/triangle.c @ 204

Last change on this file since 204 was 192, checked in by Sam Hocevar, 19 years ago
  • Changed copyleft to LGPL.
  • Property svn:keywords set to Id
File size: 2.7 KB
Line 
1/*
2 *   libcaca       ASCII-Art library
3 *   Copyright (c) 2002, 2003 Sam Hocevar <sam@zoy.org>
4 *                 All Rights Reserved
5 *
6 *   $Id: triangle.c 192 2003-11-16 12:28:29Z sam $
7 *
8 *   This library is free software; you can redistribute it and/or
9 *   modify it under the terms of the GNU Lesser General Public
10 *   License as published by the Free Software Foundation; either
11 *   version 2 of the License, or (at your option) any later version.
12 *
13 *   This library 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 GNU
16 *   Lesser General Public License for more details.
17 *
18 *   You should have received a copy of the GNU Lesser General Public
19 *   License along with this library; if not, write to the Free Software
20 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
21 *   02111-1307  USA
22 */
23
24#include "config.h"
25
26#include <stdlib.h>
27
28#include "caca.h"
29#include "caca_internals.h"
30
31void caca_draw_triangle(int x1, int y1, int x2, int y2, int x3, int y3, char c)
32{
33    caca_draw_line(x1, y1, x2, y2, c);
34    caca_draw_line(x2, y2, x3, y3, c);
35    caca_draw_line(x3, y3, x1, y1, c);
36}
37
38void caca_draw_thin_triangle(int x1, int y1, int x2, int y2, int x3, int y3)
39{
40    caca_draw_thin_line(x1, y1, x2, y2);
41    caca_draw_thin_line(x2, y2, x3, y3);
42    caca_draw_thin_line(x3, y3, x1, y1);
43}
44
45void caca_fill_triangle(int x1, int y1, int x2, int y2, int x3, int y3, char c)
46{
47    int x, y, xa, xb, xmax, ymax;
48
49    /* Bubble-sort y1 <= y2 <= y3 */
50    if(y1 > y2)
51    {
52        caca_fill_triangle(x2, y2, x1, y1, x3, y3, c);
53        return;
54    }
55
56    if(y2 > y3)
57    {
58        caca_fill_triangle(x1, y1, x3, y3, x2, y2, c);
59        return;
60    }
61
62    /* Promote precision */
63    x1 *= 4;
64    x2 *= 4;
65    x3 *= 4;
66
67    xmax = caca_get_width() - 1;
68    ymax = caca_get_height() - 1;
69
70    /* Rasterize our triangle */
71    for(y = y1 < 0 ? 0 : y1; y <= y3 && y <= ymax; y++)
72    {
73        if(y <= y2)
74        {
75            xa = (y1 == y2) ? x2 : x1 + (x2 - x1) * (y - y1) / (y2 - y1);
76            xb = (y1 == y3) ? x3 : x1 + (x3 - x1) * (y - y1) / (y3 - y1);
77        }
78        else
79        {
80            xa = (y3 == y2) ? x2 : x3 + (x2 - x3) * (y - y3) / (y2 - y3);
81            xb = (y3 == y1) ? x1 : x3 + (x1 - x3) * (y - y3) / (y1 - y3);
82        }
83
84        if(xb < xa)
85        {
86            int tmp = xb;
87            xb = xa; xa = tmp;
88        }
89
90        /* Rescale xa and xb, slightly cropping */
91        xa = (xa + 2) / 4;
92        xb = (xb - 2) / 4;
93
94        if(xb < 0) continue;
95        if(xa > xmax) continue;
96        if(xa < 0) xa = 0;
97        if(xb > xmax) xb = xmax;
98
99        for(x = xa; x <= xb; x++)
100            caca_putchar(x, y, c);
101    }
102}
103
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