source: libcaca/branches/0.1/src/triangle.c

Last change on this file was 205, checked in by Sam Hocevar, 19 years ago
  • src/: + Doxygenated a few things.
  • Property svn:keywords set to Id
File size: 2.9 KB
Line 
1/*
2 *   libcaca       ASCII-Art library
3 *   Copyright (c) 2002, 2003 Sam Hocevar <sam@zoy.org>
4 *                 All Rights Reserved
5 *
6 *   This library is free software; you can redistribute it and/or
7 *   modify it under the terms of the GNU Lesser General Public
8 *   License as published by the Free Software Foundation; either
9 *   version 2 of the License, or (at your option) any later version.
10 *
11 *   This library is distributed in the hope that it will be useful,
12 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
13 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14 *   Lesser General Public License for more details.
15 *
16 *   You should have received a copy of the GNU Lesser General Public
17 *   License along with this library; if not, write to the Free Software
18 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
19 *   02111-1307  USA
20 */
21
22/**  \file triangle.c
23 *   \version \$Id: triangle.c 205 2003-11-22 12:45:25Z sam $
24 *   \author Sam Hocevar <sam@zoy.org>
25 *   \brief Triangle drawing functions
26 *
27 *   This file contains triangle drawing functions, both filled and outline.
28 */
29
30#include "config.h"
31
32#include <stdlib.h>
33
34#include "caca.h"
35#include "caca_internals.h"
36
37void caca_draw_triangle(int x1, int y1, int x2, int y2, int x3, int y3, char c)
38{
39    caca_draw_line(x1, y1, x2, y2, c);
40    caca_draw_line(x2, y2, x3, y3, c);
41    caca_draw_line(x3, y3, x1, y1, c);
42}
43
44void caca_draw_thin_triangle(int x1, int y1, int x2, int y2, int x3, int y3)
45{
46    caca_draw_thin_line(x1, y1, x2, y2);
47    caca_draw_thin_line(x2, y2, x3, y3);
48    caca_draw_thin_line(x3, y3, x1, y1);
49}
50
51void caca_fill_triangle(int x1, int y1, int x2, int y2, int x3, int y3, char c)
52{
53    int x, y, xa, xb, xmax, ymax;
54
55    /* Bubble-sort y1 <= y2 <= y3 */
56    if(y1 > y2)
57    {
58        caca_fill_triangle(x2, y2, x1, y1, x3, y3, c);
59        return;
60    }
61
62    if(y2 > y3)
63    {
64        caca_fill_triangle(x1, y1, x3, y3, x2, y2, c);
65        return;
66    }
67
68    /* Promote precision */
69    x1 *= 4;
70    x2 *= 4;
71    x3 *= 4;
72
73    xmax = caca_get_width() - 1;
74    ymax = caca_get_height() - 1;
75
76    /* Rasterize our triangle */
77    for(y = y1 < 0 ? 0 : y1; y <= y3 && y <= ymax; y++)
78    {
79        if(y <= y2)
80        {
81            xa = (y1 == y2) ? x2 : x1 + (x2 - x1) * (y - y1) / (y2 - y1);
82            xb = (y1 == y3) ? x3 : x1 + (x3 - x1) * (y - y1) / (y3 - y1);
83        }
84        else
85        {
86            xa = (y3 == y2) ? x2 : x3 + (x2 - x3) * (y - y3) / (y2 - y3);
87            xb = (y3 == y1) ? x1 : x3 + (x1 - x3) * (y - y3) / (y1 - y3);
88        }
89
90        if(xb < xa)
91        {
92            int tmp = xb;
93            xb = xa; xa = tmp;
94        }
95
96        /* Rescale xa and xb, slightly cropping */
97        xa = (xa + 2) / 4;
98        xb = (xb - 2) / 4;
99
100        if(xb < 0) continue;
101        if(xa > xmax) continue;
102        if(xa < 0) xa = 0;
103        if(xb > xmax) xb = xmax;
104
105        for(x = xa; x <= xb; x++)
106            caca_putchar(x, y, c);
107    }
108}
109
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