source: libcaca/trunk/libee/triangle.c @ 105

Last change on this file since 105 was 105, checked in by Sam Hocevar, 19 years ago
  • libee/triangle.c: + Implemented ee_fill_triangle().
  • test/demo.c: + Triangle demo.
  • Property svn:keywords set to Id
File size: 2.3 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: triangle.c 105 2003-11-09 21:36:24Z 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#include <stdlib.h>
26
27#include "ee.h"
28
29void ee_fill_triangle(int x1, int y1, int x2, int y2, int x3, int y3, char c)
30{
31    int x, y, xa, xb, xmax, ymax;
32
33    /* Bubble-sort y1 <= y2 <= y3 */
34    if(y1 > y2)
35    {
36        ee_fill_triangle(x2, y2, x1, y1, x3, y3, c);
37        return;
38    }
39
40    if(y2 > y3)
41    {
42        ee_fill_triangle(x1, y1, x3, y3, x2, y2, c);
43        return;
44    }
45
46    /* Promote precision */
47    x1 *= 4;
48    x2 *= 4;
49    x3 *= 4;
50
51    xmax = ee_get_width() - 1;
52    ymax = ee_get_height() - 1;
53
54    /* Rasterize our triangle */
55    for(y = y1 < 0 ? 0 : y1; y <= y3 && y <= ymax; y++)
56    {
57        if(y <= y2)
58        {
59            xa = (y1 == y2) ? x2 : x1 + (x2 - x1) * (y - y1) / (y2 - y1);
60            xb = (y1 == y3) ? x3 : x1 + (x3 - x1) * (y - y1) / (y3 - y1);
61        }
62        else
63        {
64            xa = (y3 == y2) ? x2 : x3 + (x2 - x3) * (y - y3) / (y2 - y3);
65            xb = (y3 == y1) ? x1 : x3 + (x1 - x3) * (y - y3) / (y1 - y3);
66        }
67
68        if(xb < xa)
69        {
70            int tmp = xb;
71            xb = xa; xa = tmp;
72        }
73
74        /* Rescale xa and xb, slightly cropping */
75        xa = (xa + 2) / 4;
76        xb = (xb - 2) / 4;
77
78        if(xb < 0) continue;
79        if(xa > xmax) continue;
80        if(xa < 0) xa = 0;
81        if(xb > xmax) xb = xmax;
82
83        for(x = xa; x <= xb; x++)
84        {
85            ee_goto(x, y);
86            ee_putchar(c);
87        }
88    }
89}
90
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