source: libcaca/trunk/cucul/triangle.c @ 811

Last change on this file since 811 was 811, checked in by Sam Hocevar, 14 years ago
  • Renamed caca_t into caca_display_t.
  • Renamed canvas handle variables from "c" to "cv". Eh ouais mon gros.
  • Property svn:keywords set to Id
File size: 4.1 KB
Line 
1/*
2 *  libcucul      Canvas for ultrafast compositing of Unicode letters
3 *  Copyright (c) 2002-2006 Sam Hocevar <sam@zoy.org>
4 *                All Rights Reserved
5 *
6 *  $Id: triangle.c 811 2006-04-18 15:11:25Z sam $
7 *
8 *  This library is free software; you can redistribute it and/or
9 *  modify it under the terms of the Do What The Fuck You Want To
10 *  Public License, Version 2, as published by Sam Hocevar. See
11 *  http://sam.zoy.org/wtfpl/COPYING for more details.
12 */
13
14/*
15 *  This file contains triangle drawing functions, both filled and outline.
16 */
17
18#include "config.h"
19
20#if !defined(__KERNEL__)
21#   include <stdlib.h>
22#endif
23
24#include "cucul.h"
25#include "cucul_internals.h"
26
27/** \brief Draw a triangle on the canvas using the given character.
28 *
29 *  \param cv The handle to the libcucul canvas.
30 *  \param x1 X coordinate of the first point.
31 *  \param y1 Y coordinate of the first point.
32 *  \param x2 X coordinate of the second point.
33 *  \param y2 Y coordinate of the second point.
34 *  \param x3 X coordinate of the third point.
35 *  \param y3 Y coordinate of the third point.
36 *  \param str UTF-8 string representing the character that should be used
37 *         to draw the triangle outline.
38 *  \return void
39 */
40void cucul_draw_triangle(cucul_canvas_t *cv, int x1, int y1, int x2, int y2,
41                         int x3, int y3, char const *str)
42{
43    cucul_draw_line(cv, x1, y1, x2, y2, str);
44    cucul_draw_line(cv, x2, y2, x3, y3, str);
45    cucul_draw_line(cv, x3, y3, x1, y1, str);
46}
47
48/** \brief Draw a thin triangle on the canvas.
49 *
50 *  \param cv The handle to the libcucul canvas.
51 *  \param x1 X coordinate of the first point.
52 *  \param y1 Y coordinate of the first point.
53 *  \param x2 X coordinate of the second point.
54 *  \param y2 Y coordinate of the second point.
55 *  \param x3 X coordinate of the third point.
56 *  \param y3 Y coordinate of the third point.
57 *  \return void
58 */
59void cucul_draw_thin_triangle(cucul_canvas_t *cv, int x1, int y1,
60                              int x2, int y2, int x3, int y3)
61{
62    cucul_draw_thin_line(cv, x1, y1, x2, y2);
63    cucul_draw_thin_line(cv, x2, y2, x3, y3);
64    cucul_draw_thin_line(cv, x3, y3, x1, y1);
65}
66
67/** \brief Fill a triangle on the canvas using the given character.
68 *
69 *  \param cv The handle to the libcucul canvas.
70 *  \param x1 X coordinate of the first point.
71 *  \param y1 Y coordinate of the first point.
72 *  \param x2 X coordinate of the second point.
73 *  \param y2 Y coordinate of the second point.
74 *  \param x3 X coordinate of the third point.
75 *  \param y3 Y coordinate of the third point.
76 *  \param str UTF-8 string representing the character that should be used
77 *         to fill the triangle.
78 *  \return void
79 */
80void cucul_fill_triangle(cucul_canvas_t *cv, int x1, int y1, int x2, int y2,
81                         int x3, int y3, char const *str)
82{
83    int x, y, xa, xb, xmax, ymax;
84    uint32_t ch;
85
86    /* Bubble-sort y1 <= y2 <= y3 */
87    if(y1 > y2)
88    {
89        cucul_fill_triangle(cv, x2, y2, x1, y1, x3, y3, str);
90        return;
91    }
92
93    if(y2 > y3)
94    {
95        cucul_fill_triangle(cv, x1, y1, x3, y3, x2, y2, str);
96        return;
97    }
98
99    /* Promote precision */
100    x1 *= 4;
101    x2 *= 4;
102    x3 *= 4;
103
104    xmax = cv->width - 1;
105    ymax = cv->height - 1;
106
107    ch = _cucul_utf8_to_utf32(str);
108
109    /* Rasterize our triangle */
110    for(y = y1 < 0 ? 0 : y1; y <= y3 && y <= ymax; y++)
111    {
112        if(y <= y2)
113        {
114            xa = (y1 == y2) ? x2 : x1 + (x2 - x1) * (y - y1) / (y2 - y1);
115            xb = (y1 == y3) ? x3 : x1 + (x3 - x1) * (y - y1) / (y3 - y1);
116        }
117        else
118        {
119            xa = (y3 == y2) ? x2 : x3 + (x2 - x3) * (y - y3) / (y2 - y3);
120            xb = (y3 == y1) ? x1 : x3 + (x1 - x3) * (y - y3) / (y1 - y3);
121        }
122
123        if(xb < xa)
124        {
125            int tmp = xb;
126            xb = xa; xa = tmp;
127        }
128
129        /* Rescale xa and xb, slightly cropping */
130        xa = (xa + 2) / 4;
131        xb = (xb - 2) / 4;
132
133        if(xb < 0) continue;
134        if(xa > xmax) continue;
135        if(xa < 0) xa = 0;
136        if(xb > xmax) xb = xmax;
137
138        for(x = xa; x <= xb; x++)
139            _cucul_putchar32(cv, x, y, ch);
140    }
141}
142
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