source: libcaca/trunk/cucul/triangle.c @ 2299

Last change on this file since 2299 was 2299, checked in by Sam Hocevar, 12 years ago
  • Remove #include <stdint.h> etc. from "common.h". Instead, make sure that <cucul.h> will provide the C99 types, even if libcaca has been installed.
  • Rename what's left of "common.h" to "stubs.h".
  • Remove all references to erroneous <inttypes.h> from source files.
  • Property svn:keywords set to Id
File size: 4.5 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 2299 2008-04-19 12:42:50Z sam $
7 *
8 *  This library is free software. It comes without any warranty, to
9 *  the extent permitted by applicable law. You can redistribute it
10 *  and/or modify it under the terms of the Do What The Fuck You Want
11 *  To Public License, Version 2, as published by Sam Hocevar. See
12 *  http://sam.zoy.org/wtfpl/COPYING for more details.
13 */
14
15/*
16 *  This file contains triangle drawing functions, both filled and outline.
17 */
18
19#include "config.h"
20
21#if !defined(__KERNEL__)
22#   include <stdlib.h>
23#endif
24
25#include "cucul.h"
26#include "cucul_internals.h"
27
28/** \brief Draw a triangle on the canvas using the given character.
29 *
30 *  This function never fails.
31 *
32 *  \param cv The handle to the libcucul canvas.
33 *  \param x1 X coordinate of the first point.
34 *  \param y1 Y coordinate of the first point.
35 *  \param x2 X coordinate of the second point.
36 *  \param y2 Y coordinate of the second point.
37 *  \param x3 X coordinate of the third point.
38 *  \param y3 Y coordinate of the third point.
39 *  \param ch UTF-32 character to be used to draw the triangle outline.
40 *  \return This function always returns 0.
41 */
42int cucul_draw_triangle(cucul_canvas_t *cv, int x1, int y1, int x2, int y2,
43                        int x3, int y3, unsigned long int ch)
44{
45    cucul_draw_line(cv, x1, y1, x2, y2, ch);
46    cucul_draw_line(cv, x2, y2, x3, y3, ch);
47    cucul_draw_line(cv, x3, y3, x1, y1, ch);
48
49    return 0;
50}
51
52/** \brief Draw a thin triangle on the canvas.
53 *
54 *  This function never fails.
55 *
56 *  \param cv The handle to the libcucul canvas.
57 *  \param x1 X coordinate of the first point.
58 *  \param y1 Y coordinate of the first point.
59 *  \param x2 X coordinate of the second point.
60 *  \param y2 Y coordinate of the second point.
61 *  \param x3 X coordinate of the third point.
62 *  \param y3 Y coordinate of the third point.
63 *  \return This function always returns 0.
64 */
65int cucul_draw_thin_triangle(cucul_canvas_t *cv, int x1, int y1,
66                             int x2, int y2, int x3, int y3)
67{
68    cucul_draw_thin_line(cv, x1, y1, x2, y2);
69    cucul_draw_thin_line(cv, x2, y2, x3, y3);
70    cucul_draw_thin_line(cv, x3, y3, x1, y1);
71
72    return 0;
73}
74
75/** \brief Fill a triangle on the canvas using the given character.
76 *
77 *  This function never fails.
78 *
79 *  \param cv The handle to the libcucul canvas.
80 *  \param x1 X coordinate of the first point.
81 *  \param y1 Y coordinate of the first point.
82 *  \param x2 X coordinate of the second point.
83 *  \param y2 Y coordinate of the second point.
84 *  \param x3 X coordinate of the third point.
85 *  \param y3 Y coordinate of the third point.
86 *  \param ch UTF-32 character to be used to fill the triangle.
87 *  \return This function always returns 0.
88 */
89int cucul_fill_triangle(cucul_canvas_t *cv, int x1, int y1, int x2, int y2,
90                        int x3, int y3, unsigned long int ch)
91{
92    int x, y, xmin, xmax, ymin, ymax;
93    long int xx1, xx2, xa, xb, sl21, sl31, sl32;
94
95    /* Bubble-sort y1 <= y2 <= y3 */
96    if(y1 > y2)
97        return cucul_fill_triangle(cv, x2, y2, x1, y1, x3, y3, ch);
98
99    if(y2 > y3)
100        return cucul_fill_triangle(cv, x1, y1, x3, y3, x2, y2, ch);
101
102    /* Compute slopes and promote precision */
103    sl21 = (y2 == y1) ? 0 : (x2 - x1) * 0x10000 / (y2 - y1);
104    sl31 = (y3 == y1) ? 0 : (x3 - x1) * 0x10000 / (y3 - y1);
105    sl32 = (y3 == y2) ? 0 : (x3 - x2) * 0x10000 / (y3 - y2);
106
107    x1 *= 0x10000;
108    x2 *= 0x10000;
109    x3 *= 0x10000;
110
111    ymin = y1 < 0 ? 0 : y1;
112    ymax = y3 + 1 < (int)cv->height ? y3 + 1 : (int)cv->height;
113
114    if(ymin < y2)
115    {
116        xa = x1 + sl21 * (ymin - y1);
117        xb = x1 + sl31 * (ymin - y1);
118    }
119    else if(ymin == y2)
120    {
121        xa = x2;
122        xb = (y1 == y3) ? x3 : x1 + sl31 * (ymin - y1);
123    }
124    else /* (ymin > y2) */
125    {
126        xa = x3 + sl32 * (ymin - y3);
127        xb = x3 + sl31 * (ymin - y3);
128    }
129
130    /* Rasterize our triangle */
131    for(y = ymin; y < ymax; y++)
132    {
133        /* Rescale xa and xb, recentering the division */
134        if(xa < xb)
135        {
136            xx1 = (xa + 0x800) / 0x10000;
137            xx2 = (xb + 0x801) / 0x10000;
138        }
139        else
140        {
141            xx1 = (xb + 0x800) / 0x10000;
142            xx2 = (xa + 0x801) / 0x10000;
143        }
144
145        xmin = xx1 < 0 ? 0 : xx1;
146        xmax = xx2 + 1 < (int)cv->width ? xx2 + 1 : (int)cv->width;
147
148        for(x = xmin; x < xmax; x++)
149            cucul_put_char(cv, x, y, ch);
150
151        xa += y < y2 ? sl21 : sl32;
152        xb += sl31;
153    }
154
155    return 0;
156}
157
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