1 | /* |
---|
2 | * libcaca Colour ASCII-Art library |
---|
3 | * Copyright (c) 2002-2006 Sam Hocevar <sam@zoy.org> |
---|
4 | * All Rights Reserved |
---|
5 | * |
---|
6 | * $Id: triangle.c 2821 2008-09-27 13:12:46Z 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 "caca.h" |
---|
26 | #include "caca_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 libcaca 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 | */ |
---|
42 | int caca_draw_triangle(caca_canvas_t *cv, int x1, int y1, int x2, int y2, |
---|
43 | int x3, int y3, uint32_t ch) |
---|
44 | { |
---|
45 | caca_draw_line(cv, x1, y1, x2, y2, ch); |
---|
46 | caca_draw_line(cv, x2, y2, x3, y3, ch); |
---|
47 | caca_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 libcaca 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 | */ |
---|
65 | int caca_draw_thin_triangle(caca_canvas_t *cv, int x1, int y1, |
---|
66 | int x2, int y2, int x3, int y3) |
---|
67 | { |
---|
68 | caca_draw_thin_line(cv, x1, y1, x2, y2); |
---|
69 | caca_draw_thin_line(cv, x2, y2, x3, y3); |
---|
70 | caca_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 libcaca 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 | */ |
---|
89 | int caca_fill_triangle(caca_canvas_t *cv, int x1, int y1, int x2, int y2, |
---|
90 | int x3, int y3, uint32_t ch) |
---|
91 | { |
---|
92 | int x, y, xmin, xmax, ymin, ymax; |
---|
93 | int xx1, xx2, xa, xb, sl21, sl31, sl32; |
---|
94 | |
---|
95 | /* Bubble-sort y1 <= y2 <= y3 */ |
---|
96 | if(y1 > y2) |
---|
97 | return caca_fill_triangle(cv, x2, y2, x1, y1, x3, y3, ch); |
---|
98 | |
---|
99 | if(y2 > y3) |
---|
100 | return caca_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 < cv->height ? y3 + 1 : 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 < cv->width ? xx2 + 1 : cv->width; |
---|
147 | |
---|
148 | for(x = xmin; x < xmax; x++) |
---|
149 | caca_put_char(cv, x, y, ch); |
---|
150 | |
---|
151 | xa += y < y2 ? sl21 : sl32; |
---|
152 | xb += sl31; |
---|
153 | } |
---|
154 | |
---|
155 | return 0; |
---|
156 | } |
---|
157 | |
---|