source: libcaca/trunk/cucul/conic.c @ 540

Last change on this file since 540 was 540, checked in by Sam Hocevar, 14 years ago
  • Polished the driver split a bit (still no events, except resize events), properly credited authors and documented a few things.
  • Property svn:keywords set to Id
File size: 5.4 KB
Line 
1/*
2 *  libcucul      Unicode canvas library
3 *  Copyright (c) 2002-2006 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 Do What The Fuck You Want To
8 *  Public License, Version 2, as published by Sam Hocevar. See
9 *  http://sam.zoy.org/wtfpl/COPYING for more details.
10 */
11
12/** \file conic.c
13 *  \version \$Id: conic.c 540 2006-03-07 09:17:35Z sam $
14 *  \author Sam Hocevar <sam@zoy.org>
15 *  \brief Ellipse and circle drawing
16 *
17 *  This file contains ellipse and circle drawing functions, both filled
18 *  and outline.
19 */
20
21#include "config.h"
22
23#include <stdlib.h>
24
25#include "cucul.h"
26#include "cucul_internals.h"
27
28static void ellipsepoints(cucul_t *, int, int, int, int, char);
29
30/**
31 * \brief Draw a circle on the screen using the given character.
32 *
33 * \param x Center X coordinate.
34 * \param y Center Y coordinate.
35 * \param r Circle radius.
36 * \param c Character to draw the circle outline with.
37 * \return void
38 */
39void cucul_draw_circle(cucul_t *qq, int x, int y, int r, char c)
40{
41    int test, dx, dy;
42
43    /* Optimized Bresenham. Kick ass. */
44    for(test = 0, dx = 0, dy = r ; dx <= dy ; dx++)
45    {
46        ellipsepoints(qq, x, y, dx, dy, c);
47        ellipsepoints(qq, x, y, dy, dx, c);
48
49        test += test > 0 ? dx - dy-- : dx;
50    }
51}
52
53/**
54 * \brief Fill an ellipse on the screen using the given character.
55 *
56 * \param xo Center X coordinate.
57 * \param yo Center Y coordinate.
58 * \param a Ellipse X radius.
59 * \param b Ellipse Y radius.
60 * \param c Character to fill the ellipse with.
61 * \return void
62 */
63void cucul_fill_ellipse(cucul_t *qq, int xo, int yo, int a, int b, char c)
64{
65    int d2;
66    int x = 0;
67    int y = b;
68    int d1 = b*b - (a*a*b) + (a*a/4);
69
70    while(a*a*y - a*a/2 > b*b*(x+1))
71    {
72        if(d1 < 0)
73        {
74            d1 += b*b*(2*x+1); /* XXX: "Computer Graphics" has + 3 here. */
75        }
76        else
77        {
78            d1 += b*b*(2*x*1) + a*a*(-2*y+2);
79            cucul_draw_line(qq, xo - x, yo - y, xo + x, yo - y, c);
80            cucul_draw_line(qq, xo - x, yo + y, xo + x, yo + y, c);
81            y--;
82        }
83        x++;
84    }
85
86    cucul_draw_line(qq, xo - x, yo - y, xo + x, yo - y, c);
87    cucul_draw_line(qq, xo - x, yo + y, xo + x, yo + y, c);
88
89    d2 = b*b*(x+0.5)*(x+0.5) + a*a*(y-1)*(y-1) - a*a*b*b;
90    while(y > 0)
91    {
92        if(d2 < 0)
93        {
94            d2 += b*b*(2*x+2) + a*a*(-2*y+3);
95            x++;
96        }
97        else
98        {
99            d2 += a*a*(-2*y+3);
100        }
101
102        y--;
103        cucul_draw_line(qq, xo - x, yo - y, xo + x, yo - y, c);
104        cucul_draw_line(qq, xo - x, yo + y, xo + x, yo + y, c);
105    }
106}
107
108/**
109 * \brief Draw an ellipse on the screen using the given character.
110 *
111 * \param xo Center X coordinate.
112 * \param yo Center Y coordinate.
113 * \param a Ellipse X radius.
114 * \param b Ellipse Y radius.
115 * \param c Character to draw the ellipse outline with.
116 * \return void
117 */
118void cucul_draw_ellipse(cucul_t *qq, int xo, int yo, int a, int b, char c)
119{
120    int d2;
121    int x = 0;
122    int y = b;
123    int d1 = b*b - (a*a*b) + (a*a/4);
124
125    ellipsepoints(qq, xo, yo, x, y, c);
126
127    while(a*a*y - a*a/2 > b*b*(x+1))
128    {
129        if(d1 < 0)
130        {
131            d1 += b*b*(2*x+1); /* XXX: "Computer Graphics" has + 3 here. */
132        }
133        else
134        {
135            d1 += b*b*(2*x*1) + a*a*(-2*y+2);
136            y--;
137        }
138        x++;
139        ellipsepoints(qq, xo, yo, x, y, c);
140    }
141
142    d2 = b*b*(x+0.5)*(x+0.5) + a*a*(y-1)*(y-1) - a*a*b*b;
143    while(y > 0)
144    {
145        if(d2 < 0)
146        {
147            d2 += b*b*(2*x+2) + a*a*(-2*y+3);
148            x++;
149        }
150        else
151        {
152            d2 += a*a*(-2*y+3);
153        }
154
155        y--;
156        ellipsepoints(qq, xo, yo, x, y, c);
157    }
158}
159
160/**
161 * \brief Draw a thin ellipse on the screen.
162 *
163 * \param xo Center X coordinate.
164 * \param yo Center Y coordinate.
165 * \param a Ellipse X radius.
166 * \param b Ellipse Y radius.
167 * \return void
168 */
169void cucul_draw_thin_ellipse(cucul_t *qq, int xo, int yo, int a, int b)
170{
171    /* FIXME: this is not correct */
172    int d2;
173    int x = 0;
174    int y = b;
175    int d1 = b*b - (a*a*b) + (a*a/4);
176
177    ellipsepoints(qq, xo, yo, x, y, '-');
178
179    while(a*a*y - a*a/2 > b*b*(x+1))
180    {
181        if(d1 < 0)
182        {
183            d1 += b*b*(2*x+1); /* XXX: "Computer Graphics" has + 3 here. */
184        }
185        else
186        {
187            d1 += b*b*(2*x*1) + a*a*(-2*y+2);
188            y--;
189        }
190        x++;
191        ellipsepoints(qq, xo, yo, x, y, '-');
192    }
193
194    d2 = b*b*(x+0.5)*(x+0.5) + a*a*(y-1)*(y-1) - a*a*b*b;
195    while(y > 0)
196    {
197        if(d2 < 0)
198        {
199            d2 += b*b*(2*x+2) + a*a*(-2*y+3);
200            x++;
201        }
202        else
203        {
204            d2 += a*a*(-2*y+3);
205        }
206
207        y--;
208        ellipsepoints(qq, xo, yo, x, y, '|');
209    }
210}
211
212static void ellipsepoints(cucul_t *qq, int xo, int yo, int x, int y, char c)
213{
214    uint8_t b = 0;
215
216    if(xo + x >= 0 && xo + x < (int)qq->width)
217        b |= 0x1;
218    if(xo - x >= 0 && xo - x < (int)qq->width)
219        b |= 0x2;
220    if(yo + y >= 0 && yo + y < (int)qq->height)
221        b |= 0x4;
222    if(yo - y >= 0 && yo - y < (int)qq->height)
223        b |= 0x8;
224
225    if((b & (0x1|0x4)) == (0x1|0x4))
226        cucul_putchar(qq, xo + x, yo + y, c);
227
228    if((b & (0x2|0x4)) == (0x2|0x4))
229        cucul_putchar(qq, xo - x, yo + y, c);
230
231    if((b & (0x1|0x8)) == (0x1|0x8))
232        cucul_putchar(qq, xo + x, yo - y, c);
233
234    if((b & (0x2|0x8)) == (0x2|0x8))
235        cucul_putchar(qq, xo - x, yo - y, c);
236}
237
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