source: ttyvaders/trunk/libee/conic.c @ 148

Last change on this file since 148 was 148, checked in by Sam Hocevar, 17 years ago
  • libee/graphics.c: + Moved ee_putstr() and ee_putchar() in here.
  • libee/ee.h: + Got rid of ee_goto(). + Moved <slang.h> or <curses.h> into libee.
  • Replaced ee_goto()/ee_putstr() pairs with ee_putstr().
  • Ditto for ee_putchar().
  • Property svn:keywords set to Id
File size: 2.8 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: conic.c 148 2003-11-10 23:38:50Z 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#ifdef USE_SLANG
26#   include <slang.h>
27#elif USE_NCURSES
28#   include <curses.h>
29#endif
30
31#include <stdlib.h>
32#include <inttypes.h>
33
34#include "ee.h"
35
36static void ellipsepoints(int, int, int, int, char);
37
38void ee_draw_circle(int x, int y, int r, char c)
39{
40    int test, dx, dy;
41
42    /* Optimized Bresenham. Kick ass. */
43    for(test = 0, dx = 0, dy = r ; dx <= dy ; dx++)
44    {
45        ellipsepoints(x, y, dx, dy, c);
46        ellipsepoints(x, y, dy, dx, c);
47
48        test += test > 0 ? dx - dy-- : dx;
49    }
50}
51
52void ee_draw_ellipse(int xo, int yo, int a, int b, char c)
53{
54    int d2;
55    int x = 0;
56    int y = b;
57    int d1 = b*b - (a*a*b) + (a*a/4);
58
59    ellipsepoints(xo, yo, x, y, c);
60
61    while( a*a*y - a*a/2 > b*b*(x+1))
62    {
63        if(d1 < 0)
64        {
65            d1 += b*b*(2*x+1); /* XXX: "Computer Graphics" has + 3 here. */
66        }
67        else
68        {
69            d1 += b*b*(2*x*1) + a*a*(-2*y+2);
70            y--;
71        }
72        x++;
73        ellipsepoints(xo, yo, x, y, c);
74    }
75
76    d2 = b*b*(x+0.5)*(x+0.5) + a*a*(y-1)*(y-1) - a*a*b*b;
77    while(y > 0)
78    {
79        if(d2 < 0)
80        {
81            d2 += b*b*(2*x+2) + a*a*(-2*y+3);
82            x++;
83        }
84        else
85        {
86            d2 += a*a*(-2*y+3);
87        }
88
89        y--;
90        ellipsepoints(xo, yo, x, y, c);
91    }
92}
93
94static void ellipsepoints(int xo, int yo, int x, int y, char c)
95{
96    uint8_t b = 0;
97
98    if(xo + x >= 0 && xo + x < ee_get_width())
99        b |= 0x1;
100    if(xo - x >= 0 && xo - x < ee_get_width())
101        b |= 0x2;
102    if(yo + y >= 0 && yo + y < ee_get_height())
103        b |= 0x4;
104    if(yo - y >= 0 && yo - y < ee_get_height())
105        b |= 0x8;
106
107    if((b & (0x1|0x4)) == (0x1|0x4))
108        ee_putchar(xo + x, yo + y, c);
109
110    if((b & (0x2|0x4)) == (0x2|0x4))
111        ee_putchar(xo - x, yo + y, c);
112
113    if((b & (0x1|0x8)) == (0x1|0x8))
114        ee_putchar(xo + x, yo - y, c);
115
116    if((b & (0x2|0x8)) == (0x2|0x8))
117        ee_putchar(xo - x, yo - y, c);
118}
119
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