]> git.sur5r.net Git - cc65/blob - libsrc/tgi/tgi_arc.c
Fixed _textcolor definition.
[cc65] / libsrc / tgi / tgi_arc.c
1 /*****************************************************************************/
2 /*                                                                           */
3 /*                                 tgi_arc.c                                 */
4 /*                                                                           */
5 /*                            Draw an ellipse arc                            */
6 /*                                                                           */
7 /*                                                                           */
8 /*                                                                           */
9 /* (C) 2002-2009, Ullrich von Bassewitz                                      */
10 /*                Roemerstrasse 52                                           */
11 /*                D-70794 Filderstadt                                        */
12 /* EMail:         uz@cc65.org                                                */
13 /*                                                                           */
14 /*                                                                           */
15 /* This software is provided 'as-is', without any expressed or implied       */
16 /* warranty.  In no event will the authors be held liable for any damages    */
17 /* arising from the use of this software.                                    */
18 /*                                                                           */
19 /* Permission is granted to anyone to use this software for any purpose,     */
20 /* including commercial applications, and to alter it and redistribute it    */
21 /* freely, subject to the following restrictions:                            */
22 /*                                                                           */
23 /* 1. The origin of this software must not be misrepresented; you must not   */
24 /*    claim that you wrote the original software. If you use this software   */
25 /*    in a product, an acknowledgment in the product documentation would be  */
26 /*    appreciated but is not required.                                       */
27 /* 2. Altered source versions must be plainly marked as such, and must not   */
28 /*    be misrepresented as being the original software.                      */
29 /* 3. This notice may not be removed or altered from any source              */
30 /*    distribution.                                                          */
31 /*                                                                           */
32 /*****************************************************************************/
33
34
35
36 #include <tgi.h>
37 #include <tgi/tgi-kernel.h>
38 #include <cc65.h>
39
40
41
42 /*****************************************************************************/
43 /*                                   Code                                    */
44 /*****************************************************************************/
45
46
47
48 void __fastcall__ tgi_arc (int x, int y, unsigned char rx, unsigned char ry,
49                            unsigned sa, unsigned ea)
50 /* Draw an ellipse arc with center at x/y and radii rx/ry using the current
51 ** drawing color. The arc covers the angle between sa and ea (startangle and
52 ** endangle), which must be in the range 0..360 (otherwise the function may
53 ** bevave unextectedly).
54 */
55 {
56     int x1, y1, x2, y2;
57     unsigned char inc;
58     unsigned char done = 0;
59
60     /* Bail out if there's nothing to do */
61     if (sa > ea) {
62         return;
63     }
64
65     /* Determine the number of segments to use. This may be refined ... */
66     if (rx + ry >= 25) {
67         inc = 12;
68     } else {
69         inc = 24;
70     }
71
72     /* Calculate the start coords */
73     x1 = x + tgi_imulround (rx, _cos (sa));
74     y1 = y - tgi_imulround (ry, _sin (sa));
75     do {
76         sa += inc;
77         if (sa >= ea) {
78             sa = ea;
79             done = 1;
80         }
81         x2 = x + tgi_imulround (rx, _cos (sa));
82         y2 = y - tgi_imulround (ry, _sin (sa));
83         tgi_line (x1, y1, x2, y2);
84         x1 = x2;
85         y1 = y2;
86     } while (!done);
87 }
88
89
90