libs/gfx/algo/PartialEllipse.algo.h

   1 /*****************************************************************************
   2  * This file is part of gfxprim library.                                     *
   3  *                                                                           *
   4  * Gfxprim is free software; you can redistribute it and/or                  *
   5  * modify it under the terms of the GNU Lesser General Public                *
   6  * License as published by the Free Software Foundation; either              *
   7  * version 2.1 of the License, or (at your option) any later version.        *
   8  *                                                                           *
   9  * Gfxprim is distributed in the hope that it will be useful,                *
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of            *
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU         *
  12  * Lesser General Public License for more details.                           *
  13  *                                                                           *
  14  * You should have received a copy of the GNU Lesser General Public          *
  15  * License along with gfxprim; if not, write to the Free Software            *
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor,                        *
  17  * Boston, MA  02110-1301  USA                                               *
  18  *                                                                           *
  19  * Copyright (C) 2009-2010 Jiri "BlueBear" Dluhos                            *
  20  *                         <jiri.bluebear.dluhos@gmail.com>                  *
  21  *                                                                           *
  22  * Copyright (C) 2009-2012 Cyril Hrubis <metan@ucw.cz>                       *
  23  *                                                                           *
  24  *****************************************************************************/
  25
  26 #include "GP_AngleUtils.h"
  27
  28 #include <math.h>
  29
  30 /*
  31  * This macro defines a partial ellipse drawing function.
  32  * Arguments:
  33  *     PIXMAP_T - user-defined type of drawing pixmap (passed to PUTPIXEL)
  34  *     PIXVAL_T  - user-defined pixel value type (passed to PUTPIXEL)
  35  *     PUTPIXEL  - a pixel drawing function f(pixmap, x, y, pixval)
  36  *     FN_NAME   - name of the function to be defined
  37  */
  38 #define DEF_PARTIAL_ELLIPSE_FN(FN_NAME, PIXMAP_T, PIXVAL_T, PUTPIXEL) \
  39 static void FN_NAME(PIXMAP_T pixmap, int xcenter, int ycenter, int a, int b, \
  40         int start, int end, PIXVAL_T pixval) \
  41 { \
  42         double startAngle = GP_NormalizeAngle(2*M_PI*(start / 360000.0)); \
  43         double endAngle = GP_NormalizeAngle(2*M_PI*(end / 360000.0)); \
  44 \
  45         int x; \
  46         for (x = -a; x <= a; x++) { \
  47                 double angle = acos(((double) x) / a); \
  48                 double y = floor(b*sin(angle)); \
  49                 if (GP_AngleInRange(angle, startAngle, endAngle)) { \
  50                         PUTPIXEL(pixmap, xcenter+x, ycenter-y, pixval); \
  51                 } \
  52                 if (GP_AngleInRange(2*M_PI - angle, startAngle, endAngle)) { \
  53                         PUTPIXEL(pixmap, xcenter+x, ycenter+y, pixval); \
  54                 } \
  55         } \
  56 \
  57         int y; \
  58         for (y = -b; y <= b; y++) { \
  59                 double angle = asin(((double) y) / b); \
  60                 double x = floor(a*cos(angle)); \
  61                 if (GP_AngleInRange(angle, startAngle, endAngle)) { \
  62                         PUTPIXEL(pixmap, xcenter+x, ycenter-y, pixval); \
  63                 } \
  64                 if (GP_AngleInRange(M_PI - angle, startAngle, endAngle)) { \
  65                         PUTPIXEL(pixmap, xcenter-x, ycenter-y, pixval); \
  66                 } \
  67         } \
  68 }
  69