libx/object/xline.c

   1 /*
   2  *  ZeX/OS
   3  *  Copyright (C) 2007  Tomas 'ZeXx86' Jedrzejek (zexx86@zexos.org)
   4  *
   5  *  This program is free software: you can redistribute it and/or modify
   6  *  it under the terms of the GNU General Public License as published by
   7  *  the Free Software Foundation, either version 3 of the License, or
   8  *  (at your option) any later version.
   9  *
  10  *  This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License
  16  *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17  */
  18
  19 #include <libx/base.h>
  20
  21 void xline (unsigned x1, unsigned y1, unsigned x2, unsigned y2, unsigned color)
  22 {//             x1 = 450, y1 = 200, x1 = 500, y2 = 250 -- ok
  23  //             x1 = 450, y1 = 250, x1 = 500, y2 = 200 -- spatne
  24
  25         float opacnex = 1;
  26         float opacney = 1;
  27
  28         /* vektor s(delkax, delkay) */
  29         int delkax = 0;
  30         int delkay = 0;
  31
  32         if (x1 > x2) {
  33                 opacnex = -1;
  34                 delkax = (signed) x1 - (signed) x2;
  35         } else
  36                 delkax = (signed) x2 - (signed) x1;
  37
  38         if (y1 > y2) {
  39                 opacney = -1;
  40                 delkay = (signed) y1 - (signed) y2;
  41         } else
  42                 delkay = (signed) y2 - (signed) y1;
  43
  44         int a = 0;
  45         int b = 0;
  46
  47         if (delkax == 0) {
  48                 for (b = y1; b <= ((signed) y1+delkay); b ++)
  49                         xpixel (x1, b, color);
  50
  51                 return;
  52         }
  53
  54         if (delkay == 0) {
  55                 for (a = x1; a <= ((signed) x1+delkax); a ++)
  56                         xpixel (a, y1, color);
  57
  58                 return;
  59         }
  60
  61         /* parametricka rovnice */
  62         float i = 0;
  63         unsigned last_x = 0;
  64         unsigned last_y = 0;
  65
  66         while (i < 1) {
  67                 float x = (float) x1 + (float) delkax * i * opacnex;
  68                 float y = (float) y1 + (float) delkay * i * opacney;
  69
  70                 if (last_x != x && last_y != y)
  71                         xpixel ((unsigned) x, (unsigned) y, color);
  72
  73                 last_x = (unsigned) x;
  74                 last_y = (unsigned) y;
  75
  76                 i += 0.01f;
  77         }
  78 }