test/random-intersections.c

   1 /*
   2  * Copyright © 2006 M Joonas Pihlaja
   3  *
   4  * Permission is hereby granted, free of charge, to any person
   5  * obtaining a copy of this software and associated documentation
   6  * files (the "Software"), to deal in the Software without
   7  * restriction, including without limitation the rights to use, copy,
   8  * modify, merge, publish, distribute, sublicense, and/or sell copies
   9  * of the Software, and to permit persons to whom the Software is
  10  * furnished to do so, subject to the following conditions:
  11  *
  12  * The above copyright notice and this permission notice shall be
  13  * included in all copies or substantial portions of the Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  16  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  17  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  18  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  19  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  20  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  21  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  22  * SOFTWARE.
  23  *
  24  * Author: M Joonas Pihlaja <jpihlaja@cc.helsinki.fi>
  25  */
  26 #include "cairo-test.h"
  27
  28 static cairo_test_draw_function_t draw;
  29 #define SIZE 512
  30 #define NUM_SEGMENTS 128
  31
  32 cairo_test_t test = {
  33     "random-intersections",
  34     "Tests the tessellator trapezoid generation and intersection computation",
  35     SIZE+3, SIZE+3,
  36     draw
  37 };
  38
  39 static uint32_t state;
  40 static double
  41 uniform_random (double minval, double maxval)
  42 {
  43     static uint32_t const poly = 0x9a795537U;
  44     uint32_t n = 32;
  45     while (n-->0)
  46         state = 2*state < state ? (2*state ^ poly) : 2*state;
  47     return minval + state * (maxval - minval) / 4294967296.0;
  48 }
  49
  50 static cairo_test_status_t
  51 draw (cairo_t *cr, int width, int height)
  52 {
  53     int i;
  54
  55     cairo_set_source_rgb (cr, 0, 0, 0);
  56     cairo_paint (cr);
  57
  58     state = 0x12345678;
  59     cairo_translate (cr, 1, 1);
  60     cairo_set_fill_rule (cr, CAIRO_FILL_RULE_EVEN_ODD);
  61
  62     cairo_move_to (cr, 0, 0);
  63     for (i = 0; i < NUM_SEGMENTS; i++) {
  64         double x = uniform_random (0, width);
  65         double y = uniform_random (0, height);
  66         cairo_line_to (cr, x, y);
  67     }
  68     cairo_close_path (cr);
  69
  70     cairo_set_source_rgb (cr, 1, 0, 0);
  71     cairo_fill_preserve (cr);
  72     cairo_set_source_rgb (cr, 0, 1, 0);
  73     cairo_set_line_width (cr, 0.5);
  74     cairo_stroke (cr);
  75
  76     return CAIRO_TEST_SUCCESS;
  77 }
  78
  79 int
  80 main (void)
  81 {
  82     return cairo_test (&test);
  83 }