Developer Documentation
RandomNumberGenerator.cc
1 /* ========================================================================= *
2  * *
3  * OpenMesh *
4  * Copyright (c) 2001-2015, RWTH-Aachen University *
5  * Department of Computer Graphics and Multimedia *
6  * All rights reserved. *
7  * www.openmesh.org *
8  * *
9  *---------------------------------------------------------------------------*
10  * This file is part of OpenMesh. *
11  *---------------------------------------------------------------------------*
12  * *
13  * Redistribution and use in source and binary forms, with or without *
14  * modification, are permitted provided that the following conditions *
15  * are met: *
16  * *
17  * 1. Redistributions of source code must retain the above copyright notice, *
18  * this list of conditions and the following disclaimer. *
19  * *
20  * 2. Redistributions in binary form must reproduce the above copyright *
21  * notice, this list of conditions and the following disclaimer in the *
22  * documentation and/or other materials provided with the distribution. *
23  * *
24  * 3. Neither the name of the copyright holder nor the names of its *
25  * contributors may be used to endorse or promote products derived from *
26  * this software without specific prior written permission. *
27  * *
28  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS *
29  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED *
30  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A *
31  * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER *
32  * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, *
33  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, *
34  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR *
35  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF *
36  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING *
37  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS *
38  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. *
39  * *
40  * ========================================================================= */
41 
42 //=============================================================================
43 //
44 // Helper Functions for generating a random number between 0.0 and 1.0 with
45 // a garantueed resolution
46 //
47 //=============================================================================
48 
49 
50 //== INCLUDES =================================================================
51 
52 
53 #include <OpenMesh/Core/Utils/RandomNumberGenerator.hh>
54 
55 
56 //== NAMESPACES ===============================================================
57 
58 
59 namespace OpenMesh {
60 
61 
62 //== IMPLEMENTATION ===========================================================
63 
65  resolution_(_resolution),
66  iterations_(1),
67  maxNum_(RAND_MAX + 1.0)
68 {
69  double tmp = double(resolution_);
70  while (tmp > (double(RAND_MAX) + 1.0) ) {
71  iterations_++;
72  tmp /= (double(RAND_MAX) + 1.0);
73  }
74 
75  for ( unsigned int i = 0 ; i < iterations_ - 1; ++i ) {
76  maxNum_ *= (RAND_MAX + 1.0);
77  }
78 }
79 
80 //-----------------------------------------------------------------------------
81 
83  double randNum = 0.0;
84  for ( unsigned int i = 0 ; i < iterations_; ++i ) {
85  randNum *= (RAND_MAX + 1.0);
86  randNum += rand();
87  }
88 
89  return randNum / maxNum_;
90 }
91 
92 double RandomNumberGenerator::resolution() const {
93  return maxNum_;
94 }
95 
96 //=============================================================================
97 } // namespace OpenMesh
98 //=============================================================================
RandomNumberGenerator(const size_t _resolution)
Constructor.
double getRand() const
returns a random double between 0.0 and 1.0 with a guaranteed resolution
double maxNum_
maximum random number generated, which is used for normalization
size_t iterations_
number of "blocks" of RAND_MAX that make up the desired _resolution
const size_t resolution_
desired resolution