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randomizer.I
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1/**
2 * PANDA 3D SOFTWARE
3 * Copyright (c) Carnegie Mellon University. All rights reserved.
4 *
5 * All use of this software is subject to the terms of the revised BSD
6 * license. You should have received a copy of this license along
7 * with this source code in a file named "LICENSE."
8 *
9 * @file randomizer.I
10 * @author drose
11 * @date 2007-01-18
12 */
13
14/**
15 * If seed is nonzero, it is used to define the tables; if it is zero a random
16 * seed is generated.
17 */
19Randomizer(unsigned long seed) :
20 _mersenne(seed != 0 ? seed : get_next_seed())
21{
22}
23
24/**
25 *
26 */
28Randomizer(const Randomizer &copy) :
29 _mersenne(copy._mersenne)
30{
31}
32
33/**
34 *
35 */
36void Randomizer::
37operator = (const Randomizer &copy) {
38 _mersenne = copy._mersenne;
39}
40
41/**
42 * Returns a random integer in the range [0, range).
43 */
44INLINE int Randomizer::
45random_int(int range) {
46 return (int)floor(random_real((double)range));
47}
48
49/**
50 * Returns a random double in the range [0, range).
51 */
52INLINE double Randomizer::
53random_real(double range) {
54 return (range * _mersenne.get_uint31()) / ((double)0x80000000);
55}
56
57/**
58 * Returns a random double in the range [-0.5, 0.5).
59 */
60INLINE double Randomizer::
62 return random_real(1.0f) - 0.5f;
63}
64
65/**
66 * Returns a random seed value for the next global Randomizer object.
67 */
68INLINE unsigned long Randomizer::
70 if (!_got_first_seed) {
71 _next_seed = Mersenne((unsigned long)time(nullptr));
72 _got_first_seed = true;
73 }
74 return _next_seed.get_uint31();
75}
76
77/**
78 * Returns a unique seed value based on the seed value passed to this
79 * Randomizer object (and on its current state).
80 */
81INLINE unsigned long Randomizer::
82get_seed() {
83 return _mersenne.get_uint31();
84}
A handy class to return random numbers.
Definition randomizer.h:26
double random_real_unit()
Returns a random double in the range [-0.5, 0.5).
Definition randomizer.I:61
Randomizer(unsigned long seed=0)
If seed is nonzero, it is used to define the tables; if it is zero a random seed is generated.
Definition randomizer.I:19
unsigned long get_seed()
Returns a unique seed value based on the seed value passed to this Randomizer object (and on its curr...
Definition randomizer.I:82
double random_real(double range)
Returns a random double in the range [0, range).
Definition randomizer.I:53
static unsigned long get_next_seed()
Returns a random seed value for the next global Randomizer object.
Definition randomizer.I:69
int random_int(int range)
Returns a random integer in the range [0, range).
Definition randomizer.I:45