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perlinNoise2.cxx
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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 perlinNoise2.cxx
10 * @author drose
11 * @date 2005-10-05
12 */
13
14#include "perlinNoise2.h"
15#include "cmath.h"
16
17/**
18 * Returns the noise function of the three inputs.
19 */
21noise(const LVecBase2d &value) const {
22 // If this triggers, you passed in 0 for table_size.
23 nassertr(!_index.empty(), make_nan(0.0));
24
25 // Convert the vector to our local coordinate space.
26 LVecBase2d vec = _input_xform.xform_point(value);
27
28 double x = vec[0];
29 double y = vec[1];
30
31 // Find unit square that contains point.
32 double xf = cfloor(x);
33 double yf = cfloor(y);
34
35 int X = ((int)xf) & _table_size_mask;
36 int Y = ((int)yf) & _table_size_mask;
37
38 // Find relative x,y of point in square.
39 x -= xf;
40 y -= yf;
41
42 // Compute fade curves for each of x,y.
43 double u = fade(x);
44 double v = fade(y);
45
46 // Hash coordinates of the 4 square corners (A, B, A + 1, and B + 1)
47 nassertr(X >= 0 && X + 1 < _index.size(), make_nan(0.0));
48 int A = _index[X] + Y;
49 int B = _index[X + 1] + Y;
50
51 nassertr(A >= 0 && A + 1 < _index.size(), make_nan(0.0));
52 nassertr(B >= 0 && B + 1 < _index.size(), make_nan(0.0));
53
54 // and add blended results from 4 corners of square.
55 double result =
56 lerp(v, lerp(u, grad(_index[A], x, y),
57 grad(_index[B], x - 1, y)),
58 lerp(u, grad(_index[A + 1], x, y - 1),
59 grad(_index[B + 1], x - 1, y - 1)));
60
61 return result;
62}
63
64/**
65 * Come up with a random rotation to apply to the input coordinates. This
66 * will reduce the problem of the singularities on the axes, by sending the
67 * axes in some crazy direction.
68 */
69void PerlinNoise2::
70init_unscaled_xform() {
71 double rot = _randomizer.random_real(360.0f);
72 _unscaled_xform = LMatrix3d::rotate_mat(rot);
73
74 // And come up with a random translation too, just so the singularity at (0,
75 // 0) is also unpredicatable.
76 _unscaled_xform.set_row(2, LVecBase2d(_randomizer.random_real_unit(),
77 _randomizer.random_real_unit()));
78}
double noise(double x, double y) const
Returns the noise function of the three inputs.
PANDA 3D SOFTWARE Copyright (c) Carnegie Mellon University.
PANDA 3D SOFTWARE Copyright (c) Carnegie Mellon University.