1 /*
2 * Licensed to the Hipparchus project under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The Hipparchus project licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * https://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 package org.hipparchus.samples.complex;
19
20 import org.hipparchus.complex.Complex;
21 import org.hipparchus.util.FastMath;
22 import org.hipparchus.util.MathUtils;
23
24 /** Domain coloring enhancing both phase and module changes.
25 * <p>
26 * Value encodes both phase and module using two sawtooth functions.
27 * </p>
28 * <p>
29 * The sawtooth functions are computed from a natural logarithm and fractional parts.
30 * They enhance both phase and modules changes with discontinuities and dark cells.
31 * </p>
32 */
33 public class SawToothPhaseModuleValue extends DomainColoring {
34
35 /** Minimum brightness. */
36 private final double minBrightness;
37
38 /** Maximum brightness. */
39 private final double maxBrightness;
40
41 /** Number of lines per cycle. */
42 private final int nbLines;
43
44 /** Simple constructor.
45 * @param saturation constant saturation
46 * @param minBrightness minimum brightness
47 * @param maxBrightness maximum brightness
48 * @param nbLines number of lines per cycle
49 */
50 protected SawToothPhaseModuleValue(final double saturation,
51 final double minBrightness, final double maxBrightness,
52 final int nbLines) {
53 super(saturation);
54 this.minBrightness = minBrightness;
55 this.maxBrightness = maxBrightness;
56 this.nbLines = nbLines;
57 }
58
59 /** Compute periodic fractional brightness.
60 * @param x continuous value
61 * @param s scaling factor
62 * @return fractional brightness
63 */
64 private double fractionalBrightness(final double x, final double s) {
65 double f = x * nbLines / s;
66 return minBrightness + (maxBrightness - minBrightness) * (f - FastMath.floor(f));
67 }
68
69 /** {@inheritDoc} */
70 @Override
71 public double value(final Complex z) {
72 final double module = z.norm();
73 final double bM = fractionalBrightness(FastMath.log(module), MathUtils.TWO_PI);
74 final double bP = fractionalBrightness(hue(z), 1.0);
75 return bM * bP;
76 }
77
78 }