1 package org.djunits.quantity;
2
3 import org.djunits.quantity.def.Quantity;
4 import org.djunits.unit.AbstractUnit;
5 import org.djunits.unit.UnitRuntimeException;
6 import org.djunits.unit.Unitless;
7 import org.djunits.unit.scale.LinearScale;
8 import org.djunits.unit.scale.Scale;
9 import org.djunits.unit.si.SIUnit;
10 import org.djunits.unit.system.UnitSystem;
11
12 /**
13 * Solid angle is the two-dimensional angle in three-dimensional space, measured in steradians (sr).
14 * <p>
15 * Copyright (c) 2025-2026 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved. See
16 * for project information <a href="https://djunits.org" target="_blank">https://djunits.org</a>. The DJUNITS project is
17 * distributed under a <a href="https://djunits.org/docs/license.html" target="_blank">three-clause BSD-style license</a>.
18 * @author Alexander Verbraeck
19 */
20 public class SolidAngle extends Quantity<SolidAngle>
21 {
22 /** Constant with value zero. */
23 public static final SolidAngle ZERO = ofSi(0.0);
24
25 /** Constant with value one. */
26 public static final SolidAngle ONE = ofSi(1.0);
27
28 /** Constant with value NaN. */
29 @SuppressWarnings("checkstyle:constantname")
30 public static final SolidAngle NaN = ofSi(Double.NaN);
31
32 /** Constant with value POSITIVE_INFINITY. */
33 public static final SolidAngle POSITIVE_INFINITY = ofSi(Double.POSITIVE_INFINITY);
34
35 /** Constant with value NEGATIVE_INFINITY. */
36 public static final SolidAngle NEGATIVE_INFINITY = ofSi(Double.NEGATIVE_INFINITY);
37
38 /** Constant with value MAX_VALUE. */
39 public static final SolidAngle POS_MAXVALUE = ofSi(Double.MAX_VALUE);
40
41 /** Constant with value -MAX_VALUE. */
42 public static final SolidAngle NEG_MAXVALUE = ofSi(-Double.MAX_VALUE);
43
44 /** */
45 private static final long serialVersionUID = 600L;
46
47 /**
48 * Instantiate a SolidAngle quantity with a unit.
49 * @param valueInUnit the value, expressed in the unit
50 * @param unit the unit in which the value is expressed
51 */
52 public SolidAngle(final double valueInUnit, final SolidAngle.Unit unit)
53 {
54 super(valueInUnit, unit);
55 }
56
57 /**
58 * Return a SolidAngle instance based on an SI value.
59 * @param si the si value
60 * @return the SolidAngle instance based on an SI value
61 */
62 public static SolidAngle ofSi(final double si)
63 {
64 return new SolidAngle(si, SolidAngle.Unit.SI);
65 }
66
67 @Override
68 public SolidAngle instantiateSi(final double si)
69 {
70 return ofSi(si);
71 }
72
73 @Override
74 public SIUnit siUnit()
75 {
76 return SolidAngle.Unit.SI_UNIT;
77 }
78
79 /**
80 * Returns a SolidAngle representation of a textual representation of a value with a unit. The String representation that
81 * can be parsed is the double value in the unit, followed by a localized or English abbreviation of the unit. Spaces are
82 * allowed, but not required, between the value and the unit.
83 * @param text the textual representation to parse into a SolidAngle
84 * @return the Scalar representation of the value in its unit
85 * @throws IllegalArgumentException when the text cannot be parsed
86 * @throws NullPointerException when the text argument is null
87 */
88 public static SolidAngle valueOf(final String text)
89 {
90 return Quantity.valueOf(text, ZERO);
91 }
92
93 /**
94 * Returns a SolidAngle based on a value and the textual representation of the unit, which can be localized.
95 * @param valueInUnit the value, expressed in the unit as given by unitString
96 * @param unitString the textual representation of the unit
97 * @return the Scalar representation of the value in its unit
98 * @throws IllegalArgumentException when the unit cannot be parsed or is incorrect
99 * @throws NullPointerException when the unitString argument is null
100 */
101 public static SolidAngle of(final double valueInUnit, final String unitString)
102 {
103 return Quantity.of(valueInUnit, unitString, ZERO);
104 }
105
106 @Override
107 public SolidAngle.Unit getDisplayUnit()
108 {
109 return (SolidAngle.Unit) super.getDisplayUnit();
110 }
111
112 /**
113 * Calculate the division of SolidAngle and SolidAngle, which results in a Dimensionless quantity.
114 * @param v quantity
115 * @return quantity as a division of SolidAngle and SolidAngle
116 */
117 public final Dimensionless divide(final SolidAngle v)
118 {
119 return new Dimensionless(this.si() / v.si(), Unitless.BASE);
120 }
121
122 /**
123 * Calculate the multiplication of SolidAngle and LuminousIntensity, which results in a LuminousFlux scalar.
124 * @param v scalar
125 * @return scalar as a multiplication of SolidAngle and LuminousIntensity
126 */
127 public final LuminousFlux multiply(final LuminousIntensity v)
128 {
129 return new LuminousFlux(this.si() * v.si(), LuminousFlux.Unit.SI);
130 }
131
132 /******************************************************************************************************/
133 /********************************************** UNIT CLASS ********************************************/
134 /******************************************************************************************************/
135
136 /**
137 * SolidAngle.Unit encodes the units of solid angles.
138 * <p>
139 * Copyright (c) 2025-2026 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved.
140 * See for project information <a href="https://djunits.org" target="_blank">https://djunits.org</a>. The DJUNITS project is
141 * distributed under a <a href="https://djunits.org/docs/license.html" target="_blank">three-clause BSD-style license</a>.
142 * @author Alexander Verbraeck
143 */
144 @SuppressWarnings("checkstyle:constantname")
145 public static class Unit extends AbstractUnit<SolidAngle.Unit, SolidAngle>
146 {
147 /** The dimensions of the solid angle: sr. */
148 public static final SIUnit SI_UNIT = SIUnit.of("sr");
149
150 /** Steradian. */
151 public static final SolidAngle.Unit sr = new SolidAngle.Unit("sr", "steradian", 1.0, UnitSystem.SI_DERIVED);
152
153 /** The SI or BASE unit. */
154 public static final SolidAngle.Unit SI = sr;
155
156 /** square degree. */
157 public static final SolidAngle.Unit sq_deg =
158 sr.deriveUnit("sq.deg", "square degree", (Math.PI / 180.0) * (Math.PI / 180.0), UnitSystem.SI_DERIVED);
159
160 /**
161 * Create a new SolidAngle unit.
162 * @param id the id or main abbreviation of the unit
163 * @param name the full name of the unit
164 * @param scaleFactorToBaseUnit the scale factor of the unit to convert it TO the base (SI) unit
165 * @param unitSystem the unit system such as SI or IMPERIAL
166 */
167 public Unit(final String id, final String name, final double scaleFactorToBaseUnit, final UnitSystem unitSystem)
168 {
169 super(id, name, new LinearScale(scaleFactorToBaseUnit), unitSystem);
170 }
171
172 /**
173 * Return a derived unit for this unit, with textual abbreviation(s) and a display abbreviation.
174 * @param textualAbbreviation the textual abbreviation of the unit, which doubles as the id
175 * @param displayAbbreviation the display abbreviation of the unit
176 * @param name the full name of the unit
177 * @param scale the scale to use to convert between this unit and the standard (e.g., SI, BASE) unit
178 * @param unitSystem unit system, e.g. SI or Imperial
179 */
180 public Unit(final String textualAbbreviation, final String displayAbbreviation, final String name, final Scale scale,
181 final UnitSystem unitSystem)
182 {
183 super(textualAbbreviation, displayAbbreviation, name, scale, unitSystem);
184 }
185
186 @Override
187 public SIUnit siUnit()
188 {
189 return SI_UNIT;
190 }
191
192 @Override
193 public Unit getBaseUnit()
194 {
195 return SI;
196 }
197
198 @Override
199 public SolidAngle ofSi(final double si)
200 {
201 return SolidAngle.ofSi(si);
202 }
203
204 @Override
205 public Unit deriveUnit(final String textualAbbreviation, final String displayAbbreviation, final String name,
206 final double scaleFactor, final UnitSystem unitSystem)
207 {
208 if (getScale() instanceof LinearScale ls)
209 {
210 return new SolidAngle.Unit(textualAbbreviation, displayAbbreviation, name,
211 new LinearScale(ls.getScaleFactorToBaseUnit() * scaleFactor), unitSystem);
212 }
213 throw new UnitRuntimeException("Only possible to derive a unit from a unit with a linear scale");
214 }
215
216 }
217 }