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.Units;
8 import org.djunits.unit.scale.LinearScale;
9 import org.djunits.unit.scale.Scale;
10 import org.djunits.unit.si.SIUnit;
11 import org.djunits.unit.system.UnitSystem;
12
13 /**
14 * Solid angle is the two-dimensional angle in three-dimensional space, measured in steradians (sr).
15 * <p>
16 * Copyright (c) 2025-2026 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved. See
17 * for project information <a href="https://djunits.org" target="_blank">https://djunits.org</a>. The DJUNITS project is
18 * distributed under a <a href="https://djunits.org/docs/license.html" target="_blank">three-clause BSD-style license</a>.
19 * @author Alexander Verbraeck
20 */
21 public class SolidAngle extends Quantity<SolidAngle>
22 {
23 /** Constant with value zero. */
24 public static final SolidAngle ZERO = SolidAngle.ofSi(0.0);
25
26 /** Constant with value one. */
27 public static final SolidAngle ONE = SolidAngle.ofSi(1.0);
28
29 /** Constant with value NaN. */
30 @SuppressWarnings("checkstyle:constantname")
31 public static final SolidAngle NaN = SolidAngle.ofSi(Double.NaN);
32
33 /** Constant with value POSITIVE_INFINITY. */
34 public static final SolidAngle POSITIVE_INFINITY = SolidAngle.ofSi(Double.POSITIVE_INFINITY);
35
36 /** Constant with value NEGATIVE_INFINITY. */
37 public static final SolidAngle NEGATIVE_INFINITY = SolidAngle.ofSi(Double.NEGATIVE_INFINITY);
38
39 /** Constant with value MAX_VALUE. */
40 public static final SolidAngle POS_MAXVALUE = SolidAngle.ofSi(Double.MAX_VALUE);
41
42 /** Constant with value -MAX_VALUE. */
43 public static final SolidAngle NEG_MAXVALUE = SolidAngle.ofSi(-Double.MAX_VALUE);
44
45 /** */
46 private static final long serialVersionUID = 600L;
47
48 /**
49 * Instantiate a SolidAngle quantity with a unit.
50 * @param valueInUnit the value, expressed in the unit
51 * @param unit the unit in which the value is expressed
52 */
53 public SolidAngle(final double valueInUnit, final SolidAngle.Unit unit)
54 {
55 super(valueInUnit, unit);
56 }
57
58 /**
59 * Instantiate a SolidAngle quantity with a unit, expressed as a String.
60 * @param valueInUnit the value, expressed in the unit
61 * @param abbreviation the String abbreviation of the unit in which the value is expressed
62 */
63 public SolidAngle(final double valueInUnit, final String abbreviation)
64 {
65 this(valueInUnit, Units.resolve(SolidAngle.Unit.class, abbreviation));
66 }
67
68 /**
69 * Construct SolidAngle quantity.
70 * @param value Scalar from which to construct this instance
71 */
72 public SolidAngle(final SolidAngle value)
73 {
74 super(value.si(), SolidAngle.Unit.SI);
75 setDisplayUnit(value.getDisplayUnit());
76 }
77
78 /**
79 * Return a SolidAngle instance based on an SI value.
80 * @param si the si value
81 * @return the SolidAngle instance based on an SI value
82 */
83 public static SolidAngle ofSi(final double si)
84 {
85 return new SolidAngle(si, SolidAngle.Unit.SI);
86 }
87
88 @Override
89 public SolidAngle instantiateSi(final double si)
90 {
91 return ofSi(si);
92 }
93
94 @Override
95 public SIUnit siUnit()
96 {
97 return SolidAngle.Unit.SI_UNIT;
98 }
99
100 /**
101 * Returns a SolidAngle representation of a textual representation of a value with a unit. The String representation that
102 * can be parsed is the double value in the unit, followed by a localized or English abbreviation of the unit. Spaces are
103 * allowed, but not required, between the value and the unit.
104 * @param text the textual representation to parse into a SolidAngle
105 * @return the Scalar representation of the value in its unit
106 * @throws IllegalArgumentException when the text cannot be parsed
107 * @throws NullPointerException when the text argument is null
108 */
109 public static SolidAngle valueOf(final String text)
110 {
111 return Quantity.valueOf(text, ZERO);
112 }
113
114 /**
115 * Returns a SolidAngle based on a value and the textual representation of the unit, which can be localized.
116 * @param valueInUnit the value, expressed in the unit as given by unitString
117 * @param unitString the textual representation of the unit
118 * @return the Scalar representation of the value in its unit
119 * @throws IllegalArgumentException when the unit cannot be parsed or is incorrect
120 * @throws NullPointerException when the unitString argument is null
121 */
122 public static SolidAngle of(final double valueInUnit, final String unitString)
123 {
124 return Quantity.of(valueInUnit, unitString, ZERO);
125 }
126
127 @Override
128 public SolidAngle.Unit getDisplayUnit()
129 {
130 return (SolidAngle.Unit) super.getDisplayUnit();
131 }
132
133 /**
134 * Calculate the division of SolidAngle and SolidAngle, which results in a Dimensionless quantity.
135 * @param v quantity
136 * @return quantity as a division of SolidAngle and SolidAngle
137 */
138 public final Dimensionless divide(final SolidAngle v)
139 {
140 return new Dimensionless(this.si() / v.si(), Unitless.BASE);
141 }
142
143 /**
144 * Calculate the multiplication of SolidAngle and LuminousIntensity, which results in a LuminousFlux scalar.
145 * @param v scalar
146 * @return scalar as a multiplication of SolidAngle and LuminousIntensity
147 */
148 public final LuminousFlux multiply(final LuminousIntensity v)
149 {
150 return new LuminousFlux(this.si() * v.si(), LuminousFlux.Unit.SI);
151 }
152
153 /******************************************************************************************************/
154 /********************************************** UNIT CLASS ********************************************/
155 /******************************************************************************************************/
156
157 /**
158 * SolidAngle.Unit encodes the units of solid angles.
159 * <p>
160 * Copyright (c) 2025-2026 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved.
161 * See for project information <a href="https://djunits.org" target="_blank">https://djunits.org</a>. The DJUNITS project is
162 * distributed under a <a href="https://djunits.org/docs/license.html" target="_blank">three-clause BSD-style license</a>.
163 * @author Alexander Verbraeck
164 */
165 @SuppressWarnings("checkstyle:constantname")
166 public static class Unit extends AbstractUnit<SolidAngle.Unit, SolidAngle>
167 {
168 /** The dimensions of the solid angle: sr. */
169 public static final SIUnit SI_UNIT = SIUnit.of("sr");
170
171 /** Steradian. */
172 public static final SolidAngle.Unit sr = new SolidAngle.Unit("sr", "steradian", 1.0, UnitSystem.SI_DERIVED);
173
174 /** The SI or BASE unit. */
175 public static final SolidAngle.Unit SI = sr;
176
177 /** square degree. */
178 public static final SolidAngle.Unit sq_deg =
179 sr.deriveUnit("sq.deg", "square degree", (Math.PI / 180.0) * (Math.PI / 180.0), UnitSystem.SI_DERIVED);
180
181 /**
182 * Create a new SolidAngle unit.
183 * @param id the id or main abbreviation of the unit
184 * @param name the full name of the unit
185 * @param scaleFactorToBaseUnit the scale factor of the unit to convert it TO the base (SI) unit
186 * @param unitSystem the unit system such as SI or IMPERIAL
187 */
188 public Unit(final String id, final String name, final double scaleFactorToBaseUnit, final UnitSystem unitSystem)
189 {
190 super(id, name, new LinearScale(scaleFactorToBaseUnit), unitSystem);
191 }
192
193 /**
194 * Return a derived unit for this unit, with textual abbreviation(s) and a display abbreviation.
195 * @param textualAbbreviation the textual abbreviation of the unit, which doubles as the id
196 * @param displayAbbreviation the display abbreviation of the unit
197 * @param name the full name of the unit
198 * @param scale the scale to use to convert between this unit and the standard (e.g., SI, BASE) unit
199 * @param unitSystem unit system, e.g. SI or Imperial
200 */
201 public Unit(final String textualAbbreviation, final String displayAbbreviation, final String name, final Scale scale,
202 final UnitSystem unitSystem)
203 {
204 super(textualAbbreviation, displayAbbreviation, name, scale, unitSystem);
205 }
206
207 @Override
208 public SIUnit siUnit()
209 {
210 return SI_UNIT;
211 }
212
213 @Override
214 public Unit getBaseUnit()
215 {
216 return SI;
217 }
218
219 @Override
220 public SolidAngle ofSi(final double si)
221 {
222 return SolidAngle.ofSi(si);
223 }
224
225 @Override
226 public Unit deriveUnit(final String textualAbbreviation, final String displayAbbreviation, final String name,
227 final double scaleFactor, final UnitSystem unitSystem)
228 {
229 if (getScale() instanceof LinearScale ls)
230 {
231 return new SolidAngle.Unit(textualAbbreviation, displayAbbreviation, name,
232 new LinearScale(ls.getScaleFactorToBaseUnit() * scaleFactor), unitSystem);
233 }
234 throw new UnitRuntimeException("Only possible to derive a unit from a unit with a linear scale");
235 }
236
237 }
238 }