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| 1 | +# Summary |
| 2 | +Proposal API for additional math types to bring it up to feature parity with other popular math libraries i.e. `SlimDX`, `SharpDX`, or `Stride3D`. Leveraging modern .NET features such as `INumber<T>` and vectorization. |
| 3 | + |
| 4 | +# Contributors |
| 5 | +- Daniel Keenan (dfkeenan) |
| 6 | + |
| 7 | +# Current Status |
| 8 | +- [x] Proposed |
| 9 | +- [ ] Discussed with API Review Board (ARB) |
| 10 | +- [ ] Approved |
| 11 | +- [ ] Implemented |
| 12 | + |
| 13 | +# Design Decisions |
| 14 | +- This proposal should compliment/augment the proposed 3.0 implementation of `Silk.Net.Maths`, matching `System.Numerics` where possible, with concessions for design oversights in that api. |
| 15 | +- This proposal assumes no knowledge of the 2.x Math library. |
| 16 | +- Text herein marked **INFORMATIVE** does not form a normative part of this proposal, and is for background only. |
| 17 | +- Within this proposal, the key words **must**, **required**, **shall**, **should**, **recommended**, **may**, **could**, and **optional** are to be interpreted as described in [RFC 2119 - Key words for use in RFCs to Indicate Requirement Levels](https://www.ietf.org/rfc/rfc2119.txt). The additional key word **optionally** is an alternate form of **optional**, for use where grammatically appropriate. These key words are highlighted in the proposal for clarity. |
| 18 | + |
| 19 | + |
| 20 | + |
| 21 | +# Proposed API |
| 22 | + |
| 23 | +## Angle |
| 24 | + |
| 25 | +* `IParsable<TSelf>`, `ISpanParsable<TSelf>`, `IUtf8SpanParsable<TSelf>` |
| 26 | + * must parse angle in degrees using `IParsable<TScalar>`, `ISpanParsable<TScalar>`, `IUtf8SpanParsable<TSelf>` |
| 27 | + * optional handle `°` character |
| 28 | + |
| 29 | +* `IFormattable`, `IUtf8SpanFormattable` |
| 30 | + * must produce text in degrees with default format of 2 decimal places. i.e. format string `0.##` |
| 31 | + * optional include `°` character. i.e. format string `0.##°` |
| 32 | + |
| 33 | +Interface implementations not included for brevity. |
| 34 | + |
| 35 | +```csharp |
| 36 | +/// <summary> |
| 37 | +/// Represents a unit independant angle using a floating-point |
| 38 | +/// internal representation. |
| 39 | +/// </summary> |
| 40 | +public readonly struct Angle<TScalar> |
| 41 | + : IEquatable<Angle<TScalar>> |
| 42 | + , IEqualityOperators<Angle<TScalar>,Angle<TScalar>, bool> |
| 43 | + , IComparable<Angle<TScalar>> |
| 44 | + , IComparisonOperators<Angle<TScalar>,Angle<TScalar>, bool> |
| 45 | + , IAdditionOperators<Angle<TScalar>,Angle<TScalar>,Angle<TScalar>> |
| 46 | + , IDivisionOperators<Angle<TScalar>, TScalar, Angle<TScalar>> |
| 47 | + , IDivisionOperators<TScalar, Angle<TScalar>, Angle<TScalar>> |
| 48 | + , IMultiplyOperators<Angle<TScalar>, TScalar, Angle<TScalar>> |
| 49 | + , IMultiplyOperators<TScalar, Angle<TScalar>, Angle<TScalar>> |
| 50 | + , IModulusOperators<Angle<TScalar>, Angle<TScalar>, Angle<TScalar>> |
| 51 | + , ISubtractionOperators<Angle<TScalar>,Angle<TScalar>,Angle<TScalar>> |
| 52 | + , IParsable<Angle<TScalar>> |
| 53 | + , ISpanParsable<Angle<TScalar>> |
| 54 | + , IUtf8SpanParsable<Angle<TScalar>> |
| 55 | + , IFormattable |
| 56 | + , IUtf8SpanFormattable |
| 57 | + where TScalar : IFloatingPointIeee754<TScalar> |
| 58 | +{ |
| 59 | + internal Angle(TScalar radians) { } |
| 60 | + |
| 61 | + /// <summary>Angle in degrees in the range [0, 360]. Without fractional component.</summary> |
| 62 | + public TScalar Degrees { get; } |
| 63 | + |
| 64 | + /// <summary>Angle in degrees in the range [0, 360]. With fractional component.</summary> |
| 65 | + public TScalar TotalDegrees { get; } |
| 66 | + |
| 67 | + /// <summary>Angle in radians in range [π, -π].</summary> |
| 68 | + public TScalar Radians { get; } |
| 69 | + |
| 70 | + /// <summary>Angle in radians in range [0, 2π].</summary> |
| 71 | + public TScalar PositiveRadians { get; } |
| 72 | + |
| 73 | + /// <summary>Gets or sets the minutes component of the degrees this Silk.NET.Maths.Angle<TScalar> represents.</summary> |
| 74 | + public TScalar Minutes { get; } |
| 75 | + |
| 76 | + /// <summary>Gets or sets the seconds of the degrees this Silk.NET.Maths.Angle<TScalar> represents.</summary> |
| 77 | + public TScalar Seconds { get; } |
| 78 | + |
| 79 | + |
| 80 | + /// <summary> |
| 81 | + /// Gets a System.Boolean that determines whether this Silk.NET.Maths.Angle<TScalar> |
| 82 | + /// is a right angle (i.e. 90° or π/2). |
| 83 | + /// </summary> |
| 84 | + public bool IsRight { get; } |
| 85 | + |
| 86 | + /// <summary> |
| 87 | + /// Gets a System.Boolean that determines whether this Silk.NET.Maths.Angle<TScalar> |
| 88 | + /// is a straight angle (i.e. 180° or π). |
| 89 | + /// </summary> |
| 90 | + public bool IsStraight { get; } |
| 91 | + |
| 92 | + /// <summary> |
| 93 | + /// Gets a System.Boolean that determines whether this Silk.NET.Maths.Angle<TScalar> |
| 94 | + /// is a full rotation angle (i.e. 360° or 2π). |
| 95 | + /// </summary> |
| 96 | + public bool IsFullRotation { get; } |
| 97 | + |
| 98 | + /// <summary> |
| 99 | + /// Gets a System.Boolean that determines whether this Silk.NET.Maths.Angle<TScalar> |
| 100 | + /// is an oblique angle (i.e. is not 90° or a multiple of 90°). |
| 101 | + /// </summary> |
| 102 | + public bool IsOblique { get; } |
| 103 | + |
| 104 | + /// <summary> |
| 105 | + /// Gets a System.Boolean that determines whether this Silk.NET.Maths.Angle<TScalar> |
| 106 | + /// is an acute angle (i.e. less than 90° but greater than 0°). |
| 107 | + /// </summary> |
| 108 | + public bool IsAcute { get; } |
| 109 | + |
| 110 | + /// <summary> |
| 111 | + /// Gets a System.Boolean that determines whether this Silk.NET.Maths.Angle<TScalar> |
| 112 | + /// is an obtuse angle (i.e. greater than 90° but less than 180°). |
| 113 | + /// </summary> |
| 114 | + public bool IsObtuse { get; } |
| 115 | + |
| 116 | + /// <summary> |
| 117 | + /// Gets a System.Boolean that determines whether this Silk.NET.Maths.Angle<TScalar> |
| 118 | + /// is a reflex angle (i.e. greater than 180° but less than 360°). |
| 119 | + /// </summary> |
| 120 | + public bool IsReflex { get; } |
| 121 | + |
| 122 | + /// <summary> |
| 123 | + /// Gets a Silk.NET.Maths.Angle<TScalar> instance that complements this angle (i.e. the two angles add to 90°). |
| 124 | + /// </summary> |
| 125 | + public Angle<TScalar> Complement { get; } |
| 126 | + |
| 127 | + /// <summary> |
| 128 | + /// Gets a Silk.NET.Maths.Angle<TScalar> instance that supplements this angle (i.e. the two angles add to 180°). |
| 129 | + /// </summary> |
| 130 | + public Angle<TScalar> Supplement { get; } |
| 131 | + |
| 132 | + /// <summary>Implicit cast in radians</summary> |
| 133 | + public static implicit operator TScalar(Angle<TScalar> angle) => default; |
| 134 | +} |
| 135 | + |
| 136 | +``` |
| 137 | + |
| 138 | + |
| 139 | + |
| 140 | +```csharp |
| 141 | + |
| 142 | +public static class Angle |
| 143 | +{ |
| 144 | + public static Angle<TScalar> FromRadians<TScalar>(TScalar radians) |
| 145 | + where TScalar : IFloatingPointIeee754<TScalar> |
| 146 | + => default; |
| 147 | + |
| 148 | + public static Angle<TScalar> FromDegrees<TScalar>(TScalar degrees) |
| 149 | + where TScalar : IFloatingPointIeee754<TScalar> |
| 150 | + => default; |
| 151 | + |
| 152 | + public static Angle<TScalar> FromDegrees<TScalar>(TScalar degrees, TScalar minutes, TScalar seconds) |
| 153 | + where TScalar : IFloatingPointIeee754<TScalar> |
| 154 | + => default; |
| 155 | + |
| 156 | + public static Angle<TScalar> Min<TScalar>(Angle<TScalar> left, Angle<TScalar> right) |
| 157 | + where TScalar : IFloatingPointIeee754<TScalar> |
| 158 | + => default; |
| 159 | + |
| 160 | + public static Angle<TScalar> Max<TScalar>(Angle<TScalar> left, Angle<TScalar> right) |
| 161 | + where TScalar : IFloatingPointIeee754<TScalar> |
| 162 | + => default; |
| 163 | + |
| 164 | + public static Angle<TScalar> Add<TScalar>(Angle<TScalar> left, Angle<TScalar> right) |
| 165 | + where TScalar : IFloatingPointIeee754<TScalar> |
| 166 | + => default; |
| 167 | + |
| 168 | + public static Angle<TScalar> Subtract<TScalar>(Angle<TScalar> left, Angle<TScalar> right) |
| 169 | + where TScalar : IFloatingPointIeee754<TScalar> |
| 170 | + => default; |
| 171 | + |
| 172 | + public static Angle<TScalar> Multiply<TScalar>(Angle<TScalar> left, TScalar right) |
| 173 | + where TScalar : IFloatingPointIeee754<TScalar> |
| 174 | + => default; |
| 175 | + |
| 176 | + public static Angle<TScalar> Divide<TScalar>(Angle<TScalar> left, TScalar right) |
| 177 | + where TScalar : IFloatingPointIeee754<TScalar> |
| 178 | + => default; |
| 179 | + |
| 180 | + public static Angle<TScalar> Clamp<TScalar>(Angle<TScalar> value, Angle<TScalar> min, Angle<TScalar> max) |
| 181 | + where TScalar : IFloatingPointIeee754<TScalar> |
| 182 | + => default; |
| 183 | + |
| 184 | + public static Angle<TScalar> Atan2<TScalar>(TScalar y, TScalar x) |
| 185 | + where TScalar : IFloatingPointIeee754<TScalar> |
| 186 | + => default; |
| 187 | + |
| 188 | + public static Angle<TScalar> ArcTan<TScalar>(TScalar y, TScalar x) |
| 189 | + where TScalar : IFloatingPointIeee754<TScalar> |
| 190 | + => default; |
| 191 | + |
| 192 | + public static Angle<TScalar> ArcSin<TScalar>(TScalar sin) |
| 193 | + where TScalar : IFloatingPointIeee754<TScalar> |
| 194 | + => default; |
| 195 | + |
| 196 | + public static Angle<TScalar> ArcCos<TScalar>(TScalar cos) |
| 197 | + where TScalar : IFloatingPointIeee754<TScalar> |
| 198 | + => default; |
| 199 | + |
| 200 | + public static Angle<TScalar> Between<TScalar>(in Vector2F<TScalar> left, in Vector2F<TScalar> right) |
| 201 | + where TScalar : IFloatingPointIeee754<TScalar> |
| 202 | + => default; |
| 203 | + |
| 204 | + public static Angle<TScalar> Between<TScalar>(in Vector3F<TScalar> left, in Vector3F<TScalar> right) |
| 205 | + where TScalar : IFloatingPointIeee754<TScalar> |
| 206 | + => default; |
| 207 | + |
| 208 | + public static Angle<TScalar> ZeroAngle<TScalar>() |
| 209 | + where TScalar : IFloatingPointIeee754<TScalar> |
| 210 | + => default; |
| 211 | + |
| 212 | + public static Angle<TScalar> RightAngle<TScalar>() |
| 213 | + where TScalar : IFloatingPointIeee754<TScalar> |
| 214 | + => default; |
| 215 | + |
| 216 | + public static Angle<TScalar> StraightAngle<TScalar>() |
| 217 | + where TScalar : IFloatingPointIeee754<TScalar> |
| 218 | + => default; |
| 219 | + |
| 220 | + public static Angle<TScalar> FullRotationAngle<TScalar>() |
| 221 | + where TScalar : IFloatingPointIeee754<TScalar> |
| 222 | + => default; |
| 223 | +} |
| 224 | +``` |
| 225 | + |
| 226 | +# Meeting Agenda/Notes |
| 227 | +## TDB |
| 228 | +* Degrees, minutes and seconds are not fractional. Should they be changed to an integer type (`int`)? |
| 229 | + * ```csharp |
| 230 | + public int Degrees { get; } |
| 231 | + public int Minutes { get; } |
| 232 | + public int Seconds { get; } |
| 233 | + |
| 234 | + public static Angle<TScalar> FromDegrees<TScalar>(int degrees, int minutes, int seconds) |
| 235 | + where TScalar : IFloatingPointIeee754<TScalar> |
| 236 | + => default; |
| 237 | + ``` |
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