fix: CS0660, CS0661

Author: ikpil

src/Box2D.NET/B2BodyId.cs

@@ -2,13 +2,14 @@
 // SPDX-FileCopyrightText: 2025 Ikpil Choi(ikpil@naver.com)
 // SPDX-License-Identifier: MIT
 
+using System;
 using System.Runtime.CompilerServices;
 using static Box2D.NET.B2Ids;
 
 namespace Box2D.NET
 {
     /// Body id references a body instance. This should be treated as an opaque handle.
-    public readonly struct B2BodyId
+    public readonly struct B2BodyId : IEquatable<B2BodyId>
     {
         public readonly int index1;
         public readonly ushort world0;
@@ -50,5 +51,27 @@ public B2BodyId(int index1, ushort world0, ushort generation)
         {
             return !(a == b);
         }
+
+        public bool Equals(B2BodyId other)
+        {
+            return this == other;
+        }
+
+        public override bool Equals(object obj)
+        {
+            if (obj is B2BodyId other)
+            {
+                return Equals(other);
+            }
+
+            return false;
+        }
+
+        // GetHashCode 메서드 구현
+        public override int GetHashCode()
+        {
+            ulong ua = b2StoreBodyId(this);
+            return ua.GetHashCode();
+        }
     }
 }

src/Box2D.NET/B2Vec2.cs

@@ -2,6 +2,7 @@
 // SPDX-FileCopyrightText: 2025 Ikpil Choi(ikpil@naver.com)
 // SPDX-License-Identifier: MIT
 
+using System;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 
@@ -10,7 +11,7 @@ namespace Box2D.NET
     /// 2D vector
     /// This can be used to represent a point or free vector
     [StructLayout(LayoutKind.Sequential)]
-    public struct B2Vec2
+    public struct B2Vec2 : IEquatable<B2Vec2>
     {
         /// coordinates
         public float X, Y;
@@ -76,5 +77,25 @@ public B2Vec2(float x, float y)
         {
             return !(a == b);
         }
+
+        public bool Equals(B2Vec2 other)
+        {
+            return this == other;
+        }
+
+        public override bool Equals(object obj)
+        {
+            if (obj is B2Vec2 other)
+            {
+                return Equals(other);
+            }
+
+            return false;
+        }
+
+        public override int GetHashCode()
+        {
+            return (X, Y).GetHashCode();
+        }
     }
 }

src/Box2D.NET/B2Worlds.cs

@@ -873,7 +873,7 @@ internal static void b2DrawShape(B2DebugDraw draw, B2Shape shape, B2Transform xf
 
                 case B2ShapeType.b2_polygonShape:
                 {
-                    ref readonly B2Polygon poly = ref shape.us.polygon;
+                    ref B2Polygon poly = ref shape.us.polygon;
                     draw.DrawSolidPolygonFcn(xf, poly.vertices.AsSpan(), poly.count, poly.radius, color, draw.context);
                 }
                     break;