refactor: moved 2D primitives from Physics2D to Core

Engine.Core/Primitives/Triangle.cs

@@ -0,0 +1,47 @@
+using System;
+
+namespace Syntriax.Engine.Core;
+
+[System.Diagnostics.DebuggerDisplay("A: {A.ToString(), nq}, B: {B.ToString(), nq}, B: {C.ToString(), nq}")]
+public readonly struct Triangle(Vector2D A, Vector2D B, Vector2D C)
+{
+    public readonly Vector2D A { get; init; } = A;
+    public readonly Vector2D B { get; init; } = B;
+    public readonly Vector2D C { get; init; } = C;
+
+    public readonly float Area
+        => .5f * MathF.Abs(
+                A.X * (B.Y - C.Y) +
+                B.X * (C.Y - A.Y) +
+                C.X * (A.Y - B.Y)
+            );
+
+    public static Circle GetCircumCircle(Triangle triangle)
+    {
+        Vector2D midAB = (triangle.A + triangle.B) / 2f;
+        Vector2D midBC = (triangle.B + triangle.C) / 2f;
+
+        float slopeAB = (triangle.B.Y - triangle.A.Y) / (triangle.B.X - triangle.A.X);
+        float slopeBC = (triangle.C.Y - triangle.B.Y) / (triangle.C.X - triangle.B.X);
+
+        Vector2D center;
+        if (MathF.Abs(slopeAB - slopeBC) > float.Epsilon)
+        {
+            float x = (slopeAB * slopeBC * (triangle.A.Y - triangle.C.Y) + slopeBC * (triangle.A.X + triangle.B.X) - slopeAB * (triangle.B.X + triangle.C.X)) / (2f * (slopeBC - slopeAB));
+            float y = -(x - (triangle.A.X + triangle.B.X) / 2f) / slopeAB + (triangle.A.Y + triangle.B.Y) / 2f;
+            center = new Vector2D(x, y);
+        }
+        else
+            center = (midAB + midBC) * .5f;
+
+        return new(center, Vector2D.Distance(center, triangle.A));
+    }
+
+    public static bool ApproximatelyEquals(Triangle left, Triangle right)
+        => left.A.ApproximatelyEquals(right.A) && left.B.ApproximatelyEquals(right.B) && left.C.ApproximatelyEquals(right.C);
+}
+
+public static class TriangleExtensions
+{
+    public static bool ApproximatelyEquals(this Triangle left, Triangle right) => Triangle.ApproximatelyEquals(left, right);
+}