From 6a5d10980ae37983c7bd65f32d253c3c4212ee5c Mon Sep 17 00:00:00 2001
From: Syntriax <syntriax@gmail.com>
Date: Tue, 23 Jan 2024 19:15:43 +0300
Subject: [PATCH] refactor: Triangle

---
 Engine.Physics2D/Primitives/Triangle.cs | 68 +++++++++++--------------
 1 file changed, 29 insertions(+), 39 deletions(-)

diff --git a/Engine.Physics2D/Primitives/Triangle.cs b/Engine.Physics2D/Primitives/Triangle.cs
index 5ffcd6a..8ab76ec 100644
--- a/Engine.Physics2D/Primitives/Triangle.cs
+++ b/Engine.Physics2D/Primitives/Triangle.cs
@@ -6,49 +6,39 @@ namespace Syntriax.Engine.Physics2D.Primitives;
 
 public record Triangle(Vector2D A, Vector2D B, Vector2D C)
 {
-    public float Area => MathF.Abs((
-            A.X * (B.Y - C.Y) +
-            B.X * (C.Y - A.Y) +
-            C.X * (A.Y - B.Y)
-            ) * .5f);
+    public float Area
+        => .5f * MathF.Abs(
+                A.X * (B.Y - C.Y) +
+                B.X * (C.Y - A.Y) +
+                C.X * (A.Y - B.Y)
+            );
 
-    public Circle CircumCircle
+    public static Circle GetCircumCircle(Triangle triangle)
     {
-        get
+        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)
         {
-            Vector2D midAB = (A + B) / 2;
-            Vector2D midBC = (B + C) / 2;
-
-            float slopeAB = (B.Y - A.Y) / (B.X - A.X);
-            float slopeBC = (C.Y - B.Y) / (C.X - B.X);
-
-            Vector2D center;
-            if (MathF.Abs(slopeAB - slopeBC) > float.Epsilon)
-            {
-                float x = (slopeAB * slopeBC * (A.Y - C.Y) + slopeBC * (A.X + B.X) - slopeAB * (B.X + C.X)) / (2 * (slopeBC - slopeAB));
-                float y = -(x - (A.X + B.X) / 2) / slopeAB + (A.Y + B.Y) / 2;
-                center = new Vector2D(x, y);
-            }
-            else
-                center = (midAB + midBC) * .5f;
-
-            return new(center, Vector2D.Distance(center, A));
+            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 bool Overlaps(Vector2D point)
-    {
-        float originalTriangleArea = Area;
-
-        float pointTriangleArea1 = new Triangle(point, B, C).Area;
-        float pointTriangleArea2 = new Triangle(A, point, C).Area;
-        float pointTriangleArea3 = new Triangle(A, B, point).Area;
-
-        float pointTriangleAreasSum = pointTriangleArea1 + pointTriangleArea2 + pointTriangleArea3;
-
-        return originalTriangleArea.ApproximatelyEquals(pointTriangleAreasSum, float.Epsilon * 3f);
-    }
-
-    public bool ApproximatelyEquals(Triangle other)
-        => A.ApproximatelyEquals(other.A) && B.ApproximatelyEquals(other.B) && C.ApproximatelyEquals(other.C);
+    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);
 }