From 1c95dd1591848ebcf0a33a0e2d357889d2271bcb Mon Sep 17 00:00:00 2001
From: Evan Hemsley <evan@moonside.games>
Date: Fri, 25 Oct 2019 13:14:37 -0700
Subject: [PATCH] optimized EPA2D

---
 Bonk/Bonk.csproj        |  1 +
 Bonk/EPA2D.cs           | 14 +++----
 Bonk/SimplexVertices.cs | 91 -----------------------------------------
 3 files changed, 8 insertions(+), 98 deletions(-)
 delete mode 100644 Bonk/SimplexVertices.cs

diff --git a/Bonk/Bonk.csproj b/Bonk/Bonk.csproj
index 7999b43..2110f49 100644
--- a/Bonk/Bonk.csproj
+++ b/Bonk/Bonk.csproj
@@ -17,5 +17,6 @@
   <ItemGroup>
     <PackageReference Include="MoonTools.Core.Structs" Version="1.0.1"/>
     <PackageReference Include="morelinq" Version="3.2.0"/>
+    <PackageReference Include="Collections.Pooled" Version="1.0.82"/>
   </ItemGroup>
 </Project>
\ No newline at end of file
diff --git a/Bonk/EPA2D.cs b/Bonk/EPA2D.cs
index 6b3e1a5..9b04e43 100644
--- a/Bonk/EPA2D.cs
+++ b/Bonk/EPA2D.cs
@@ -4,11 +4,10 @@
  * https://blog.hamaluik.ca/posts/building-a-collision-engine-part-2-2d-penetration-vectors/
  */
 
+using Collections.Pooled;
 using Microsoft.Xna.Framework;
-using MoonTools.Core.Bonk.Extensions;
 using MoonTools.Core.Structs;
 using System;
-using System.Collections.Generic;
 
 namespace MoonTools.Core.Bonk
 {
@@ -18,15 +17,14 @@ namespace MoonTools.Core.Bonk
         CounterClockwise
     }
 
-    // TODO: convert SimplexVertices to PooledList
     public static class EPA2D
     {
         // vector returned gives direction from A to B
-        public static Vector2 Intersect(IShape2D shapeA, Transform2D Transform2DA, IShape2D shapeB, Transform2D Transform2DB, Simplex givenSimplex)
+        public static Vector2 Intersect(IShape2D shapeA, Transform2D Transform2DA, IShape2D shapeB, Transform2D Transform2DB, Simplex simplex)
         {
-            var simplexVertices = new SimplexVertices(new Vector2?[36]);
+            var simplexVertices = new PooledList<Vector2>(36, ClearMode.Always);
 
-            foreach (var vertex in givenSimplex.Vertices)
+            foreach (var vertex in simplex.Vertices)
             {
                 simplexVertices.Add(vertex);
             }
@@ -57,10 +55,12 @@ namespace MoonTools.Core.Bonk
                 }
             }
 
+            simplexVertices.Dispose();
+
             return intersection;
         }
 
-        private static Edge FindClosestEdge(PolygonWinding winding, SimplexVertices simplexVertices)
+        private static Edge FindClosestEdge(PolygonWinding winding, PooledList<Vector2> simplexVertices)
         {
             var closestDistance = float.PositiveInfinity;
             var closestNormal = Vector2.Zero;
diff --git a/Bonk/SimplexVertices.cs b/Bonk/SimplexVertices.cs
deleted file mode 100644
index b89b753..0000000
--- a/Bonk/SimplexVertices.cs
+++ /dev/null
@@ -1,91 +0,0 @@
-using System;
-using System.Collections;
-using System.Collections.Generic;
-using Microsoft.Xna.Framework;
-
-namespace MoonTools.Core.Bonk
-{
-    public struct SimplexVertices : IEnumerable<Vector2>
-    {
-        public Vector2?[] vertices;
-
-        /// <summary>
-        /// Make sure to pass in all nulls
-        /// </summary>
-        public SimplexVertices(Vector2?[] vertices)
-        {
-            this.vertices = vertices;
-        }
-
-        public Vector2 this[int key]
-        {
-            get
-            {
-                if (!vertices[key].HasValue) { throw new IndexOutOfRangeException(); }
-                return vertices[key].Value;
-            }
-            set
-            {
-                vertices[key] = value;
-            }
-        }
-
-        public int Count {
-            get
-            {
-                for (int i = 0; i < vertices.Length; i++)
-                {
-                    if (!vertices[i].HasValue) { return i; }
-                }
-                return vertices.Length;
-            }
-        }
-
-        public void Add(Vector2 vertex)
-        {
-            if (Count > vertices.Length - 1) { throw new IndexOutOfRangeException(); }
-
-            vertices[Count] = vertex;
-        }
-
-        public void Insert(int index, Vector2 vertex)
-        {
-            if (Count >= vertices.Length || index > vertices.Length - 1) { throw new IndexOutOfRangeException(); }
-
-            var currentCount = Count;
-
-            for (int i = currentCount - 1; i >= index; i--)
-            {
-                vertices[i + 1] = vertices[i];
-            }
-
-            vertices[index] = vertex;
-        }
-
-        public IEnumerator<Vector2> GetEnumerator()
-        {
-            foreach (Vector2? vec in vertices)
-            {
-                if (!vec.HasValue) { yield break; }
-                yield return vec.Value;
-            }
-        }
-
-        public void RemoveAt(int index)
-        {
-            if (index > vertices.Length - 1 || index > Count) { throw new ArgumentOutOfRangeException(); }
-
-            for (int i = vertices.Length - 2; i >= index; i--)
-            {
-                vertices[i] = vertices[i + 1];
-            }
-
-            vertices[vertices.Length - 1] = null;
-        }
-
-        IEnumerator IEnumerable.GetEnumerator()
-        {
-            return GetEnumerator();
-        }
-    }
-}
\ No newline at end of file