gc-related optimizations

.gitignore

@@ -1,2 +1,3 @@
 bin/
 obj/
+.vscode

Bonk/Bonk.csproj

@@ -16,5 +16,6 @@
   </PropertyGroup>
   <ItemGroup>
     <PackageReference Include="MoonTools.Core.Structs" Version="1.0.1"/>
+    <PackageReference Include="morelinq" Version="3.2.0"/>
   </ItemGroup>
 </Project>

Bonk/EPA2D.cs

@@ -5,6 +5,7 @@
  */
 
 using Microsoft.Xna.Framework;
+using MoonTools.Core.Bonk.Extensions;
 using MoonTools.Core.Structs;
 using System;
 using System.Collections.Generic;
@@ -20,14 +21,15 @@ namespace MoonTools.Core.Bonk
     public static class EPA2D
     {
         // vector returned gives direction from A to B
-        public static Vector2 Intersect(IShape2D shapeA, Transform2D Transform2DA, IShape2D shapeB, Transform2D Transform2DB, IEnumerable<Vector2> givenSimplexVertices)
+        public static Vector2 Intersect(IShape2D shapeA, Transform2D Transform2DA, IShape2D shapeB, Transform2D Transform2DB, (Func<Vector2, Vector2>, Vector2, Vector2) givenSimplexVertices)
         {
             var simplexVertices = new SimplexVertices(new Vector2?[36]);
 
-            foreach (var vertex in givenSimplexVertices)
+            var (simplexSupport, a, b) = givenSimplexVertices;
-            {
+            simplexVertices.Add(simplexSupport(a));
-                simplexVertices.Add(vertex);
+            simplexVertices.Add(simplexSupport(b));
-            }
+            simplexVertices.Add(simplexSupport(-a));
+            simplexVertices.Add(simplexSupport(-b));
 
             var e0 = (simplexVertices[1].X - simplexVertices[0].X) * (simplexVertices[1].Y + simplexVertices[0].Y);
             var e1 = (simplexVertices[2].X - simplexVertices[1].X) * (simplexVertices[2].Y + simplexVertices[1].Y);

Bonk/GJK2D.cs

@@ -1,126 +1,87 @@
-/*
+using Microsoft.Xna.Framework;
- * Implementation of the GJK collision algorithm
- * Based on some math blogs
- * https://blog.hamaluik.ca/posts/building-a-collision-engine-part-1-2d-gjk-collision-detection/
- * and some code from https://github.com/kroitor/gjk.c
- */
-
-using Microsoft.Xna.Framework;
 using MoonTools.Core.Structs;
 using System;
+using MoonTools.Core.Bonk.Extensions;
 
 namespace MoonTools.Core.Bonk
 {
     public static class GJK2D
     {
-        private enum SolutionStatus
+        public static bool TestCollision(IShape2D shapeA, Transform2D transformA, IShape2D shapeB, Transform2D transformB)
         {
-            NoIntersection,
+            return OriginInside(MinkowskiDifference(shapeA, transformA, shapeB, transformB));
-            Intersection,
-            StillSolving
         }
 
-        public static ValueTuple<bool, SimplexVertices> TestCollision(IShape2D shapeA, Transform2D Transform2DA, IShape2D shapeB, Transform2D Transform2DB)
+        public static (bool, (Func<Vector2, Vector2>, Vector2, Vector2)) CollisionAndSimplex(IShape2D shapeA, Transform2D transformA, IShape2D shapeB, Transform2D transformB)
         {
-            var vertices = new SimplexVertices(new Vector2?[] { null, null, null, null });
+            var support = MinkowskiDifference(shapeA, transformA, shapeB, transformB);
+            var result = OriginInsideWithSimplex(support);
+            return (result.Item1, (support, result.Item2, result.Item3));
+        }
 
-            const SolutionStatus solutionStatus = SolutionStatus.StillSolving;
+        private static Func<Vector2, Vector2> MinkowskiDifference(IShape2D shapeA, Transform2D transformA, IShape2D shapeB, Transform2D transformB)
-            var direction = Transform2DB.Position - Transform2DA.Position;
+        {
+            return direction => shapeA.Support(direction, transformA) - shapeB.Support(-direction, transformB);
+        }
 
-            var result = (solutionStatus, direction);
+        private static bool OriginInside(Func<Vector2, Vector2> support)
+        {
+            var a = support(Vector2.UnitX);
+            var b = support(-a);
 
-            while (result.solutionStatus == SolutionStatus.StillSolving)
+            return Vector2.Dot(a, b) > 0 ? false : CheckSimplex(support, a, b);
+        }
+
+        private static (bool, Vector2, Vector2) OriginInsideWithSimplex(Func<Vector2, Vector2> support)
+        {
+            var a = support(Vector2.UnitX);
+            var b = support(-a);
+
+            return Vector2.Dot(a, b) > 0 ? (false, a, b) : Simplex(support, a, b);
+        }
+
+        private static bool CheckSimplex(Func<Vector2, Vector2> support, Vector2 a, Vector2 b)
+        {
+            var axb = a.Cross(b);
+            var c = support((b - a).Perpendicular());
+            var axc = a.Cross(c);
+            var bxc = b.Cross(c);
+            var cxb = -bxc;
+
+            return (b - a) == Vector2.Zero || (axb.Y > 0 != bxc.Y > 0 ? CheckSimplex(support, b, c) : (axc.Y > 0 != cxb.Y > 0 ? CheckSimplex(support, a, c) : true));
+        }
+
+        private static (bool, Vector2, Vector2) Simplex(Func<Vector2, Vector2> support, Vector2 a, Vector2 b)
+        {
+            if ((b - a) == Vector2.Zero)
             {
-                result = EvolveSimplex(shapeA, Transform2DA, shapeB, Transform2DB, vertices, result.direction);
+                return (false, a, b);
             }
-
+            else
-            return ValueTuple.Create(result.solutionStatus == SolutionStatus.Intersection, vertices);
-        }
-
-        private static (SolutionStatus, Vector2) EvolveSimplex(IShape2D shapeA, Transform2D Transform2DA, IShape2D shapeB, Transform2D Transform2DB, SimplexVertices vertices, Vector2 direction)
-        {
-            switch(vertices.Count)
             {
-                case 0:
+                var c = support((b - a).Perpendicular());
-                    if (direction == Vector2.Zero)
+                var axb = a.Cross(b);
+                var bxc = b.Cross(c);
+
+                if (axb.Y > 0 != bxc.Y > 0)
+                {
+                    return Simplex(support, b, c);
+                }
+                else
+                {
+                    var axc = a.Cross(c);
+                    var cxb = -bxc;
+
+                    if (axc.Y > 0 != cxb.Y > 0)
                     {
-                        direction = Vector2.UnitX;
+                        return Simplex(support, a, b);
                     }
-                    break;
-
-                case 1:
-                    direction *= -1;
-                    break;
-
-                case 2:
-                    var ab = vertices[1] - vertices[0];
-                    var a0 = vertices[0] * -1;
-
-                    direction = TripleProduct(ab, a0, ab);
-                    if (direction == Vector2.Zero)
-                    {
-                        direction = Perpendicular(ab);
-                    }
-                    break;
-
-                case 3:
-                    var c0 = vertices[2] * -1;
-                    var bc = vertices[1] - vertices[2];
-                    var ca = vertices[0] - vertices[2];
-
-                    var bcNorm = TripleProduct(ca, bc, bc);
-                    var caNorm = TripleProduct(bc, ca, ca);
-
-                    // the origin is outside line bc
-                    // get rid of a and add a new support in the direction of bcNorm
-                    if (Vector2.Dot(bcNorm, c0) > 0)
-                    {
-                        vertices.RemoveAt(0);
-                        direction = bcNorm;
-                    }
-                    // the origin is outside line ca
-                    // get rid of b and add a new support in the direction of caNorm
-                    else if (Vector2.Dot(caNorm, c0) > 0)
-                    {
-                        vertices.RemoveAt(1);
-                        direction = caNorm;
-                    }
-                    // the origin is inside both ab and ac,
-                    // so it must be inside the triangle!
                     else
                     {
-                        return (SolutionStatus.Intersection, direction);
+                        return (true, a, b);
                     }
-                    break;
+                }
             }
-
-            return (AddSupport(shapeA, Transform2DA, shapeB, Transform2DB, vertices, direction) ?
-                SolutionStatus.StillSolving :
-                SolutionStatus.NoIntersection, direction);
-        }
-
-        private static bool AddSupport(IShape2D shapeA, Transform2D Transform2DA, IShape2D shapeB, Transform2D Transform2DB, SimplexVertices vertices, Vector2 direction)
-        {
-            var newVertex = shapeA.Support(direction, Transform2DA) - shapeB.Support(-direction, Transform2DB);
-            vertices.Add(newVertex);
-            return Vector2.Dot(direction, newVertex) >= 0;
-        }
-
-        private static Vector2 TripleProduct(Vector2 a, Vector2 b, Vector2 c)
-        {
-            var A = new Vector3(a.X, a.Y, 0);
-            var B = new Vector3(b.X, b.Y, 0);
-            var C = new Vector3(c.X, c.Y, 0);
-
-            var first = Vector3.Cross(A, B);
-            var second = Vector3.Cross(first, C);
-
-            return new Vector2(second.X, second.Y);
-        }
-
-        private static Vector2 Perpendicular(Vector2 v)
-        {
-            return new Vector2(v.Y, -v.X);
         }
     }
 }

Bonk/Line.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using Microsoft.Xna.Framework;
 using MoonTools.Core.Structs;
 
@@ -6,17 +7,28 @@ namespace MoonTools.Core.Bonk
 {
     public struct Line : IShape2D, IEquatable<IShape2D>
     {
-        private Position2D[] vertices;
+        private Position2D v0;
+        private Position2D v1;
+
+        private IEnumerable<Position2D> vertices
+        {
+            get
+            {
+                yield return v0;
+                yield return v0;
+            }
+        }
 
         public Line(Position2D start, Position2D end)
         {
-            vertices = new Position2D[2] { start, end };
+            v0 = start;
+            v1 = end;
         }
 
         public Vector2 Support(Vector2 direction, Transform2D transform)
         {
-            var TransformedStart = Vector2.Transform(vertices[0], transform.TransformMatrix);
+            var TransformedStart = Vector2.Transform(v0, transform.TransformMatrix);
-            var TransformedEnd = Vector2.Transform(vertices[1], transform.TransformMatrix);
+            var TransformedEnd = Vector2.Transform(v1, transform.TransformMatrix);
             return Vector2.Dot(TransformedStart, direction) > Vector2.Dot(TransformedEnd, direction) ?
                 TransformedStart :
                 TransformedEnd;
@@ -32,7 +44,7 @@ namespace MoonTools.Core.Bonk
             if (other is Line)
             {
                 var otherLine = (Line)other;
-                return vertices[0].ToVector2() == otherLine.vertices[0].ToVector2() && vertices[1].ToVector2() == otherLine.vertices[1].ToVector2();
+                return v0.ToVector2() == otherLine.v0.ToVector2() && v1.ToVector2() == otherLine.v1.ToVector2();
             }
 
             return false;

Bonk/Rectangle.cs

@@ -1,6 +1,9 @@
 using System;
+using System.Collections.Generic;
+using System.Linq;
 using Microsoft.Xna.Framework;
 using MoonTools.Core.Structs;
+using MoreLinq;
 
 namespace MoonTools.Core.Bonk
 {
@@ -11,7 +14,16 @@ namespace MoonTools.Core.Bonk
         public int MaxX { get; }
         public int MaxY { get; }
 
-        private Position2D[] vertices;
+        private IEnumerable<Position2D> vertices
+        {
+            get
+            {
+                yield return new Position2D(MinX, MinY);
+                yield return new Position2D(MinX, MaxY);
+                yield return new Position2D(MaxX, MinY);
+                yield return new Position2D(MaxX, MaxY);
+            }
+        }
 
         public Rectangle(int minX, int minY, int maxX, int maxY)
         {
@@ -19,33 +31,11 @@ namespace MoonTools.Core.Bonk
             MinY = minY;
             MaxX = maxX;
             MaxY = maxY;
-
-            vertices = new Position2D[4]
-            {
-                new Position2D(minX, minY),
-                new Position2D(minX, maxY),
-                new Position2D(maxX, minY),
-                new Position2D(maxX, maxY)
-            };
         }
 
         public Vector2 Support(Vector2 direction, Transform2D transform)
         {
-            var furthestDistance = float.NegativeInfinity;
+            return vertices.Select(vertex => Vector2.Transform(vertex, transform.TransformMatrix)).MaxBy(transformed => Vector2.Dot(transformed, direction)).First();
-            var furthestVertex = Vector2.Transform(vertices[0], transform.TransformMatrix);
-
-            foreach (var v in vertices)
-            {
-                var TransformedVertex = Vector2.Transform(v, transform.TransformMatrix);
-                var distance = Vector2.Dot(TransformedVertex, direction);
-                if (distance > furthestDistance)
-                {
-                    furthestDistance = distance;
-                    furthestVertex = TransformedVertex;
-                }
-            }
-
-            return furthestVertex;
         }
 
         public AABB AABB(Transform2D Transform2D)

Bonk/Vector2Extensions.cs

@@ -0,0 +1,18 @@
+using Microsoft.Xna.Framework;
+
+namespace MoonTools.Core.Bonk.Extensions
+{
+    public static class Vector2Extensions
+    {
+        public static Vector2 Cross(this Vector2 a, Vector2 b)
+        {
+            var vec3 = Vector3.Cross(new Vector3(a.X, a.Y, 0), new Vector3(b.X, b.Y, 0));
+            return new Vector2(vec3.X, vec3.Y);
+        }
+
+        public static Vector2 Perpendicular(this Vector2 v)
+        {
+            return new Vector2(v.Y, -v.X);
+        }
+    }
+}

Test/EPA2DTest.cs

@@ -18,11 +18,11 @@ namespace Tests
             var squareB = new MoonTools.Core.Bonk.Rectangle(-1, -1, 1, 1);
             var transformB = new Transform2D(new Vector2(1.5f, 0));
 
-            var test = GJK2D.TestCollision(squareA, transformA, squareB, transformB);
+            var (result, simplex) = GJK2D.CollisionAndSimplex(squareA, transformA, squareB, transformB);
 
-            Assert.That(test.Item1, Is.True);
+            result.Should().BeTrue();
 
-            var intersection = EPA2D.Intersect(squareA, transformA, squareB, transformB, test.Item2);
+            var intersection = EPA2D.Intersect(squareA, transformA, squareB, transformB, simplex);
 
             intersection.X.Should().Be(1f);
             intersection.Y.Should().Be(0);
@@ -36,11 +36,11 @@ namespace Tests
             var circleB = new Circle(1);
             var transformB = new Transform2D(new Vector2(1, 1));
 
-            var test = GJK2D.TestCollision(circleA, transformA, circleB, transformB);
+            var (result, simplex) = GJK2D.CollisionAndSimplex(circleA, transformA, circleB, transformB);
 
-            Assert.That(test.Item1, Is.True);
+            result.Should().BeTrue();
 
-            var intersection = EPA2D.Intersect(circleA, transformA, circleB, transformB, test.Item2);
+            var intersection = EPA2D.Intersect(circleA, transformA, circleB, transformB, simplex);
 
             var ix = circleA.Radius * (float)Math.Cos(Math.PI / 4) - (circleB.Radius * (float)Math.Cos(5 * Math.PI / 4) + transformB.Position.X);
             var iy = circleA.Radius * (float)Math.Sin(Math.PI / 4) - (circleB.Radius * (float)Math.Sin(5 * Math.PI / 4) + transformB.Position.Y);
@@ -57,11 +57,11 @@ namespace Tests
             var square = new MoonTools.Core.Bonk.Rectangle(-1, -1, 1, 1);
             var transformB = Transform2D.DefaultTransform;
 
-            var test = GJK2D.TestCollision(line, transformA, square, transformB);
+            var (result, simplex) = GJK2D.CollisionAndSimplex(line, transformA, square, transformB);
 
-            Assert.That(test.Item1, Is.True);
+            result.Should().BeTrue();
 
-            var intersection = EPA2D.Intersect(line, transformA, square, transformB, test.Item2);
+            var intersection = EPA2D.Intersect(line, transformA, square, transformB, simplex);
 
             intersection.X.Should().Be(-1);
             intersection.Y.Should().Be(1);

Test/GJK2DTest.cs

@@ -2,6 +2,7 @@
 using MoonTools.Core.Bonk;
 using MoonTools.Core.Structs;
 using Microsoft.Xna.Framework;
+using FluentAssertions;
 
 namespace Tests
 {
@@ -13,7 +14,7 @@ namespace Tests
             var lineA = new Line(new Position2D(-1, -1), new Position2D(1, 1));
             var lineB = new Line(new Position2D(-1, 1), new Position2D(1, -1));
 
-            Assert.IsTrue(GJK2D.TestCollision(lineA, Transform2D.DefaultTransform, lineB, Transform2D.DefaultTransform).Item1);
+            GJK2D.TestCollision(lineA, Transform2D.DefaultTransform, lineB, Transform2D.DefaultTransform).Should().BeTrue();
         }
 
         [Test]
@@ -22,7 +23,7 @@ namespace Tests
             var lineA = new Line(new Position2D(0, 1), new Position2D(1, 0));
             var lineB = new Line(new Position2D(-1, -1), new Position2D(-2, -2));
 
-            Assert.IsFalse(GJK2D.TestCollision(lineA, Transform2D.DefaultTransform, lineB, Transform2D.DefaultTransform).Item1);
+            GJK2D.TestCollision(lineA, Transform2D.DefaultTransform, lineB, Transform2D.DefaultTransform).Should().BeFalse();
         }
 
         [Test]
@@ -33,7 +34,7 @@ namespace Tests
             var circleB = new Circle(2);
             var transformB = new Transform2D(new Vector2(1, 1));
 
-            Assert.IsTrue(GJK2D.TestCollision(circleA, transformA, circleB, transformB).Item1);
+            Assert.IsTrue(GJK2D.TestCollision(circleA, transformA, circleB, transformB));
         }
 
         [Test]
@@ -44,7 +45,7 @@ namespace Tests
             var circleB = new Circle(2);
             var transformB = new Transform2D(new Vector2(5, 5));
 
-            Assert.IsFalse(GJK2D.TestCollision(circleA, transformA, circleB, transformB).Item1);
+            Assert.IsFalse(GJK2D.TestCollision(circleA, transformA, circleB, transformB));
         }
 
         [Test]
@@ -64,7 +65,7 @@ namespace Tests
 
             var transformB = new Transform2D(new Vector2(0.5f, 0.5f));
 
-            Assert.IsTrue(GJK2D.TestCollision(shapeA, transformA, shapeB, transformB).Item1);
+            Assert.IsTrue(GJK2D.TestCollision(shapeA, transformA, shapeB, transformB));
         }
 
         [Test]
@@ -84,7 +85,7 @@ namespace Tests
 
             var transformB = new Transform2D(new Vector2(5, 0));
 
-            Assert.IsFalse(GJK2D.TestCollision(shapeA, transformA, shapeB, transformB).Item1);
+            Assert.IsFalse(GJK2D.TestCollision(shapeA, transformA, shapeB, transformB));
         }
 
         [Test]
@@ -101,7 +102,7 @@ namespace Tests
 
             var transformB = Transform2D.DefaultTransform;
 
-            Assert.IsTrue(GJK2D.TestCollision(line, transformA, polygon, transformB).Item1);
+            Assert.IsTrue(GJK2D.TestCollision(line, transformA, polygon, transformB));
         }
 
         [Test]
@@ -118,7 +119,7 @@ namespace Tests
 
             var transformB = Transform2D.DefaultTransform;
 
-            Assert.IsFalse(GJK2D.TestCollision(line, transformA, polygon, transformB).Item1);
+            Assert.IsFalse(GJK2D.TestCollision(line, transformA, polygon, transformB));
         }
 
         [Test]
@@ -129,7 +130,7 @@ namespace Tests
             var circle = new Circle(1);
             var transformB = Transform2D.DefaultTransform;
 
-            Assert.IsTrue(GJK2D.TestCollision(line, transformA, circle, transformB).Item1);
+            Assert.IsTrue(GJK2D.TestCollision(line, transformA, circle, transformB));
         }
 
         [Test]
@@ -140,7 +141,7 @@ namespace Tests
             var circle = new Circle(1);
             var transformB = Transform2D.DefaultTransform;
 
-            Assert.IsFalse(GJK2D.TestCollision(line, transformA, circle, transformB).Item1);
+            Assert.IsFalse(GJK2D.TestCollision(line, transformA, circle, transformB));
         }
 
         [Test]
@@ -156,7 +157,7 @@ namespace Tests
 
             var transformB = Transform2D.DefaultTransform;
 
-            Assert.IsTrue(GJK2D.TestCollision(circle, transformA, square, transformB).Item1);
+            Assert.IsTrue(GJK2D.TestCollision(circle, transformA, square, transformB));
         }
 
         [Test]
@@ -171,7 +172,7 @@ namespace Tests
             );
             var squareTransform = Transform2D.DefaultTransform;
 
-            Assert.IsFalse(GJK2D.TestCollision(circle, circleTransform, square, squareTransform).Item1);
+            Assert.IsFalse(GJK2D.TestCollision(circle, circleTransform, square, squareTransform));
         }
 
         [Test]
@@ -183,7 +184,7 @@ namespace Tests
             var rectangleB = new MoonTools.Core.Bonk.Rectangle(-1, -1, 1, 1);
             var transformB = new Transform2D(new Vector2(1, 0));
 
-            Assert.IsTrue(GJK2D.TestCollision(rectangleA, transformA, rectangleB, transformB).Item1);
+            Assert.IsTrue(GJK2D.TestCollision(rectangleA, transformA, rectangleB, transformB));
         }
 
         [Test]
@@ -195,7 +196,7 @@ namespace Tests
             var rectangleB = new MoonTools.Core.Bonk.Rectangle(-1, -1, 1, 1);
             var transformB = new Transform2D(new Vector2(1, 0));
 
-            Assert.IsTrue(GJK2D.TestCollision(rectangleA, transformA, rectangleB, transformB).Item1);
+            Assert.IsTrue(GJK2D.TestCollision(rectangleA, transformA, rectangleB, transformB));
         }
     }
 }

Test/Test.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFramework>netcoreapp2.2</TargetFramework>
+    <TargetFramework>netcoreapp3.0</TargetFramework>
     <IsPackable>false</IsPackable>
   </PropertyGroup>
   <ItemGroup>