optimization for circle overlap + remove position data from point

Bonk/NarrowPhase/NarrowPhase.cs

@@ -65,11 +65,23 @@ namespace MoonTools.Core.Bonk
             {
                 return TestRectangleOverlap(rectangleA, transformA, rectangleB, transformB);
             }
+            else if (shapeA is Point && shapeB is Rectangle && transformB.Rotation == 0)
+            {
+                return TestPointRectangleOverlap((Point)shapeA, transformA, (Rectangle)shapeB, transformB);
+            }
+            else if (shapeA is Rectangle && shapeB is Point && transformA.Rotation == 0)
+            {
+                return TestPointRectangleOverlap((Point)shapeB, transformB, (Rectangle)shapeA, transformA);
+            }
+            else if (shapeA is Circle circleA && shapeB is Circle circleB && transformA.Scale.X == transformA.Scale.Y && transformB.Scale.X == transformB.Scale.Y)
+            {
+                return TestCircleOverlap(circleA, transformA, circleB, transformB);
+            }
             return FindCollisionSimplex(shapeA, transformA, shapeB, transformB).Item1;
         }
 
         /// <summary>
-        /// Fast path for overlapping rectangles. If the transforms have non-zero rotation this will be inaccurate.
+        /// Fast path for axis-aligned rectangles. If the transforms have non-zero rotation this will be inaccurate.
         /// </summary>
         /// <param name="rectangleA"></param>
         /// <param name="transformA"></param>
@@ -84,6 +96,44 @@ namespace MoonTools.Core.Bonk
             return firstAABB.Left <= secondAABB.Right && firstAABB.Right >= secondAABB.Left && firstAABB.Top <= secondAABB.Bottom && firstAABB.Bottom >= secondAABB.Top;
         }
 
+        /// <summary>
+        /// Fast path for overlapping point and axis-aligned rectangle. The rectangle transform must have non-zero rotation.
+        /// </summary>
+        /// <param name="point"></param>
+        /// <param name="pointTransform"></param>
+        /// <param name="rectangle"></param>
+        /// <param name="rectangleTransform"></param>
+        /// <returns></returns>
+        public static bool TestPointRectangleOverlap(Point point, Transform2D pointTransform, Rectangle rectangle, Transform2D rectangleTransform)
+        {
+            var transformedPoint = pointTransform.Position;
+            var AABB = rectangle.TransformedAABB(rectangleTransform);
+
+            return transformedPoint.X >= AABB.Left && transformedPoint.X <= AABB.Right && transformedPoint.Y <= AABB.Bottom && transformedPoint.Y >= AABB.Top;
+        }
+
+        /// <summary>
+        /// Fast path for overlapping circles. The circles must have uniform scaling.
+        /// </summary>
+        /// <param name="circleA"></param>
+        /// <param name="transformA"></param>
+        /// <param name="circleB"></param>
+        /// <param name="transformB"></param>
+        /// <returns></returns>
+        public static bool TestCircleOverlap(Circle circleA, Transform2D transformA, Circle circleB, Transform2D transformB)
+        {
+            var radiusA = circleA.Radius * transformA.Scale.X;
+            var radiusB = circleB.Radius * transformB.Scale.Y;
+
+            var centerA = transformA.Position;
+            var centerB = transformB.Position;
+
+            var distanceSquared = (centerA - centerB).LengthSquared();
+            var radiusSumSquared = (radiusA + radiusB) * (radiusA + radiusB);
+
+            return distanceSquared <= radiusSumSquared;
+        }
+
         /// <summary>
         /// Tests if the two shape-transform pairs are overlapping, and returns a simplex that can be used by the EPA algorithm to determine a miminum separating vector.
         /// </summary>

Bonk/Shapes/Point.cs

@@ -6,21 +6,9 @@ namespace MoonTools.Core.Bonk
 {
     public struct Point : IShape2D, IEquatable<Point>
     {
-        private Position2D _position;
+        private Position2D Position { get; }
         public AABB AABB { get; }
 
-        public Point(Position2D position)
-        {
-            _position = position;
-            AABB = new AABB(position, position);
-        }
-
-        public Point(int x, int y)
-        {
-            _position = new Position2D(x, y);
-            AABB = new AABB(x, y, x, y);
-        }
-
         public AABB TransformedAABB(Transform2D transform)
         {
             return AABB.Transformed(AABB, transform);
@@ -28,7 +16,7 @@ namespace MoonTools.Core.Bonk
 
         public Vector2 Support(Vector2 direction, Transform2D transform)
         {
-            return Vector2.Transform(_position.ToVector2(), transform.TransformMatrix);
+            return Vector2.Transform(Position.ToVector2(), transform.TransformMatrix);
         }
 
         public override bool Equals(object obj)
@@ -43,22 +31,22 @@ namespace MoonTools.Core.Bonk
 
         public bool Equals(Point other)
         {
-            return _position == other._position;
+            return Position == other.Position;
         }
 
         public override int GetHashCode()
         {
-            return HashCode.Combine(_position);
+            return HashCode.Combine(Position);
         }
 
         public static bool operator ==(Point a, Point b)
         {
-            return a.Equals(b);
+            return true;
         }
 
         public static bool operator !=(Point a, Point b)
         {
-            return !(a == b);
+            return false;
         }
     }
 }

Test/Equality.cs

@@ -15,36 +15,27 @@ namespace Tests
             [Test]
             public void PointEqual()
             {
-                var a = new Point(1, 1);
+                var a = new Point();
-                var b = new Point(1, 1);
+                var b = new Point();
 
                 a.Equals(b).Should().BeTrue();
             }
 
-            [Test]
-            public void PointNotEqual()
-            {
-                var a = new Point(1, 1);
-                var b = new Point(-1, 1);
-
-                a.Equals(b).Should().BeFalse();
-            }
-
             [Test]
             public void PointEqualOperator()
             {
-                var a = new Point(1, 1);
+                var a = new Point();
-                var b = new Point(1, 1);
+                var b = new Point();
                 (a == b).Should().BeTrue();
             }
 
             [Test]
             public void PointNotEqualOperator()
             {
-                var a = new Point(1, 1);
+                var a = new Point();
-                var b = new Point(-1, 1);
+                var b = new Point();
 
-                (a != b).Should().BeTrue();
+                (a != b).Should().BeFalse();
             }
         }
 

Test/GJK2DTest.cs

@@ -12,8 +12,8 @@ namespace Tests
         [Test]
         public void PointLineOverlapping()
         {
-            var point = new Point(-3, -3);
+            var point = new Point();
-            var pointTransform = new Transform2D(new Position2D(4, 4));
+            var pointTransform = new Transform2D(new Position2D(1, 1));
             var line = new Line(new Position2D(-2, -2), new Position2D(2, 2));
 
             NarrowPhase.TestCollision(point, pointTransform, line, Transform2D.DefaultTransform).Should().BeTrue();
@@ -22,10 +22,11 @@ namespace Tests
         [Test]
         public void PointLineNotOverlapping()
         {
-            var point = new Point(1, 1);
+            var point = new Point();
+            var pointTransform = new Transform2D(new Position2D(1, 1));
             var line = new Line(new Position2D(-3, -2), new Position2D(-9, -5));
 
-            NarrowPhase.TestCollision(point, Transform2D.DefaultTransform, line, Transform2D.DefaultTransform).Should().BeFalse();
+            NarrowPhase.TestCollision(point, pointTransform, line, Transform2D.DefaultTransform).Should().BeFalse();
         }
 
         [Test]
@@ -43,7 +44,7 @@ namespace Tests
         [Test]
         public void PointCircleNotOverlapping()
         {
-            var point = new Point(0, 0);
+            var point = new Point();
             var pointTransform = new Transform2D(new Position2D(3, 0));
             var circle = new Circle(1);
 
@@ -53,7 +54,7 @@ namespace Tests
         [Test]
         public void PointRectangleOverlapping()
         {
-            var point = new Point(1, 1);
+            var point = new Point();
             var rectangle = new Rectangle(-2, -2, 2, 2);
 
             NarrowPhase.TestCollision(point, Transform2D.DefaultTransform, rectangle, Transform2D.DefaultTransform).Should().BeTrue();
@@ -62,16 +63,18 @@ namespace Tests
         [Test]
         public void PointRectangleNotOverlapping()
         {
-            var point = new Point(5, 5);
+            var point = new Point();
+            var pointTransform = new Transform2D(new Position2D(5, 5));
             var rectangle = new Rectangle(-2, -2, 2, 2);
 
-            NarrowPhase.TestCollision(point, Transform2D.DefaultTransform, rectangle, Transform2D.DefaultTransform).Should().BeFalse();
+            NarrowPhase.TestCollision(point, pointTransform, rectangle, Transform2D.DefaultTransform).Should().BeFalse();
         }
 
         [Test]
         public void PointPolygonOverlapping()
         {
-            var point = new Point(1, 1);
+            var point = new Point();
+            var pointTransform = new Transform2D(new Position2D(1, 1));
             var polygon = new Polygon(ImmutableArray.Create(
                 new Position2D(-2, -2),
                 new Position2D(-3, 2),
@@ -79,13 +82,14 @@ namespace Tests
                 new Position2D(3, -2)
             ));
 
-            NarrowPhase.TestCollision(point, Transform2D.DefaultTransform, polygon, Transform2D.DefaultTransform).Should().BeTrue();
+            NarrowPhase.TestCollision(point, pointTransform, polygon, Transform2D.DefaultTransform).Should().BeTrue();
         }
 
         [Test]
         public void PointPolygonNotOverlapping()
         {
-            var point = new Point(5, 5);
+            var point = new Point();
+            var pointTransform = new Transform2D(new Position2D(5, 5));
             var polygon = new Polygon(ImmutableArray.Create(
                 new Position2D(-2, -2),
                 new Position2D(-3, 2),
@@ -93,7 +97,7 @@ namespace Tests
                 new Position2D(3, -2)
             ));
 
-            NarrowPhase.TestCollision(point, Transform2D.DefaultTransform, polygon, Transform2D.DefaultTransform).Should().BeFalse();
+            NarrowPhase.TestCollision(point, pointTransform, polygon, Transform2D.DefaultTransform).Should().BeFalse();
         }
 
         [Test]

Test/SpatialHashTest.cs

@@ -1,4 +1,4 @@
-using FluentAssertions;
+using FluentAssertions;
 using NUnit.Framework;
 using MoonTools.Core.Structs;
 using MoonTools.Core.Bonk;
@@ -34,8 +34,8 @@ namespace Tests
             var line = new Line(new Position2D(20, -4), new Position2D(22, -12));
             var lineTransform = new Transform2D(new Vector2(0, 0));
 
-            var point = new Point(8, 8);
+            var point = new Point();
-            var pointTransform = Transform2D.DefaultTransform;
+            var pointTransform = new Transform2D(new Position2D(8, 8));
 
             spatialHash.Insert(0, rectA, rectATransform);
             spatialHash.Insert(1, rectB, rectBTransform);