From c6d2bad23ecf8ffbaa47c48078c72cc8def74d90 Mon Sep 17 00:00:00 2001
From: Syntriax <syntriax@gmail.com>
Date: Fri, 26 Jan 2024 18:56:31 +0300
Subject: [PATCH] feat: Basic Shape to Shape Collision Detection

---
 Engine.Physics2D/CollisionDetector.cs | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/Engine.Physics2D/CollisionDetector.cs b/Engine.Physics2D/CollisionDetector.cs
index 9a8f109..b8a4953 100644
--- a/Engine.Physics2D/CollisionDetector.cs
+++ b/Engine.Physics2D/CollisionDetector.cs
@@ -38,7 +38,26 @@ public class CollisionDetector : ICollisionDetector
 
     private static bool DetectShapeShape(IShapeCollider2D left, IShapeCollider2D right, out CollisionDetectionInformation? collisionInformation)
     {
-        throw new System.NotImplementedException();
+        collisionInformation = default;
+
+        var vertices = left.ShapeWorld.Vertices;
+        int count = vertices.Count;
+
+        for (int indexProjection = 0; indexProjection < count; indexProjection++)
+        {
+            Vector2D projectionVector = vertices[indexProjection].FromTo(vertices[(indexProjection + 1) % count]).Perpendicular().Normalized;
+
+            Projection leftProjection = left.ShapeWorld.ToProjection(projectionVector);
+            Projection rightProjection = right.ShapeWorld.ToProjection(projectionVector);
+
+            if (!leftProjection.Overlaps(rightProjection, out float depth))
+                return false;
+
+            if (collisionInformation == default || Math.Abs(collisionInformation.Penetration) > Math.Abs(depth))
+                collisionInformation = new(left, right, projectionVector, depth);
+        }
+
+        return true;
     }
 
     private static bool DetectShapeCircle(IShapeCollider2D shapeCollider, ICircleCollider2D circleCollider, out CollisionDetectionInformation? collisionInformation)