rigidbody, forces and collision testing

PhysicsEngine/Physics/Bodies/Circle.cs

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+using System;
+using System.Numerics;
+using Raylib_cs;
+
+namespace PhysicsEngine
+{
+    public class Circle : Body
+    {
+        public float Radius;
+
+        public Circle(Vector2 position, float radius, float mass)
+        {
+            Position = position;
+            Radius = radius;
+            Mass = mass;
+            
+            if (mass > 0.0f)
+            {
+                MomentOfInertia = 0.5f * mass * radius * radius;
+            }
+        }
+
+        public override void Draw(float pixelsPerMeter = 100.0f)
+        {
+            DrawHelper.DrawCircleBody(Position, Radius, Rotation, BaseColor, pixelsPerMeter);
+        }
+
+        public override void ApplyAerodynamicDrag(float dt)
+        {
+            if (DragCoefficient <= 0.0f) return;
+
+            const float airDensity = 1.225f;
+            float area = Radius * 2.0f;
+            float speed = Velocity.Length();
+
+            if (speed > 0.0001f)
+            {
+                Vector2 dragDir = -Vector2.Normalize(Velocity);
+                float dragMagnitude = 0.5f * airDensity * speed * speed * DragCoefficient * area;
+                ApplyForce(dragDir * dragMagnitude);
+            }
+        }
+    }
+}