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Source/Engine/Physics/Collisions.cs

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+// Copyright (c) 2012-2020 Wojciech Figat. All rights reserved.
+
+using System;
+using System.Collections;
+using System.Collections.Generic;
+
+namespace FlaxEngine
+{
+    /// <summary>
+    /// Contains a collision information passed to the OnCollisionEnter/OnCollisionExit events.
+    /// </summary>
+    unsafe partial struct Collision : IEnumerable<ContactPoint>
+    {
+        private class ContactsEnumerator : IEnumerator<ContactPoint>
+        {
+            private Collision _c;
+            private int _index;
+
+            public ContactsEnumerator(ref Collision c)
+            {
+                _c = c;
+                _index = 0;
+            }
+
+            public bool MoveNext()
+            {
+                if (_index == _c.ContactsCount - 1)
+                    return false;
+                _index++;
+                return true;
+            }
+
+            public void Reset()
+            {
+                _index = 0;
+            }
+
+            ContactPoint IEnumerator<ContactPoint>.Current
+            {
+                get
+                {
+                    if (_index == _c.ContactsCount)
+                        throw new InvalidOperationException("Enumeration ended.");
+                    fixed (ContactPoint* ptr = &_c.Contacts0)
+                        return ptr[_index];
+                }
+            }
+
+            public object Current
+            {
+                get
+                {
+                    if (_index == _c.ContactsCount)
+                        throw new InvalidOperationException("Enumeration ended.");
+                    fixed (ContactPoint* ptr = &_c.Contacts0)
+                        return ptr[_index];
+                }
+            }
+
+            public void Dispose()
+            {
+                _c = new Collision();
+            }
+        }
+
+        /// <summary>
+        /// The contacts locations.
+        /// </summary>
+        /// <remarks>
+        /// This property allocates an array of contact points.
+        /// </remarks>
+        public ContactPoint[] Contacts
+        {
+            get
+            {
+                var result = new ContactPoint[ContactsCount];
+                fixed (ContactPoint* ptr = &Contacts0)
+                {
+                    for (int i = 0; i < ContactsCount; i++)
+                        result[i] = ptr[i];
+                }
+                return result;
+            }
+        }
+
+        /// <summary>
+        /// The relative linear velocity of the two colliding objects.
+        /// </summary>
+        /// <remarks>
+        /// Can be used to detect stronger collisions.
+        /// </remarks>
+        public Vector3 RelativeVelocity
+        {
+            get
+            {
+                Vector3.Subtract(ref ThisVelocity, ref OtherVelocity, out var result);
+                return result;
+            }
+        }
+
+        /// <summary>
+        /// The first collider (this instance). It may be null if this actor is not the <see cref="Collider"/> (eg. <see cref="Terrain"/>).
+        /// </summary>
+        public Collider ThisCollider => ThisActor as Collider;
+
+        /// <summary>
+        /// The second collider (other instance). It may be null if this actor is not the <see cref="Collider"/> (eg. <see cref="Terrain"/>).
+        /// </summary>
+        public Collider OtherCollider => OtherActor as Collider;
+
+        /// <inheritdoc />
+        IEnumerator<ContactPoint> IEnumerable<ContactPoint>.GetEnumerator()
+        {
+            return new ContactsEnumerator(ref this);
+        }
+
+        /// <inheritdoc />
+        IEnumerator IEnumerable.GetEnumerator()
+        {
+            return new ContactsEnumerator(ref this);
+        }
+    }
+}