Fixed submarines bouncing on characters submarines that are laying on the ocean floor. Not a very realistic way to handle the collisions - the sub just stops as if it had collided with the level walls (making it seem as if the characters were made of concrete), maybe make the collisions gib the character?

Closes #152

Barotrauma/BarotraumaShared/Source/Map/SubmarineBody.cs

@@ -373,21 +373,8 @@ namespace Barotrauma
             Limb limb = f2.Body.UserData as Limb;
             if (limb != null)
             {
-                bool collision = HandleLimbCollision(contact, limb);
-
-                if (collision && limb.Mass > 100.0f)
-                {
-                    Vector2 normal = Vector2.Normalize(Body.SimPosition - limb.SimPosition);
-
-                    float impact = Math.Min(Vector2.Dot(Velocity - limb.LinearVelocity, -normal), 50.0f) / 5.0f * Math.Min(limb.Mass / 200.0f, 1);
-
-                    ApplyImpact(impact, -normal, contact);
-                    foreach (Submarine dockedSub in submarine.DockedTo)
-                    {
-                        dockedSub.SubBody.ApplyImpact(impact, -normal, contact);
-                    }
-                }
-
+                bool collision = CheckLimbCollision(contact, limb);
+                if (collision) HandleLimbCollision(contact, limb);
                 return collision;
             }
 
@@ -408,18 +395,18 @@ namespace Barotrauma
             return true;
         }
 
-        private bool HandleLimbCollision(Contact contact, Limb limb)
+        private bool CheckLimbCollision(Contact contact, Limb limb)
         {
             if (limb.character.Submarine != null) return false;
 
-            Vector2 normal2;
+            Vector2 contactNormal;
             FixedArray2<Vector2> points;
-            contact.GetWorldManifold(out normal2, out points);
+            contact.GetWorldManifold(out contactNormal, out points);
 
             Vector2 normalizedVel = limb.character.AnimController.Collider.LinearVelocity == Vector2.Zero ?
                 Vector2.Zero : Vector2.Normalize(limb.character.AnimController.Collider.LinearVelocity);
 
-            Vector2 targetPos = ConvertUnits.ToDisplayUnits(points[0] - normal2);
+            Vector2 targetPos = ConvertUnits.ToDisplayUnits(points[0] - contactNormal);
             Hull newHull = Hull.FindHull(targetPos, null);
 
             if (newHull == null)
@@ -440,6 +427,73 @@ namespace Barotrauma
             return false;
         }
 
+        private void HandleLimbCollision(Contact contact, Limb limb)
+        {
+            if (limb.Mass > 100.0f)
+            {
+                Vector2 normal = Vector2.Normalize(Body.SimPosition - limb.SimPosition);
+
+                float impact = Math.Min(Vector2.Dot(Velocity - limb.LinearVelocity, -normal), 50.0f) / 5.0f * Math.Min(limb.Mass / 200.0f, 1);
+
+                ApplyImpact(impact, -normal, contact);
+                foreach (Submarine dockedSub in submarine.DockedTo)
+                {
+                    dockedSub.SubBody.ApplyImpact(impact, -normal, contact);
+                }
+            }
+
+            //find all contacts between the limb and level walls
+            List<Contact> levelContacts = new List<Contact>();
+            ContactEdge contactEdge = limb.body.FarseerBody.ContactList;
+            while (contactEdge.Next != null)
+            {
+                if (contactEdge.Contact.Enabled &&
+                    contactEdge.Other.UserData is VoronoiCell &&
+                    contactEdge.Contact.IsTouching)
+                {
+                    levelContacts.Add(contactEdge.Contact);
+                }
+                contactEdge = contactEdge.Next;
+            }
+
+            if (levelContacts.Count == 0) return;
+
+            //if the limb is in contact with the level, apply an artifical impact to prevent the sub from bouncing on top of it
+            //not a very realistic way to handle the collisions (makes it seem as if the characters were made of reinforced concrete),
+            //but more realistic than bouncing and prevents using characters as "bumpers" that prevent all collision damage
+
+            //TODO: apply impact damage and/or gib the character that got crushed between the sub and the level?
+            Vector2 avgContactNormal = Vector2.Zero;
+            foreach (Contact levelContact in levelContacts)
+            {
+                Vector2 contactNormal;
+                FixedArray2<Vector2> temp;
+                levelContact.GetWorldManifold(out contactNormal, out temp);
+
+                //if the contact normal is pointing from the limb towards the level cell it's touching, flip the normal
+                VoronoiCell cell = levelContact.FixtureB.Body.UserData is VoronoiCell ?
+                    ((VoronoiCell)levelContact.FixtureB.Body.UserData) : ((VoronoiCell)levelContact.FixtureA.Body.UserData);
+
+                var cellDiff = ConvertUnits.ToDisplayUnits(limb.body.SimPosition) - cell.Center;
+                if (Vector2.Dot(contactNormal, cellDiff) < 0)
+                {
+                    contactNormal = -contactNormal;
+                }
+
+                avgContactNormal += contactNormal;
+
+                //apply impacts at the positions where this sub is touching the limb
+                ApplyImpact((Vector2.Dot(-Velocity, contactNormal) / 2.0f) / levelContacts.Count, contactNormal, levelContact);
+            }
+            avgContactNormal /= levelContacts.Count;
+            
+            float contactDot = Vector2.Dot(Body.LinearVelocity, -avgContactNormal);
+            if (contactDot > 0.0f)
+            {
+                Body.LinearVelocity -= Vector2.Normalize(Body.LinearVelocity) * contactDot;
+            }
+        }
+
         private void HandleLevelCollision(Contact contact, VoronoiCell cell)
         {
             var collisionNormal = Vector2.Normalize(ConvertUnits.ToDisplayUnits(Body.SimPosition) - cell.Center);