Level cells that overlap with ruins are removed during level generation (instead of just disabling collisions with them), background sprites can spawn on ruin walls

Subsurface/Source/Characters/BackgroundSprite/BackgroundSpriteManager.cs

@@ -133,46 +133,67 @@ namespace Barotrauma
 
             if (!prefab.SpawnOnWalls) return randomPos;
 
-            var cells = level.GetCells(randomPos);
-
-            if (!cells.Any()) return null;
-
-            VoronoiCell cell = cells[Rand.Int(cells.Count, false)];
             List<GraphEdge> edges = new List<GraphEdge>();
             List<Vector2> normals = new List<Vector2>();
-            foreach (GraphEdge edge in cell.edges)
+
+            var cells = level.GetCells(randomPos);
+
+            if (cells.Any())
             {
-                if (!edge.isSolid || edge.OutsideLevel) continue;
+                VoronoiCell cell = cells[Rand.Int(cells.Count, false)];
 
-                Vector2 normal = edge.GetNormal(cell);
+                foreach (GraphEdge edge in cell.edges)
+                {
+                    if (!edge.isSolid || edge.OutsideLevel) continue;
 
-                if (prefab.Alignment.HasFlag(Alignment.Bottom) && normal.Y < -0.5f)
+                    Vector2 normal = edge.GetNormal(cell);
-                {
-                    edges.Add(edge);
-                }
-                else if (prefab.Alignment.HasFlag(Alignment.Top) && normal.Y > 0.5f)
-                {
-                    edges.Add(edge);
-                }
-                else if (prefab.Alignment.HasFlag(Alignment.Left) && normal.X < -0.5f)
-                {
-                    edges.Add(edge);
-                }
-                else if (prefab.Alignment.HasFlag(Alignment.Right) && normal.X > 0.5f)
-                {
-                    edges.Add(edge);
-                }
-                else
-                {
-                    continue;
-                }
                 
-                normals.Add(normal);
+                    if (prefab.Alignment.HasFlag(Alignment.Bottom) && normal.Y < -0.5f)
+                    {
+                        edges.Add(edge);
+                    }
+                    else if (prefab.Alignment.HasFlag(Alignment.Top) && normal.Y > 0.5f)
+                    {
+                        edges.Add(edge);
+                    }
+                    else if (prefab.Alignment.HasFlag(Alignment.Left) && normal.X < -0.5f)
+                    {
+                        edges.Add(edge);
+                    }
+                    else if (prefab.Alignment.HasFlag(Alignment.Right) && normal.X > 0.5f)
+                    {
+                        edges.Add(edge);
+                    }
+                    else
+                    {
+                        continue;
+                    }
+
+                    normals.Add(normal);
+                }
+            }
+
+            foreach (RuinGeneration.Ruin ruin in Level.Loaded.Ruins)
+            {
+                Rectangle expandedArea = ruin.Area;
+                expandedArea.Inflate(ruin.Area.Width, ruin.Area.Height);
+                if (!expandedArea.Contains(randomPos)) continue;
+
+                foreach (var ruinShape in ruin.RuinShapes)
+                {
+                    foreach (var wall in ruinShape.Walls)
+                    {
+                        if (!prefab.Alignment.HasFlag(ruinShape.GetLineAlignment(wall))) continue;
+
+                        edges.Add(new GraphEdge(wall.A, wall.B));
+                        normals.Add((wall.A + wall.B) / 2.0f - ruinShape.Center);
+                    }
+                }
             }
 
             if (!edges.Any()) return null;
 
-            int index = Rand.Int(edges.Count,false);
+            int index = Rand.Int(edges.Count, false);
             closestEdge = edges[index];
             edgeNormal = normals[index];
 

Subsurface/Source/Map/Levels/Level.cs

@@ -732,7 +732,13 @@ namespace Barotrauma
                     {
                         if (MathUtils.GetLineRectangleIntersection(e.point1, e.point2, ruinShape.Rect) != null)
                         {
-                            cell.CellType = CellType.Empty;
+                            cell.CellType = CellType.Removed;
+
+                            int x = (int)Math.Floor(cell.Center.X / GridCellSize);
+                            int y = (int)Math.Floor(cell.Center.Y / GridCellSize);
+
+                            cellGrid[x, y].Remove(cell);
+                            cells.Remove(cell);
                             break;
                         }
                     }

Subsurface/Source/Map/Levels/Voronoi.cs

@@ -538,10 +538,8 @@ namespace Voronoi2
 		
 		private void pushGraphEdge( Site leftSite, Site rightSite, Vector2 point1, Vector2 point2 )
 		{
-			GraphEdge newEdge = new GraphEdge ();
+			GraphEdge newEdge = new GraphEdge(point1, point2);
 			allEdges.Add ( newEdge );
-            newEdge.point1 = point1;
-            newEdge.point2 = point2;
     			
 			newEdge.site1 = leftSite;
 			newEdge.site2 = rightSite;

Subsurface/Source/Map/Levels/VoronoiElements.cs

@@ -155,18 +155,14 @@ namespace Voronoi2
 
             for (int i = 1; i < vertices.Length; i++ )
             {
-                GraphEdge ge = new GraphEdge();
+                GraphEdge ge = new GraphEdge(vertices[i-1], vertices[i]);
-                ge.point1 = vertices[i-1];
-                ge.point2 = vertices[i];
 
                 System.Diagnostics.Debug.Assert(ge.point1 != ge.point2);
 
                 edges.Add(ge);
             }
 
-            GraphEdge lastEdge = new GraphEdge();
+            GraphEdge lastEdge = new GraphEdge(vertices[0], vertices[vertices.Length-1]);
-            lastEdge.point1 = vertices[0];
-            lastEdge.point2 = vertices[vertices.Length-1];
 
             edges.Add(lastEdge);
 
@@ -208,6 +204,12 @@ namespace Voronoi2
             get { return (point1 + point2) / 2.0f; }
         }
 
+        public GraphEdge(Vector2 point1, Vector2 point2)
+        {
+            this.point1 = point1;
+            this.point2 = point2;
+        }
+
         public VoronoiCell AdjacentCell(VoronoiCell cell)
         {
             if (cell1==cell)