Improve preview of terrain pasting to better take height level into account

Author: Rampastring

src/TSMapEditor/Models/MapTile.cs

@@ -57,6 +57,19 @@ public MapTile(byte[] data) : base(data) { }
 
         public List<(Structure Source, double DistanceInLeptons)> LightSources { get; set; } = new();
 
+        /// <summary>
+        /// Returns the display height level of this cell.
+        /// If the cell has a valid preview height level defined, returns the preview height level.
+        /// Otherwise returns the actual, non-preview height level.
+        /// </summary>
+        public int GetLevelOrPreviewLevel()
+        {
+            if (PreviewLevel > -1)
+                return PreviewLevel;
+
+            return Level;
+        }
+
         public void ApplyPreview(TileImage previewTileImage, int previewSubTileIndex, int previewLevel, Lighting lighting, LightingPreviewMode lightingPreviewMode, bool lightDisabledLightSources)
         {
             PreviewTileImage = previewTileImage;

src/TSMapEditor/Rendering/MapView.cs

@@ -1643,8 +1643,8 @@ public void Draw(bool isActive, TechnoBase technoUnderCursor, MapTile tileUnderC
 
             if (isActive && tileUnderCursor != null && cursorAction != null)
             {
-                cursorAction.PostMapDraw(tileUnderCursor.CoordsToPoint());
                 cursorAction.DrawPreview(tileUnderCursor.CoordsToPoint(), Camera.TopLeftPoint);
+                cursorAction.PostMapDraw(tileUnderCursor.CoordsToPoint());
             }
         }
 

src/TSMapEditor/UI/CursorActions/CopyTerrainCursorActionBase.cs

@@ -47,8 +47,8 @@ protected void CopyFromCells(List<Point2D> cellsToCopy)
                 }
             });
 
-            copiedMapData.Width = (ushort)(endX - startX);
-            copiedMapData.Height = (ushort)(endY - startY);
+            copiedMapData.Width = (ushort)((endX - startX) + 1);
+            copiedMapData.Height = (ushort)((endY - startY) + 1);
 
             // To handle height, we first look up the lowest height level of the copied
             // area. Any cell higher than that gets assigned an offset for its height.

src/TSMapEditor/UI/CursorActions/PasteTerrainCursorAction.cs

@@ -141,7 +141,7 @@ private void GenerateGraphicalEdges()
                 foundationHashSet.Add(entry.Offset);
             });
 
-            edges = Helpers.CreateEdges(copiedMapData.Width + 2, copiedMapData.Height + 2, foundationHashSet.ToList());
+            edges = Helpers.CreateEdges(copiedMapData.Width + 1, copiedMapData.Height + 1, foundationHashSet.ToList());
         }
 
         public override void PreMapDraw(Point2D cellCoords)
@@ -259,6 +259,23 @@ public override void PostMapDraw(Point2D cellCoords)
             CursorActionTarget.AddRefreshPoint(cellCoords, maxOffset);
         }
 
+        private Point2D GetEdgeCoordsCompensated(Point2D originalEdgeCoords)
+        {
+            // Edges partially run outside of the foundation of the copied cell. For example, a 1x1 copied area has a 2x2 edge foundation.
+            // Compensate for that here.
+
+            int x = originalEdgeCoords.X;
+            int y = originalEdgeCoords.Y;
+
+            if (x >= copiedMapData.Width)
+                x--;
+
+            if (y >= copiedMapData.Height)
+                y--;
+
+            return new Point2D(x, y);
+        }
+
         public override void DrawPreview(Point2D cellCoords, Point2D cameraTopLeftPoint)
         {
             if (KeyboardCommands.Instance.PlaceTerrainBelow.AreKeysOrModifiersDown(Keyboard))
@@ -275,13 +292,13 @@ public override void DrawPreview(Point2D cellCoords, Point2D cameraTopLeftPoint)
 
                 if (!CursorActionTarget.Is2DMode)
                 {
-                    var cell = Map.GetTile(edgeCell0);
+                    var cell = Map.GetTile(cellCoords + GetEdgeCoordsCompensated(edge[0]));
                     if (cell != null)
-                        heightOffset0 = Constants.CellHeight * cell.Level;
+                        heightOffset0 = Constants.CellHeight * cell.GetLevelOrPreviewLevel();
 
-                    cell = Map.GetTile(edgeCell1);
+                    cell = Map.GetTile(cellCoords + GetEdgeCoordsCompensated(edge[1]));
                     if (cell != null)
-                        heightOffset1 = Constants.CellHeight * cell.Level;
+                        heightOffset1 = Constants.CellHeight * cell.GetLevelOrPreviewLevel();
                 }
 
                 // Translate edge vertices from cell coordinate space to world coordinate space.