Fix overlay overlapping with buildings and vehicles

Author: Rampastring

src/TSMapEditor/Rendering/ObjectRenderers/BuildingRenderer.cs

@@ -126,7 +126,7 @@ protected override float GetDepthFromPosition(Structure gameObject, int bottomDr
                 height = southernmostCell.Level;
             }
 
-            return ((CellMath.CellTopLeftPointFromCellCoords(southernmostCell.CoordsToPoint(), Map).Y + Constants.CellSizeY) / (float)Map.HeightInPixelsWithCellHeight) * Constants.DownwardsDepthRenderSpace +
+            return ((CellMath.CellTopLeftPointFromCellCoords(southernmostCell.CoordsToPoint(), Map).Y + Constants.CellSizeY * 2) / (float)Map.HeightInPixelsWithCellHeight) * Constants.DownwardsDepthRenderSpace +
                 (height * Constants.DepthRenderStep);
         }
 

src/TSMapEditor/Rendering/ObjectRenderers/ObjectRenderer.cs

@@ -293,17 +293,21 @@ public virtual void DrawShadow(T gameObject)
 
         protected virtual float GetDepthFromPosition(T gameObject, int bottomDrawPoint)
         {
-            // In this generic implementation, we only use the cell to fetch its height.
-            // Otherwise, position-related depth is calculated from the bottom draw point of the object.
+            // Calculate position-related depth from the bottom draw point of the object.
+            // Snap the texture height to the southernmost pixel coordinate of the southernmost
+            // cell that this object's texture overlaps.
             var cell = Map.GetTile(gameObject.Position);
+            int cellY = CellMath.CellTopLeftPointFromCellCoords(gameObject.Position, Map).Y;
+            int dy = bottomDrawPoint - cellY;
+            int extraHeightForSnap = dy % Constants.CellHeight;
 
             int height = 0;
             if (cell != null)
             {
                 height = cell.Level;
             }
 
-            return ((bottomDrawPoint + (height * Constants.CellHeight) + Constants.CellSizeY) / (float)Map.HeightInPixelsWithCellHeight) * Constants.DownwardsDepthRenderSpace +
+            return ((bottomDrawPoint + (height * Constants.CellHeight) + extraHeightForSnap) / (float)Map.HeightInPixelsWithCellHeight) * Constants.DownwardsDepthRenderSpace +
                 (height * Constants.DepthRenderStep);
         }
 
@@ -485,7 +489,7 @@ private void RenderFrame(T gameObject, PositionedTexture frame, PositionedTextur
                 depthAddition = 1.0f;
 
             // Add extra depth so objects show above terrain despite float imprecision
-            depthAddition += Constants.DepthEpsilon;
+            // depthAddition += Constants.DepthEpsilon;
 
             // There can be a gap between the end of the texture and the bottom-most cell for objects,
             // with more "circular" graphics. This can reduce depth when it's calculated in the shader.

src/TSMapEditor/Rendering/ObjectRenderers/UnitRenderer.cs

@@ -44,7 +44,7 @@ protected override float GetDepthFromPosition(Unit gameObject, int bottomDrawPoi
                 height = cell.Level;
             }
 
-            return ((CellMath.CellTopLeftPointFromCellCoords(cell.CoordsToPoint(), Map).Y + Constants.CellSizeY) / (float)Map.HeightInPixelsWithCellHeight) * Constants.DownwardsDepthRenderSpace +
+            return ((CellMath.CellTopLeftPointFromCellCoords(cell.CoordsToPoint(), Map).Y + (Constants.CellSizeY * 2)) / (float)Map.HeightInPixelsWithCellHeight) * Constants.DownwardsDepthRenderSpace +
                 (height * Constants.DepthRenderStep);
         }