Account for ramps in terrain height calculations.

OpenRA.Game/Graphics/TerrainSpriteLayer.cs

@@ -68,8 +68,12 @@ void UpdatePaletteIndices()
 
 		public void Update(CPos cell, Sprite sprite)
 		{
-			var xyz = sprite == null ? float3.Zero :
-				worldRenderer.Screen3DPosition(map.CenterOfCell(cell)) + sprite.Offset - 0.5f * sprite.Size;
+			var xyz = float3.Zero;
+			if (sprite != null)
+			{
+				var cellOrigin = map.CenterOfCell(cell) - new WVec(0, 0, map.Grid.Ramps[map.Ramp[cell]].CenterHeightOffset);
+				xyz = worldRenderer.Screen3DPosition(cellOrigin) + sprite.Offset - 0.5f * sprite.Size;
+			}
 
 			Update(cell.ToMPos(map.Grid.Type), sprite, xyz);
 		}

OpenRA.Game/Graphics/Viewport.cs

@@ -260,11 +260,9 @@ public CPos ViewToWorld(int2 view)
 				var s = worldRenderer.ScreenPxPosition(p);
 				if (Math.Abs(s.X - world.X) <= tileSize.Width && Math.Abs(s.Y - world.Y) <= tileSize.Height)
 				{
-					var ramp = map.Ramp.Contains(uv) ? map.Ramp[uv] : 0;
-					var corners = map.Grid.Ramps[ramp].Corners;
-					var pos = map.CenterOfCell(uv.ToCPos(map));
-					var screen = corners.Select(c => worldRenderer.ScreenPxPosition(pos + c)).ToArray();
-
+					var ramp = map.Grid.Ramps[map.Ramp.Contains(uv) ? map.Ramp[uv] : 0];
+					var pos = map.CenterOfCell(uv.ToCPos(map)) - new WVec(0, 0, ramp.CenterHeightOffset);
+					var screen = ramp.Corners.Select(c => worldRenderer.ScreenPxPosition(pos + c)).ToArray();
 					if (screen.PolygonContains(world))
 						return uv.ToCPos(map);
 				}

OpenRA.Game/Map/Map.cs

@@ -820,23 +820,47 @@ public WPos CenterOfCell(CPos cell)
 			// (c) u, v coordinates run diagonally to the cell axes, and we define
 			//     1024 as the length projected onto the primary cell axis
 			//  - 512 * sqrt(2) = 724
-			var z = Height.Contains(cell) ? 724 * Height[cell] : 0;
+			var z = Height.Contains(cell) ? 724 * Height[cell] + Grid.Ramps[Ramp[cell]].CenterHeightOffset : 0;
 			return new WPos(724 * (cell.X - cell.Y + 1), 724 * (cell.X + cell.Y + 1), z);
 		}
 
 		public WPos CenterOfSubCell(CPos cell, SubCell subCell)
 		{
 			var index = (int)subCell;
 			if (index >= 0 && index < Grid.SubCellOffsets.Length)
-				return CenterOfCell(cell) + Grid.SubCellOffsets[index];
+			{
+				var center = CenterOfCell(cell);
+				var offset = Grid.SubCellOffsets[index];
+				var ramp = Ramp.Contains(cell) ? Ramp[cell] : 0;
+				if (ramp != 0)
+				{
+					var r = Grid.Ramps[ramp];
+					offset += new WVec(0, 0, r.HeightOffset(offset.X, offset.Y) - r.CenterHeightOffset);
+				}
+
+				return center + offset;
+			}
+
 			return CenterOfCell(cell);
 		}
 
 		public WDist DistanceAboveTerrain(WPos pos)
 		{
+			if (Grid.Type == MapGridType.Rectangular)
+				return new WDist(pos.Z);
+
+			// Apply ramp offset
 			var cell = CellContaining(pos);
-			var delta = pos - CenterOfCell(cell);
-			return new WDist(delta.Z);
+			var offset = pos - CenterOfCell(cell);
+
+			var ramp = Ramp[cell];
+			if (ramp != 0)
+			{
+				var r = Grid.Ramps[ramp];
+				return new WDist(offset.Z + r.CenterHeightOffset - r.HeightOffset(offset.X, offset.Y));
+			}
+
+			return new WDist(offset.Z);
 		}
 
 		public WVec Offset(CVec delta, int dz)

OpenRA.Game/Map/MapGrid.cs

@@ -24,6 +24,7 @@ public enum RampCornerHeight { Low = 0, Half = 1, Full = 2 }
 
 	public struct CellRamp
 	{
+		public readonly int CenterHeightOffset;
 		public readonly WVec[] Corners;
 		public readonly WVec[][] Polygons;
 
@@ -68,9 +69,13 @@ public CellRamp(MapGridType type, RampCornerHeight tl = RampCornerHeight.Low, Ra
 			}
 			else
 				Polygons = new[] { Corners };
+
+			// Initial value must be asigned before HeightOffset can be called
+			CenterHeightOffset = 0;
+			CenterHeightOffset = HeightOffset(0, 0);
 		}
 
-		public WDist DistanceAboveTerrain(WVec delta)
+		public int HeightOffset(int dX, int dY)
 		{
 			// Enumerate over the polygons, assuming that they are triangles
 			// If the ramp is not split we will take the first three vertices of the corners as a valid triangle
@@ -80,17 +85,16 @@ public WDist DistanceAboveTerrain(WVec delta)
 			for (var i = 0; i < Polygons.Length; i++)
 			{
 				p = Polygons[i];
-				u = ((p[1].Y - p[2].Y) * (delta.X - p[2].X) - (p[1].X - p[2].X) * (delta.Y - p[2].Y)) / 1024;
-				v = ((p[0].X - p[2].X) * (delta.Y - p[2].Y) - (p[0].Y - p[2].Y) * (delta.X - p[2].X)) / 1024;
+				u = ((p[1].Y - p[2].Y) * (dX - p[2].X) - (p[1].X - p[2].X) * (dY - p[2].Y)) / 1024;
+				v = ((p[0].X - p[2].X) * (dY - p[2].Y) - (p[0].Y - p[2].Y) * (dX - p[2].X)) / 1024;
 
 				// Point is within the triangle if 0 <= u,v <= 1024
 				if (u >= 0 && u <= 1024 && v >= 0 && v <= 1024)
 					break;
 			}
 
 			// Calculate w from u,v and interpolate height
-			var dz = (u * p[0].Z + v * p[1].Z + (1024 - u - v) * p[2].Z) / 1024;
-			return new WDist(delta.Z - dz);
+			return (u * p[0].Z + v * p[1].Z + (1024 - u - v) * p[2].Z) / 1024;
 		}
 	}
 

OpenRA.Mods.Common/Activities/Move/Move.cs

@@ -464,6 +464,7 @@ void UpdateCenterLocation(Actor self, Mobile mobile)
 					else
 						pos = WPos.Lerp(From, To, moveFraction, MoveFractionTotal);
 
+					pos -= new WVec(WDist.Zero, WDist.Zero, self.World.Map.DistanceAboveTerrain(pos));
 					mobile.SetVisualPosition(self, pos);
 				}
 				else

OpenRA.Mods.Common/Traits/World/TerrainGeometryOverlay.cs

@@ -64,7 +64,7 @@ IEnumerable<IRenderable> IRenderAnnotations.RenderAnnotations(Actor self, WorldR
 
 				var height = (int)map.Height[uv];
 				var r = map.Grid.Ramps[map.Ramp[uv]];
-				var pos = map.CenterOfCell(uv.ToCPos(map));
+				var pos = map.CenterOfCell(uv.ToCPos(map)) - new WVec(0, 0, r.CenterHeightOffset);
 				var width = uv == mouseCell ? 3 : 1;
 
 				// Colors change between points, so render separately