Update default level a bit

assets/textures/terrain_blend/bricky_inner.png.import

@@ -0,0 +1,14 @@
+[remap]
+
+importer="image"
+type="Image"
+uid="uid://n7hbvgjiktlg"
+path="res://.godot/imported/bricky_inner.png-b94122a758411344f70f7c2760d21808.image"
+
+[deps]
+
+source_file="res://assets/textures/terrain_blend/bricky_inner.png"
+dest_files=["res://.godot/imported/bricky_inner.png-b94122a758411344f70f7c2760d21808.image"]
+
+[params]
+

assets/textures/terrain_blend/bricky_outer.png.import

@@ -0,0 +1,14 @@
+[remap]
+
+importer="image"
+type="Image"
+uid="uid://c8ntkfa6t0t4a"
+path="res://.godot/imported/bricky_outer.png-8d14c741e6e00049a6f23c5a7f0ba31a.image"
+
+[deps]
+
+source_file="res://assets/textures/terrain_blend/bricky_outer.png"
+dest_files=["res://.godot/imported/bricky_outer.png-8d14c741e6e00049a6f23c5a7f0ba31a.image"]
+
+[params]
+

assets/textures/terrain_blend/bricky_straight.png.import

@@ -0,0 +1,14 @@
+[remap]
+
+importer="image"
+type="Image"
+uid="uid://cl5gio1e8md5p"
+path="res://.godot/imported/bricky_straight.png-6b7be3b817156c5655dc51c502e77349.image"
+
+[deps]
+
+source_file="res://assets/textures/terrain_blend/bricky_straight.png"
+dest_files=["res://.godot/imported/bricky_straight.png-6b7be3b817156c5655dc51c502e77349.image"]
+
+[params]
+

assets/textures/terrain_blend/default.png.import

@@ -0,0 +1,14 @@
+[remap]
+
+importer="image"
+type="Image"
+uid="uid://bd65fhvitmpis"
+path="res://.godot/imported/default.png-16f623a6df352f7770c4e23ca5d9106b.image"
+
+[deps]
+
+source_file="res://assets/textures/terrain_blend/default.png"
+dest_files=["res://.godot/imported/default.png-16f623a6df352f7770c4e23ca5d9106b.image"]
+
+[params]
+

assets/textures/terrain_blend/grassy_inner.png.import

@@ -0,0 +1,14 @@
+[remap]
+
+importer="image"
+type="Image"
+uid="uid://cglldg71qap5f"
+path="res://.godot/imported/grassy_inner.png-dbbcf6e38e5a9f6ac5aa0bd1d57058a3.image"
+
+[deps]
+
+source_file="res://assets/textures/terrain_blend/grassy_inner.png"
+dest_files=["res://.godot/imported/grassy_inner.png-dbbcf6e38e5a9f6ac5aa0bd1d57058a3.image"]
+
+[params]
+

assets/textures/terrain_blend/grassy_outer.png.import

@@ -0,0 +1,14 @@
+[remap]
+
+importer="image"
+type="Image"
+uid="uid://cxwk1srj6obxh"
+path="res://.godot/imported/grassy_outer.png-23c05e3ec7820ad524433733076341dc.image"
+
+[deps]
+
+source_file="res://assets/textures/terrain_blend/grassy_outer.png"
+dest_files=["res://.godot/imported/grassy_outer.png-23c05e3ec7820ad524433733076341dc.image"]
+
+[params]
+

assets/textures/terrain_blend/grassy_straight.png.import

@@ -0,0 +1,14 @@
+[remap]
+
+importer="image"
+type="Image"
+uid="uid://cqgah04b0buil"
+path="res://.godot/imported/grassy_straight.png-f11f767de0d78d943ad64f3bc3a0dc4c.image"
+
+[deps]
+
+source_file="res://assets/textures/terrain_blend/grassy_straight.png"
+dest_files=["res://.godot/imported/grassy_straight.png-f11f767de0d78d943ad64f3bc3a0dc4c.image"]
+
+[params]
+

terrain/SideAndCornerExtensions.cs

@@ -0,0 +1,29 @@
+public static class SideAndCornerExtensions
+{
+	public static (Corner, Corner) GetCorners(this Side side)
+		=> side switch {
+			Side.Left   => (Corner.TopLeft, Corner.BottomLeft),
+			Side.Top    => (Corner.TopLeft, Corner.TopRight),
+			Side.Right  => (Corner.TopRight, Corner.BottomRight),
+			Side.Bottom => (Corner.BottomLeft, Corner.BottomRight),
+			_ => throw new ArgumentException($"Invalid Side value '{side}'", nameof(side)),
+		};
+
+	public static Side GetOpposite(this Side side)
+		=> side switch {
+			Side.Left   => Side.Right,
+			Side.Top    => Side.Bottom,
+			Side.Right  => Side.Left,
+			Side.Bottom => Side.Top,
+			_ => throw new ArgumentException($"Invalid Side value '{side}'", nameof(side)),
+		};
+
+	public static Corner GetOpposite(this Corner corner)
+		=> corner switch {
+			Corner.TopLeft     => Corner.BottomRight,
+			Corner.TopRight    => Corner.BottomLeft,
+			Corner.BottomRight => Corner.TopLeft,
+			Corner.BottomLeft  => Corner.TopRight,
+			_ => throw new ArgumentException($"Invalid Corner value '{corner}'", nameof(corner)),
+		};
+}

terrain/Terrain+Editing.cs

@@ -1,9 +1,9 @@
 [Tool]
 public partial class Terrain
 {
-	bool _unhandledMouseMotion = false; // Used to detect when mouse moves off the terrain.
-	TilePos? _tileHover = null;         // Position of currently hovered tile.
-	bool _isSelecting = false;          // Whether left mouse is held down to select tiles.
+	bool _unhandledMotion = false; // Used to detect when mouse moves off the terrain.
+	TilePos? _tileHover = null;    // Position of currently hovered tile.
+	bool _isSelecting = false;     // Whether left mouse is held down to select tiles.
 	(TilePos, TilePos)? _selection = null;
 
 	public override void _Input(InputEvent ev)
@@ -37,11 +37,14 @@ public partial class Terrain
 				var innerPos = selection.GetTileFor(innerCorner);
 				var outerPos = innerPos.GetNeighbor(innerCorner);
 
-				var innerHeight = GetCornerHeights(innerPos)[innerCorner];
-				var outerHeight = GetCornerHeights(outerPos)[outerCorner];
+				var outerTile   = GetTile(outerPos);
+				var innerHeight = GetTile(innerPos).Height[innerCorner];
+				var outerHeight = outerTile.Height[outerCorner];
 
-				if (IsEqualApprox(outerHeight, innerHeight))
-					SetCornerHeight(outerPos, outerCorner, innerHeight + amount);
+				if (IsEqualApprox(outerHeight, innerHeight)) {
+					outerTile.Height[outerCorner] = innerHeight + amount;
+					SetTile(outerPos, outerTile);
+				}
 			}
 
 			// Raise connected sides.
@@ -49,40 +52,59 @@ public partial class Terrain
 				foreach (var innerPos in selection.GetTilesFor(side)) {
 					var outerPos = innerPos.GetNeighbor(side);
 
-					var innerHeights = GetCornerHeights(innerPos);
-					var outerHeights = GetCornerHeights(outerPos);
+					var innerTile = GetTile(innerPos);
+					var outerTile = GetTile(outerPos);
 
 					var (innerCorner1, innerCorner2) = side.GetCorners();
 					var (outerCorner1, outerCorner2) = side.GetOpposite().GetCorners();
 
-					var current = outerHeights;
 					var changed = false;
-
 					var matchingCorners = new[]{ (innerCorner1, outerCorner1), (innerCorner2, outerCorner2) };
 					foreach (var (innerCorner, outerCorner) in matchingCorners) {
-						var innerHeight = innerHeights[innerCorner];
-						var outerHeight = outerHeights[outerCorner];
+						var innerHeight = innerTile.Height[innerCorner];
+						var outerHeight = outerTile.Height[outerCorner];
 
 						if (IsEqualApprox(outerHeight, innerHeight)) {
-							current = current.With(outerCorner, innerHeight + amount);
+							outerTile.Height[outerCorner] = innerHeight + amount;
 							changed = true;
 						}
 					}
-
-					if (changed) SetCornerHeights(outerPos, current);
+					if (changed) SetTile(outerPos, outerTile);
 				}
 			}
 
 			// Raise selected tiles themselves.
-			foreach (var tile in selection.GetAllTiles())
-				AdjustTileHeight(tile, amount);
+			foreach (var pos in selection.GetAllTiles()) {
+				var tile = GetTile(pos);
+				tile.Height.Adjust(amount);
+				SetTile(pos, tile);
+			}
+
+			UpdateMeshAndShape();
+			NotifyPropertyListChanged();
+		}
+
+		if ((ev is InputEventMouseButton { ButtonIndex: var wheel2, Pressed: var pressed2, CtrlPressed: true })
+		 && (wheel2 is MouseButton.WheelUp or MouseButton.WheelDown) && (_selection != null))
+		{
+			GetViewport().SetInputAsHandled();
+			if (!pressed2) return;
+
+			var amount = (wheel2 == MouseButton.WheelUp) ? 1 : -1;
+			var selection = TileRegion.From(_selection.Value);
+
+			foreach (var pos in selection.GetAllTiles()) {
+				var tile = GetTile(pos);
+				tile.TexturePrimary = PosMod(tile.TexturePrimary + amount, 4);
+				SetTile(pos, tile);
+			}
 
 			UpdateMeshAndShape();
 			NotifyPropertyListChanged();
 		}
 
 		if (ev is InputEventMouseMotion)
-			_unhandledMouseMotion = true;
+			_unhandledMotion = true;
 	}
 
 	public override void _InputEvent(Camera3D camera, InputEvent ev, Vector3 position, Vector3 normal, int shapeIdx)
@@ -99,7 +121,7 @@ public partial class Terrain
 		}
 
 		if (ev is InputEventMouseMotion) {
-			_unhandledMouseMotion = false;
+			_unhandledMotion = false;
 			_tileHover = tilePos;
 			if (_isSelecting) _selection = _selection.Value with { Item2 = tilePos };
 		}
@@ -113,7 +135,7 @@ public partial class Terrain
 			_isSelecting = false;
 		}
 
-		if (_unhandledMouseMotion)
+		if (_unhandledMotion)
 			_tileHover = null;
 
 		if ((_tileHover != null) || (_selection != null)) {
@@ -135,7 +157,7 @@ public partial class Terrain
 			}
 
 			if (_tileHover is TilePos hover) {
-				var corners = GetCornersPosition(hover);
+				var corners = GetTileCornerPositions(hover);
 				var margin  = 0.1f;
 				mesh.SurfaceSetColor(Colors.Black);
 				AddQuad(corners.TopLeft     + new Vector3(-margin, 0, -margin),
@@ -147,7 +169,7 @@ public partial class Terrain
 			mesh.SurfaceSetColor(Colors.Blue);
 			if (_selection is (TilePos, TilePos) selection)
 				foreach (var pos in TileRegion.From(selection).GetAllTiles()) {
-					var corners = GetCornersPosition(pos);
+					var corners = GetTileCornerPositions(pos);
 					AddQuad(corners.TopLeft, corners.TopRight, corners.BottomLeft, corners.BottomRight);
 				}
 

terrain/Terrain.cs

@@ -26,6 +26,18 @@ public partial class Terrain
 	}
 
 
+	public Tile GetTile(TilePos pos)
+		=> (Tiles?.TryGetValue(pos.ToVector2I(), out var result) == true)
+			? Tile.FromDictionary(result.AsGodotDictionary()) : default;
+
+	public void SetTile(TilePos pos, Tile value)
+	{
+		var key  = pos.ToVector2I();
+		var dict = value.ToDictionary();
+		if (dict == null) Tiles.Remove(key);
+		else              Tiles[key] = dict;
+	}
+
 	public bool Contains(TilePos pos)
 		=> (pos.X >= 0) && (pos.X < Size.X)
 		&& (pos.Y >= 0) && (pos.Y < Size.Y);
@@ -35,83 +47,6 @@ public partial class Terrain
 		=> new(RoundToInt(localPos.X / TileSize + Size.X / 2.0f),
 		       RoundToInt(localPos.Z / TileSize + Size.Y / 2.0f));
 
-	public Corners<float> GetCornerHeights(TilePos pos)
-		=> GetTileRaw(pos) switch {
-			{ VariantType: Variant.Type.Nil }                  => default,
-			{ VariantType: Variant.Type.Float } v              => Corners<float>.From((float)v),
-			{ VariantType: Variant.Type.PackedFloat32Array } v => Corners<float>.From((float[])v),
-			_ => throw new Exception("Invalid type in Points dictionary"),
-		};
-
-	public void SetCornerHeight(TilePos pos, Corner corner, float value)
-		=> SetCornerHeights(pos, default(Corners<float?>).With(corner, value));
-	public void SetCornerHeights(TilePos pos, Corners<float> values)
-		=> SetCornerHeights(pos, new Corners<float?>(values.TopLeft, values.TopRight, values.BottomRight, values.BottomLeft));
-	public void SetCornerHeights(TilePos pos, Corners<float?> values)
-	{
-		if (!Contains(pos)) return;
-
-		var current = GetCornerHeights(pos);
-		var changed = false;
-
-		foreach (var corner in Enum.GetValues<Corner>())
-			if (values[corner] is float value)
-				{ current = current.With(corner, value); changed = true; }
-		if (!changed) return;
-
-		if      (current.IsZeroApprox())  RemoveTileRaw(pos);
-		else if (current.IsEqualApprox()) SetTileRaw(pos, current.TopLeft);
-		else                              SetTileRaw(pos, current.ToArray());
-	}
-
-	public void SetTileHeight(TilePos pos, float value)
-	{
-		if (!Contains(pos)) return;
-		if (IsZeroApprox(value)) RemoveTileRaw(pos);
-		else                     SetTileRaw(pos, value);
-	}
-
-	public void AdjustTileHeight(TilePos pos, float relative)
-	{
-		if (relative == 0) return;
-		if (!Contains(pos)) return;
-		switch (GetTileRaw(pos)) {
-			case { VariantType: Variant.Type.Nil }:
-				SetTileRaw(pos, relative);
-				break;
-			case { VariantType: Variant.Type.Float } num:
-				var newNum = (float)num + relative;
-				if (IsZeroApprox(newNum)) RemoveTileRaw(pos);
-				else                      SetTileRaw(pos, newNum);
-				break;
-			case { VariantType: Variant.Type.PackedFloat32Array } nums:
-				var newNums = (float[])nums;
-				for (var i = 0; i < 4; i++) newNums[i] += relative;
-				SetTileRaw(pos, newNums);
-				break;
-			default: throw new Exception("Invalid type in Points dictionary");
-		};
-	}
-
-	public Corners<Vector3> GetCornersPosition(TilePos pos)
-	{
-		var heights = GetCornerHeights(pos);
-		var vx   = (pos.X - Size.X / 2.0f) * TileSize;
-		var vz   = (pos.Y - Size.Y / 2.0f) * TileSize;
-		var half = TileSize / 2;
-		return new(new(vx - half, heights[Corner.TopLeft    ], vz - half),
-		           new(vx + half, heights[Corner.TopRight   ], vz - half),
-		           new(vx + half, heights[Corner.BottomRight], vz + half),
-		           new(vx - half, heights[Corner.BottomLeft ], vz + half));
-	}
-
-	Variant GetTileRaw(TilePos pos)
-		=> (Tiles?.TryGetValue(pos.ToVector2I(), out var result) == true) ? result : default;
-	void SetTileRaw(TilePos pos, Variant value)
-		=> (Tiles ??= [])[pos.ToVector2I()] = value;
-	void RemoveTileRaw(TilePos pos)
-		=> Tiles?.Remove(pos.ToVector2I());
-
 
 	void UpdateMeshAndShape()
 	{
@@ -138,33 +73,51 @@ public partial class Terrain
 			AddPoint(v3, uv3);
 		}
 
-		var rnd = new Random();
+		// TODO: Don't hardcode.
+		var num_textures       = 4;
+		var num_blend_textures = 7;
+
+		var rnd  = new Random();
 		for (var x = 0; x < Size.X; x++)
 			for (var z = 0; z < Size.Y; z++) {
-				var corners = GetCornersPosition(new(x, z));
+				var tile    = GetTile(new(x, z));
+				var corners = GetTileCornerPositions(new(x, z), tile);
+
+				// Randomly select two different textures and one blend texture.
+				mesh.SurfaceSetColor(new(
+					(float)tile.TexturePrimary   / num_textures,
+					(float)tile.TextureSecondary / num_textures,
+					(float)tile.TextureBlend     / num_blend_textures
+				));
+
+				var sorted = new (Corner Corner, float Height)[] {
+					(Corner.TopLeft     , tile.Height.TopLeft    ),
+					(Corner.TopRight    , tile.Height.TopRight   ),
+					(Corner.BottomRight , tile.Height.BottomRight),
+					(Corner.BottomLeft  , tile.Height.BottomLeft ),
+				};
+				Array.Sort(sorted, (a, b) => a.Height.CompareTo(b.Height));
 
 				// Find the "ideal way" to split the quad for the tile into two triangles.
 				// This is done by finding the corner with the least variance between its neighboring corners.
-				var sorted  = corners.ToSorted((a, b) => a.Y.CompareTo(b.Y));
-				var minDiff = Abs(sorted[0].Value.Y - sorted[2].Value.Y); // Difference between lowest and 3rd lowest point.
-				var maxDiff = Abs(sorted[3].Value.Y - sorted[1].Value.Y); // Difference between highest and 3rd highest point.
+				var minDiff = Abs(sorted[0].Height - sorted[2].Height); // Difference between lowest and 3rd lowest point.
+				var maxDiff = Abs(sorted[3].Height - sorted[1].Height); // Difference between highest and 3rd highest point.
+				var first   = sorted[(minDiff > maxDiff) ? 0 : 3].Corner;
 
-				mesh.SurfaceSetUV2(new(rnd.Next(4), 0.0f));
-				var first = sorted[(minDiff > maxDiff) ? 0 : 3].Corner;
 				if (first is Corner.TopLeft or Corner.BottomRight) {
 					AddTriangle(corners.TopLeft    , new(0.0f, 0.0f),
-								corners.TopRight   , new(1.0f, 0.0f),
-								corners.BottomLeft , new(0.0f, 1.0f));
+					            corners.TopRight   , new(1.0f, 0.0f),
+					            corners.BottomLeft , new(0.0f, 1.0f));
 					AddTriangle(corners.TopRight   , new(1.0f, 0.0f),
-								corners.BottomRight, new(1.0f, 1.0f),
-								corners.BottomLeft , new(0.0f, 1.0f));
+					            corners.BottomRight, new(1.0f, 1.0f),
+					            corners.BottomLeft , new(0.0f, 1.0f));
 				} else {
 					AddTriangle(corners.TopRight   , new(1.0f, 0.0f),
-								corners.BottomRight, new(1.0f, 1.0f),
-								corners.TopLeft    , new(0.0f, 0.0f));
+					            corners.BottomRight, new(1.0f, 1.0f),
+					            corners.TopLeft    , new(0.0f, 0.0f));
 					AddTriangle(corners.BottomRight, new(1.0f, 1.0f),
-								corners.BottomLeft , new(0.0f, 1.0f),
-								corners.TopLeft    , new(0.0f, 0.0f));
+					            corners.BottomLeft , new(0.0f, 1.0f),
+					            corners.TopLeft    , new(0.0f, 0.0f));
 				}
 			}
 
@@ -175,11 +128,25 @@ public partial class Terrain
 	}
 
 
+	public Corners<Vector3> GetTileCornerPositions(TilePos pos)
+		=> GetTileCornerPositions(pos, GetTile(pos));
+	public Corners<Vector3> GetTileCornerPositions(TilePos pos, Tile tile)
+	{
+		var half = TileSize / 2;
+		var vx = (pos.X - Size.X / 2.0f) * TileSize;
+		var vz = (pos.Y - Size.Y / 2.0f) * TileSize;
+		return new(new(vx - half, tile.Height.TopLeft    , vz - half),
+		           new(vx + half, tile.Height.TopRight   , vz - half),
+		           new(vx + half, tile.Height.BottomRight, vz + half),
+		           new(vx - half, tile.Height.BottomLeft , vz + half));
+	}
+
+
 	ImmediateMesh GetOrCreateMesh(string name)
 	{
 		var meshInstance = (MeshInstance3D)GetNodeOrNull(name);
 		if (meshInstance == null) {
-			meshInstance = new() { Name = name, Mesh = new ImmediateMesh() };
+			meshInstance = new(){ Name = name, Mesh = new ImmediateMesh() };
 			AddChild(meshInstance);
 			meshInstance.Owner = this;
 		}
@@ -190,125 +157,10 @@ public partial class Terrain
 	{
 		var collisionShape = (CollisionShape3D)GetNodeOrNull(name);
 		if (collisionShape == null) {
-			collisionShape = new() { Name = name, Shape = new ConcavePolygonShape3D() };
+			collisionShape = new(){ Name = name, Shape = new ConcavePolygonShape3D() };
 			AddChild(collisionShape);
 			collisionShape.Owner = this;
 		}
 		return (ConcavePolygonShape3D)collisionShape.Shape;
 	}
-
-
-	public readonly record struct TilePos(int X, int Y)
-	{
-		public TilePos GetNeighbor(Side side)
-			=> side switch {
-				Side.Left   => new(X - 1, Y),
-				Side.Top    => new(X, Y - 1),
-				Side.Right  => new(X + 1, Y),
-				Side.Bottom => new(X, Y + 1),
-				_ => throw new ArgumentException($"Invalid Side value '{side}'", nameof(side)),
-			};
-
-		public TilePos GetNeighbor(Corner corner)
-			=> corner switch {
-				Corner.TopLeft     => new(X - 1, Y - 1),
-				Corner.TopRight    => new(X + 1, Y - 1),
-				Corner.BottomRight => new(X + 1, Y + 1),
-				Corner.BottomLeft  => new(X - 1, Y + 1),
-				_ => throw new ArgumentException($"Invalid Corner value '{corner}'", nameof(corner)),
-			};
-
-		public static TilePos From(Vector2I value) => new(value.X, value.Y);
-		public Vector2I ToVector2I() => new(X, Y);
-	}
-
-	public readonly record struct Corners<T>
-		(T TopLeft, T TopRight, T BottomRight, T BottomLeft)
-	{
-		public T this[Corner corner] {
-			get => corner switch {
-				Corner.TopLeft     => TopLeft,
-				Corner.TopRight    => TopRight,
-				Corner.BottomRight => BottomRight,
-				Corner.BottomLeft  => BottomLeft,
-				_ => throw new ArgumentException($"Invalid Corner value '{corner}'", nameof(corner)),
-			};
-			init { switch (corner) {
-				case Corner.TopLeft     : TopLeft     = value; break;
-				case Corner.TopRight    : TopRight    = value; break;
-				case Corner.BottomRight : BottomRight = value; break;
-				case Corner.BottomLeft  : BottomLeft  = value; break;
-				default: throw new ArgumentException($"Invalid Corner value '{corner}'", nameof(corner));
-			} }
-		}
-
-		public static Corners<T> From(T value) => new()
-			{ TopLeft = value, TopRight = value, BottomRight = value, BottomLeft = value };
-		public static Corners<T> From(T[] values) => new()
-			{ TopLeft = values[0], TopRight = values[1], BottomRight = values[2], BottomLeft = values[3] };
-
-		public Corners<T> With(Corner corner, T value)
-			=> new((corner == Corner.TopLeft)     ? value : TopLeft,
-			       (corner == Corner.TopRight)    ? value : TopRight,
-			       (corner == Corner.BottomRight) ? value : BottomRight,
-			       (corner == Corner.BottomLeft)  ? value : BottomLeft);
-
-		public T[] ToArray()
-			=> [ TopLeft, TopRight, BottomRight, BottomLeft ];
-
-		public (Corner Corner, T Value)[] ToSorted(Comparison<T> comparison)
-		{
-			var result = new (Corner Corner, T Value)[] {
-				(Corner.TopLeft     , TopLeft    ),
-				(Corner.TopRight    , TopRight   ),
-				(Corner.BottomRight , BottomRight),
-				(Corner.BottomLeft  , BottomLeft ),
-			};
-			Array.Sort(result, (a, b) => comparison(a.Value, b.Value));
-			return result;
-		}
-	}
-}
-
-public static class CornersExtensions
-{
-	public static bool IsZeroApprox(this Terrain.Corners<float> self)
-		=> Mathf.IsZeroApprox(self.TopLeft)     && Mathf.IsZeroApprox(self.TopRight)
-		&& Mathf.IsZeroApprox(self.BottomRight) && Mathf.IsZeroApprox(self.BottomLeft);
-
-	public static bool IsEqualApprox(this Terrain.Corners<float> self)
-		=> Mathf.IsEqualApprox(self.TopLeft, self.TopRight)
-		&& Mathf.IsEqualApprox(self.TopLeft, self.BottomRight)
-		&& Mathf.IsEqualApprox(self.TopLeft, self.BottomLeft);
-}
-
-// TODO: Put this in a different file.
-public static class TerrainExtensions
-{
-	public static (Corner, Corner) GetCorners(this Side side)
-		=> side switch {
-			Side.Left   => (Corner.TopLeft, Corner.BottomLeft),
-			Side.Top    => (Corner.TopLeft, Corner.TopRight),
-			Side.Right  => (Corner.TopRight, Corner.BottomRight),
-			Side.Bottom => (Corner.BottomLeft, Corner.BottomRight),
-			_ => throw new ArgumentException($"Invalid Side value '{side}'", nameof(side)),
-		};
-
-	public static Side GetOpposite(this Side side)
-		=> side switch {
-			Side.Left   => Side.Right,
-			Side.Top    => Side.Bottom,
-			Side.Right  => Side.Left,
-			Side.Bottom => Side.Top,
-			_ => throw new ArgumentException($"Invalid Side value '{side}'", nameof(side)),
-		};
-
-	public static Corner GetOpposite(this Corner corner)
-		=> corner switch {
-			Corner.TopLeft     => Corner.BottomRight,
-			Corner.TopRight    => Corner.BottomLeft,
-			Corner.BottomRight => Corner.TopLeft,
-			Corner.BottomLeft  => Corner.TopRight,
-			_ => throw new ArgumentException($"Invalid Corner value '{corner}'", nameof(corner)),
-		};
 }

terrain/Tile.cs

@@ -0,0 +1,129 @@
+using Dictionary = Godot.Collections.Dictionary;
+
+public readonly record struct TilePos(int X, int Y)
+{
+	public TilePos GetNeighbor(Side side)
+		=> side switch {
+			Side.Left   => new(X - 1, Y),
+			Side.Top    => new(X, Y - 1),
+			Side.Right  => new(X + 1, Y),
+			Side.Bottom => new(X, Y + 1),
+			_ => throw new ArgumentException($"Invalid Side value '{side}'", nameof(side)),
+		};
+
+	public TilePos GetNeighbor(Corner corner)
+		=> corner switch {
+			Corner.TopLeft     => new(X - 1, Y - 1),
+			Corner.TopRight    => new(X + 1, Y - 1),
+			Corner.BottomRight => new(X + 1, Y + 1),
+			Corner.BottomLeft  => new(X - 1, Y + 1),
+			_ => throw new ArgumentException($"Invalid Corner value '{corner}'", nameof(corner)),
+		};
+
+	public static TilePos From(Vector2I value) => new(value.X, value.Y);
+	public Vector2I ToVector2I() => new(X, Y);
+}
+
+public struct Tile
+{
+	public Corners<float> Height;
+
+	// TODO: Replace with enum or something more permanent?
+	public int TexturePrimary;
+	public int TextureSecondary;
+	public int TextureBlend;
+
+
+	public static Tile FromDictionary(Dictionary dict)
+	{
+		if (dict == null) return default;
+
+		float topLeft, topRight, bottomRight, bottomLeft;
+		switch (dict["heights"]) {
+			case { VariantType: Variant.Type.Float } variant:
+				var height = (float)variant;
+				(topLeft, topRight, bottomRight, bottomLeft) = (height, height, height, height);
+				break;
+			case { VariantType: Variant.Type.PackedFloat32Array } variant:
+				var heights = (float[])variant;
+				(topLeft, topRight, bottomRight, bottomLeft) = (heights[0], heights[1], heights[2], heights[3]);
+				break;
+			default: throw new Exception("Invalid variant type");
+		};
+
+		int texturePrimary, textureSecondary, textureBlend;
+		switch (dict["texture"]) {
+			case { VariantType: Variant.Type.Int } variant:
+				var texture = (int)variant;
+				(texturePrimary, textureSecondary, textureBlend) = (texture, 0, 0);
+				break;
+			case { VariantType: Variant.Type.PackedInt32Array } variant:
+				var textures = (int[])variant;
+				(texturePrimary, textureSecondary, textureBlend) = (textures[0], textures[1], textures[2]);
+				break;
+			default: throw new Exception("Invalid variant type");
+		};
+
+		return new(){
+			Height = new(topLeft, topRight, bottomRight, bottomLeft),
+			TexturePrimary   = texturePrimary,
+			TextureSecondary = textureSecondary,
+			TextureBlend     = textureBlend,
+		};
+	}
+
+	public readonly Dictionary ToDictionary()
+	{
+		if (Height.IsZeroApprox() && (TexturePrimary == 0) && (TextureBlend == 0))
+			return null;
+		return new(){
+			["heights"] = Height.IsEqualApprox() ? Height.TopLeft : new[]{ Height.TopLeft, Height.TopRight, Height.BottomRight, Height.BottomLeft },
+			["texture"] = (TextureBlend == 0) ? TexturePrimary : new[]{ TexturePrimary, TextureSecondary, TextureBlend },
+		};
+	}
+}
+
+public struct Corners<T>(T topLeft, T topRight, T bottomRight, T bottomLeft)
+{
+	public T TopLeft     = topLeft;
+	public T TopRight    = topRight;
+	public T BottomRight = bottomRight;
+	public T BottomLeft  = bottomLeft;
+
+	public T this[Corner corner] {
+		readonly get => corner switch {
+			Corner.TopLeft     => TopLeft,
+			Corner.TopRight    => TopRight,
+			Corner.BottomRight => BottomRight,
+			Corner.BottomLeft  => BottomLeft,
+			_ => throw new ArgumentException($"Invalid Corner value '{corner}'", nameof(corner)),
+		};
+		set { switch (corner) {
+			case Corner.TopLeft     : TopLeft     = value; break;
+			case Corner.TopRight    : TopRight    = value; break;
+			case Corner.BottomRight : BottomRight = value; break;
+			case Corner.BottomLeft  : BottomLeft  = value; break;
+			default: throw new ArgumentException($"Invalid Corner value '{corner}'", nameof(corner));
+		} }
+	}
+}
+
+public static class CornersExtensions
+{
+	public static void Adjust(this ref Corners<float> self, float amount)
+	{
+		self.TopLeft     += amount;
+		self.TopRight    += amount;
+		self.BottomRight += amount;
+		self.BottomLeft  += amount;
+	}
+
+	public static bool IsZeroApprox(this Corners<float> self)
+		=> Mathf.IsZeroApprox(self.TopLeft    ) && Mathf.IsZeroApprox(self.TopRight  )
+		&& Mathf.IsZeroApprox(self.BottomRight) && Mathf.IsZeroApprox(self.BottomLeft);
+
+	public static bool IsEqualApprox(this Corners<float> self)
+		=> Mathf.IsEqualApprox(self.TopLeft, self.TopRight   )
+		&& Mathf.IsEqualApprox(self.TopLeft, self.BottomRight)
+		&& Mathf.IsEqualApprox(self.TopLeft, self.BottomLeft );
+}

terrain/terrain_material.tres

@@ -1,15 +1,28 @@
-[gd_resource type="ShaderMaterial" load_steps=7 format=4 uid="uid://doe8owgx4jeu1"]
+[gd_resource type="ShaderMaterial" load_steps=15 format=4 uid="uid://doe8owgx4jeu1"]
 
 [ext_resource type="Shader" path="res://terrain/terrain_shader.gdshader" id="1_mf55c"]
+
 [ext_resource type="Image" uid="uid://b0jp1dyxugbr7" path="res://assets/textures/terrain/grass.png" id="5_mau31"]
 [ext_resource type="Image" uid="uid://bpo7mkr6sctqr" path="res://assets/textures/terrain/dirt.png" id="6_xc3ue"]
 [ext_resource type="Image" uid="uid://dqyqg6yt7yk3k" path="res://assets/textures/terrain/rock.png" id="7_84wdo"]
 [ext_resource type="Image" uid="uid://bkwjxg6g2itag" path="res://assets/textures/terrain/sand.png" id="8_3fpcn"]
 
+[ext_resource type="Image" uid="uid://bd65fhvitmpis" path="res://assets/textures/terrain_blend/default.png" id="5_qdlds"]
+[ext_resource type="Image" uid="uid://cqgah04b0buil" path="res://assets/textures/terrain_blend/grassy_straight.png" id="6_s3ccy"]
+[ext_resource type="Image" uid="uid://cxwk1srj6obxh" path="res://assets/textures/terrain_blend/grassy_outer.png" id="7_wgbkx"]
+[ext_resource type="Image" uid="uid://cglldg71qap5f" path="res://assets/textures/terrain_blend/grassy_inner.png" id="8_dm7dx"]
+[ext_resource type="Image" uid="uid://cl5gio1e8md5p" path="res://assets/textures/terrain_blend/bricky_straight.png" id="9_fwpox"]
+[ext_resource type="Image" uid="uid://c8ntkfa6t0t4a" path="res://assets/textures/terrain_blend/bricky_outer.png" id="10_kq5au"]
+[ext_resource type="Image" uid="uid://n7hbvgjiktlg" path="res://assets/textures/terrain_blend/bricky_inner.png" id="11_0i2i8"]
+
 [sub_resource type="Texture2DArray" id="Texture2DArray_3nq13"]
 _images = Array[Image]([ExtResource("5_mau31"), ExtResource("6_xc3ue"), ExtResource("7_84wdo"), ExtResource("8_3fpcn")])
 
+[sub_resource type="Texture2DArray" id="Texture2DArray_3nq14"]
+_images = Array[Image]([ExtResource("5_qdlds"), ExtResource("6_s3ccy"), ExtResource("7_wgbkx"), ExtResource("8_dm7dx"), ExtResource("9_fwpox"), ExtResource("10_kq5au"), ExtResource("11_0i2i8")])
+
 [resource]
 render_priority = 0
 shader = ExtResource("1_mf55c")
 shader_parameter/textures = SubResource("Texture2DArray_3nq13")
+shader_parameter/blend_textures = SubResource("Texture2DArray_3nq14")

terrain/terrain_shader.gdshader

@@ -1,10 +1,22 @@
 shader_type spatial;
 render_mode blend_mix, depth_draw_opaque, cull_back, diffuse_burley, specular_schlick_ggx;
 
-uniform sampler2DArray textures : source_color, filter_linear_mipmap, repeat_enable;
+uniform sampler2DArray textures       : source_color, filter_linear_mipmap, repeat_enable;
+uniform sampler2DArray blend_textures : source_color, filter_nearest_mipmap, repeat_enable;
 
 void fragment() {
-	ALBEDO = texture(textures, vec3(UV, UV2.x)).rgb;
+	int num_textures       = textureSize(textures, 0).z;
+	int num_blend_textures = textureSize(blend_textures, 0).z;
+
+	float tex_primary_index   = COLOR.r * float(num_textures);
+	float tex_secondary_index = COLOR.g * float(num_textures);
+	float tex_blend_index     = COLOR.b * float(num_blend_textures);
+
+	vec4 tex_primary   = texture(textures, vec3(UV, tex_primary_index));
+	vec4 tex_secondary = texture(textures, vec3(UV, tex_secondary_index));
+
+	vec4 blend = texture(blend_textures, vec3(UV, tex_blend_index));
+	ALBEDO = mix(tex_secondary, tex_primary, blend.a).rgb;
 
 	METALLIC  = 0.0;
 	SPECULAR  = 0.5;