From 294f3b82ef39c99d39d14c0ffc09012c5253c1e5 Mon Sep 17 00:00:00 2001
From: MDietermann <mdietermann253@gmail.com>
Date: Sun, 31 May 2026 21:51:57 +0200
Subject: [PATCH] feat: add WorldConstants, SurfacePalette and IBiome contract

---
 World/WorldGen/IBiome.cs         | 17 +++++++++++++++++
 World/WorldGen/SurfacePalette.cs |  7 +++++++
 World/WorldGen/WorldConstants.cs | 10 ++++++++++
 3 files changed, 34 insertions(+)
 create mode 100644 World/WorldGen/IBiome.cs
 create mode 100644 World/WorldGen/SurfacePalette.cs
 create mode 100644 World/WorldGen/WorldConstants.cs

diff --git a/World/WorldGen/IBiome.cs b/World/WorldGen/IBiome.cs
new file mode 100644
index 0000000..6b573cc
--- /dev/null
+++ b/World/WorldGen/IBiome.cs
@@ -0,0 +1,17 @@
+using VoxelEngine.World.Blocks;
+
+namespace VoxelEngine.World.WorldGen;
+
+public interface IBiome
+{
+    string Name { get; }
+
+    // Absolute target surface height at the column (continuous, pre-rounding).
+    float SampleHeight(NoiseSource noise, float worldX, float worldZ);
+
+    SurfacePalette Surface { get; }
+
+    // Surface block for a given height; lets biomes vary the top by altitude
+    // (e.g. Mountains use Snow above the snow line). Defaults to Surface.Top.
+    IBlock TopBlock(int worldY);
+}
diff --git a/World/WorldGen/SurfacePalette.cs b/World/WorldGen/SurfacePalette.cs
new file mode 100644
index 0000000..5c6a908
--- /dev/null
+++ b/World/WorldGen/SurfacePalette.cs
@@ -0,0 +1,7 @@
+using VoxelEngine.World.Blocks;
+
+namespace VoxelEngine.World.WorldGen;
+
+// Surface block layering for a biome: the top block, the filler band below it,
+// and the deep "under" block (stone). Filler depth is fixed at 3 blocks.
+public readonly record struct SurfacePalette(IBlock Top, IBlock Filler, IBlock Under);
diff --git a/World/WorldGen/WorldConstants.cs b/World/WorldGen/WorldConstants.cs
new file mode 100644
index 0000000..5bf055a
--- /dev/null
+++ b/World/WorldGen/WorldConstants.cs
@@ -0,0 +1,10 @@
+using VoxelChunk = VoxelEngine.World.Chunk.Chunk;
+
+namespace VoxelEngine.World.WorldGen;
+
+public static class WorldConstants
+{
+    public const int WorldHeightChunks = 8;
+    public const int WorldHeight = WorldConstants.WorldHeightChunks * VoxelChunk.Size; // 128
+    public const int SeaLevel = 64;
+}