From 39375b83ead8e65d9f162ec1be47d96bd5823225 Mon Sep 17 00:00:00 2001
From: MDietermann <marvin.dietermann@hive-brain.de>
Date: Mon, 1 Jun 2026 10:45:58 +0200
Subject: [PATCH] refactor: extract shared ChunkMath.FloorDiv helper

---
 Core/ChunkMath.cs | 13 +++++++++++++
 Game/Player.cs    | 13 +++----------
 World/World.cs    | 36 ++++++++++++------------------------
 3 files changed, 28 insertions(+), 34 deletions(-)
 create mode 100644 Core/ChunkMath.cs

diff --git a/Core/ChunkMath.cs b/Core/ChunkMath.cs
new file mode 100644
index 0000000..d8f096d
--- /dev/null
+++ b/Core/ChunkMath.cs
@@ -0,0 +1,13 @@
+namespace VoxelEngine.Core;
+
+internal static class ChunkMath
+{
+    // Floor division: floors toward negative infinity (not toward zero like C#'s /).
+    // Required for correct world-coord -> chunk-index mapping for negative coordinates.
+    internal static int FloorDiv(int value, int size)
+    {
+        int q = value / size;
+        if (value % size != 0 && value < 0) q--;
+        return q;
+    }
+}
diff --git a/Game/Player.cs b/Game/Player.cs
index 94fd03e..270a37f 100644
--- a/Game/Player.cs
+++ b/Game/Player.cs
@@ -20,9 +20,9 @@ public sealed class Player
         {
             Vector3 p = this.Position;
             return new Vector3i(
-                Player.FloorDiv((int)MathF.Floor(p.X), VoxelChunk.Size),
-                Player.FloorDiv((int)MathF.Floor(p.Y), VoxelChunk.Size),
-                Player.FloorDiv((int)MathF.Floor(p.Z), VoxelChunk.Size));
+                ChunkMath.FloorDiv((int)MathF.Floor(p.X), VoxelChunk.Size),
+                ChunkMath.FloorDiv((int)MathF.Floor(p.Y), VoxelChunk.Size),
+                ChunkMath.FloorDiv((int)MathF.Floor(p.Z), VoxelChunk.Size));
         }
     }
 
@@ -35,11 +35,4 @@ public sealed class Player
     public void Move(Vector3 delta) => this.Camera.Move(delta);
 
     public void AddRotation(float yawDelta, float pitchDelta) => this.Camera.AddRotation(yawDelta, pitchDelta);
-
-    private static int FloorDiv(int value, int size)
-    {
-        int q = value / size;
-        if (value % size != 0 && value < 0) q--;
-        return q;
-    }
 }
diff --git a/World/World.cs b/World/World.cs
index 938a929..f6ea3b5 100644
--- a/World/World.cs
+++ b/World/World.cs
@@ -1,22 +1,17 @@
 using System.Collections;
 using OpenTK.Mathematics;
+using VoxelEngine.Core;
 using VoxelEngine.World.Blocks;
 using VoxelEngine.World.Persistence;
 
 namespace VoxelEngine.World;
 
-public sealed class World : IWorld, IEnumerable<KeyValuePair<Vector3i, Chunk.Chunk>>
+public sealed class World(BlockRegistry registry, IChunkModificationStore modStore)
+    : IWorld, IEnumerable<KeyValuePair<Vector3i, Chunk.Chunk>>
 {
     private readonly Dictionary<Vector3i, Chunk.Chunk> _chunks = new();
-    private readonly BlockRegistry _registry;
 
-    public IChunkModificationStore ModificationStore { get; }
-
-    public World(BlockRegistry registry, IChunkModificationStore modStore)
-    {
-        this._registry = registry;
-        this.ModificationStore = modStore;
-    }
+    public IChunkModificationStore ModificationStore { get; } = modStore;
 
     public void SetChunk(Vector3i chunkPos, Chunk.Chunk chunk) => this._chunks[chunkPos] = chunk;
 
@@ -27,25 +22,25 @@ public sealed class World : IWorld, IEnumerable<KeyValuePair<Vector3i, Chunk.Chu
     public IBlock GetBlock(int worldX, int worldY, int worldZ)
     {
         Vector3i chunkPos = new(
-            World.FloorDiv(worldX, Chunk.Chunk.Size),
-            World.FloorDiv(worldY, Chunk.Chunk.Size),
-            World.FloorDiv(worldZ, Chunk.Chunk.Size));
+            ChunkMath.FloorDiv(worldX, Chunk.Chunk.Size),
+            ChunkMath.FloorDiv(worldY, Chunk.Chunk.Size),
+            ChunkMath.FloorDiv(worldZ, Chunk.Chunk.Size));
 
         Chunk.Chunk? chunk = this.GetChunk(chunkPos);
-        if (chunk == null) return this._registry.Air;
+        if (chunk == null) return registry.Air;
 
         int localX = worldX - chunkPos.X * Chunk.Chunk.Size;
         int localY = worldY - chunkPos.Y * Chunk.Chunk.Size;
         int localZ = worldZ - chunkPos.Z * Chunk.Chunk.Size;
-        return this._registry.Get(chunk[localX, localY, localZ]);
+        return registry.Get(chunk[localX, localY, localZ]);
     }
 
     public bool SetBlock(int worldX, int worldY, int worldZ, ushort blockId)
     {
         Vector3i chunkPos = new(
-            World.FloorDiv(worldX, Chunk.Chunk.Size),
-            World.FloorDiv(worldY, Chunk.Chunk.Size),
-            World.FloorDiv(worldZ, Chunk.Chunk.Size));
+            ChunkMath.FloorDiv(worldX, Chunk.Chunk.Size),
+            ChunkMath.FloorDiv(worldY, Chunk.Chunk.Size),
+            ChunkMath.FloorDiv(worldZ, Chunk.Chunk.Size));
 
         Chunk.Chunk? chunk = this.GetChunk(chunkPos);
 
@@ -65,13 +60,6 @@ public sealed class World : IWorld, IEnumerable<KeyValuePair<Vector3i, Chunk.Chu
         return true;
     }
 
-    private static int FloorDiv(int value, int size)
-    {
-        int q = value / size;
-        if (value % size != 0 && value < 0) q--;
-        return q;
-    }
-
     public IEnumerator<KeyValuePair<Vector3i, Chunk.Chunk>> GetEnumerator() => this._chunks.GetEnumerator();
 
     IEnumerator IEnumerable.GetEnumerator() => this.GetEnumerator();