feat: Minecraft Clone MVP – prozedurale Welt, Blöcke, Abbauen/Setzen

- Weltgenerierung: FBM-Terrain, 3 Biome (Plains/Wald/Wüste), Höhlen, Wasser, Bäume
- Blöcke: Grass, Dirt, Stein, Sand, Holz, Blätter, Wasser (+Bedrock)
- Interaktion: DDA-Voxel-Raycast, Abbauen (LMB) & Setzen (RMB), Hotbar 1-6
- Spieler: First-Person, Gravitation, AABB-Kollision, Springen, Fly-Mode (F)
- Engine: Chunk-Streaming (16x16x64), Face-Culling, opaker+transparenter Pass
- Stack: Three.js + simplex-noise via CDN, prozedurale Texturen, kein Build-Step

Co-Authored-By: Claude <noreply@anthropic.com>

js/constants.js

@@ -0,0 +1,93 @@
+// Globale Konstanten und Block-/Biome-Definitionen
+
+// --- Welt-Dimensionen ---
+export const CHUNK_SIZE = 16;        // X und Z Ausdehnung eines Chunks
+export const CHUNK_HEIGHT = 64;      // Y Ausdehnung eines Chunks
+export const SEA_LEVEL = 26;
+export const WORLD_SEED = 1337;
+
+// --- Block-Typen ---
+export const BLOCK = {
+  AIR: 0,
+  GRASS: 1,
+  DIRT: 2,
+  STONE: 3,
+  SAND: 4,
+  WOOD: 5,
+  LEAVES: 6,
+  WATER: 7,
+  BEDROCK: 8,
+};
+
+// Welche Bloecke fuer den Spieler nicht solide sind (keine Kollision, durchschaubar)
+export function isTransparent(id) {
+  return id === BLOCK.AIR || id === BLOCK.WATER;
+}
+export function isSolid(id) {
+  return id !== BLOCK.AIR && id !== BLOCK.WATER;
+}
+// Wasser als einziger (halb-)transparenter Renderblock
+export function isRenderTransparent(id) {
+  return id === BLOCK.WATER;
+}
+
+// --- Biome ---
+export const BIOME = { PLAINS: 0, FOREST: 1, DESERT: 2 };
+
+// --- Texturatlas ---
+export const ATLAS_COLS = 16;            // Tiles pro Reihe
+export const TILE_PX = 16;               // Pixel pro Tile
+export const ATLAS_PX = ATLAS_COLS * TILE_PX; // 256
+
+// Tile-Indizes im Atlas (Reihe 0)
+export const TILE = {
+  GRASS_TOP: 0,
+  GRASS_SIDE: 1,
+  DIRT: 2,
+  STONE: 3,
+  SAND: 4,
+  WOOD_TOP: 5,
+  WOOD_SIDE: 6,
+  LEAVES: 7,
+  WATER: 8,
+};
+
+// Liefert (col,row) im Atlas fuer einen Block + Seite ('top'|'bottom'|'side')
+export function tileFor(block, side) {
+  let idx;
+  switch (block) {
+    case BLOCK.GRASS:
+      idx = side === 'top' ? TILE.GRASS_TOP : side === 'bottom' ? TILE.DIRT : TILE.GRASS_SIDE;
+      break;
+    case BLOCK.DIRT:   idx = TILE.DIRT; break;
+    case BLOCK.STONE:  idx = TILE.STONE; break;
+    case BLOCK.SAND:   idx = TILE.SAND; break;
+    case BLOCK.WOOD:
+      idx = (side === 'top' || side === 'bottom') ? TILE.WOOD_TOP : TILE.WOOD_SIDE;
+      break;
+    case BLOCK.LEAVES: idx = TILE.LEAVES; break;
+    case BLOCK.WATER:  idx = TILE.WATER; break;
+    default:           idx = TILE.STONE;
+  }
+  return { col: idx % ATLAS_COLS, row: Math.floor(idx / ATLAS_COLS) };
+}
+
+// Bloecke, die per Hotbar gesetzt werden koennen
+export const HOTBAR = [
+  BLOCK.GRASS,
+  BLOCK.DIRT,
+  BLOCK.STONE,
+  BLOCK.SAND,
+  BLOCK.WOOD,
+  BLOCK.LEAVES,
+];
+
+// Anzeige-Farben pro Block fuer die Hotbar-Symbole
+export const BLOCK_COLOR = {
+  [BLOCK.GRASS]: '#6ab04c',
+  [BLOCK.DIRT]:  '#8b5a2b',
+  [BLOCK.STONE]: '#8a8a8a',
+  [BLOCK.SAND]:  '#e6d8a8',
+  [BLOCK.WOOD]:  '#6e4f2a',
+  [BLOCK.LEAVES]:'#3f8a2f',
+};