BiomeSelector: drastically simplified implementation and made more robust

- Doesn't need to be pre-populated with biomes prior to calculating the heatmap - now population of biomes is entirely dependent on the lookup function, improving consistency
- Uses an abstract class method for lookup instead of callback (use anonymous class instead)
- Faster because the heatmap is directly populated with biomes instead of biome IDs, removing an unnecessary lookup.

src/pocketmine/level/generator/biome/BiomeSelector.php

@@ -24,49 +24,48 @@ declare(strict_types=1);
 namespace pocketmine\level\generator\biome;
 
 use pocketmine\level\biome\Biome;
+use pocketmine\level\biome\UnknownBiome;
 use pocketmine\level\generator\noise\Simplex;
 use pocketmine\utils\Random;
 
-class BiomeSelector{
+abstract class BiomeSelector{
-
-	/** @var Biome */
-	private $fallback;
-
 	/** @var Simplex */
 	private $temperature;
 	/** @var Simplex */
 	private $rainfall;
 
-	/** @var Biome[] */
+	/** @var Biome[]|\SplFixedArray */
-	private $biomes = [];
-
-	/** @var \SplFixedArray */
 	private $map = null;
 
-	/** @var callable */
+	public function __construct(Random $random){
-	private $lookup;
-
-	public function __construct(Random $random, callable $lookup, Biome $fallback){
-		$this->fallback = $fallback;
-		$this->lookup = $lookup;
 		$this->temperature = new Simplex($random, 2, 1 / 16, 1 / 512);
 		$this->rainfall = new Simplex($random, 2, 1 / 16, 1 / 512);
 	}
 
+	/**
+	 * Lookup function called by recalculate() to determine the biome to use for this temperature and rainfall.
+	 *
+	 * @param float $temperature
+	 * @param float $rainfall
+	 *
+	 * @return int biome ID 0-255
+	 */
+	abstract protected function lookup(float $temperature, float $rainfall) : int;
+
 	public function recalculate(){
 		$this->map = new \SplFixedArray(64 * 64);
 
 		for($i = 0; $i < 64; ++$i){
 			for($j = 0; $j < 64; ++$j){
-				$this->map[$i + ($j << 6)] = call_user_func($this->lookup, $i / 63, $j / 63);
+				$biome = Biome::getBiome($this->lookup($i / 63, $j / 63));
+				if($biome instanceof UnknownBiome){
+					throw new \RuntimeException("Unknown biome returned by selector with ID " . $biome->getId());
+				}
+				$this->map[$i + ($j << 6)] = $biome;
 			}
 		}
 	}
 
-	public function addBiome(Biome $biome){
-		$this->biomes[$biome->getId()] = $biome;
-	}
-
 	public function getTemperature($x, $z){
 		return ($this->temperature->noise2D($x, $z, true) + 1) / 2;
 	}
@@ -85,7 +84,6 @@ class BiomeSelector{
 		$temperature = (int) ($this->getTemperature($x, $z) * 63);
 		$rainfall = (int) ($this->getRainfall($x, $z) * 63);
 
-		$biomeId = $this->map[$temperature + ($rainfall << 6)];
+		return $this->map[$temperature + ($rainfall << 6)];
-		return $this->biomes[$biomeId] ?? $this->fallback;
 	}
 }

src/pocketmine/level/generator/normal/Normal.php

@@ -107,56 +107,46 @@ class Normal extends Generator{
 		$this->random->setSeed($this->level->getSeed());
 		$this->noiseBase = new Simplex($this->random, 4, 1 / 4, 1 / 32);
 		$this->random->setSeed($this->level->getSeed());
-		$this->selector = new BiomeSelector($this->random, function($temperature, $rainfall){
+		$this->selector = new class($this->random) extends BiomeSelector{
-			if($rainfall < 0.25){
+			protected function lookup(float $temperature, float $rainfall) : int{
-				if($temperature < 0.7){
-					return Biome::OCEAN;
-				}elseif($temperature < 0.85){
-					return Biome::RIVER;
-				}else{
-					return Biome::SWAMP;
-				}
-			}elseif($rainfall < 0.60){
-				if($temperature < 0.25){
-					return Biome::ICE_PLAINS;
-				}elseif($temperature < 0.75){
-					return Biome::PLAINS;
-				}else{
-					return Biome::DESERT;
-				}
-			}elseif($rainfall < 0.80){
-				if($temperature < 0.25){
-					return Biome::TAIGA;
-				}elseif($temperature < 0.75){
-					return Biome::FOREST;
-				}else{
-					return Biome::BIRCH_FOREST;
-				}
-			}else{
-				//FIXME: This will always cause River to be used since the rainfall is always greater than 0.8 if we
-				//reached this branch. However I don't think that substituting temperature for rainfall is correct given
-				//that mountain biomes are supposed to be pretty cold.
 				if($rainfall < 0.25){
-					return Biome::MOUNTAINS;
+					if($temperature < 0.7){
-				}elseif($rainfall < 0.70){
+						return Biome::OCEAN;
-					return Biome::SMALL_MOUNTAINS;
+					}elseif($temperature < 0.85){
+						return Biome::RIVER;
+					}else{
+						return Biome::SWAMP;
+					}
+				}elseif($rainfall < 0.60){
+					if($temperature < 0.25){
+						return Biome::ICE_PLAINS;
+					}elseif($temperature < 0.75){
+						return Biome::PLAINS;
+					}else{
+						return Biome::DESERT;
+					}
+				}elseif($rainfall < 0.80){
+					if($temperature < 0.25){
+						return Biome::TAIGA;
+					}elseif($temperature < 0.75){
+						return Biome::FOREST;
+					}else{
+						return Biome::BIRCH_FOREST;
+					}
 				}else{
-					return Biome::RIVER;
+					//FIXME: This will always cause River to be used since the rainfall is always greater than 0.8 if we
+					//reached this branch. However I don't think that substituting temperature for rainfall is correct given
+					//that mountain biomes are supposed to be pretty cold.
+					if($rainfall < 0.25){
+						return Biome::MOUNTAINS;
+					}elseif($rainfall < 0.70){
+						return Biome::SMALL_MOUNTAINS;
+					}else{
+						return Biome::RIVER;
+					}
 				}
 			}
-		}, Biome::getBiome(Biome::OCEAN));
+		};
-
-		$this->selector->addBiome(Biome::getBiome(Biome::OCEAN));
-		$this->selector->addBiome(Biome::getBiome(Biome::PLAINS));
-		$this->selector->addBiome(Biome::getBiome(Biome::DESERT));
-		$this->selector->addBiome(Biome::getBiome(Biome::MOUNTAINS));
-		$this->selector->addBiome(Biome::getBiome(Biome::FOREST));
-		$this->selector->addBiome(Biome::getBiome(Biome::TAIGA));
-		$this->selector->addBiome(Biome::getBiome(Biome::SWAMP));
-		$this->selector->addBiome(Biome::getBiome(Biome::RIVER));
-		$this->selector->addBiome(Biome::getBiome(Biome::ICE_PLAINS));
-		$this->selector->addBiome(Biome::getBiome(Biome::SMALL_MOUNTAINS));
-		$this->selector->addBiome(Biome::getBiome(Biome::BIRCH_FOREST));
 
 		$this->selector->recalculate();