Move biome calculation to BiomeGen

BiomeGen defines an interface that, given a set of BiomeParams, computes biomes
for a given area using the algorithm implemented by that specific BiomeGen.
This abstracts away the old system where each mapgen supplied the noises
required for biome generation.

src/mg_biome.h

@@ -22,6 +22,16 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 #include "objdef.h"
 #include "nodedef.h"
+#include "noise.h"
+
+class Settings;
+class BiomeManager;
+
+////
+//// Biome
+////
+
+#define BIOME_NONE ((u8)0)
 
 enum BiomeType
 {
@@ -56,10 +66,122 @@ public:
 	virtual void resolveNodeNames();
 };
 
+
+////
+//// BiomeGen
+////
+
+enum BiomeGenType {
+	BIOMEGEN_ORIGINAL,
+};
+
+struct BiomeParams {
+	virtual void readParams(const Settings *settings) = 0;
+	virtual void writeParams(Settings *settings) const = 0;
+	virtual ~BiomeParams() {}
+
+	int seed;
+};
+
+class BiomeGen {
+public:
+	virtual ~BiomeGen() {}
+	virtual BiomeGenType getType() const = 0;
+
+	// Calculates the biome at the exact position provided.  This function can
+	// be called at any time, but may be less efficient than the latter methods,
+	// depending on implementation.
+	virtual Biome *calcBiomeAtPoint(v3s16 pos) const = 0;
+
+	// Computes any intermediate results needed for biome generation.  Must be
+	// called before using any of: getBiomes, getBiomeAtPoint, or getBiomeAtIndex.
+	// Calling this invalidates the previous results stored in biomemap.
+	virtual void calcBiomeNoise(v3s16 pmin) = 0;
+
+	// Gets all biomes in current chunk using each corresponding element of
+	// heightmap as the y position, then stores the results by biome index in
+	// biomemap (also returned)
+	virtual u8 *getBiomes(s16 *heightmap) = 0;
+
+	// Gets a single biome at the specified position, which must be contained
+	// in the region formed by m_pmin and (m_pmin + m_csize - 1).
+	virtual Biome *getBiomeAtPoint(v3s16 pos) const = 0;
+
+	// Same as above, but uses a raw numeric index correlating to the (x,z) position.
+	virtual Biome *getBiomeAtIndex(size_t index, s16 y) const = 0;
+
+	// Result of calcBiomes bulk computation.
+	u8 *biomemap;
+
+protected:
+	BiomeManager *m_bmgr;
+	v3s16 m_pmin;
+	v3s16 m_csize;
+};
+
+
+////
+//// BiomeGen implementations
+////
+
+//
+// Original biome algorithm (Whittaker's classification + surface height)
+//
+
+struct BiomeParamsOriginal : public BiomeParams {
+	BiomeParamsOriginal() :
+		np_heat(50, 50, v3f(750.0, 750.0, 750.0), 5349, 3, 0.5, 2.0),
+		np_humidity(50, 50, v3f(750.0, 750.0, 750.0), 842, 3, 0.5, 2.0),
+		np_heat_blend(0, 1.5, v3f(8.0, 8.0, 8.0), 13, 2, 1.0, 2.0),
+		np_humidity_blend(0, 1.5, v3f(8.0, 8.0, 8.0), 90003, 2, 1.0, 2.0)
+	{
+	}
+
+	virtual void readParams(const Settings *settings);
+	virtual void writeParams(Settings *settings) const;
+
+	NoiseParams np_heat;
+	NoiseParams np_humidity;
+	NoiseParams np_heat_blend;
+	NoiseParams np_humidity_blend;
+};
+
+class BiomeGenOriginal : public BiomeGen {
+public:
+	BiomeGenOriginal(BiomeManager *biomemgr,
+		BiomeParamsOriginal *params, v3s16 chunksize);
+	virtual ~BiomeGenOriginal();
+
+	BiomeGenType getType() const { return BIOMEGEN_ORIGINAL; }
+
+	Biome *calcBiomeAtPoint(v3s16 pos) const;
+	void calcBiomeNoise(v3s16 pmin);
+
+	u8 *getBiomes(s16 *heightmap);
+	Biome *getBiomeAtPoint(v3s16 pos) const;
+	Biome *getBiomeAtIndex(size_t index, s16 y) const;
+
+	Biome *calcBiomeFromNoise(float heat, float humidity, s16 y) const;
+
+	float *heatmap;
+	float *humidmap;
+
+private:
+	BiomeParamsOriginal *m_params;
+
+	Noise *noise_heat;
+	Noise *noise_humidity;
+	Noise *noise_heat_blend;
+	Noise *noise_humidity_blend;
+};
+
+
+////
+//// BiomeManager
+////
+
 class BiomeManager : public ObjDefManager {
 public:
-	static const char *OBJECT_TITLE;
-
 	BiomeManager(IGameDef *gamedef);
 	virtual ~BiomeManager();
 
@@ -73,15 +195,36 @@ public:
 		return new Biome;
 	}
 
+	BiomeGen *createBiomeGen(BiomeGenType type, BiomeParams *params, v3s16 chunksize)
+	{
+		switch (type) {
+		case BIOMEGEN_ORIGINAL:
+			return new BiomeGenOriginal(this,
+				(BiomeParamsOriginal *)params, chunksize);
+		default:
+			return NULL;
+		}
+	}
+
+	static BiomeParams *createBiomeParams(BiomeGenType type)
+	{
+		switch (type) {
+		case BIOMEGEN_ORIGINAL:
+			return new BiomeParamsOriginal;
+		default:
+			return NULL;
+		}
+	}
+
 	virtual void clear();
 
-	void calcBiomes(s16 sx, s16 sy, float *heat_map, float *humidity_map,
-		s16 *height_map, u8 *biomeid_map);
-	Biome *getBiome(float heat, float humidity, s16 y);
+	// Looks for pos in the biome cache, and if non-existent, looks up by noise
+	u8 getBiomeAtPoint(v3s16 pos);
 
 private:
 	IGameDef *m_gamedef;
+
 };
 
-#endif
 
+#endif