Vertical biome blend: Tune blend patterns

[oweals/minetest.git] / src / mapgen / mg_biome.cpp

diff --git a/src/mapgen/mg_biome.cpp b/src/mapgen/mg_biome.cpp
index 8dbb78e59e092b692a4e88be0f79641cc5479bf3..eb12fcc737872493406bfe60af638f33bd3c236b 100644 (file)
--- a/src/mapgen/mg_biome.cpp
+++ b/src/mapgen/mg_biome.cpp
@@ -1,7 +1,7 @@
 /*
 Minetest
-Copyright (C) 2014-2016 kwolekr, Ryan Kwolek <kwolekr@minetest.net>
-Copyright (C) 2014-2017 paramat
+Copyright (C) 2014-2018 kwolekr, Ryan Kwolek <kwolekr@minetest.net>
+Copyright (C) 2014-2018 paramat
 
 This program is free software; you can redistribute it and/or modify
 it under the terms of the GNU Lesser General Public License as published by
@@ -50,6 +50,7 @@ BiomeManager::BiomeManager(Server *server) :
        b->y_max           = MAX_MAP_GENERATION_LIMIT;
        b->heat_point      = 0.0;
        b->humidity_point  = 0.0;
+       b->vertical_blend  = 0;
 
        b->m_nodenames.emplace_back("mapgen_stone");
        b->m_nodenames.emplace_back("mapgen_stone");
@@ -83,8 +84,66 @@ void BiomeManager::clear()
        m_objects.resize(1);
 }
 
-////////////////////////////////////////////////////////////////////////////////
 
+// For BiomeGen type 'BiomeGenOriginal'
+float BiomeManager::getHeatAtPosOriginal(v3s16 pos, NoiseParams &np_heat,
+       NoiseParams &np_heat_blend, u64 seed)
+{
+       return
+               NoisePerlin2D(&np_heat,       pos.X, pos.Z, seed) +
+               NoisePerlin2D(&np_heat_blend, pos.X, pos.Z, seed);
+}
+
+
+// For BiomeGen type 'BiomeGenOriginal'
+float BiomeManager::getHumidityAtPosOriginal(v3s16 pos, NoiseParams &np_humidity,
+       NoiseParams &np_humidity_blend, u64 seed)
+{
+       return
+               NoisePerlin2D(&np_humidity,       pos.X, pos.Z, seed) +
+               NoisePerlin2D(&np_humidity_blend, pos.X, pos.Z, seed);
+}
+
+
+// For BiomeGen type 'BiomeGenOriginal'
+Biome *BiomeManager::getBiomeFromNoiseOriginal(float heat, float humidity, s16 y)
+{
+       Biome *biome_closest = nullptr;
+       Biome *biome_closest_blend = nullptr;
+       float dist_min = FLT_MAX;
+       float dist_min_blend = FLT_MAX;
+
+       for (size_t i = 1; i < getNumObjects(); i++) {
+               Biome *b = (Biome *)getRaw(i);
+               if (!b || y > b->y_max + b->vertical_blend || y < b->y_min)
+                       continue;
+
+               float d_heat = heat - b->heat_point;
+               float d_humidity = humidity - b->humidity_point;
+               float dist = (d_heat * d_heat) + (d_humidity * d_humidity);
+
+               if (y <= b->y_max) { // Within y limits of biome b
+                       if (dist < dist_min) {
+                               dist_min = dist;
+                               biome_closest = b;
+                       }
+               } else if (dist < dist_min_blend) { // Blend area above biome b
+                       dist_min_blend = dist;
+                       biome_closest_blend = b;
+               }
+       }
+
+       mysrand(y + (heat + humidity) / 2);
+       if (biome_closest_blend &&
+                       myrand_range(0, biome_closest_blend->vertical_blend) >=
+                       y - biome_closest_blend->y_max)
+               return biome_closest_blend;
+
+       return (biome_closest) ? biome_closest : (Biome *)getRaw(BIOME_NONE);
+}
+
+
+////////////////////////////////////////////////////////////////////////////////
 
 void BiomeParamsOriginal::readParams(const Settings *settings)
 {
@@ -137,7 +196,7 @@ BiomeGenOriginal::~BiomeGenOriginal()
        delete noise_humidity_blend;
 }
 
-
+// Only usable in a mapgen thread
 Biome *BiomeGenOriginal::calcBiomeAtPoint(v3s16 pos) const
 {
        float heat =
@@ -201,25 +260,42 @@ Biome *BiomeGenOriginal::getBiomeAtIndex(size_t index, s16 y) const
 
 Biome *BiomeGenOriginal::calcBiomeFromNoise(float heat, float humidity, s16 y) const
 {
-       Biome *b, *biome_closest = NULL;
+       Biome *biome_closest = nullptr;
+       Biome *biome_closest_blend = nullptr;
        float dist_min = FLT_MAX;
+       float dist_min_blend = FLT_MAX;
 
        for (size_t i = 1; i < m_bmgr->getNumObjects(); i++) {
-               b = (Biome *)m_bmgr->getRaw(i);
-               if (!b || y > b->y_max || y < b->y_min)
+               Biome *b = (Biome *)m_bmgr->getRaw(i);
+               if (!b || y > b->y_max + b->vertical_blend || y < b->y_min)
                        continue;
 
-               float d_heat     = heat     - b->heat_point;
+               float d_heat = heat - b->heat_point;
                float d_humidity = humidity - b->humidity_point;
-               float dist = (d_heat * d_heat) +
-                                        (d_humidity * d_humidity);
-               if (dist < dist_min) {
-                       dist_min = dist;
-                       biome_closest = b;
+               float dist = (d_heat * d_heat) + (d_humidity * d_humidity);
+
+               if (y <= b->y_max) { // Within y limits of biome b
+                       if (dist < dist_min) {
+                               dist_min = dist;
+                               biome_closest = b;
+                       }
+               } else if (dist < dist_min_blend) { // Blend area above biome b
+                       dist_min_blend = dist;
+                       biome_closest_blend = b;
                }
        }
 
-       return biome_closest ? biome_closest : (Biome *)m_bmgr->getRaw(BIOME_NONE);
+       // Carefully tune pseudorandom seed variation to avoid single node dither
+       // and create larger scale blending patterns similar to horizontal biome
+       // blend.
+       mysrand(y + (heat + humidity) / 2);
+
+       if (biome_closest_blend &&
+                       myrand_range(0, biome_closest_blend->vertical_blend) >=
+                       y - biome_closest_blend->y_max)
+               return biome_closest_blend;
+
+       return (biome_closest) ? biome_closest : (Biome *)m_bmgr->getRaw(BIOME_NONE);   
 }