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Biomes: Add vertical biome blend (#6853)

Add 'vertical blend' parameter to biome registration that defines how
many nodes above the biome's 'y max' limit the blend will extend.
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paramat authored and nerzhul committed Jan 4, 2018
1 parent ff2ceed commit 549cfd9db80c858bdc8d23a237ea57ccf5f68400
Showing with 38 additions and 19 deletions.
  1. +9 −9 doc/lua_api.txt
  2. +27 −10 src/mapgen/mg_biome.cpp
  3. +1 −0 src/mapgen/mg_biome.h
  4. +1 −0 src/script/lua_api/l_mapgen.cpp
@@ -4989,18 +4989,18 @@ Definition tables
y_min = 1,
y_max = 31000,
-- ^ Lower and upper limits for biome.
vertical_blend = 8,
-- ^ Vertical distance in nodes above 'y_max' over which the biome will
-- ^ blend with the biome above.
-- ^ Set to 0 for no vertical blend. Defaults to 0.
heat_point = 0,
humidity_point = 50,
-- ^ Characteristic average temperature and humidity for the biome.
-- ^ These values create 'biome points' on a voronoi diagram that has heat
-- ^ and humidity as axes. The resulting voronoi cells determine which
-- ^ heat/humidity points belong to which biome, and therefore determine
-- ^ the area and location of each biome in the world.
-- ^ The biome points need to be carefully and evenly spaced on the voronoi
-- ^ diagram to result in roughly equal size biomes.
-- ^ Characteristic temperature and humidity for the biome.
-- ^ These values create 'biome points' on a voronoi diagram with heat and
-- ^ humidity as axes. The resulting voronoi cells determine the
-- ^ distribution of the biomes.
-- ^ Heat and humidity have average values of 50, vary mostly between
-- ^ 0 and 100 but also often exceed these values.
-- ^ Heat is not in degrees Celsius, both values are abstract.
-- ^ 0 and 100 but can exceed these values.
}

### Decoration definition (`register_decoration`)
@@ -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");
@@ -201,25 +202,41 @@ 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.
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);
}


@@ -67,6 +67,7 @@ class Biome : public ObjDef, public NodeResolver {
s16 y_max;
float heat_point;
float humidity_point;
s16 vertical_blend;

virtual void resolveNodeNames();
};
@@ -392,6 +392,7 @@ Biome *read_biome_def(lua_State *L, int index, INodeDefManager *ndef)
b->y_max = getintfield_default(L, index, "y_max", 31000);
b->heat_point = getfloatfield_default(L, index, "heat_point", 0.f);
b->humidity_point = getfloatfield_default(L, index, "humidity_point", 0.f);
b->vertical_blend = getintfield_default(L, index, "vertical_blend", 0);
b->flags = 0; //reserved

std::vector<std::string> &nn = b->m_nodenames;

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