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Valleys mapgen code rewrite (#8101) 

Shorter, simpler, clearer and more consistent with other mapgens,
while preserving functionality.
Base terrain shape is unchanged.
With the 'vary river depth' option disabled, river surface level
is unchanged.
Behaviour of the 4 heat/humidity/river depth options is very
slightly changed due to bugfixes and code cleanup (the mapgen is
'unstable').
Apply heat and humidity gradients above water_level instead of
above y = 0.
This commit is contained in:
Paramat 2019-03-14 00:27:16 +00:00 committed by GitHub
parent e22a69d61a
commit aafbdd442f
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 122 additions and 257 deletions
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352
src/mapgen/mapgen_valleys.cpp
View File

@ -1,7 +1,7 @@
/*
Minetest
Copyright (C) 2016-2018 Duane Robertson <duane@duanerobertson.com>
Copyright (C) 2016-2018 paramat
Copyright (C) 2016-2019 Duane Robertson <duane@duanerobertson.com>
Copyright (C) 2016-2019 paramat
Based on Valleys Mapgen by Gael de Sailly
(https://forum.minetest.net/viewtopic.php?f=9&t=11430)
@ -24,6 +24,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "mapgen.h"
#include "voxel.h"
#include "noise.h"
@ -53,9 +54,6 @@ FlagDesc flagdesc_mapgen_valleys[] = {
};
////////////////////////////////////////////////////////////////////////////////
MapgenValleys::MapgenValleys(int mapgenid, MapgenValleysParams *params,
EmergeManager *emerge)
: MapgenBasic(mapgenid, params, emerge)
@ -63,8 +61,6 @@ MapgenValleys::MapgenValleys(int mapgenid, MapgenValleysParams *params,
// NOTE: MapgenValleys has a hard dependency on BiomeGenOriginal
m_bgen = (BiomeGenOriginal *)biomegen;
BiomeParamsOriginal *bp = (BiomeParamsOriginal *)params->bparams;
spflags = params->spflags;
altitude_chill = params->altitude_chill;
river_depth_bed = params->river_depth + 1.0f;
@ -95,8 +91,6 @@ MapgenValleys::MapgenValleys(int mapgenid, MapgenValleysParams *params,
MapgenBasic::np_cave1 = params->np_cave1;
MapgenBasic::np_cave2 = params->np_cave2;
MapgenBasic::np_cavern = params->np_cavern;
humidity_adjust = bp->np_humidity.offset - 50.0f;
}
@ -185,9 +179,6 @@ void MapgenValleysParams::writeParams(Settings *settings) const
}
////////////////////////////////////////////////////////////////////////////////
void MapgenValleys::makeChunk(BlockMakeData *data)
{
// Pre-conditions
@ -220,19 +211,16 @@ void MapgenValleys::makeChunk(BlockMakeData *data)
// biome-related noises.
m_bgen->calcBiomeNoise(node_min);
// Generate noise maps and base terrain height.
// Modify heat and humidity maps.
calculateNoise();
// Generate base terrain with initial heightmaps
// Generate terrain
s16 stone_surface_max_y = generateTerrain();
// Recalculate heightmap
// Create heightmap
updateHeightmap(node_min, node_max);
// Place biome-specific nodes and build biomemap
if (flags & MG_BIOMES)
if (flags & MG_BIOMES) {
generateBiomes();
}
// Generate tunnels, caverns and large randomwalk caves
if (flags & MG_CAVES) {
@ -281,244 +269,151 @@ void MapgenValleys::makeChunk(BlockMakeData *data)
}
void MapgenValleys::calculateNoise()
{
int x = node_min.X;
int y = node_min.Y - 1;
int z = node_min.Z;
noise_inter_valley_slope->perlinMap2D(x, z);
noise_rivers->perlinMap2D(x, z);
noise_terrain_height->perlinMap2D(x, z);
noise_valley_depth->perlinMap2D(x, z);
noise_valley_profile->perlinMap2D(x, z);
noise_inter_valley_fill->perlinMap3D(x, y, z);
float heat_offset = 0.0f;
float humidity_scale = 1.0f;
// Altitude chill tends to reduce the average heat.
if (spflags & MGVALLEYS_ALT_CHILL)
heat_offset = 5.0f;
// River humidity tends to increase the humidity range.
if (spflags & MGVALLEYS_HUMID_RIVERS)
humidity_scale = 0.8f;
for (s32 index = 0; index < csize.X * csize.Z; index++) {
m_bgen->heatmap[index] += heat_offset;
m_bgen->humidmap[index] *= humidity_scale;
}
TerrainNoise tn;
u32 index = 0;
for (tn.z = node_min.Z; tn.z <= node_max.Z; tn.z++)
for (tn.x = node_min.X; tn.x <= node_max.X; tn.x++, index++) {
// The parameters that we actually need to generate terrain are passed
// by address (and the return value).
tn.terrain_height = noise_terrain_height->result[index];
// River noise is replaced with base terrain, which is basically the
// height of the water table.
tn.rivers = &noise_rivers->result[index];
// Valley depth noise is replaced with the valley number that represents
// the height of terrain over rivers and is used to determine how close
// a river is for humidity calculation.
tn.valley = &noise_valley_depth->result[index];
tn.valley_profile = noise_valley_profile->result[index];
// Slope noise is replaced by the calculated slope which is used to get
// terrain height in the slow method, to create sharper mountains.
tn.slope = &noise_inter_valley_slope->result[index];
tn.inter_valley_fill = noise_inter_valley_fill->result[index];
// This is the actual terrain height.
float mount = terrainLevelFromNoise(&tn);
noise_terrain_height->result[index] = mount;
}
}
float MapgenValleys::terrainLevelFromNoise(TerrainNoise *tn)
{
// The square function changes the behaviour of this noise: very often
// small, and sometimes very high.
float valley_d = MYSQUARE(*tn->valley);
// valley_d is here because terrain is generally higher where valleys are
// deep (mountains). base represents the height of the rivers, most of the
// surface is above.
float base = tn->terrain_height + valley_d;
// "river" represents the distance from the river
float river = std::fabs(*tn->rivers) - river_size_factor;
// Use the curve of the function 1-exp(-(x/a)^2) to model valleys.
// "valley" represents the height of the terrain, from the rivers.
float tv = std::fmax(river / tn->valley_profile, 0.0f);
*tn->valley = valley_d * (1.0f - std::exp(-MYSQUARE(tv)));
// Approximate height of the terrain at this point
float mount = base + *tn->valley;
*tn->slope *= *tn->valley;
// Base ground is returned as rivers since it's basically the water table.
*tn->rivers = base;
// Rivers are placed where "river" is negative, so where the original noise
// value is close to zero.
if (river < 0.0f) {
// Use the the function -sqrt(1-x^2) which models a circle
float tr = river / river_size_factor + 1.0f;
float depth = (river_depth_bed *
std::sqrt(std::fmax(0.0f, 1.0f - MYSQUARE(tr))));
// base - depth : height of the bottom of the river
// water_level - 3 : don't make rivers below 3 nodes under the surface.
// We use three because that's as low as the swamp biomes go.
// There is no logical equivalent to this using rangelim.
mount =
std::fmin(std::fmax(base - depth, (float)(water_level - 3)), mount);
// Slope has no influence on rivers
*tn->slope = 0.0f;
}
return mount;
}
// This avoids duplicating the code in terrainLevelFromNoise, adding only the
// final step of terrain generation without a noise map.
float MapgenValleys::adjustedTerrainLevelFromNoise(TerrainNoise *tn)
{
float mount = terrainLevelFromNoise(tn);
float result = mount;
s16 y_start = myround(mount);
float fill =
NoisePerlin3D(&noise_inter_valley_fill->np, tn->x, y_start, tn->z, seed);
bool is_ground = fill * *tn->slope >= y_start - mount;
s16 search_direction = is_ground ? 1 : -1;
for (s16 i = 1; i <= 1000; i++) {
s16 y = y_start + i * search_direction;
fill =
NoisePerlin3D(&noise_inter_valley_fill->np, tn->x, y, tn->z, seed);
bool was_ground = is_ground;
is_ground = fill * *tn->slope >= y - mount;
if (is_ground)
result = y;
if (is_ground != was_ground)
break;
}
return result;
}
int MapgenValleys::getSpawnLevelAtPoint(v2s16 p)
{
// Check if in a river
float rivers = NoisePerlin2D(&noise_rivers->np, p.X, p.Y, seed);
if (std::fabs(rivers) < river_size_factor)
return MAX_MAP_GENERATION_LIMIT; // Unsuitable spawn point
// Check if in a river channel
float n_rivers = NoisePerlin2D(&noise_rivers->np, p.X, p.Y, seed);
if (std::fabs(n_rivers) <= river_size_factor)
// Unsuitable spawn point
return MAX_MAP_GENERATION_LIMIT;
s16 level_at_point = terrainLevelAtPoint(p.X, p.Y);
if (level_at_point <= water_level ||
level_at_point > water_level + 16)
return MAX_MAP_GENERATION_LIMIT; // Unsuitable spawn point
float n_slope = NoisePerlin2D(&noise_inter_valley_slope->np, p.X, p.Y, seed);
float n_terrain_height = NoisePerlin2D(&noise_terrain_height->np, p.X, p.Y, seed);
float n_valley = NoisePerlin2D(&noise_valley_depth->np, p.X, p.Y, seed);
float n_valley_profile = NoisePerlin2D(&noise_valley_profile->np, p.X, p.Y, seed);
// +1 to account for biome dust that can be 1 node deep
return level_at_point + 1;
}
float valley_d = n_valley * n_valley;
float base = n_terrain_height + valley_d;
float river = std::fabs(n_rivers) - river_size_factor;
float tv = std::fmax(river / n_valley_profile, 0.0f);
float valley_h = valley_d * (1.0f - std::exp(-tv * tv));
float surface_y = base + valley_h;
float slope = n_slope * valley_h;
float river_y = base - 1.0f;
// Raising the maximum spawn level above 'water_level + 16' is necessary for custom
// parameters that set average terrain level much higher than water_level.
s16 max_spawn_y = std::fmax(
noise_terrain_height->np.offset +
noise_valley_depth->np.offset * noise_valley_depth->np.offset,
water_level + 16);
float MapgenValleys::terrainLevelAtPoint(s16 x, s16 z)
{
TerrainNoise tn;
// Starting spawn search at max_spawn_y + 128 ensures 128 nodes of open
// space above spawn position. Avoids spawning in possibly sealed voids.
for (s16 y = max_spawn_y + 128; y >= water_level; y--) {
float n_fill = NoisePerlin3D(&noise_inter_valley_fill->np, p.X, y, p.Y, seed);
float surface_delta = (float)y - surface_y;
float density = slope * n_fill - surface_delta;
float rivers = NoisePerlin2D(&noise_rivers->np, x, z, seed);
float valley = NoisePerlin2D(&noise_valley_depth->np, x, z, seed);
float inter_valley_slope =
NoisePerlin2D(&noise_inter_valley_slope->np, x, z, seed);
if (density > 0.0f) { // If solid
// Sometimes surface level is below river water level in places that are not
// river channels.
if (y < water_level || y > max_spawn_y || y < (s16)river_y)
// Unsuitable spawn point
return MAX_MAP_GENERATION_LIMIT;
tn.x = x;
tn.z = z;
tn.terrain_height = NoisePerlin2D(&noise_terrain_height->np, x, z, seed);
tn.rivers = &rivers;
tn.valley = &valley;
tn.valley_profile = NoisePerlin2D(&noise_valley_profile->np, x, z, seed);
tn.slope = &inter_valley_slope;
tn.inter_valley_fill = 0.0f;
return adjustedTerrainLevelFromNoise(&tn);
// y + 2 because y is surface and due to biome 'dust' nodes.
return y + 2;
}
}
// Unsuitable spawn position, no ground found
return MAX_MAP_GENERATION_LIMIT;
}
int MapgenValleys::generateTerrain()
{
// Raising this reduces the rate of evaporation
static const float evaporation = 300.0f;
static const float humidity_dropoff = 4.0f;
// Constant to convert altitude chill to heat
static const float alt_to_heat = 20.0f;
// Humidity reduction by altitude
static const float alt_to_humid = 10.0f;
MapNode n_air(CONTENT_AIR);
MapNode n_river_water(c_river_water_source);
MapNode n_stone(c_stone);
MapNode n_water(c_water_source);
noise_inter_valley_slope->perlinMap2D(node_min.X, node_min.Z);
noise_rivers->perlinMap2D(node_min.X, node_min.Z);
noise_terrain_height->perlinMap2D(node_min.X, node_min.Z);
noise_valley_depth->perlinMap2D(node_min.X, node_min.Z);
noise_valley_profile->perlinMap2D(node_min.X, node_min.Z);
noise_inter_valley_fill->perlinMap3D(node_min.X, node_min.Y - 1, node_min.Z);
const v3s16 &em = vm->m_area.getExtent();
s16 surface_max_y = -MAX_MAP_GENERATION_LIMIT;
u32 index_2d = 0;
for (s16 z = node_min.Z; z <= node_max.Z; z++)
for (s16 x = node_min.X; x <= node_max.X; x++, index_2d++) {
float river_y = noise_rivers->result[index_2d];
float surface_y = noise_terrain_height->result[index_2d];
float slope = noise_inter_valley_slope->result[index_2d];
float t_heat = m_bgen->heatmap[index_2d];
float n_slope = noise_inter_valley_slope->result[index_2d];
float n_rivers = noise_rivers->result[index_2d];
float n_terrain_height = noise_terrain_height->result[index_2d];
float n_valley = noise_valley_depth->result[index_2d];
float n_valley_profile = noise_valley_profile->result[index_2d];
heightmap[index_2d] = -MAX_MAP_GENERATION_LIMIT;
float valley_d = n_valley * n_valley;
// 'base' represents the level of the river banks
float base = n_terrain_height + valley_d;
// 'river' represents the distance from the river edge
float river = std::fabs(n_rivers) - river_size_factor;
// Use the curve of the function 1-exp(-(x/a)^2) to model valleys.
// 'valley_h' represents the height of the terrain, from the rivers.
float tv = std::fmax(river / n_valley_profile, 0.0f);
float valley_h = valley_d * (1.0f - std::exp(-tv * tv));
// Approximate height of the terrain
float surface_y = base + valley_h;
float slope = n_slope * valley_h;
// River water surface is 1 node below river banks
float river_y = base - 1.0f;
if (surface_y > surface_max_y)
surface_max_y = std::ceil(surface_y);
// Rivers are placed where 'river' is negative
if (river < 0.0f) {
// Use the the function -sqrt(1-x^2) which models a circle
float tr = river / river_size_factor + 1.0f;
float depth = (river_depth_bed *
std::sqrt(std::fmax(0.0f, 1.0f - tr * tr)));
// There is no logical equivalent to this using rangelim
surface_y = std::fmin(
std::fmax(base - depth, (float)(water_level - 3)),
surface_y);
slope = 0.0f;
}
// Optionally vary river depth according to heat and humidity
if (spflags & MGVALLEYS_VARY_RIVER_DEPTH) {
float heat = ((spflags & MGVALLEYS_ALT_CHILL) &&
(surface_y > 0.0f || river_y > 0.0f)) ?
t_heat - alt_to_heat *
std::fmax(surface_y, river_y) / altitude_chill :
float t_heat = m_bgen->heatmap[index_2d];
float heat = (spflags & MGVALLEYS_ALT_CHILL) ?
// Match heat value calculated below in
// 'Optionally decrease heat with altitude'.
// In rivers, 'ground height ignoring riverbeds' is 'base'.
// As this only affects river water we can assume y > water_level.
t_heat + 5.0f - (base - water_level) * 20.0f / altitude_chill :
t_heat;
float delta = m_bgen->humidmap[index_2d] - 50.0f;
if (delta < 0.0f) {
float t_evap = (heat - 32.0f) / evaporation;
float t_evap = (heat - 32.0f) / 300.0f;
river_y += delta * std::fmax(t_evap, 0.08f);
}
}
// Highest solid node in column
s16 column_max_y = surface_y;
u32 index_3d = (z - node_min.Z) * zstride_1u1d + (x - node_min.X);
u32 index_data = vm->m_area.index(x, node_min.Y - 1, z);
for (s16 y = node_min.Y - 1; y <= node_max.Y + 1; y++) {
if (vm->m_data[index_data].getContent() == CONTENT_IGNORE) {
float fill = noise_inter_valley_fill->result[index_3d];
float n_fill = noise_inter_valley_fill->result[index_3d];
float surface_delta = (float)y - surface_y;
bool river = y < river_y - 1;
// Density = density noise + density gradient
float density = slope * n_fill - surface_delta;
if (slope * fill > surface_delta) {
if (density > 0.0f) {
vm->m_data[index_data] = n_stone; // Stone
if (y > heightmap[index_2d])
heightmap[index_2d] = y;
if (y > surface_max_y)
surface_max_y = y;
if (y > column_max_y)
column_max_y = y;
} else if (y <= water_level) {
vm->m_data[index_data] = n_water; // Water
} else if (river) {
} else if (y <= (s16)river_y) {
vm->m_data[index_data] = n_river_water; // River water
} else {
vm->m_data[index_data] = n_air; // Air
@ -529,26 +424,13 @@ int MapgenValleys::generateTerrain()
index_3d += ystride;
}
if (heightmap[index_2d] == -MAX_MAP_GENERATION_LIMIT) {
s16 surface_y_int = myround(surface_y);
if (surface_y_int > node_max.Y + 1 ||
surface_y_int < node_min.Y - 1) {
// If surface_y is outside the chunk, it's good enough
heightmap[index_2d] = surface_y_int;
} else {
// If the ground is outside of this chunk, but surface_y is
// within the chunk, give a value outside.
heightmap[index_2d] = node_min.Y - 2;
}
}
// Optionally increase humidity around rivers
if (spflags & MGVALLEYS_HUMID_RIVERS) {
// Compensate to avoid increasing average humidity
m_bgen->humidmap[index_2d] *= 0.8f;
// Ground height ignoring riverbeds
float t_alt = std::fmax(noise_rivers->result[index_2d],
(float)heightmap[index_2d]);
float water_depth = (t_alt - river_y) / humidity_dropoff;
float t_alt = std::fmax(base, (float)column_max_y);
float water_depth = (t_alt - base) / 4.0f;
m_bgen->humidmap[index_2d] *=
1.0f + std::pow(0.5f, std::fmax(water_depth, 1.0f));
}
@ -556,21 +438,23 @@ int MapgenValleys::generateTerrain()
// Optionally decrease humidity with altitude
if (spflags & MGVALLEYS_ALT_DRY) {
// Ground height ignoring riverbeds
float t_alt = std::fmax(noise_rivers->result[index_2d],
(float)heightmap[index_2d]);
if (t_alt > 0.0f)
float t_alt = std::fmax(base, (float)column_max_y);
// Only decrease above water_level
if (t_alt > water_level)
m_bgen->humidmap[index_2d] -=
alt_to_humid * t_alt / altitude_chill;
(t_alt - water_level) * 10.0f / altitude_chill;
}
// Optionally decrease heat with altitude
if (spflags & MGVALLEYS_ALT_CHILL) {
// Compensate to avoid reducing the average heat
m_bgen->heatmap[index_2d] += 5.0f;
// Ground height ignoring riverbeds
float t_alt = std::fmax(noise_rivers->result[index_2d],
(float)heightmap[index_2d]);
if (t_alt > 0.0f)
float t_alt = std::fmax(base, (float)column_max_y);
// Only decrease above water_level
if (t_alt > water_level)
m_bgen->heatmap[index_2d] -=
alt_to_heat * t_alt / altitude_chill;
(t_alt - water_level) * 20.0f / altitude_chill;
}
}

27
src/mapgen/mapgen_valleys.h
View File

@ -1,11 +1,11 @@
/*
Minetest
Copyright (C) 2016-2018 Duane Robertson <duane@duanerobertson.com>
Copyright (C) 2016-2018 paramat
Copyright (C) 2016-2019 Duane Robertson <duane@duanerobertson.com>
Copyright (C) 2016-2019 paramat
Based on Valleys Mapgen by Gael de Sailly
(https://forum.minetest.net/viewtopic.php?f=9&t=11430)
and mapgen_v7 by kwolekr and paramat.
and mapgen_v7, mapgen_flat by kwolekr and paramat.
Licensing changed by permission of Gael de Sailly.
@ -24,20 +24,16 @@ with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#pragma once
#include "mapgen.h"
/////////////////// Mapgen Valleys flags
#define MGVALLEYS_ALT_CHILL 0x01
#define MGVALLEYS_HUMID_RIVERS 0x02
#define MGVALLEYS_VARY_RIVER_DEPTH 0x04
#define MGVALLEYS_ALT_DRY 0x08
// Feed only one variable into these
#define MYSQUARE(x) (x) * (x)
#define MYCUBE(x) (x) * (x) * (x)
class BiomeManager;
class BiomeGenOriginal;
@ -79,16 +75,6 @@ struct MapgenValleysParams : public MapgenParams {
void writeParams(Settings *settings) const;
};
struct TerrainNoise {
s16 x;
s16 z;
float terrain_height;
float *rivers;
float *valley;
float valley_profile;
float *slope;
float inter_valley_fill;
};
class MapgenValleys : public MapgenBasic {
public:
@ -106,7 +92,6 @@ private:
BiomeGenOriginal *m_bgen;
float altitude_chill;
float humidity_adjust;
float river_depth_bed;
float river_size_factor;
@ -121,9 +106,5 @@ private:
Noise *noise_valley_depth;
Noise *noise_valley_profile;
float terrainLevelAtPoint(s16 x, s16 z);
void calculateNoise();
virtual int generateTerrain();
float terrainLevelFromNoise(TerrainNoise *tn);
float adjustedTerrainLevelFromNoise(TerrainNoise *tn);
};