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Mgvalleys: Make river depth variation and humidity drop optional (#7532)

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Add 2 new mapgen flags to make river depth variation and humidity drop
with altitude independently optional, instead of both being enabled by
the 'humid rivers' flag.

Simplify and clarify related code by removing a low priority
optimisation regarding 't_heat'.
Remove unnecessary optimisation bools and use spflags directly instead.
Improve and fix documentation in settingtypes.txt.
A few minor code cleanups.
This commit is contained in:
Paramat 2018-07-18 03:34:05 +01:00 • committed by GitHub
parent ade7a1cbcf
commit bc9bb63aed
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3 changed files with 62 additions and 58 deletions
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78
src/mapgen/mapgen_valleys.cpp
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@ -44,10 +44,12 @@ with this program; if not, write to the Free Software Foundation, Inc.,
#include <cmath>
static FlagDesc flagdesc_mapgen_valleys[] = {
{"altitude_chill", MGVALLEYS_ALT_CHILL},
{"humid_rivers", MGVALLEYS_HUMID_RIVERS},
{NULL, 0}
FlagDesc flagdesc_mapgen_valleys[] = {
{"altitude_chill", MGVALLEYS_ALT_CHILL},
{"humid_rivers", MGVALLEYS_HUMID_RIVERS},
{"vary_river_depth", MGVALLEYS_VARY_RIVER_DEPTH},
{"altitude_dry", MGVALLEYS_ALT_DRY},
{NULL, 0}
};
@ -94,8 +96,6 @@ MapgenValleys::MapgenValleys(int mapgenid, MapgenValleysParams *params,
MapgenBasic::np_cave2 = params->np_cave2;
MapgenBasic::np_cavern = params->np_cavern;
humid_rivers = (spflags & MGVALLEYS_HUMID_RIVERS);
use_altitude_chill = (spflags & MGVALLEYS_ALT_CHILL);
humidity_adjust = bp->np_humidity.offset - 50.0f;
}
@ -298,10 +298,10 @@ void MapgenValleys::calculateNoise()
float heat_offset = 0.0f;
float humidity_scale = 1.0f;
// Altitude chill tends to reduce the average heat.
if (use_altitude_chill)
if (spflags & MGVALLEYS_ALT_CHILL)
heat_offset = 5.0f;
// River humidity tends to increase the humidity range.
if (humid_rivers)
if (spflags & MGVALLEYS_HUMID_RIVERS)
humidity_scale = 0.8f;
for (s32 index = 0; index < csize.X * csize.Z; index++) {
@ -477,17 +477,16 @@ int MapgenValleys::generateTerrain()
if (surface_y > surface_max_y)
surface_max_y = std::ceil(surface_y);
if (humid_rivers) {
// Derive heat from (base) altitude. This will be most correct
// at rivers, since other surface heights may vary below.
if (use_altitude_chill && (surface_y > 0.0f || river_y > 0.0f))
t_heat -= alt_to_heat *
std::fmax(surface_y, river_y) / altitude_chill;
// If humidity is low or heat is high, lower the water table
// 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 :
t_heat;
float delta = m_bgen->humidmap[index_2d] - 50.0f;
if (delta < 0.0f) {
float t_evap = (t_heat - 32.0f) / evaporation;
float t_evap = (heat - 32.0f) / evaporation;
river_y += delta * std::fmax(t_evap, 0.08f);
}
}
@ -534,33 +533,32 @@ int MapgenValleys::generateTerrain()
}
}
if (humid_rivers) {
// Use base ground (water table) in a riverbed, to avoid an
// unnatural rise in humidity.
float t_alt = std::fmax(noise_rivers->result[index_2d],
(float)heightmap[index_2d]);
float humid = m_bgen->humidmap[index_2d];
float water_depth = (t_alt - river_y) / humidity_dropoff;
humid *= 1.0f + std::pow(0.5f, std::fmax(water_depth, 1.0f));
// Reduce humidity with altitude (ignoring riverbeds)
if (t_alt > 0.0f)
humid -= alt_to_humid * t_alt / altitude_chill;
m_bgen->humidmap[index_2d] = humid;
}
// Assign the heat adjusted by any changed altitudes.
// The altitude will change about half the time.
if (use_altitude_chill) {
// Optionally increase humidity around rivers
if (spflags & MGVALLEYS_HUMID_RIVERS) {
// 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;
m_bgen->humidmap[index_2d] *=
1.0f + std::pow(0.5f, std::fmax(water_depth, 1.0f));
}
if (humid_rivers && heightmap[index_2d] == (s16)myround(surface_y))
// The altitude hasn't changed. Use the first result
m_bgen->heatmap[index_2d] = t_heat;
else if (t_alt > 0.0f)
// 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)
m_bgen->humidmap[index_2d] -=
alt_to_humid * t_alt / altitude_chill;
}
// Optionally decrease heat with altitude
if (spflags & MGVALLEYS_ALT_CHILL) {
// Ground height ignoring riverbeds
float t_alt = std::fmax(noise_rivers->result[index_2d],
(float)heightmap[index_2d]);
if (t_alt > 0.0f)
m_bgen->heatmap[index_2d] -=
alt_to_heat * t_alt / altitude_chill;
}