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

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

diff --git a/src/mapgen/mapgen_valleys.cpp b/src/mapgen/mapgen_valleys.cpp
index 843acb69034fdcbf80c8953fe191547823c462fa..0a0f93a75f054c11d643495db8c11d314ffb4d52 100644 (file)
--- a/src/mapgen/mapgen_valleys.cpp
+++ b/src/mapgen/mapgen_valleys.cpp
@@ -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;
 }
 
@@ -231,7 +231,8 @@ void MapgenValleys::makeChunk(BlockMakeData *data)
        updateHeightmap(node_min, node_max);
 
        // Place biome-specific nodes and build biomemap
-       generateBiomes();
+       if (flags & MG_BIOMES)
+               generateBiomes();
 
        // Generate tunnels, caverns and large randomwalk caves
        if (flags & MG_CAVES) {
@@ -265,7 +266,8 @@ void MapgenValleys::makeChunk(BlockMakeData *data)
        m_emerge->oremgr->placeAllOres(this, blockseed, node_min, node_max);
 
        // Sprinkle some dust on top after everything else was generated
-       dustTopNodes();
+       if (flags & MG_BIOMES)
+               dustTopNodes();
 
        updateLiquid(&data->transforming_liquid, full_node_min, full_node_max);
 
@@ -296,10 +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++) {
@@ -475,17 +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);
                        }
                }
@@ -532,33 +533,32 @@ int MapgenValleys::generateTerrain()
                        }
                }
 
-               if (humid_rivers) {
-                       // Use base ground (water table) in a riverbed, to avoid an
-                       // unnatural rise in humidity.
+               // 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 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));
+                       m_bgen->humidmap[index_2d] *=
+                               1.0f + std::pow(0.5f, std::fmax(water_depth, 1.0f));
+               }
 
-                       // Reduce humidity with altitude (ignoring riverbeds)
+               // 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)
-                               humid -= alt_to_humid * t_alt / altitude_chill;
-
-                       m_bgen->humidmap[index_2d] = humid;
+                               m_bgen->humidmap[index_2d] -=
+                                       alt_to_humid * t_alt / altitude_chill;
                }
 
-               // Assign the heat adjusted by any changed altitudes.
-               // The altitude will change about half the time.
-               if (use_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 (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)
+                       if (t_alt > 0.0f)
                                m_bgen->heatmap[index_2d] -=
                                        alt_to_heat * t_alt / altitude_chill;
                }