forked from Mirrorlandia_minetest/minetest
Mgvalleys: Add Dry Riverbeds
Lower water table where base humidity is low. Alter heat and humidity to compensate for river humidity and altitude chill. Correct misuse of surface_max_y in generateTerrain. Remove sand trails in the water at river mouths. Remove river water below water_level. Correct heat/humidity calculations where noises are less than zero. Correct heightmap errors as much as possible. Make humidity calculations more readable.
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@ -399,8 +399,21 @@ void MapgenValleys::calculateNoise()
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//mapgen_profiler->avg("noisemaps", tcn.stop() / 1000.f);
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float heat_offset = 0.f;
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float humidity_scale = 1.f;
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// Altitude chill tends to reduce the average heat.
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if (use_altitude_chill)
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heat_offset = 5.f;
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// River humidity tends to increase the humidity range.
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if (humid_rivers) {
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humidity_scale = 0.8f;
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}
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for (s32 index = 0; index < csize.X * csize.Z; index++) {
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noise_heat->result[index] += noise_heat_blend->result[index];
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noise_heat->result[index] += noise_heat_blend->result[index] + heat_offset;
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noise_humidity->result[index] *= humidity_scale;
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noise_humidity->result[index] += noise_humidity_blend->result[index];
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}
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@ -481,9 +494,10 @@ float MapgenValleys::terrainLevelFromNoise(TerrainNoise *tn)
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}
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// base - depth : height of the bottom of the river
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// water_level - 6 : don't make rivers below 6 nodes under the surface
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// water_level - 3 : don't make rivers below 3 nodes under the surface
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// We use three because that's as low as the swamp biomes go.
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// There is no logical equivalent to this using rangelim.
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mount = MYMIN(MYMAX(base - depth, (float) (water_level - 6)), mount);
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mount = MYMIN(MYMAX(base - depth, (float)(water_level - 3)), mount);
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// Slope has no influence on rivers.
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*tn->slope = 0.f;
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@ -503,7 +517,7 @@ float MapgenValleys::adjustedTerrainLevelFromNoise(TerrainNoise *tn)
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for (s16 y = y_start; y <= y_start + 1000; y++) {
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float fill = NoisePerlin3D(&noise_inter_valley_fill->np, tn->x, y, tn->z, seed);
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if (fill * *tn->slope <= y - mount) {
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if (fill * *tn->slope < y - mount) {
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mount = MYMAX(y - 1, mount);
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break;
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}
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@ -552,6 +566,15 @@ float MapgenValleys::terrainLevelAtPoint(s16 x, s16 z)
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int MapgenValleys::generateTerrain()
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{
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// Raising this reduces the rate of evaporation.
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static const float evaporation = 300.f;
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// from the lua
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static const float humidity_dropoff = 4.f;
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// constant to convert altitude chill (compatible with lua) to heat
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static const float alt_to_heat = 20.f;
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// humidity reduction by altitude
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static const float alt_to_humid = 10.f;
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MapNode n_air(CONTENT_AIR);
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MapNode n_river_water(c_river_water_source);
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MapNode n_sand(c_sand);
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@ -564,42 +587,56 @@ int MapgenValleys::generateTerrain()
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for (s16 z = node_min.Z; z <= node_max.Z; z++)
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for (s16 x = node_min.X; x <= node_max.X; x++, index_2d++) {
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s16 river_y = floor(noise_rivers->result[index_2d]);
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s16 surface_y = floor(noise_terrain_height->result[index_2d]);
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float river_y = noise_rivers->result[index_2d];
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float surface_y = noise_terrain_height->result[index_2d];
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float slope = noise_inter_valley_slope->result[index_2d];
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float t_heat = noise_heat->result[index_2d];
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heightmap[index_2d] = surface_y;
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heightmap[index_2d] = -MAX_MAP_GENERATION_LIMIT;
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if (surface_y > surface_max_y)
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surface_max_y = surface_y;
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surface_max_y = ceil(surface_y);
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if (humid_rivers) {
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// Derive heat from (base) altitude. This will be most correct
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// at rivers, since other surface heights may vary below.
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if (use_altitude_chill && (surface_y > 0.f || river_y > 0.f))
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t_heat -= alt_to_heat * MYMAX(surface_y, river_y) / altitude_chill;
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// If humidity is low or heat is high, lower the water table.
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float delta = noise_humidity->result[index_2d] - 50.f;
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if (delta < 0.f) {
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float t_evap = (t_heat - 32.f) / evaporation;
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river_y += delta * MYMAX(t_evap, 0.08f);
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}
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}
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u32 index_3d = (z - node_min.Z) * zstride + (x - node_min.X);
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u32 index_data = vm->m_area.index(x, node_min.Y - 1, z);
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// Mapgens concern themselves with stone and water.
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for (s16 y = node_min.Y - 1; y <= node_max.Y + 1; y++) {
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float fill = 0.f;
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fill = noise_inter_valley_fill->result[index_3d];
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if (vm->m_data[index_data].getContent() == CONTENT_IGNORE) {
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bool river = (river_y > surface_y);
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float fill = noise_inter_valley_fill->result[index_3d];
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float surface_delta = (float)y - surface_y;
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bool river = y + 1 < river_y;
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if (river && y == surface_y) {
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if (fabs(surface_delta) <= 0.5f && y > water_level && river) {
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// river bottom
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vm->m_data[index_data] = n_sand;
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} else if (river && y <= surface_y) {
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} else if (slope * fill > surface_delta) {
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// ground
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vm->m_data[index_data] = n_stone;
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} else if (river && y < river_y) {
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// river
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vm->m_data[index_data] = n_river_water;
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} else if ((!river) && myround(fill * slope) >= y - surface_y) {
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// ground
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vm->m_data[index_data] = n_stone;
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heightmap[index_2d] = surface_max_y = y;
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if (y > heightmap[index_2d])
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heightmap[index_2d] = y;
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if (y > surface_max_y)
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surface_max_y = y;
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} else if (y <= water_level) {
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// sea
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vm->m_data[index_data] = n_water;
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} else if (river) {
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// river
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vm->m_data[index_data] = n_river_water;
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} else {
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vm->m_data[index_data] = n_air;
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}
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@ -609,18 +646,51 @@ int MapgenValleys::generateTerrain()
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index_3d += ystride;
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}
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// Although the original valleys adjusts humidity by distance
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// from seawater, this causes problems with the default biomes.
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// Adjust only by freshwater proximity.
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const float humidity_offset = 0.8f; // derived by testing
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if (humid_rivers)
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noise_humidity->result[index_2d] *= (1 + pow(0.5f, MYMAX((surface_max_y
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- noise_rivers->result[index_2d]) / 3.f, 0.f))) * humidity_offset;
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// This happens if we're generating a chunk that doesn't
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// contain the terrain surface, in which case, we need
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// to set heightmap to a value outside of the chunk,
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// to avoid confusing lua mods that use heightmap.
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if (heightmap[index_2d] == -MAX_MAP_GENERATION_LIMIT) {
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s16 surface_y_int = myround(surface_y);
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if (surface_y_int > node_max.Y + 1 || surface_y_int < node_min.Y - 1) {
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// If surface_y is outside the chunk, it's good enough.
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heightmap[index_2d] = surface_y_int;
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} else {
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// If the ground is outside of this chunk, but surface_y
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// is within the chunk, give a value outside.
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heightmap[index_2d] = node_min.Y - 2;
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}
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}
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// Assign the heat adjusted by altitude.
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if (use_altitude_chill && surface_max_y > 0)
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noise_heat->result[index_2d] *=
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pow(0.5f, (surface_max_y - altitude_chill / 3.f) / altitude_chill);
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if (humid_rivers) {
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// Use base ground (water table) in a riverbed, to
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// avoid an unnatural rise in humidity.
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float t_alt = MYMAX(noise_rivers->result[index_2d], (float)heightmap[index_2d]);
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float humid = noise_humidity->result[index_2d];
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float water_depth = (t_alt - river_y) / humidity_dropoff;
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humid *= 1.f + pow(0.5f, MYMAX(water_depth, 1.f));
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// Reduce humidity with altitude (ignoring riverbeds).
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// This is similar to the lua version's seawater adjustment,
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// but doesn't increase the base humidity, which causes
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// problems with the default biomes.
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if (t_alt > 0.f)
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humid -= alt_to_humid * t_alt / altitude_chill;
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noise_humidity->result[index_2d] = humid;
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}
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// Assign the heat adjusted by any changed altitudes.
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// The altitude will change about half the time.
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if (use_altitude_chill) {
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// ground height ignoring riverbeds
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float t_alt = MYMAX(noise_rivers->result[index_2d], (float)heightmap[index_2d]);
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if (humid_rivers && heightmap[index_2d] == (s16)myround(surface_y))
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// The altitude hasn't changed. Use the first result.
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noise_heat->result[index_2d] = t_heat;
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else if (t_alt > 0.f)
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noise_heat->result[index_2d] -= alt_to_heat * t_alt / altitude_chill;
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}
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}
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return surface_max_y;
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@ -645,7 +715,7 @@ MgStoneType MapgenValleys::generateBiomes(float *heat_map, float *humidity_map)
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// generated mapchunk or if not, a node of overgenerated base terrain.
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content_t c_above = vm->m_data[vi + em.X].getContent();
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bool air_above = c_above == CONTENT_AIR;
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bool water_above = (c_above == c_water_source);
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bool water_above = (c_above == c_water_source || c_above == c_river_water_source);
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// If there is air or water above enable top/filler placement, otherwise force
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// nplaced to stone level by setting a number exceeding any possible filler depth.
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@ -714,7 +784,7 @@ MgStoneType MapgenValleys::generateBiomes(float *heat_map, float *humidity_map)
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water_above = true;
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} else if (c == c_river_water_source) {
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vm->m_data[vi] = MapNode(biome->c_river_water);
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nplaced = U16_MAX; // Sand was already placed under rivers.
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nplaced = depth_top; // Enable filler placement for next surface
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air_above = false;
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water_above = true;
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} else if (c == CONTENT_AIR) {
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