// This keeps us from having to maintain two similar sets of
// complicated code to determine ground level.
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, in arbitrary units.
float river = fabs(*tn->rivers) - river_size_factor;
// Use the curve of the function 1-exp(-(x/a)^2) to model valleys.
// Making "a" vary (0 < a <= 1) changes the shape of the valleys.
// Try it with a geometry software !
// (here x = "river" and a = valley_profile).
// "valley" represents the height of the terrain, from the rivers.
{
float t = river / tn->valley_profile;
*tn->valley = valley_d * (1.f - exp(- MYSQUARE(t)));
}
// approximate height of the terrain at this point
float mount = base + *tn->valley;
*tn->slope *= *tn->valley;
// Rivers are placed where "river" is negative, so where the original
// noise value is close to zero.
// Base ground is returned as rivers since it's basically the water table.
*tn->rivers = base;
if (river < 0.f) {
// Use the the function -sqrt(1-x^2) which models a circle.
float depth;
{
float t = river / river_size_factor + 1;
depth = (river_depth_bed * sqrt(MYMAX(0, 1.f - MYSQUARE(t))));
}
// 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 = MYMIN(MYMAX(base - depth, (float)(water_level - 3)), mount);
// Slope has no influence on rivers.
*tn->slope = 0.f;
}
return mount;
}
void MapgenValleys::generateCaves(s16 max_stone_y)
{
if (max_stone_y < node_min.Y)
return;
noise_cave1->perlinMap3D(node_min.X, node_min.Y - 1, node_min.Z);
noise_cave2->perlinMap3D(node_min.X, node_min.Y - 1, node_min.Z);
PseudoRandom ps(blockseed + 72202);
MapNode n_air(CONTENT_AIR);
MapNode n_lava(c_lava_source);
MapNode n_water(c_river_water_source);
v3s16 em = vm->m_area.getExtent();
// Cave blend distance near YMIN, YMAX
const float massive_cave_blend = 128.f;
// noise threshold for massive caves
const float massive_cave_threshold = 0.6f;
// mct: 1 = small rare caves, 0.5 1/3rd ground volume, 0 = 1/2 ground volume.
float yblmin = -map_gen_limit + massive_cave_blend * 1.5f;
float yblmax = massive_cave_depth - massive_cave_blend * 1.5f;
bool made_a_big_one = false;
// Cache the tcave values as they only vary by altitude.
if (node_max.Y <= massive_cave_depth) {
noise_massive_caves->perlinMap3D(node_min.X, node_min.Y - 1, node_min.Z);
for (s16 y = node_min.Y - 1; y <= node_max.Y + 1; y++) {
float tcave = massive_cave_threshold;
if (y < yblmin) {
float t = (yblmin - y) / massive_cave_blend;
tcave += MYSQUARE(t);
} else if (y > yblmax) {
float t = (y - yblmax) / massive_cave_blend;
tcave += MYSQUARE(t);
}
tcave_cache[y - node_min.Y + 1] = tcave;
}
}
// lava_depth varies between one and ten as you approach
// the bottom of the world.
s16 lava_depth = ceil((lava_max_height - node_min.Y + 1) * 10.f / map_gen_limit);
// This allows random lava spawns to be less common at the surface.
s16 lava_chance = MYCUBE(lava_features_lim) * lava_depth;
// water_depth varies between ten and one on the way down.
s16 water_depth = ceil((map_gen_limit - abs(node_min.Y) + 1) * 10.f / map_gen_limit);
// This allows random water spawns to be more common at the surface.
s16 water_chance = MYCUBE(water_features_lim) * water_depth;
// Reduce the odds of overflows even further.
if (node_max.Y > water_level) {
lava_chance /= 5;
water_chance /= 5;
}
u32 index_2d = 0;
u32 index_3d = 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++) {
Biome *biome = (Biome *)bmgr->getRaw(biomemap[index_2d]);
bool air_above = false;
bool underground = false;
u32 index_data = vm->m_area.index(x, node_max.Y + 1, z);
index_3d = (z - node_min.Z) * zstride + (csize.Y + 1) * ystride + (x - node_min.X);
// Dig caves on down loop to check for air above.
for (s16 y = node_max.Y + 1;
y >= node_min.Y - 1;
y--, index_3d -= ystride, vm->m_area.add_y(em, index_data, -1)) {
float terrain = noise_terrain_height->result[index_2d];
// Saves some time.
if (y > terrain + 10) {
air_above = true;
continue;
} else if (y < terrain - 40) {
underground = true;
}
// Dig massive caves.
if (node_max.Y <= massive_cave_depth
&& noise_massive_caves->result[index_3d]
> tcave_cache[y - node_min.Y + 1]) {
vm->m_data[index_data] = n_air;
made_a_big_one = true;
}
content_t c = vm->m_data[index_data].getContent();
float d1 = contour(noise_cave1->result[index_3d]);
float d2 = contour(noise_cave2->result[index_3d]);
// River water is not set as ground content
// in the default game. This can produce strange results
// when a cave undercuts a river. However, that's not for
// the mapgen to correct. Fix it in lua.
if (c == CONTENT_AIR) {
air_above = true;
} else if (d1 * d2 > 0.3f && ndef->get(c).is_ground_content) {
// in a cave
vm->m_data[index_data] = n_air;
air_above = true;
} else if (air_above && (c == biome->c_filler || c == biome->c_stone)) {
// at the cave floor
s16 sr = ps.range(0,39);
u32 j = index_data;
vm->m_area.add_y(em, j, 1);
if (sr > terrain - y) {
// Put dirt in caves near the surface.
if (underground)
vm->m_data[index_data] = MapNode(biome->c_filler);
else
vm->m_data[index_data] = MapNode(biome->c_top);
} else if (sr < 3 && underground) {
sr = abs(ps.next());
if (lava_features_lim > 0 && y <= lava_max_height
&& c == biome->c_stone && sr < lava_chance)
vm->m_data[j] = n_lava;
sr -= lava_chance;
// If sr < 0 then we should have already placed lava --
// don't immediately dump water on it.
if (water_features_lim > 0 && y <= cave_water_max_height
&& sr >= 0 && sr < water_chance)
vm->m_data[j] = n_water;
}
air_above = false;
underground = true;
} else if (c == biome->c_filler || c == biome->c_stone) {
air_above = false;
underground = true;
} else {
air_above = false;
}
}
}
if (node_max.Y <= large_cave_depth && (!made_a_big_one)) {
u32 bruises_count = ps.range(0, 2);
for (u32 i = 0; i < bruises_count; i++) {
CaveV5 cave(this, &ps);
cave.makeCave(node_min, node_max, max_stone_y);
}
}
}
void MapgenValleys::generateCaves(s16 max_stone_y, s16 large_cave_depth)
{
if (max_stone_y < node_min.Y)
return;
noise_cave1->perlinMap3D(node_min.X, node_min.Y - 1, node_min.Z);
noise_cave2->perlinMap3D(node_min.X, node_min.Y - 1, node_min.Z);
PseudoRandom ps(blockseed + 72202);
MapNode n_air(CONTENT_AIR);
MapNode n_lava(c_lava_source);
MapNode n_water(c_river_water_source);
v3s16 em = vm->m_area.getExtent();
// Cave blend distance near YMIN, YMAX
const float massive_cave_blend = 128.f;
// noise threshold for massive caves
const float massive_cave_threshold = 0.6f;
// mct: 1 = small rare caves, 0.5 1/3rd ground volume, 0 = 1/2 ground volume.
float yblmin = -map_gen_limit + massive_cave_blend * 1.5f;
float yblmax = massive_cave_depth - massive_cave_blend * 1.5f;
bool made_a_big_one = false;
// Cache the tcave values as they only vary by altitude.
if (node_max.Y <= massive_cave_depth) {
noise_massive_caves->perlinMap3D(node_min.X, node_min.Y - 1, node_min.Z);
for (s16 y = node_min.Y - 1; y <= node_max.Y; y++) {
float tcave = massive_cave_threshold;
if (y < yblmin) {
float t = (yblmin - y) / massive_cave_blend;
tcave += MYSQUARE(t);
} else if (y > yblmax) {
float t = (y - yblmax) / massive_cave_blend;
tcave += MYSQUARE(t);
}
tcave_cache[y - node_min.Y + 1] = tcave;
}
}
// lava_depth varies between one and ten as you approach
// the bottom of the world.
s16 lava_depth = ceil((lava_max_height - node_min.Y + 1) * 10.f / map_gen_limit);
// This allows random lava spawns to be less common at the surface.
s16 lava_chance = MYCUBE(lava_features_lim) * lava_depth;
// water_depth varies between ten and one on the way down.
s16 water_depth = ceil((map_gen_limit - abs(node_min.Y) + 1) * 10.f / map_gen_limit);
// This allows random water spawns to be more common at the surface.
s16 water_chance = MYCUBE(water_features_lim) * water_depth;
// Reduce the odds of overflows even further.
if (node_max.Y > water_level) {
lava_chance /= 3;
water_chance /= 3;
}
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++) {
Biome *biome = (Biome *)m_bmgr->getRaw(biomemap[index_2d]);
bool tunnel_air_above = false;
bool is_under_river = false;
bool underground = false;
u32 index_data = vm->m_area.index(x, node_max.Y, z);
u32 index_3d = (z - node_min.Z) * zstride_1d + csize.Y * ystride + (x - node_min.X);
// Dig caves on down loop to check for air above.
// Don't excavate the overgenerated stone at node_max.Y + 1,
// this creates a 'roof' over the tunnel, preventing light in
// tunnels at mapchunk borders when generating mapchunks upwards.
// This 'roof' is removed when the mapchunk above is generated.
for (s16 y = node_max.Y; y >= node_min.Y - 1; y--,
index_3d -= ystride,
vm->m_area.add_y(em, index_data, -1)) {
float terrain = noise_terrain_height->result[index_2d];
// Saves some time.
if (y > terrain + 10)
continue;
else if (y < terrain - 40)
underground = true;
// Dig massive caves.
if (node_max.Y <= massive_cave_depth
&& noise_massive_caves->result[index_3d]
> tcave_cache[y - node_min.Y + 1]) {
vm->m_data[index_data] = n_air;
made_a_big_one = true;
continue;
}
content_t c = vm->m_data[index_data].getContent();
// Detect river water to place riverbed nodes in tunnels
if (c == biome->c_river_water)
is_under_river = true;
float d1 = contour(noise_cave1->result[index_3d]);
float d2 = contour(noise_cave2->result[index_3d]);
if (d1 * d2 > cave_width && ndef->get(c).is_ground_content) {
// in a tunnel
vm->m_data[index_data] = n_air;
tunnel_air_above = true;
} else if (c == biome->c_filler || c == biome->c_stone) {
if (tunnel_air_above) {
// at the tunnel floor
s16 sr = ps.range(0, 39);
u32 j = index_data;
vm->m_area.add_y(em, j, 1);
if (sr > terrain - y) {
// Put biome nodes in tunnels near the surface
if (is_under_river)
vm->m_data[index_data] = MapNode(biome->c_riverbed);
else if (underground)
vm->m_data[index_data] = MapNode(biome->c_filler);
else
vm->m_data[index_data] = MapNode(biome->c_top);
} else if (sr < 3 && underground) {
sr = abs(ps.next());
if (lava_features_lim > 0 && y <= lava_max_height
&& c == biome->c_stone && sr < lava_chance)
vm->m_data[j] = n_lava;
sr -= lava_chance;
// If sr < 0 then we should have already placed lava --
// don't immediately dump water on it.
if (water_features_lim > 0 && y <= cave_water_max_height
&& sr >= 0 && sr < water_chance)
vm->m_data[j] = n_water;
}
}
tunnel_air_above = false;
underground = true;
} else {
tunnel_air_above = false;
}
}
}
if (node_max.Y <= large_cave_depth && !made_a_big_one) {
u32 bruises_count = ps.range(0, 2);
for (u32 i = 0; i < bruises_count; i++) {
CavesRandomWalk cave(ndef, &gennotify, seed, water_level,
c_water_source, c_lava_source);
cave.makeCave(vm, node_min, node_max, &ps, true, max_stone_y, heightmap);
}
}
}
