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Mapgen: Fix biome Y calculation regression

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BiomeGen::getNextTransitionY(y) did not guarantee the condition (y < biome_y_min)
of the next loop because the function may return the value (biome_y_min - 1).
Hence, the biome was not updated until one Y coordinate after.
This commit is contained in:
SmallJoker 2024-11-28 22:12:24 +01:00 • committed by SmallJoker
parent 50928b9759
commit 480eb7d816
5 changed files with 24 additions and 15 deletions
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16
src/mapgen/mapgen.cpp
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@ -644,7 +644,7 @@ void MapgenBasic::generateBiomes()
u16 depth_riverbed = 0;
u32 vi = vm->m_area.index(x, node_max.Y, z);
s16 biome_y_min = biomegen->getNextTransitionY(node_max.Y);
s16 biome_y_next = biomegen->getNextTransitionY(node_max.Y);
// Check node at base of mapchunk above, either a node of a previously
// generated mapchunk or if not, a node of overgenerated base terrain.
@ -661,23 +661,29 @@ void MapgenBasic::generateBiomes()
for (s16 y = node_max.Y; y >= node_min.Y; y--) {
content_t c = vm->m_data[vi].getContent();
const bool biome_outdated = !biome || y <= biome_y_next;
// Biome is (re)calculated:
// 1. At the surface of stone below air or water.
// 2. At the surface of water below air.
// 3. When stone or water is detected but biome has not yet been calculated.
// 4. When stone or water is detected just below a biome's lower limit.
bool is_stone_surface = (c == c_stone) &&
(air_above || water_above || !biome || y < biome_y_min); // 1, 3, 4
(air_above || water_above || biome_outdated); // 1, 3, 4
bool is_water_surface =
(c == c_water_source || c == c_river_water_source) &&
(air_above || !biome || y < biome_y_min); // 2, 3, 4
(air_above || biome_outdated); // 2, 3, 4
if (is_stone_surface || is_water_surface) {
if (!biome || y < biome_y_min) {
if (biome_outdated) {
// (Re)calculate biome
biome = biomegen->getBiomeAtIndex(index, v3s16(x, y, z));
biome_y_min = biomegen->getNextTransitionY(y);
biome_y_next = biomegen->getNextTransitionY(y);
if (x == node_min.X && z == node_min.Z && false) {
dstream << "biomegen: biome at " << y << " is " << biome->name
<< ", next at " << biome_y_next << std::endl;
}
}
// Add biome to biomemap at first stone surface detected