Noise: Prevent unittest crash caused by division by zero

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

diff --git a/src/mapgen.cpp b/src/mapgen.cpp
index b095d34c8756ea1d2f004fa604b2b8b62b702125..f73930e6e3ae434951f67b261aa3be97aed8c0d2 100644 (file)
--- a/src/mapgen.cpp
+++ b/src/mapgen.cpp
@@ -237,7 +237,7 @@ u32 Mapgen::getBlockSeed2(v3s16 p, s32 seed)
 // Returns Y one under area minimum if not found
 s16 Mapgen::findGroundLevelFull(v2s16 p2d)
 {
-       v3s16 em = vm->m_area.getExtent();
+       const v3s16 &em = vm->m_area.getExtent();
        s16 y_nodes_max = vm->m_area.MaxEdge.Y;
        s16 y_nodes_min = vm->m_area.MinEdge.Y;
        u32 i = vm->m_area.index(p2d.X, y_nodes_max, p2d.Y);
@@ -257,7 +257,7 @@ s16 Mapgen::findGroundLevelFull(v2s16 p2d)
 // Returns -MAX_MAP_GENERATION_LIMIT if not found
 s16 Mapgen::findGroundLevel(v2s16 p2d, s16 ymin, s16 ymax)
 {
-       v3s16 em = vm->m_area.getExtent();
+       const v3s16 &em = vm->m_area.getExtent();
        u32 i = vm->m_area.index(p2d.X, ymax, p2d.Y);
        s16 y;
 
@@ -275,7 +275,7 @@ s16 Mapgen::findGroundLevel(v2s16 p2d, s16 ymin, s16 ymax)
 // Returns -MAX_MAP_GENERATION_LIMIT if not found or if ground is found first
 s16 Mapgen::findLiquidSurface(v2s16 p2d, s16 ymin, s16 ymax)
 {
-       v3s16 em = vm->m_area.getExtent();
+       const v3s16 &em = vm->m_area.getExtent();
        u32 i = vm->m_area.index(p2d.X, ymax, p2d.Y);
        s16 y;
 
@@ -344,7 +344,7 @@ inline bool Mapgen::isLiquidHorizontallyFlowable(u32 vi, v3s16 em)
 void Mapgen::updateLiquid(UniqueQueue<v3s16> *trans_liquid, v3s16 nmin, v3s16 nmax)
 {
        bool isignored, isliquid, wasignored, wasliquid, waschecked, waspushed;
-       v3s16 em  = vm->m_area.getExtent();
+       const v3s16 &em  = vm->m_area.getExtent();
 
        for (s16 z = nmin.Z + 1; z <= nmax.Z - 1; z++)
        for (s16 x = nmin.X + 1; x <= nmax.X - 1; x++) {
@@ -467,7 +467,7 @@ void Mapgen::propagateSunlight(v3s16 nmin, v3s16 nmax, bool propagate_shadow)
        //TimeTaker t("propagateSunlight");
        VoxelArea a(nmin, nmax);
        bool block_is_underground = (water_level >= nmax.Y);
-       v3s16 em = vm->m_area.getExtent();
+       const v3s16 &em = vm->m_area.getExtent();
 
        // NOTE: Direct access to the low 4 bits of param1 is okay here because,
        // by definition, sunlight will never be in the night lightbank.
@@ -621,13 +621,13 @@ MapgenBasic::~MapgenBasic()
 }
 
 
-MgStoneType MapgenBasic::generateBiomes()
+MgStoneType MapgenBasic::generateBiomes(s16 biome_zero_level)
 {
        // can't generate biomes without a biome generator!
        assert(biomegen);
        assert(biomemap);
 
-       v3s16 em = vm->m_area.getExtent();
+       const v3s16 &em = vm->m_area.getExtent();
        u32 index = 0;
        MgStoneType stone_type = MGSTONE_STONE;
 
@@ -673,7 +673,10 @@ MgStoneType MapgenBasic::generateBiomes()
                                (air_above || !biome);
 
                        if (is_stone_surface || is_water_surface) {
-                               biome = biomegen->getBiomeAtIndex(index, y);
+                               // Limit to +-MAX MAP GENERATION LIMIT to work with biome y_min / y_max.
+                               s32 relative_y = rangelim(y - biome_zero_level,
+                                       -MAX_MAP_GENERATION_LIMIT, MAX_MAP_GENERATION_LIMIT);
+                               biome = biomegen->getBiomeAtIndex(index, relative_y);
 
                                if (biomemap[index] == BIOME_NONE && is_stone_surface)
                                        biomemap[index] = biome->index;
@@ -761,7 +764,7 @@ void MapgenBasic::dustTopNodes()
        if (node_max.Y < water_level)
                return;
 
-       v3s16 em = vm->m_area.getExtent();
+       const v3s16 &em = vm->m_area.getExtent();
        u32 index = 0;
 
        for (s16 z = node_min.Z; z <= node_max.Z; z++)