Mgv7: Avoid divide-by-zero errors

Some settings of paramters can cause mgv7 variables to be -inf, nan or -nan.
This can cause massive vertical columns of water to appear above sea level.

diff --git a/src/mapgen_v7.cpp b/src/mapgen_v7.cpp
index 5d150ee1c9c16976fd071529382b317eb1a182b5..d74d050ef9d947a106bcfcd482a95ac3d52f0c67 100644 (file)
--- a/src/mapgen_v7.cpp
+++ b/src/mapgen_v7.cpp
@@ -59,7 +59,7 @@ MapgenV7::MapgenV7(int mapgenid, MapgenV7Params *params, EmergeManager *emerge)
        this->large_cave_depth    = params->large_cave_depth;
        this->lava_depth          = params->lava_depth;
        this->float_mount_density = params->float_mount_density;
-       this->float_mount_height  = params->float_mount_height;
+       float_mount_height_lim    = MYMAX(params->float_mount_height, 1.0f);
        this->floatland_level     = params->floatland_level;
        this->shadow_limit        = params->shadow_limit;
        this->cavern_limit        = params->cavern_limit;
@@ -382,7 +382,8 @@ float MapgenV7::baseTerrainLevelFromMap(int index)
 
 bool MapgenV7::getMountainTerrainAtPoint(s16 x, s16 y, s16 z)
 {
-       float mnt_h_n = NoisePerlin2D(&noise_mount_height->np, x, z, seed);
+       float mnt_h_n =
+                       MYMAX(NoisePerlin2D(&noise_mount_height->np, x, z, seed), 1.0f);
        float density_gradient = -((float)y / mnt_h_n);
        float mnt_n = NoisePerlin3D(&noise_mountain->np, x, y, z, seed);
 
@@ -392,7 +393,7 @@ bool MapgenV7::getMountainTerrainAtPoint(s16 x, s16 y, s16 z)
 
 bool MapgenV7::getMountainTerrainFromMap(int idx_xyz, int idx_xz, s16 y)
 {
-       float mounthn = noise_mount_height->result[idx_xz];
+       float mounthn = MYMAX(noise_mount_height->result[idx_xz], 1.0f);
        float density_gradient = -((float)y / mounthn);
        float mountn = noise_mountain->result[idx_xyz];
 
@@ -404,8 +405,8 @@ bool MapgenV7::getFloatlandMountainFromMap(int idx_xyz, int idx_xz, s16 y)
 {
        // Make rim 2 nodes thick to match floatland base terrain
        float density_gradient = (y >= floatland_level) ?
-               -pow((float)(y - floatland_level) / float_mount_height, 0.75f) :
-               -pow((float)(floatland_level - 1 - y) / float_mount_height, 0.75f);
+               -pow((float)(y - floatland_level) / float_mount_height_lim, 0.75f) :
+               -pow((float)(floatland_level - 1 - y) / float_mount_height_lim, 0.75f);
 
        float floatn = noise_mountain->result[idx_xyz] + float_mount_density;
 
@@ -421,7 +422,8 @@ void MapgenV7::floatBaseExtentFromMap(s16 *float_base_min, s16 *float_base_max,
 
        float n_base = noise_floatland_base->result[idx_xz];
        if (n_base > 0.0f) {
-               float n_base_height = noise_float_base_height->result[idx_xz];
+               float n_base_height =
+                               MYMAX(noise_float_base_height->result[idx_xz], 1.0f);
                float amp = n_base * n_base_height;
                float ridge = n_base_height / 3.0f;
                base_min = floatland_level - amp / 1.5f;

diff --git a/src/mapgen_v7.h b/src/mapgen_v7.h
index 7b4364ef1772010e0fe2f0f991dc5db7df9a7ac3..b88d90dee455ef82270b750359bbf5008be3d3db 100644 (file)
--- a/src/mapgen_v7.h
+++ b/src/mapgen_v7.h
@@ -106,6 +106,8 @@ private:
        Noise *noise_float_base_height;
        Noise *noise_mountain;
        Noise *noise_ridge;
+
+       float float_mount_height_lim;
 };
 
 #endif