Dungeons: Do not remove nodes that have 'is_ground_content = false' (#8423)

Like randomwalk caves, preserve nodes that have 'is_ground_content = false',
to avoid dungeons that generate out beyond the edge of a mapchunk destroying
nodes added by mods in 'register_on_generated()'.

Issue discovered by, and original PR by, argyle77.

diff --git a/doc/lua_api.txt b/doc/lua_api.txt
index 899c0abdbbc6893d3f9214f2ae777bfa9a2147d9..9ac37e8815604b97165aadeb5990e56a5a609688 100644 (file)
--- a/doc/lua_api.txt
+++ b/doc/lua_api.txt
@@ -6040,7 +6040,11 @@ Used by `minetest.register_node`.
         place_param2 = nil,  -- Force value for param2 when player places node
 
         is_ground_content = true,
-        -- If false, the cave generator will not carve through this node
+        -- If false, the cave generator and dungeon generator will not carve
+        -- through this node.
+        -- Specifically, this stops mod-added nodes being removed by caves and
+        -- dungeons when those generate in a neighbor mapchunk and extend out
+        -- beyond the edge of that mapchunk.
 
         sunlight_propagates = false,
         -- If true, sunlight will go infinitely through this node

diff --git a/src/mapgen/dungeongen.cpp b/src/mapgen/dungeongen.cpp
index 77ac05770769d3fd10ffc0a0c3dcc5ce4674260e..3acd22877fd49d0efc04154994b8ad566e40d99b 100644 (file)
--- a/src/mapgen/dungeongen.cpp
+++ b/src/mapgen/dungeongen.cpp
@@ -100,8 +100,11 @@ void DungeonGen::generate(MMVManip *vm, u32 bseed, v3s16 nmin, v3s16 nmax)
 
        if (dp.only_in_ground) {
                // Set all air and liquid drawtypes to be untouchable to make dungeons
-               // open to air and liquids. Optionally set ignore to be untouchable to
-               // prevent projecting dungeons.
+               // open to air and liquids.
+               // Optionally set ignore to be untouchable to prevent projecting dungeons.
+               // Like randomwalk caves, preserve nodes that have 'is_ground_content = false',
+               // to avoid dungeons that generate out beyond the edge of a mapchunk destroying
+               // nodes added by mods in 'register_on_generated()'.
                for (s16 z = nmin.Z; z <= nmax.Z; z++) {
                        for (s16 y = nmin.Y; y <= nmax.Y; y++) {
                                u32 i = vm->m_area.index(nmin.X, y, z);
@@ -109,7 +112,8 @@ void DungeonGen::generate(MMVManip *vm, u32 bseed, v3s16 nmin, v3s16 nmax)
                                        content_t c = vm->m_data[i].getContent();
                                        NodeDrawType dtype = ndef->get(c).drawtype;
                                        if (dtype == NDT_AIRLIKE || dtype == NDT_LIQUID ||
-                                                       (preserve_ignore && c == CONTENT_IGNORE))
+                                                       (preserve_ignore && c == CONTENT_IGNORE) ||
+                                                       !ndef->get(c).is_ground_content)
                                                vm->m_flags[i] |= VMANIP_FLAG_DUNGEON_PRESERVE;
                                        i++;
                                }