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.
minetest · Mar 26, 2019 · 5e7662c · 5e7662c
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Showing 2 changed files with 12 additions and 4 deletions.
diff --git 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
@@ -100,16 +100,20 @@ 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);
 				for (s16 x = nmin.X; x <= nmax.X; x++) {
 					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++;
 				}