Add "nether outpost"

As a temporary solution until large nether fortresses are there.
This is just a little tower containing some warts and a blaze
spawner.

mods/ITEMS/mcl_crimson/init.lua

@@ -6,11 +6,11 @@ local modpath = minetest.get_modpath(modname)
 -- adapted for mcl2 by cora
 
 local function generate_warped_tree(pos)
-	minetest.place_schematic(pos,modpath.."/schematics/warped_mushroom.mts","random",nil,false,"place_center_x,place_center_z")
+	minetest.place_schematic(pos,modpath.."/schematics/warped_fungus_1.mts","random",nil,false,"place_center_x,place_center_z")
 end
 
 function generate_crimson_tree(pos)
-	minetest.place_schematic(pos,modpath.."/schematics/crimson_mushroom.mts","random",nil,false,"place_center_x,place_center_z")
+	minetest.place_schematic(pos,modpath.."/schematics/crimson_fungus_1.mts","random",nil,false,"place_center_x,place_center_z")
 end
 
 minetest.register_node("mcl_crimson:warped_fungus", {

mods/MAPGEN/mcl_nether_fortresses/init.lua

@@ -0,0 +1,36 @@
+local modname = minetest.get_current_modname()
+local modpath = minetest.get_modpath(modname)
+
+mcl_structures.register_structure("nether_outpost",{
+	place_on = {"mcl_nether:netherrack","mcl_crimson:crimson_nylium","mcl_crimson:warped_nylium","mcl_blackstone:basalt","mcl_blackstone:soul_soil"},
+	noise_params = {
+		offset = 0,
+		scale = 0.00022,
+		spread = {x = 250, y = 250, z = 250},
+		seed = 333,
+		octaves = 1,
+		persist = 0.0001,
+		flags = "absvalue",
+	},
+	flags = "all_floors",
+	biomes = {"Nether","SoulsandValley","WarpedForest","CrimsonForest","BasaltDelta"},
+	on_place = function(pos,def,pr)
+		local sidelen = 15
+		local node = minetest.get_node(vector.offset(pos,1,1,0))
+		local solid = minetest.find_nodes_in_area(vector.offset(pos,-sidelen/2,-1,-sidelen/2),vector.offset(pos,sidelen/2,-1,sidelen/2),{"group:solid"})
+		local air = minetest.find_nodes_in_area(vector.offset(pos,-sidelen/2,1,-sidelen/2),vector.offset(pos,sidelen/2,4,sidelen/2),{"air"})
+		if #solid < ( sidelen * sidelen ) or
+		#air < (sidelen * sidelen ) then return false end
+		minetest.bulk_set_node(solid,node)
+		return true
+	end,
+	y_min = mcl_vars.mg_lava_nether_max,
+	y_max = mcl_vars.mg_nether_max - 30,
+	filenames = { modpath.."/schematics/nether_outpost.mts" },
+	y_offset = 0,
+	after_place = function(pos)
+		local sp = minetest.find_nodes_in_area(pos,vector.offset(pos,0,20,0),{"mcl_mobspawners:spawner"})
+		if not sp[1] then return end
+		mcl_mobspawners.setup_spawner(sp[1], "mobs_mc:blaze", 0, minetest.LIGHT_MAX+1, 10, 3, -1)
+	end
+})

mods/MAPGEN/mcl_nether_fortresses/mod.conf

@@ -0,0 +1,3 @@
+name = mcl_nether_fortresses
+author = cora
+depends = mcl_init, mcl_structures, mcl_mobspawners

mods/MAPGEN/mcl_structures/api.lua

@@ -8,6 +8,10 @@ function mcl_structures.place_structure(pos, def, pr)
 	elseif def.y_offset then
 		y_offset = def.y_offset
 	end
+	if def.on_place and not def.on_place(pos,def,pr) then
+		minetest.log("warning","[mcl_structures] "..def.name.." at "..minetest.pos_to_string(pos).." not placed. Conditions not satisfied.")
+		return false
+	end
 	if def.filenames then
 		local file = def.filenames[pr:next(1,#def.filenames)]
 		local pp = vector.offset(pos,0,y_offset,0)