morlendor autoconfiguration level, inside the limits, almost 320 levels

* morlendor must be inside the limits, but not almost the limit of the world
* morlendor are just 220 block but let enought for layers, so reserved 320
* check for nether level or just guess to -11000, error if overlaping
* check if the world is enought to fit the morlendor layers
* close https://notabug.org/TenPlus1/nssb/issues/7
* close https://codeberg.org/minenux/minetest-mod-nssb/issues/7

README.md

@@ -48,10 +48,16 @@ No new features are developed yet! Any new contribution please mantains most bac
 * tnt
 * mobs
 
-#### conflicts
+#### configurations
 
-This mod adds a dimension in the depths of the map, the [Morlendor](#mordenlor), **configurable**,
-layer and in future autodetect the `nether` and `caverealms` layers to avoid conflicts.
+This mod adds a dimension in the depths of the map, the [Morlendor](#mordenlor), **configurable**
+using the `nssb.morlendor_level` parameter as negative integer:
+
+* If `nssb.morlendor_level` is outside of `mapgen_limit`, the mod will try to autoset best setting.
+* If `nssb.morlendor_level` it overlap `nether_depth_ymax`, of nether mod, an error will raise.
+
+The morlendor level must be at least 320 layers of blocks over the limit, 
+and 1000 layers of blocks below the nether deep floor.
 
 ### New buildings
 

mapgen.lua

@@ -1,4 +1,5 @@
 local moreores = minetest.get_modpath("moreores")
+local nethermod = minetest.get_modpath("nether")
 local is_50 = nssb.is_50
 
 nssb.mymapgenis = tonumber(minetest.settings:get("mymapgenis")) or 7
@@ -6,11 +7,13 @@ if nssb.mymapgenis ~= 6 and nssb.mymapgenis ~= 7 then
 	nssb.mymapgenis = 7
 end
 
--- get gneration level from settings
+-- mapgen limits check from minetest
+local mapgen_limit = tonumber(minetest.settings:get("mapgen_limit")) or 31000
+
+-- get generation level from settings
 local level = tonumber(minetest.settings:get("nssb.morlendor_level")) or -30000
 
 -- schematics generation
-
 local posplace = {x = 0, y = level - 93, z = 0}
 local posmemory = {x = 0, y = level - 92, z = 0}
 local postest = {x = 5, y = level - 91, z = 6}
@@ -19,6 +22,30 @@ local postest = {x = 5, y = level - 91, z = 6}
 local oretype_morlan_layer
 if is_50 then oretype_morlan_layer       = "stratum"  else  oretype_morlan_layer       = "scatter" end
 
+-- mapgen limit must be at least enought before any check
+if mapgen_limit < 400 then error("[nssb] the map limit is too low, there's no space for morlendor") end
+
+-- morlendor must be inside the limits, but not almost the limit of the world, and must be almost 320 levels
+level_amount_and_limit = math.abs(mapgen_limit) - math.abs(level)
+
+while level_amount_and_limit <= 320 do
+
+	level = (math.abs(level) - math.abs(level_amount_and_limit) - 1) * -1
+	level_amount_and_limit = math.abs(mapgen_limit) - math.abs(level)
+
+	minetest.log("error", "[nssb] incompatible morlendor level, autosetting: ".. level)
+end
+
+-- detection of nether deep floor, mordenlor must be below more than player things, cos has industructible layer
+if nethermod then
+
+	local nether_df = math.abs(tonumber(minetest.settings:get("nether_depth_ymax")) or -11000)
+
+	if ( math.abs(nether_df) >= math.abs(level) + 1000 ) then
+		error("[nssb] morlendor level conflicts with nether, unable to fix, check your settings")
+	end
+end
+
 function nssb_register_buildings(
 	build, -- name of the schematic
 	rand, -- 1/rand is the probability of the spawning of the schematic if the place found is acceptable