Initial commit

README.md

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+# Spawn Builder
+Version 1.0.0
+
+## Description
+This mod generates a simple stone platform at the world origin
+or the static spawn point.
+Ideal for the `singlenode` map generator.
+
+## Usage
+Activate this *before* the spawn area got generated (ideally
+in a new world), then just join the world.
+Recommended to be used in the `singlenode` mapgen, but it works
+in other map generators, too.
+
+### Settings
+With the setting `spawnbuilder_width` you can change the width of
+the spawn platform. Note that values below 3 are not recommended.
+
+If the static spawn point (`static_spawnpoint`) is set on the
+first start of the mod, the platform is centered at this
+position instead.
+
+## Behaviour
+This mod generates a stone platform of size 33×2×33 with
+a single cobblestone in the center. Also, 3 layers
+above the platform are turned into air because the
+center position might be buried in the ground.
+
+As a safety measure, nodes with the property
+`is_ground_content=false` will never be overwritten.
+
+Also, no platform is generated if the center position is
+already in a safe spawn (in air, a few blocks below solid
+ground).
+
+## Dependencies
+This mod works with almost all subgames out of the box.
+
+The only requirement is that the subgame defines the mapgen
+aliases `mapgen_stone` and `mapgen_cobble` which is almost
+certainly the case.
+
+## License of everything in this mod
+MIT License.

description.txt

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+Generates a stone platform below the world origin or static spawn point. Ideal for the singlenode mapgen.

init.lua

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+local storage_ref = minetest.get_mod_storage()
+local stored_centerpos = {}
+local check = storage_ref:get_string("spawnbuilder_centerpos_x")
+if check ~= "" then
+	stored_centerpos.x = storage_ref:get_int("spawnbuilder_centerpos_x")
+	stored_centerpos.y = storage_ref:get_int("spawnbuilder_centerpos_y")
+	stored_centerpos.z = storage_ref:get_int("spawnbuilder_centerpos_z")
+	minetest.log("action", "[spawnbuilder] Spawn platform position loaded: "..minetest.pos_to_string(stored_centerpos))
+else
+	stored_centerpos = minetest.setting_get_pos("static_spawnpoint")
+	-- Default position
+	if not stored_centerpos then
+		stored_centerpos = { x=0, y=-1, z=0 }
+	end
+	storage_ref:set_int("spawnbuilder_centerpos_x", stored_centerpos.x)
+	storage_ref:set_int("spawnbuilder_centerpos_y", stored_centerpos.y)
+	storage_ref:set_int("spawnbuilder_centerpos_z", stored_centerpos.z)
+	minetest.log("action", "[spawnbuilder] Initial spawn platform position registered and saved: "..minetest.pos_to_string(stored_centerpos))
+end
+
+-- Width of the stored_centerpos platform
+local WIDTH
+check = storage_ref:get_string("spawnbuilder_width")
+if check ~= "" then
+	WIDTH = check
+else
+	WIDTH = tonumber(minetest.setting_get("spawnbuilder_width"))
+	if type(WIDTH) == "number" then
+		WIDTH = math.floor(WIDTH)
+	else
+		WIDTH = 33
+	end
+end
+minetest.log("action", "[spawnbuilder] Using spawn platform width of "..WIDTH..".")
+
+-- Height of the platform
+local HEIGHT = 2
+
+-- Number of air layers above the platform
+local AIRSPACE = 3
+
+-- Generates the platform or platform piece within minp and maxp with the center at centerpos
+local function generate_platform(minp, maxp, centerpos)
+	-- Get stone and cobble nodes, based on the mapgen aliases. This allows for great compability with practically
+	-- all subgames!
+	local c_stone = minetest.get_content_id("mapgen_stone")
+	local c_cobble 
+	if minetest.registered_aliases["mapgen_cobble"] == "air" or minetest.registered_aliases["mapgen_cobble"] == nil then
+		-- Fallback option: If cobble mapgen alias is inappropriate or missing, use stone instead.
+		c_cobble = c_stone
+	else
+		c_cobble = minetest.get_content_id("mapgen_cobble")
+	end
+
+	local w_neg, w_pos
+	w_pos = math.floor(WIDTH / 2)
+	if math.fmod(WIDTH, 2) == 0 then
+		w_neg = -w_pos + 1
+	else
+		w_neg = -w_pos
+	end
+
+	local xmin = math.max(centerpos.x + w_neg, minp.x)
+	local xmax = math.min(centerpos.x + w_pos, maxp.x)
+	local zmin = math.max(centerpos.z + w_neg, minp.z)
+	local zmax = math.min(centerpos.z + w_pos, maxp.z)
+	local ymin = math.max(centerpos.y - (HEIGHT-1), minp.y)
+	local ymax = math.min(centerpos.y + AIRSPACE, maxp.y)
+
+	if maxp.x >= xmin and minp.x <= xmax and maxp.y >= ymin and minp.y <= ymax and maxp.z >= zmin and minp.z <= zmax then
+		local vm, emin, emax = minetest.get_mapgen_object("voxelmanip")
+		local data = vm:get_data()
+		local area = VoxelArea:new({MinEdge=emin, MaxEdge=emax})
+
+		for x = xmin, xmax do
+			for y = ymin, ymax do
+				for z = zmin, zmax do
+					local p_pos = area:index(x, y, z)
+					local pos = {x=x,y=y,z=z}
+					if minetest.registered_nodes[minetest.get_node(pos).name].is_ground_content == true then
+						if y <= centerpos.y then
+							if x == centerpos.x and y == centerpos.y and z == centerpos.z then
+								data[p_pos] = c_cobble
+								minetest.log("action", "[spawnbuilder] Spawn platform center generated at "..minetest.pos_to_string(pos)..".")
+							else
+								data[p_pos] = c_stone
+							end
+						elseif y >= centerpos.y + 1 and y <= ymax then
+							data[p_pos] = core.CONTENT_AIR
+						end
+					end
+				end
+			end
+		end
+
+		vm:set_data(data)
+		vm:calc_lighting()
+		vm:write_to_map()
+	end
+end
+
+minetest.register_on_generated(function(minp, maxp, seed)
+	local centerpos = table.copy(stored_centerpos)
+
+	if minp.x <= centerpos.x and maxp.x >= centerpos.x and minp.y <= centerpos.y and maxp.y >= centerpos.y and minp.z <= centerpos.z and maxp.z >= centerpos.z then
+		if not WIDTH or WIDTH <= 0 then
+			minetest.log("warning", "[spawnbuilder] Invalid spawnbuilder_width. Spawn platform will NOT be generated.")
+			return
+		end
+
+		local ground = false
+		local air = true
+		-- Check for solid ground
+		for y = 3, -6, -1 do
+			local nn = minetest.get_node({x=centerpos.x, y=centerpos.y+y, centerpos.z}).name
+			local walkable = minetest.registered_nodes[nn].walkable
+			if y >= 0 and nn ~= "air" then
+				air = false
+			elseif y < 0 and walkable then
+				ground = true
+			end
+		end
+		-- Player has enough space and ground to spawn safely. No change required
+		if air and ground then
+			minetest.log("action", "[spawnbuilder] Safe player spawn detected. Spawn platform will NOT be generated.")
+			return
+		end
+	end
+
+	generate_platform(minp, maxp, centerpos)
+end)

mod.conf

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+name = spawnbuilder

settingtypes.txt

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+#Side length of the surface area of the spawn platform
+#If the number is odd, the platform will be centered at spawn.
+#Using a width lower than 3 is not recommended.
+spawnbuilder_width (Spawn platform width) int 33 1