Use per-chunk probability and 1-octave Perlin noise to simplify spawning temples

mods/MAPGEN/mcl_structures/desert_temple.lua

@@ -1,6 +1,9 @@
 local modname = minetest.get_current_modname()
 local modpath = minetest.get_modpath(modname)
 
+local per_chunk_probability = 11
+local mcl_structures_get_perlin_noise_level = mcl_structures.get_perlin_noise_level
+
 local node_list = {"mcl_core:sand", "mcl_core:sandstone", "mcl_core:redsand", "mcl_colorblocks:hardened_clay_orange"}
 
 local schematic_file = modpath .. "/schematics/mcl_structures_desert_temple.mts"
@@ -144,12 +147,10 @@ mcl_structures.register_structure({
 		},
 	},
 	on_finished_chunk = function(minp, maxp, seed, vm_context, pos_list)
-		local a = seed % 14
-		local b = (math.floor(seed / 39) + 4) % 12
-		if a ~= b then return end
-		mcl_structures.perlin_noise = mcl_structures.perlin_noise or minetest.get_perlin(329, 3, 0.6, 100)
-		local current_noise_level = mcl_structures.perlin_noise:get_3d(minp)
-		if current_noise_level > -0.3 then return end
+		local pr = PseudoRandom(seed + 999)
+		local random_number = pr:next(1, per_chunk_probability)
+		local noise = mcl_structures_get_perlin_noise_level(minp)
+		if (random_number + noise) < (per_chunk_probability - 1) then return end
 		local pos = pos_list[1]
 		if #pos_list > 1 then
 			local count = get_place_rank(pos)

mods/MAPGEN/mcl_structures/init.lua

@@ -17,7 +17,25 @@ local use_process_mapgen_chunk = false
 local on_finished_block_callbacks = {}
 local on_finished_chunk_callbacks = {}
 
-mcl_structures.perlin_noise = minetest.get_perlin(329, 3, 0.6, 100)
+local noise_params = {
+	offset = 0,
+	scale  = 1,
+	spread = {
+		x = mcl_mapgen.CS_NODES,
+		y = mcl_mapgen.CS_NODES,
+		z = mcl_mapgen.CS_NODES,
+	},
+	seed = 329,
+	octaves = 1,
+	persistence = 0.6,
+}
+
+local perlin_noise
+local get_perlin_noise_level = function(minp)
+	perlin_noise = perlin_noise or minetest.get_perlin(noise_params)
+	return perlin_noise:get_3d(minp)
+end
+mcl_structures.get_perlin_noise_level = get_perlin_noise_level
 
 local spawnstruct_hint = S("Use /help spawnstruct to see a list of avaiable types.")
 

mods/MAPGEN/mcl_structures/jungle_temple.lua

@@ -1,6 +1,9 @@
 local modname = minetest.get_current_modname()
 local modpath = minetest.get_modpath(modname)
 
+local per_chunk_probability = 8
+local mcl_structures_get_perlin_noise_level = mcl_structures.get_perlin_noise_level
+
 local node_list = {"mcl_core:dirt_with_grass", "mcl_core:dirt", "mcl_core:stone", "mcl_core:granite", "mcl_core:gravel", "mcl_core:diorite"}
 
 local schematic_file = modpath .. "/schematics/mcl_structures_jungle_temple.mts"
@@ -161,12 +164,10 @@ mcl_structures.register_structure({
 		},
 	},
 	on_finished_chunk = function(minp, maxp, seed, vm_context, pos_list)
-		local a = seed % 17
-		local b = (math.ceil(seed / 123) - 4) % 17
-		if a ~= b then return end
-		mcl_structures.perlin_noise = mcl_structures.perlin_noise or minetest.get_perlin(329, 3, 0.6, 100)
-		local current_noise_level = mcl_structures.perlin_noise:get_3d(maxp)
-		if current_noise_level < 0.8 then return end
+		local pr = PseudoRandom(seed + 132)
+		local random_number = pr:next(1, per_chunk_probability)
+		local noise = mcl_structures_get_perlin_noise_level(minp)
+		if (random_number + noise) < (per_chunk_probability - 1) then return end
 		local pos
 		local count = -1
 		for i = 1, #pos_list do

mods/MAPGEN/mcl_structures/noise_indicator.lua

@@ -1,5 +1,5 @@
 local step = 1
-local chunk_borders = true
+local chunk_borders = false
 
 local levels = {
 	[-9] = "black",
@@ -26,13 +26,15 @@ local levels = {
 local math_min, math_max = math.min, math.max
 local math_floor, math_ceil = math.floor, math.ceil
 
+local mcl_structures_get_perlin_noise_level = mcl_structures.get_perlin_noise_level
+
+local noise_offset_x_and_z = math_floor(mcl_mapgen.CS_NODES/2)
+
 mcl_mapgen.register_mapgen(function(minp, maxp, seed, vm_context)
-	mcl_structures.perlin_noise = mcl_structures.perlin_noise or minetest.get_perlin(329, 3, 0.6, 100)
-	local perlin_noise = mcl_structures.perlin_noise
 	local y0 = minp.y
 	for x0 = minp.x, maxp.x, step do
 		for z0 = minp.z, maxp.z, step do
-			local current_noise_level = perlin_noise:get_3d({x=x0, y=y0, z=z0})
+			local current_noise_level = mcl_structures_get_perlin_noise_level({x = x0 - noise_offset_x_and_z, y = y0, z = z0 - noise_offset_x_and_z})
 			local amount
 			if current_noise_level < 0 then
 				amount = math_max(math_ceil(current_noise_level * 9), -9)

mods/MAPGEN/mcl_structures/structures.lua

@@ -6,5 +6,5 @@ if not mcl_mapgen.singlenode then
 	dofile(modpath .. "/jungle_temple.lua")
 	dofile(modpath .. "/stronghold.lua")
 
-	-- dofile(modpath .. "/noise_indicator.lua")
+	dofile(modpath .. "/noise_indicator.lua")
 end