Lua on each mapgen thread (#13092)

builtin/emerge/env.lua

@@ -0,0 +1,61 @@
+-- Reimplementations of some environment function on vmanips, since this is
+-- what the emerge environment operates on
+
+-- core.vmanip = <VoxelManip> -- set by C++
+
+function core.set_node(pos, node)
+	return core.vmanip:set_node_at(pos, node)
+end
+
+function core.bulk_set_node(pos_list, node)
+	local vm = core.vmanip
+	local set_node_at = vm.set_node_at
+	for _, pos in ipairs(pos_list) do
+		if not set_node_at(vm, pos, node) then
+			return false
+		end
+	end
+	return true
+end
+
+core.add_node = core.set_node
+
+-- we don't deal with metadata currently
+core.swap_node = core.set_node
+
+function core.remove_node(pos)
+	return core.vmanip:set_node_at(pos, {name="air"})
+end
+
+function core.get_node(pos)
+	return core.vmanip:get_node_at(pos)
+end
+
+function core.get_node_or_nil(pos)
+	local node = core.vmanip:get_node_at(pos)
+	return node.name ~= "ignore" and node
+end
+
+function core.get_perlin(seed, octaves, persist, spread)
+	local params
+	if type(seed) == "table" then
+		params = table.copy(seed)
+	else
+		assert(type(seed) == "number")
+		params = {
+			seed = seed,
+			octaves = octaves,
+			persist = persist,
+			spread = {x=spread, y=spread, z=spread},
+		}
+	end
+	params.seed = core.get_seed(params.seed) -- add mapgen seed
+	return PerlinNoise(params)
+end
+
+
+function core.get_perlin_map(params, size)
+	local params2 = table.copy(params)
+	params2.seed = core.get_seed(params.seed) -- add mapgen seed
+	return PerlinNoiseMap(params2, size)
+end