ComfyFactorio/maps/biter_battles_v2/no_turret_creep.lua

local Public = {}

local type_blacklist = {
	["ammo-turret"] = true,
	["artillery-turret"] = true,
	["electric-turret"] = true,
	["fluid-turret"] = true
}

function Public.deny_building(event)
	local entity = event.created_entity
	if not entity.valid then return end
	if not type_blacklist[event.created_entity.type] then return end
	local surface = event.created_entity.surface				
	local spawners = surface.find_entities_filtered({type = "unit-spawner", area = {{entity.position.x - 70, entity.position.y - 70}, {entity.position.x + 70, entity.position.y + 70}}})
	if #spawners == 0 then return end
	
	local allowed_to_build = true
	
	for _, e in pairs(spawners) do
		if (e.position.x - entity.position.x)^2 + (e.position.y - entity.position.y)^2 < 4096 then
			allowed_to_build = false
			break
		end			
	end
	
	if allowed_to_build then return end
	
	if event.player_index then
		game.players[event.player_index].insert({name = entity.name, count = 1})		
	else	
		local inventory = event.robot.get_inventory(defines.inventory.robot_cargo)
		inventory.insert({name = entity.name, count = 1})													
	end
	
	surface.create_entity({
		name = "flying-text",
		position = entity.position,
		text = "Turret too close to spawner!",
		color = {r=0.98, g=0.66, b=0.22}
	})
	
	entity.destroy()
end

return Public