ComputerCraft Turtle Constructor

---

Description

Generates a Lua script to build a structure given in a .nbt format using ComputerCraft turtles.

This collection of scripts takes a .nbt file, converts it into a more useful .json, then parses that into a multi-dimensional array. It then performs a modified BFS on each layer to find the most efficient path for the turtle to take to build the structure, taking into account a fuel limit. This path is then converted into a series of instructions for the turtle to take, which is then written to a .lua file, the language used by ComputerCraft.

---

Files

• nbt_to_json.py
  • Uses the pythonnbt library to convert an NBT schematic into a JSON format.
• json_to_arrays.py
  • Converts the JSON of the build into typed nested arrays to be used algorithmically
• arrays_to_path.py
  • Generates an optimized path for the turtle to take using BFS that takes into account refueling
• path_to_instructions.py
  • Creates a series of instructions from a path around a 2D surface that instruct the turtle
• instructions_to_lua.py
  • Writes the instructions along with necessary helper functions to a .lua file
• functions.lua
  • Functions that are shared with each Lua program

Development Workflow

1. Spin up a local http server to download the files in MC using CC's http request API
   • python3 -m http.server 8000
2. Edit ComputerCraft config to allow localhost connections - comment out these lines in .../minecraft/saves/SaveName/serverconfig/computercraft-server.toml

[[http.rules]]
	host = "$private"
	action = "deny"

3. Put the following code in a pastebin, or just plug it into a turtle. (Can then put it on a Floppy in-game)

local request = http.get("http://localhost:8000/build.lua")
local text = request.readAll()
local file = fs.open("out.lua", "w")
file.write(text)
file.close()

4. Put the .nbt structure file in the data folder and update the path to it in main.py
5. Run python3 main.py
6. Run the previously created program in-game to download build.lua to the turtle.
7. Set up the turtle as shown - arrow shows direction of turtle:
8. Fill the coal chest with a bunch of coal / fuel, fill the wool chest with the item to build with
9. Run out on the turtle, making sure space is clear - turtle will build to its right and up while facing the coal chest

Notes / To-do

• .nbt is a space-inefficient file format for structures - more popular is Litematica's .litematic or WorldEdit's .schematic - however, for this use case, it's effective to convert the .nbt into JSON which can be easily parsed. The conversion from .litematic or .schematic can be done within the Litematica GUI as shown here.
• Fuel is essentially infinite in practice, however fuel algo needs testing when paired with event of running out of blocks - currently, fuel routes are only calculated per layer, which is incorrect, the fuel needs to be updated after a layer traversal, can be accomplished by keeping track of used fuel in path generation
• Extend 2D optimization - shortest path is not necessarily taken currently, islands is simplest example, use TSP algorithm to compute this
• Add 3D optimization - right now, shortest path is only computed by layer - complications include turtle getting trapped if shortest path takes it up and around, for example
• Add multi-block functionality - likely trivial, but annoying and might introduce certain complications - i.e., go and place all blocks of certain type then come back, or place all different blocks in a layer, etc.
• Along with multi-block functionality, could add block state functionality, i.e., stair direction or door open/closed, etc.
• Potentially limited in size by the computer_space_limit in ComputerCraft, which is 1,000,000 bytes. A 81x87x87 structure resulted in a Lua file of 864,340 bytes, which is close to the cap. However, this value can be modified. This file resulted in ~80,000 instructions, which again shows the lack of a fuel limit in practice with an advanced turtle having a fuel limit of 100,000. Of course, thie value could be changed in the config to make refueling not a problem