copy-cat: A ComputerCraft emulator for the web

May 20, 2019

One thing I’ve been working on for a little while now is revamping CC: Tweaked documentation situation. As part of that, I had the fantastic idea of “could we run CC: Tweaked in the browser?”, allowing people to run code samples with a click of a button.

Now, at the time, I wasn’t aware of EveryOS’s fantastic Mimic fork, and so I did the only thing logical and went on a long yak shaving expedition. The result of this is copy-cat, a ComputerCraft emulator which runs in your browser.

copy-cat, running the mbs shell

As it’s original aim was to be used for documentation, it aims to be as accurate and up-to-date as possible. In order to achieve this, copy-cat is built from a modified version of CC: Tweaked’s source code - both the Lua VM and Java APIs behave exactly the same1.

While this is all well and good, that’s not all copy-cat can do. There’s all sorts of other fancy features, including:

That said, there’s still lots of things missing, so if you’ve got suggestions, bug reports or would just like to help out, head over to the issue tracker! I will confess the performance is a bit lacking a times, but given that this is a Lua VM written in Java running in a Javascript VM, I’ll say that’s pretty understandable.