The Minecraft Overviewer

a high-resolution Minecraft world renderer with a LeafletJS interface

Help us test our new beta

Edit: Mar 3 2012: The new beta has now been merged into master, and as such, some parts of this post (like how to try it out) are outdated. See this post.

Edit: Mar 1 2012: updated this post for the Anvil format. -brownan

We've been working hard for the last two months to almost completely re-write a lot of the internals of The Overviewer. And now we need your help to test it out, and give us feedback!

Why have we done this?

You may be wondering why we took 2 months off from regular development to rewrite code that worked just fine. As some may have guessed, code that evolves over time tends to accumulate cruft and gets more and more difficult to work on as time goes by. Our code has been evolving for over a year now, and while it started out relatively clean, now it's not so much. As new features were added, the code strained to accommodate them. For example, the customizable north direction feature required adding a small "shim" at just about every layer of code, which is prone to cause problems because it adds complex dependencies between all layers of the program.

In short, the code was becoming increasingly difficult to work on, and more importantly, it was becoming less fun to work on. So we did what all programmers dream of doing but can't because of practical deadlines and such: re-designed most of the core components almost from scratch.

In this re-write we have completely re-thought the way all the internal components fit together and how they interact. The new interfaces between components are much cleaner and the clean separation of responsibility makes the code much easier to work on: easier to add new features, easier to fix bugs, easier to maintain.

Most of that is of no concern to end users though; people that just want to use Overviewer don't care how it works. Well, there's something for you too! Along with the rewrite we have many new features and potential features that were either impossible or prohibitively difficult before!

Here's the new fun features:

  • Multi-world! Render and display all your worlds with one unified interface.
  • Along with that, Nether and The End support!
  • Fixed north-directions to the new sun direction. (Finally!)
  • Completely re-designed configuration file format, more customizability!
  • Per-render configuration options - render one world multiple ways, render all your worlds one way, or some complex combination. It's up to you!
  • Truly customizable rendermodes: compose your own rendermode from our built-in rendermode primitives.
  • New: Anvil support
  • New: Built-in Biome Support!

Here's the new potential features -- features that are not in yet, but should be "easy" to implement with the new architecture (if there's demand for these features, they will get implemented!):

  • Configurable, pluggable caches. Configure the memory usage or even offload your cache to memcached
  • Render-farm support: get an entire cluster of machines to render your worlds!
  • Support for rendering of smaller portions or subsets of your world, and even arbitrary world transformations (Render heights 0-32, cutting off everything else? Sure! Render your world upside down? I can't imagine why, but why not!)
  • More configurable logging

We are releasing this as a "beta" at this point. The new branch is not complete yet. We still have these items to re-implement:

  • points of interest (signs, etc)
  • Overlays
  • Miscellaneous options like textures-path, skip-js, web-assets, no-signs

Additionally, it is not yet polished. For example, the output may contain lots of debug lines that got left in, any error messages may not be very friendly, and of course it may contain bugs.

But we feel like it's ready for people to try out. We're ready to start getting some feedback and some help on finding the last few bugs.

If you would like to try it out, keep reading, but know that things may still change in backwards-incompatible ways. Remember that this is a "preview" and you'd be helping us test it. It's not done yet, but we feel that it's complete enough to start soliciting feedback.

We're not building binary packages for the new branch at this time. If you would like to try it out, clone the repository and checkout the "anvil" branch:

git clone -b anvil git://

If you don't have git, you can also download a source tarball:

I've rewritten the documentation to go over the new configuration file format. See the running and config file pages of the docs to get started.

And of course, let us know in IRC or by filing an issue on the Github issue tracker if something doesn't seem right.

A follow-up post will go into more details on the new features, notably the new configuration file format. Happy Overviewing!