Just about a year ago, I acquired a 3D printer.

I've been casually reading about the progress of hobbyist 3D printing since the RepRap days, but sometime in late 2017 I decided to seriously consider whether I should get one for myself. I'd already purchased items from printing services (i.materialise and Shapeways), both existing and of my own design, and that experience taught me that I wanted to do more and to iterate cheaper and faster. As a sanity check, I made a list of further things I thought I could make with one — not general themes but specific items to solve problems I had. That list was immediately filled with ten or so items, so I bought one.

I purchased a Prusa i3 MK3 kit printer (despite, at the time, uncertainty about whether the MK3 design was flawed as a lot of people were reporting quality and reliability issues), set it up in April 2018, and have been printing things ever ever since (with very little trouble).

I've been posting my designs on Thingiverse (pictures there) and on Github — rather, those that I have declared finished and documented. There's another 30 or so that aren't published, yet.

(You can also see hints of some other ‘new hobbies’ in what I've been posting, but I'm overly fond of putting things in chronological or at least dependency order.)

I have really failed to get around to blogging what I've been doing lately, which is all software-defined radio. Let's start fixing that, in reverse order.

Yesterday, I went to a Bay Area SDR meetup, “Cyberspectrum” organized by Balint Seeber and gave a presentation of visual representations of digital signals and DSP operations. It was very well received. This video is a recording of the entire event, with my talk starting at 12:30.

My GLToyJS project now has a live instance so you can play with it without setting up your own server. Caveats: • I don't promise it will remain at this URL or that the parameter format won't change. • There is an automatic 5-minute-interval change to a new random effect which cannot be disabled (but you can undo it by going back). • It doesn't tell you if your browser doesn't have WebGL, it just stops (gray screen).

An early stage in the development of lighting in Cubes (long since past).

[I was asked about Cubes “Where do you think you might take the game play next?” and it turned into this.]

My original motivation for creating Cubes was a combination of the “blocks out of blocks” idea — which itself came from immersion in the graphics of Minecraft — and also dissatisfaction with certain bugs, limitations, and design choices in Minecraft. As a result, I’m not just building a voxel game; I’m building a game that shares what I like about Minecraft.

(What I like about Minecraft, broadly, is survival and engineering — I like building structures and machines to make my virtual life easier.)

Now, creating a Minecraft clone would be unoriginal — not just compared to Minecraft but because Minecraft clones are an entire genre. But I don’t have experience with what little exists of a genre of voxel building games to synthesize my own thing, and I myself am looking for something like Minecraft. What can I do? Here’s what I’ve been trying:

• Be different.

  Whenever I see an opportunity to do something specifically unlike Minecraft, that doesn’t compromise what I’m trying to do, I take it and see what happens. However, most of these experiments have failed; for example, Cubes originally had a larger-scaled player character, but this turned out bad because it means tunneling and building is 8× more tedious, and it reduces the apparent size of the world. Also, it leads to thinking “OK, add this feature Minecraft has — but (superficially) differently!”

• Be generic.

  This is my long-term goal, and it is one that ties neatly into the “blocks made of blocks” theme. The characteristics of blocks can be defined by building circuits (programs) inside them. What I’m aiming for is that by creating a blockset (collection of block designs which the player can build with), one is defining the game that can be played, by giving those blocks specific behaviors.

  In this way, I am working towards having a game which can be programmed to emulate Minecraft.

  (I have a working prototype of an importer for Minecraft worlds as well as for Minecraft blocks — that is, turning the terrain.png from a Minecraft texture pack into Cubes' 3D blocks — but I am not going to release that code until and unless I determine that Mojang doesn’t mind my doing so. I still love Minecraft and they deserve my not stepping on their toes that far.)

  However, this means both that Cubes itself needs to be very generic, and that the built-in example uses of such features should feel different from Minecraft.

So, returning to the original topic of “where am I going next”, I need to add the following functionality to the game world:

• Extend the circuits feature so that there can be blocks that are active and interactive (e.g. opening and closing doors, “physics” like Minecraft falling sand and growing plants).

• Add moving objects (for vehicles and mobs). I intend to generalize these so that they are worlds in themselves — this will allow large or unique vehicles, and mean that they can be designed using the same game tools.

• Add some form of resource constraints/conservation laws (as in Minecraft survival mode) — that is, you have to gather stuff to make it into other stuff. I haven’t figured out specifically how I want to do this yet, and this seems particularly tricky to make programmable. One idea that keeps coming to mind is that when you break a block, specific subcubes are “resource cubes” (according to their type in the block world) which you collect, and in order to place a block you need to have the corresponding resources for its type. However, I’m not sure I like the “raw material counter” feel of this.

• Add player attributes that can be modified (e.g. health) so that e.g. death, or other effects-by-the-world can be supported.

Less grandly, I plan to work on one of these specific technical features soon:

• Allowing circuit blocks to be rotated to change their connectivity. (Right now, circuit blocks have specific faces — e.g. on a certain one the +X direction is always the output.)
• Figure out what more circuit primitives I want to add. (Right now, the circuits are definitely not Turing-complete, and not capable of all the effects on the world they should be, but there are also already a lot of different primitives; I may have to invent new block-picking UI just to make them practical.)
• Add moving objects (bodies) — things which can collide with the terrain as the player does. The current code is entangled with player behavior, and the player does not persist in a world.
• Add subworld/multiple-world handling — the ability for more than one world (grid of blocks) to be present in the same space. Right now, there are hardwired assumptions that the player is in the single world’s coordinate system.

Another core feature which is currently missing is the ability to design a blockset and then reuse it for multiple worlds. The problem right now is that we're using a simple object-graph serializer, so each world has its own blockset which is modified independently. To fix this, it needs to be possible to save a blockset under a user-visible name, and have individual worlds which reference that blockset; also, the world generator needs to decouple blockset generation from terrain generation. The “persistence” framework which added support for multiple worlds is a step towards this; the main thing I am pondering is what the semantics of these separate-named-persistent objects are and what the user interface for editing them is.

I upgraded to Mac OS X 10.7 Lion this month, and ever since then Cubes has crashed or otherwise misbehaved on my machine. However, I have only the one to test on, so I would like your help in figuring out what the extent of the incompatibility is — whether this is a GPU driver bug or something Cubes is doing wrong.

If you have a WebGL-capable browser (such as Chrome or Firefox) and GPU, and especially if you're running Lion or are otherwise similar to my configuration, please run Cubes (no installation is required) and tell me whether it works and what your system configuration is, including these properties:

(For some MacBook Pro models such as mine, the GPU used (9600M or 9600M GT) depends on the “Graphics” setting in Energy Saver preferences.)

The problems I observe are:

• All blocks (terrain) being flat white except for lighting; the sky and particle effects still have color. (For the interested, this appears to be a mis-execution of the over-unity-to-white code introduced in commit 48674f….)
• After some amount of usage, a crash (in Firefox, the browser exits; in Chrome, the display goes gray and the Web Inspector console says “WARNING: WebGL content on the page might have caused the graphics card to reset” while the in-page text says “Previous GL errors: INVALID_OPERATION”).

I will appreciate any help as this is making it quite impractical to work on Cubes.

These may be three different things:

• The answer to the question you asked
• The solution to the problem implied by the question you asked
• The solution to the problem you actually have

I was reminded of this yesterday when, noticing that my code for Cubes was using an arbitrary constant for the near clip plane, I asked how to calculate it in a principled way.

So, this is potentially interesting. The developer of the game Braid has started a new project, The Witness. It’s apparently going to be 3D, set on an island, and involve solving puzzles scattered around the island (while being able to move freely around it). Their blog is talking a lot about their graphics engine design as opposed to the gameplay — naturally, as graphics tech is more usefully shareable and isn't inherently spoilerish.

What particularly caught my eye as “I agree with this” was their post Experiments in Texturing. Good textures are hard; it's often easier to make a good, clean model than it is to make a texture that is not jarringly unrealistic. The Witness is putting a lot of emphasis on lighting: “We’re on a low budget here, being an indie game; so not only was it an open question how to solve the Ugly Texturing problem, but we also needed to solve it with relatively little manpower. I knew that, ultimately, we could just fall back on untextured geometry with lighting, if we had good precomputed lighting.” They go on to describe using textures as accents, to add texture rather than defining significant features of the object.

As a Minecraft player (structures are built of pre-textured blocks) and former Avara map designer (graphics engine does not support textures), I entirely approve of this approach.

This is a somewhat odd cellular automaton implementation in Haskell. It encodes the shape of the world, and the stepping rule, in the data structure. Briefly:

data Cell v n = Cell {
  value     :: v,
  neighbors :: n (Cell v n),
  future    :: Cell v n }

-- Build a cell and its chain of futures, given its rule, similar neighbors,
-- and initial value.
mkCell :: Functor n => (v -> n v -> v) -> v -> n (Cell v n) -> Cell v n
mkCell rule val nei = initial
  where initial = Cell val nei (calcFuture initial)
        calcFuture c = c'
          where c' = Cell (rule (value c) (fmap value (neighbors c)))
                          (fmap future (neighbors c))
                          (calcFuture c')

data Moore c = Moore c c c c c c c c

-- Conway's Life
evalLife :: Bool -> Moore Bool -> Bool
evalLife v n = f v (sumN fromEnum n)
  where f _    3 = True
        f True 2 = True
        f _    _ = False

The remainder of the code is routines for setting up worlds and displaying them.

• GraphLife.hs — The core and text-based display
• GraphLifeGL.hs — OpenGL display