tiistai 26. helmikuuta 2019

Could Linux be made "the best development environment" for games?

It is fairly well established that Linux is not the #1 game development platform at this point in time. It is also unlikely to be the most popular one any time soon due to reasons of economics and inertia. A more interesting question, then, would be can it be made the best one? The one developers favour over all others? The one that is so smooth and where things work so well together that developers feel comfortable and productive in it? So productive that whenever they use some other environment, they get aggravated by being forced to use such a substandard platform?

Maybe.

The requirements

In this context we use "game development" as a catch all term for software development that has the following properties:
  1. The code base is huge, millions or tens of millions lines of code.
  2. Non-code assets are up to tens of gigabytes in size
  3. A program, once built, needs to be tested on a bunch of various devices (for games, using different 3D graphics cards, amounts of memory, processors etc).

What we already have

A combination of regular Linux userland and Flatpak already provides a lot. Perhaps the most unique feature is that you can get the full source code of everything in the system all the way down to the graphic cards' device drivers (certain proprietary hardware vendors notwithstanding). There is no need to guess what is happening inside the graphics stack, you can just add breakpoints and step inside it with full debug info.

Linux as a platform is also faster than competing game development systems at most things. Process invocation is faster, file systems are faster, compilations are faster, installing dependencies is faster. These are the sorts of small gains that translate to better productivity and developer happiness.

Flatpak as a deployment mechanism is also really nice.

What needs to be improved?

Many tools in the Linux development chain assume (directly or indirectly) that doing something from scratch for every change is "good enough". Once you get into large enough scale this no longer works. As an example flatpak-builder builds its packages by copying the entire source tree inside the build container. If your repository is in the gigabyte range this does not work, but instead something like bind mounting should be used. (AFAIK GNOME Builder does something like this already.) Basically every operation needs to be O(delta) instead of O(whole_shebang):
  • Any built program that runs on the developer's machine must be immediately deployable on test machines without needing to do a rebuild on a centralised build server.
  • Code rebuilds must be minimal.
  • Installs must skip files that have not changed since the last install.
  • Package creation must only account for changed files.
  • All file transfers must be delta based. Flatpak already does this for package downloads but building the repo seems to take a while.
A simple rule of thumb for this is that changing one texture in a game and deploying the result on a remote machine should not take more than 2x the amount of time it would take to transfer the file directly over with scp.

Other tooling support

Obviously there needs to be native support for distributed builds. Either distcc, IceCream or something fancier, but even more important is great debugging support.

By default the system should store full debug info and corresponding source code. It should also log all core dumps. Pressing one button should then open up the core file in an IDE with up to date source code available and ready to debug. This same functionality should also be usable for debugging crashes in the field. No crash should go unstored (assuming that there are no privacy issues at play).

Perhaps the hardest part is the tooling for non-coders. It should be possible to create new game bundles with new assets without needing to touch any "dev" tools, even when running a proprietary OS. For example there could be a web service where you could do things like "create new game install on machine X and change model file Y with this uploaded file Z". Preferably this should be doable directly from the graphics application via some sort of a plugin. 

Does something like this already exist?

Other platforms have some of these things built in and some can be added with third party products. There are probably various implementations of these ideas inside the closed doors of many current game development studios. AFAICT there does not exist a fully open product that would combine all of these in a single integrated whole. Creating that would take a fair bit of work, but once done we could say that the simplest way to set up the infrastructure to run a game studio is to get a bunch of hardware, open a terminal and type:

sudo apt install gamestudio

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