Id Software Programming Principles

Id Software Programming Principles(blog.felipe.rs)

340 points by philix001 9 years ago | 76 comments

a3n 9 years ago |

> Write your code for this game only - not for a future game. You’re going to be writing new code later because you’ll be smarter.

This really stood out for me. I'm always tempted, while writing something specific, to generalize it. I try to resist that, when I recognize it. Writing a ThingThatImWritingFramework risks ThingThatImWriting never seeing the light of day, or never being used.

alkonaut 9 years ago | |

It completely removes the fun though, if you only enjoy generalizing, optimizing, refactoring, designing, and take zero pleasure in delivering an actual usable product. If the product is Doom this shouldn't be a problem - but for most of us the product is form validation or calculations involving plywood. Making frameworks and generalization is the only reason I manage to keep doing what I do. (I'm exaggerating somewhat, but I think this is a clear distinction between two kinds of programmers those who love the code; and the craft, and those who like making products. Have too many of one kind and you'll ship a mess. Too many of the other and you'll never ship)

mikekchar 9 years ago | | |

Generalisation is always needed in a code base. However, only generalise pieces that you actually use in your code. YAGNI (You Aren't Gonna Need It) is a great principal. You should follow it -- until you need it. Then, of course, do what you need to do.

People often think that projects get slower as code is added. However, the systems we work with are dramatically more complex and based on more pre-existing code than ever before. Because that pre-existing code has been generalised out, we can write new code easily and quickly.

There are two situations that you need to think about wrt to this issue (IMHO). If someone needs to do something that you have already done in your project, it should be simple and obvious how to do it. The more often something needs to be done, the more simple and obvious it needs to be. However, if someone needs to do something that hasn't been done before (even if it is is very much related to what already exists), then all doors should be open. The code should not imply how new work should be done. It definitely shouldn't try to guess what you want to do and do it before you get there.

NumberCruncher 9 years ago | | |

>> Making frameworks and generalization is the only reason I manage to keep doing what I do.

<sarcasm> This could be written on the tombstone of JS. </sarcasm>

Koshkin 9 years ago | | |

I have seen projects drown to death in a sea of frameworks, supposedly reusable libraries and generalizations developers deemed necessary. But it was fun for some, I am sure.

lhnz 9 years ago | | |

Generalise to the simplest expression of the logic of your application. Don't generalise towards the expression of the logic of all future applications.

The article kind of already says this:

  > Keep your code absolutely simple.
  > Keep looking at your functions and figure out
  > how you simplify further.

coldtea 9 years ago | | |

>It completely removes the fun though, if you only enjoy generalizing, optimizing, refactoring, designing, and take zero pleasure in delivering an actual usable product.

Then maybe that programmer should go into teaching instead?

iabacu 9 years ago | | |

"...only enjoy generalizing, optimizing, refactoring, designing, and take zero pleasure in delivering an actual usable product"

Too many projects suffer immensely because of people who don't give a shit about delivering. In that mode, anything is an excuse: we need to reactor, we need to build a better framework, we need to revisit the requirements, etc.

Then real progress gets slowed down because of some ill fitting development philosophy that some of those folks pulled out of their asses.

What you need are wise programmers that care about delivering product, wise enough to balance long term maintenability and code health with actual delivery schedule.

The keyword is "wise".

737013 9 years ago | | |

I thought I was the only one. Thanks for taking off a load of guilt. It's okay to enjoy this stuff. Very sage comment. Never finish because of the fun of building.

zerr 9 years ago | | |

Exactly. e.g. it might be much easier (for some) to come up with a finished product/Game with Unity, with mouse clicking here and there... But it takes away all the fun of game development. On the other hand, I'm pretty sure it is hell a lot of fun working on Unity itself... So all the sweet is for their in-house devs :) (Same goes for Rails, Node, .NET, etc...)

xyzzy_plugh 9 years ago | | |

I've never thought of it this way. While I don't necessarily agree, I'm thankful for this insight.

hermitdev 9 years ago | |

This is basically the Mythical Man Month in a few lines.

You once wrote something specific, and it was great. Then you had to write a second thing, and you remember things from the first, so why not make it more general for the inevitable 3rd, 4th, 5th to come? And, then, you fail to deliver the 2nd.

arthurjj 9 years ago | | |

I don't have my copy handy, but I believe that's actually the second system effect

irfansharif 9 years ago | |

> "Write code that is easy to delete, not easy to extend."

msangi 9 years ago | | |

Absolutely! https://vimeo.com/108441214

nlyan 9 years ago | |

Generalizing is part of how you'll be smarter later though. You cannot generalize something unless you understand its essence.

It's easy to confuse abstraction (choosing to deal with one, possibly newly contrived, concept over another) and generalization (reducing the number of concepts required to explain something to a minimum). The former is like building a Haswell CPU from a description of 70s microcontroller architecture, whereas the latter is like trying to figure out what CPUs were like in the 70s by looking at a Haswell core under a microscope.

a3n 9 years ago | | |

> Write your code for this game only - not for a future game.

The quote refers to a future product, one that is very likely unspecified at best, and more likely just something that an individual contributor dreamed up. Unless we have some sort of multi-phase contract, how do we know we'll ever build another thing like this again?

Markets change, hardware changes, experience changes. Hell, building this thing may show you that you should never build another one like it.

Generalize where sensible inside the project, sure. But as the quote says, build what you're building, not what you're not.

msangi 9 years ago | |

That's indeed a very good advice.

All abstractions have a cost and no abstraction is better than the wrong abstraction.

I found this talk on the topic very interesting https://youtu.be/4anAwXYqLG8

Ace17 9 years ago | | |

In the same vein:

prefer duplication over the wrong abstraction ( https://www.sandimetz.com/blog/2016/1/20/the-wrong-abstracti... )

buzzybee 9 years ago | |

It helps to allow yourself to be philosophical about what you're writing. Sometimes a generalization just moves around the problem. Sometimes the generalization you want competes badly against cut and paste.

Increasingly I try to find a strategy that transitions towards the generalization over time by following a path of "lower friction instead of greater friction." It's easy to increase friction by adding a new configuration step, new concepts and idioms that are discordant with the rest of the environment, and then the point of doing it gets lost - you don't want to pay for that overhead most of the time, you can't ship code that way.

whazor 9 years ago | |

Their tools are also a form of generalization. Furthermore, it is definitely possible to create value by generalization.

a3n 9 years ago | | |

Yeah, sometimes. And other times, the whole contract gets spent on a framework that only makes sense if there's another contract, and ... well, I guess that never happens anymore.

Didn't someone say premature generalization is the root of all evil?

pjmlp 9 years ago | |

There is a saying in game circles, either one writes a game engine or a game, as most studios tend to die spending the publisher's money build the next great engine.

EliRivers 9 years ago | |

Factories. I've got a codebase to work with using factories everywhere. Static arrays of them. Classes are given hardcoded enums and there's macro magic all over the palce to join classes to the factories that make them, and to generate all the factories in these static arrays of factories.

Sometimes the static array of factories contains a single factory. Creating a single item. No variation, no types, just one kind of one item.

The item is needed once. In one place.

hyperpallium 9 years ago | |

If you know you're going to have to experiment a lot on some aspect of the game/product, it seems to make sense to isolate that part, removing the commonalities into some kind of framework (perhaps informal, jury-rigged, so you can iterate on just that aspect.

A bit like the Wright brothers building a wind tunnel, so they could experiment quickly with control systems.

But Id wrote some great games, so maybe I'm missing how they handled this aspect...

cryptozeus 9 years ago | |

Yeh totally..simple but so true

lubujackson 9 years ago |

It reads like a "get shit done" manifesto, and good rules of thumb for most programmers tasked with doing just that. Worth remembering that iD had some of the most advanced 3D and networking code for years and really pushed the envelope and the industry forward in many ways (first huge shareware company, first big company to allow mods, first big company to make code open source, etc.)

It is easy to slide into an OCD mindset when programming, to make things tidy and proper. It feels dirty to make stuff just work, to make stuff disposable, but evolution operates a lot like this - many little, reversible mistakes that add up to big improvements quicker than any other method.

kensai 9 years ago |

> Programming is a creative art form based in logic. Every programmer is different and will code differently. It’s the output that matters.

This one is also nice, especially for mid to large software houses. As long as a common denominator is respected, I guess.

contingencies 9 years ago | |

It's enabled by encapsulation.

tluyben2 9 years ago |

Some of these things, like focusing on the task at hand and trying to be as simple as possible, not thinking too much about the potential futures is important to me. If all would do that maybe there would not be 1000s of weird half baked npms and such.

partycoder 9 years ago |

He described how literally hundreds of projects were successfully completed in C, targeting multiple platforms, while being first to market with innovative technology, with a small team in a pre-Internet world,

These are achievements beyond belief.

eps 9 years ago |

I'd very curious to hear Carmack's take on this. After all Romero was making game levels, not the engines.

joakleaf 9 years ago | |

He was developing large parts of e.g. Doom: He didn't write the BSP traversal and texture mapper (the graphics engine), but he did write monster AI, level behavior, and level editor.

I think, I heard him state in an interview that he also did a lot of development on Quake in addition to the levels. Obviously the graphics engine was Abrash and Carmack's

rckclmbr 9 years ago | | |

I think Carmacks programming principle would be "be a genius"

pvitz 9 years ago | |

Romero made tools like DoomED and also wrote games before id.

naiyt 9 years ago | | |

Yes, he's a skilled coder as well. He just seems to get overshadowed by Carmack.

hyperpallium 9 years ago |

This is first class post-hoc bullshit. They weren't making prototypes or reusing code, they sure as hell weren't composing high-sounding principles.

They just got on with it because they were talented experienced and motivated. For that reason, the rest of the talk is very inspiring - so listen to the hour-long video (half talk, half questions), and not the article which only has the post-hoc bits. https://youtu.be/E2MIpi8pIvY

dualogy 9 years ago | |

> they were talented experienced and motivated

Agreed and that's the whole secret sauce right there, combined with: no distractions (social media or indeed even "coding forums" with constant flame-wars on this and that language/stack/paradigm) and crucially also no distracting "stack" or APIs to speak of (bare metal coding literally "on top of the BIOS" in these days, no OS/GUI/multithread/GPU APIs).

The initial core team spent their entire youths 24/7 getting insanely good at ASM and C and numerous gfx tricks and then "they just played the piano" to the best of their accumulated abilities. Observe how much longer the Dooms took compared to Wolfenstein and priors, and how much longer the Quakes took them compared to the Dooms.. as they were slowly entering the age of Windows native & Internet multiplayer even they too got slowed down a bit (were shocked how for Quake "just waiting for 'ze engine' took a year"!) compared to the earlier works --- of course still managed to ship high-quality products, but still

hyperpallium 9 years ago | | |

Another eg of distraction-free programming: http://www.atariarchives.org/deli/cottage_computer_programmi...

Hansi 9 years ago |

> "No prototypes. Just make the game. Polish as you go. Don’t depend on polish happening later. Always maintain constantly shippable code."

I disagree with this so much, prototypes and proof of concepts teach you so much but usually they are crap you will always write it better a second time. Throw away the prototype and re-write it as a much better implementation.