wolf3d VS DOOM

There are far better historical sources to study, such as Wolf3D, the classic BSD games, or even Word 1.1.

It took a long time to write that engine and porting the whole thing properly also takes time. It just moves goalposts. Why didn’t he spend 80M on a new AAA game? If he spent any less than that, he certainly can’t draw any useful conclusions.

Have you ever looked over the codebase? It’s plenty large enough to draw useful conclusions from for most people let alone someone with his vast game experience.

https://github.com/id-Software/wolf3d/tree/master/WOLFSRC

Meanwhile, you are drawing bay conclusions with no credentials out evidence. As to actual games, setting aside the fact that Wolfenstein still sees play, loads of popular games are written in JS. Lots of others are in Java or C#. None of these make your case as Haskell, Ocaml, and StandardML (SML) are in the same performance range.

As to your argument about the efficiency of objects, what do you think functional languages use? Lets use SML as an example. There’s real arrays and they are also optionally mutable (yes, there’s linked lists too, but those can be used in C++ too).

Records are basically just C structs (they are immutable by default, but can contain refs which are mutable pointers). They can contain functions because functions are first class without the mess that many languages create.

You associate functions with datatypes which gives you the best part about methods. They also give you a kind of implicit interface too due to structural typing. I’d note that closures are mathematically equivalent to objects.

Finally, modules are everything a language like Java tries to get from classes (and more), but without any of the downsides of classes themselves.

People generally like the JS paradigm of factories and object literals (even if they hate the stuff like dynamic typing or type coercion). StandardML offers the same kinds of patterns, but with sound typing, simpler syntax without the warts, more powerful syntax, and performance in the same range as go or Java.

To me, your argument sounds like the people arguing that goto is better and more natural than looping constructs or the procedural guys arguing against OOP. I think if you messed around with StandardML, it would change your mind about what programming could be in the future.

I'm not used to seeing assembly look like this. What's the wrapper stuff? Looks like C. But I thought you could inline assembly in C like here: https://github.com/id-Software/wolf3d/blob/master/WOLFSRC/DETECT.C

c) The source code was pretty vanilla standard C. No huge assembly. Around 36000 lines of "normal C" (at the time, most of C games were non-portable, you would get near and far pointers or assembly shenanigans you had in Wolf3d source). Only 4 assembly functions (draw a vertical line, a horizontal one, fixed point multiplication and division), and they were already replaced by 4 standard C functions.

id software used raycasting since it's early games like Hovertank 3D, Catacomb 3D and Wolfenstein 3D. heck, even though Doom, Duke Nukem 3D and Blood were majorly using BSP, their most simple and rustic rendering base was through raycasting.

commercially exploit or use for any commercial purpose."

[1] https://github.com/id-Software/DOOM/commit/4eb368a960647c8cc...

The original Doom had third-party audio playback routines, so the source came with a rewritten sound server: https://github.com/id-Software/DOOM/tree/master/sndserv

    The bad news:  this code only compiles and runs on linux.  We couldn't

Here's a repo for you with no test coverage and no auto-generated DI. They using unsafe pointers all over the place, too!

https://github.com/id-Software/DOOM

Shall I prepare the postage for the letter in which you'll call John Carmack an MBA? Should we send another to Chris Sawyer? I heard he didn't even write a formal design doc for Roller Coaster Tycoon!

cURL is one of the most used C libs and is an example of good quality C code. If you follow the style used there, see e.g. https://github.com/curl/curl/blob/master/lib/dynhds.h (and associated dynhds.c) you will be good.

Looking at the source of some of the old game-engines from the era that have since been released as open-source can also be helpful, like https://github.com/id-Software/DOOM.

In both cases notice how simple and elegant a lot of the code is. There is already enough complexity inherent in the problem they are solving, and that is where the focus should be.

Any IDE with a working language server to make it easy to jump around and refactor should work fine. Limitations might be due to the C language itself?

Error handling on such a fixed platform does not need to be super-advanced. You should always be within the confines of the system so there shouldn't be much that can go wrong. If stuff goes wrong anyway just being able call a function Fatal("FooBar failed with code 34") when unexpected stuff happens and have it log somewhere to be able to dig around should be enough. You never need to be able to recover and retry.

Make sure to use https://clang.llvm.org/docs/AddressSanitizer.html or a similar tool when developing outside of the PSOne.

That said, consider statically allocating global buffers for most stuff and avoid using the heap for most stuff.

Good luck working within the confines of the PSOne! Many hackers have pulled the hair from their head on that platform ;)

Probably more easily than you'd think. DOOM is open source[1], and as GP alludes, is probably the most frequently ported game in existence, so its source code almost certainly appears multiple times in GPT-4's training set, likely alongside multiple annotated explanations.

[1] https://github.com/id-Software/DOOM

I'd define an arena as the pattern where the arena itself owns N objects. So you free the arena to free all objects.

My first job was at EA working on console games (PS2, GameCube, XBox, no OS or virtual memory on any of them), and while at the time I was too junior to touch the memory allocators themselves, we were definitely not malloc-ing and freeing all the time.

It was more like you load data for the level in one stage, which creates a ton of data structures, and then you enter a loop to draw every frame quickly. There were many global variables.

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Wikipedia calls it a region, zone, arena, area, or memory context, and that seems about right:

https://en.wikipedia.org/wiki/Region-based_memory_management

It describes history from 1967 (before C was invented!) and has some good examples from Apache ("pools") and Postgres ("memory contexts").

I also just looked at these codebases:

https://github.com/mit-pdos/xv6-public (based on code from the 70's)

https://github.com/id-Software/DOOM (1997)

I looked at allocproc() in xv6, and gives you an object from a fixed global array. A lot of C code in the 80's and 90's was essentially "kernel code" in that it didn't have an OS underneath it. Embedded systems didn't run on full-fledges OSes.

DOOM tends to use a lot of what I would call "pools" -- arrays of objects of a fixed size, and that's basically what I remember from EA.

Though in g_game.c, there is definitely an arena of size 0x20000 called "demobuffer". It's used with a bump allocator.

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So I'd say

- malloc / free of individual objects was NEVER what C code looked like (aside from toy code in college)

- arena allocators were used, but global vars and pools are also very common.

- arenas are more or less wash for memory safety. they help you in some ways, but hurt you in others.

The reason C programmers don't malloc/free all the time is for speed, not memory safety. Arenas are still unsafe.

When you free an arena, you have no guarantee there's nothing that points to it anymore.

Also, something that shouldn't be underestimated is that arena allocators break tools like ASAN, which use the malloc() free() interface. This was underscored to me by writing a garbage collector -- the custom allocator "broke" ASAN, and that was actually a problem:

https://www.oilshell.org/blog/2023/01/garbage-collector.html

If you want memory safety in your C code, you should be using ASAN (dynamically instrumented allocators) and good test coverage. Arenas don't help -- they can actually hurt. An arena is a trivial idea -- the problem is more if that usage pattern actually matches your application, and apps evolve over time.

Doom