This is a personal project to rewrite Doom C in Rust. Where possible I try to keep the Doom behaviour intact, while also making some improvements. I am also trying to document everything as I go along.
I originally started by following along with https://github.com/amroibrahim/DIYDoom
Take a look at how I progressed through
Be warned that because the initial code is transliterated as much as possible from the Doom C except where that causes issues, many things may not be optimal or idiomatic rust. There will be things like dodgy casts, unrequired as casts, unused fields or args, lots of unsafe blocks etc. The main thing
I tried to do was bring up the game to a fully playable state fast, and then begin to optimise, refactor, or redesign components - it is much easier to do when you have a working playable state to begin with that can be used for play-testing and such.
The code will dramatically change pver time.
- Visplanes have been nuked. This gives quite a large speedup but is still not optimal due to extra math and nested array lookup
- Demo playback was added. You will see the effects of the gameplay being in
f32instead of fixedpoint. - The rendering is all
f32. And it is a separate crate, so changing gameplay to fixedpoint would mean only a play position conversion for rendering, and rendering staysf32.
I may convert gameplay to fixedpoint.. I'm not sure. It'll be a huge amount of work and I'd have to add the tan/sin/cos tables or convert between radians and fixedpoint manually. Considering how little the gameplay actually does I can likely take some shortcuts.
Demos are disabled by default. Use the CLI opts -E, --enable-demos to enable them (does not save option). See --help for more options.
You may notice a lot of f32 as u32 as usize. This is because a plain as usize results in:
cvttss2si rax, xmm0
mov rcx, rax
sar rcx, 63
movaps xmm1, xmm0
subss xmm1, dword ptr [rip + .LCPI1_0]
cvttss2si rdx, xmm1
and rdx, rcx
or rdx, rax
xor ecx, ecx
xorps xmm1, xmm1
ucomiss xmm0, xmm1
cmovae rcx, rdx
ucomiss xmm0, dword ptr [rip + .LCPI1_1]
mov rax, -1
cmovbe rax, rcxwhile as u32 as usize:
cvttss2si rax, xmm0
xor ecx, ecx
xorps xmm1, xmm1
ucomiss xmm0, xmm1
cmovae ecx, eax
ucomiss xmm0, dword ptr [rip + .LCPI1_0]
mov eax, -1
cmovbe eax, ecxsince on x64 the usize type is 64bits. Not a major thing, but interesting.
I use many .get_unchecked(num) on arrays I know are safe also, as this reduces instruction count from ~8 to 1.
- To retain the classic Doom look with a software renderer
- To retain the classic Doom gameplay as much as possible
- Identify and split out individual systems as crates for easy changing
- Boom improvements compatibility
And maybe write a book on all I've learned about writing a Doom engine.
- All gameplay features for Doom and Doom II
- Status bar (face, health, armour, keys, ammo, cheats)
- Powerup/damage palette effects
- Thinkers for all things
- [-] HUD (Done except for multiplayer chat)
- [-] Menu screens (partial. New game, quit)
- Play uncompresed ZDBSP maps (some textures may fail)
- Intermissions and finale
- Stats
- Episode end text
- Bunny screen
- Doom II cast
- Automap
- Demo playback
- It works but accuracy is fucked due to movement system using floats not fixedpoint
- Save/load game
- [-] Sound:
- Verify positional sound
- Verify distance and cutoff
- Check the volumes (had to divide midi track vol in half)
- Add the pitch shift
- Maybe use the
usefulnessfield.. - OPL2 emulation (a lot of work here)
- Load music from extra wads (needs
UMAPINFOparsing)
- CLI options (use
--help) - Nuked Visplanes from orbit. Code is now much faster and cleaner
See the TODO for more.
Some of the improvements I've made (so far):
- BSP used for collisions (Doom used the blockmap)
- BSP used for aiming, shooting, and LoS (Doom used the blockmap)
- Floats instead of fixed-point (this may cause slight behaviour changes)
- Basic surface shaders (ROOM renders to a surface that a shader can manipulate)
- Hi-Res and widescreen
I use and develop on Linux exclusively so although I once did a Windows build I don't maintain it.
- Distro SDL2:
cargo build
The distro requires SDL2 + SDL2-mixer to be installed along with the related dev packages including alsa-lib-devel and pulseaudio-libs-devel.
Music support requires fluidsynth or timidity to be installed along with files in the data/sound/
being installed to ~/.local/share/room4doom/sound/.
On start a user config file is created at ~/.config/room4doom/user.toml. This can be edited by hand.
Options set via CLI are saved to the user-config file.
Starting room4doom without CLI options after previously setting options then exiting will load
those options (as saved to ~/.config/room4doom/user.toml).
Use room4doom --help to see all available CLI options.
I've not been as good as I should be at this because I've been on a mad rush to implement as much as I can. Plus the nature of doing large blocks hasn't helped. misc/code-review/ has a semi-broken out series of files where I try to note things of interest, or even write a full code review. Each of these files and additions will be updated and fleshed out over time.
The magnificance of rust/cargo being able to produce a static website full of code documentation means that I try to maintain docs somewhat at https://flukejones.gitlab.io/room4doom/room4doom/index.html. Browsing wad is a good example of what I would like to achieve here.
Comparison: room4doom vs DOS 486DX2
Widescreen double-res
This work is licensed as MIT.
The primary source of information for this project is the 3DO source dump by Burger Becky, with the linux-doom source being used as a reference only when the 3DO source was not sufficient. Linux-Doom was sourced for comments, some Doom II enemy functions, and some of the seg rendering.
The original Linux Doom source as licensed under the DSL was used as an educational resource as stated under clause 2 of the DSL.
Where possible, relevant comments in the "Source Code" are kept as historical artefacts.
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