Doom-Fidorial

Doom should be able to run everywhere, even on Minecraft! This is an example on Fidorial: Doom runs on the server (a Java port of linuxdoom-1.10) and is shown on an unmodified Minecraft client, using nothing but a resource pack (core shaders) and maps.

Important

Unofficial fan project. It is not affiliated with, endorsed by or sponsored by id Software, ZeniMax Media, Bethesda, Microsoft or Mojang.

• The game engine is derived from the DOOM source code released by id Software > (id-Software/DOOM, linuxdoom-1.10), Copyright (C) 1993-1996 > id Software, Inc., now ZeniMax Media Inc., which id Software released under the > GNU General Public License, version 2. Using, modifying and redistributing this code is > subject to the terms of that license and to the rights of id Software and ZeniMax Media.
• No game data is included. The commercial IWADs (doom.wad, doom2.wad, ...) are copyrighted by > id Software and are not distributed here: use them only if you own a legitimate copy of the game. > Without an IWAD, the plugin can download Freedoom, a free and > independent game made by its own community under a BSD license.
• DOOM is a registered trademark of id Software LLC, a ZeniMax Media company. Minecraft is a trademark > of Mojang AB. All other trademarks belong to their respective owners; they are used here only to > describe what the project runs on.

Requirements

	Minimum
Minecraft client	Java Edition 26.4 Snapshot 4, unmodified (no mod, no client-side plugin)
Server	Fidorial for Minecraft 26.4 Snapshot 4, with fidorial-api 26.4-snapshot-4-build.29+0.1.0 or later, which has the player events and MapView.hang that Doom uses
Java	25, to run the server and to build the plugin
Resource pack	the pack the plugin serves must be accepted by each player: without it the screen and the sounds cannot be drawn. Set pack-required=true in doom.properties to kick players who decline it
Network	clients must reach the pack's HTTP port, pack-port (TCP 8166 by default); outside a LAN, set pack-public-url
Game data	an IWAD you own (doom.wad, doom2.wad, ...), or Internet access on the first start to download Freedoom
Players	1 to 4 per game (single player, cooperative or deathmatch); each running game uses one server thread at 35 Hz

Building

The plugin is built against fr.fidorial:fidorial-api, in the version given by fidorialApiVersion in gradle.properties. It is looked up in the local Maven repository first, then on repo.euphyllia.moe:

• by default, 26.4-snapshot-4-build.+ takes the latest build published for that Minecraft version. A precise version can be pinned instead, 26.4-snapshot-4-build.<n>+0.1.0, where <n> restarts at 1 with each Minecraft version; the GitHub pre-release of every Fidorial build gives its exact version;
• with a clone of Fidorial, run ./gradlew :fidorial-api:publishToMavenLocal there, then put the published version (for instance 26.4-snapshot-4-local+0.1.0) in fidorialApiVersion.

Java 25 is required; the Gradle wrapper downloads it when needed.

• ./gradlew build produces build/libs/DoomPlugin.jar;
• ./gradlew deploy -PfidorialServerDir=<server folder> copies it into the plugins/ folder of a server.

Usage

1. Put DoomPlugin.jar in the plugins/ folder of a Fidorial server and start it.
2. On the first start, the plugin creates plugins/doom/doom.properties. Put an IWAD in that folder (doom.wad, doom2.wad, freedoom1.wad...). Without one, Freedoom is downloaded, unless the download is turned off in doom.properties.
3. The resource pack is built on the first start (sounds and OPL music, about 1 to 2 minutes), cached in plugins/doom/cache, then served over HTTP on pack-port (8166). On the Internet, set pack-public-url (for instance http://play.example.com:8166) and open that port.
4. In game: /doom (clickable menu), /doom play [skill 1-5] [episode] [map], /doom coop ..., /doom deathmatch ..., /doom join <player>, /doom quit.

Controls

Minecraft	Doom
WASD (ZQSD on AZERTY)	move forward and back, strafe
mouse	turn
right click (held) / left click	fire
space	use (doors, switches)
Ctrl or Shift	run
1 to 7	weapons; 9: next weapon
F (swap hands)	automap
Q (drop; A on AZERTY)	toggle always run
chat: iddqd, idkfa, idclev12...	cheat codes

Other settings: /doom size <3-11>, /doom map, /doom run, /doom cheat <code>.

How it works

• Engine: engine/ is a faithful port of linuxdoom. The simulation matches the original tic for tic: the Freedoom demos play back exactly as in Chocolate Doom. Each game runs on its own thread at 35 Hz, with up to 4 players (single player, cooperative, deathmatch), and the DEHACKED lumps of IWADs are supported (texts, frames, par times).
• Picture: the 320x200 screen is cut into 4 strips of 80 columns, each sent in a map (map_item_data, only the rows that changed). The 4 maps hang with MapView.hang in invisible frames that only the player sees, in the block of their head. The text.vsh shader recognises a signature in the header of each map and stretches its quad over its part of the screen; text.fsh reads back the color code of each pixel (a hash table of the 244 map colors) and draws it with the real Doom palette, including the 14 palettes for damage, bonuses and the radiation suit.
• Sound: the DMX sounds of the WAD are encoded to Ogg Vorbis by a small built-in Java encoder and played positionally around the player. Music (MUS or MIDI) is played by an OPL2 emulation (Nuked OPL3, bit for bit) driven like the DMX driver of Doom 1.9, then encoded.
• Controls: Fidorial API events (PlayerInputEvent, PlayerUseItemEvent, PlayerSwingEvent, PlayerItemHeldEvent, PlayerSwapHandItemsEvent, PlayerDropItemEvent, PlayerMoveEvent). The player is frozen with Player.setAttributeBase (movement_speed, jump_strength and interaction ranges at 0) and given back their values with resetAttributeBase when leaving.

About tables.bin

src/main/resources/fr/euphyllia/fidorial/doom/engine/tables.bin is not game data and not executable code. It holds the three trigonometry lookup tables of tables.c in linuxdoom-1.10, copied value for value, and nothing else:

Order	Table	Entries	What it is
1	finetangent	4096	tangent of the fine angles, in 16.16 fixed point
2	finesine	10240	sine of the fine angles (5/4 of a turn, so that finecosine is a view into it), in 16.16 fixed point
3	tantoangle	2049	arctangent of a slope, as a 32-bit binary angle

Every value is a 32-bit big-endian integer, with no header: 16385 values, 65540 bytes. Tables.java reads them in this order with a DataInputStream.

They live in a file rather than in Java source because arrays that large do not fit in the 64 KB a Java method may hold. They cannot be recomputed with Math.sin either: the original values have their own rounding, and the engine needs them exactly to stay tic for tic identical to Doom.

License and credits

This project is distributed under the GNU General Public License, version 2: see LICENSE. It comes without any warranty. Fidorial itself is licensed separately; this plugin only uses its API.

Part	Derived from	License
Game engine (engine/)	DOOM source code, linuxdoom-1.10, by id Software (id-Software/DOOM)	GPL v2
engine/tables.bin	the finetangent, finesine and tantoangle tables of tables.c in linuxdoom-1.10	GPL v2
OPL2 emulation (audio/Opl2.java)	Nuked OPL3 by Nuke.YKT (Alexey Khokholov)	LGPL v2.1 or later
Music driver (audio/MusicRenderer.java)	i_oplmusic.c of Chocolate Doom by Simon Howard	GPL v2 or later
Fidorial integration, resource pack, shaders, Vorbis encoder	written for this project	GPL v2

DOOM, the original game and its data remain the property of id Software and ZeniMax Media. If you are a rights holder and believe something here should not be, please open an issue.