The little hell engine

The little hell engine (or just "little hell") is a project that aims to re-imagine the idTech 1 for the modern day.

Goals

Starting with a true to the original source port of DOOM (Chocolate DOOM) as its foundation, the little hell engine aims to:

• Foundationally shift from being a source port to being a standalone game engine
• Renovate the idTech1 codebase and bring it into the 21st century using modern C best practices, with a cozy, high-level API
• Maintain the 'soul' of idTech1, without the baggage of legacy code and support for hardware that is older than I am.
• Facilitate the creation of new boomer shooters and other retro-style games built on the same roots of DOOM.

The little hell engine uses the game code for DOOM 1 as its test bed. Development of the engine is done in tandem with the development of our own version of DOOM I (v1.9 Registered Version) running on the little hell engine. When we begin to add new functionality to the engine (as opposed to just rewriting large quantities of it), attention will switch to creating a demo game designed to showcase and utilize all of the engine functionality.

Progress

• Remove support for backing screens which draw the HUD before blitting it to the real screen (V_CopyRect())
• Create a new API called Drawable for easy management of all 2D elements such as status bars, HUDs, etc.
• Create a working demo game showcasing the engine.
• Use the Meson build system, and a Nix shell for frictionless dependency management.
• Removal of CMake and GNU Autotools
• Removal of code that provides platform support for Windows (to be re-added at a later date)
• Removal all packaging code for Win32, macOS, and Linux
• Remove emulation for GUS, PAS, PC Speaker, MIDI via Fluidsynth/Timidity/Windows, and music packs.
• Retain OPL emulation in software only. Nice and simple.
• Remove DOOM II, Plutonia/TNT, Ultimate Doom, Final Doom, Strife, Heretic, and Hexen support
• Remove deliberate emulation of bugs and quirks of Doom v1.2, v1.666, etc. Doom v1.9 is the basis of the little hell engine.
• No DeHackEd, no wad-merging like DeuTex.
• Remove the setup application. Edit the .cfg by hand. Minimalism, baby.

Lines of code aren't a metric of code quality, but they sure are a metric of code quantity.

Chocolate Doom (203f5da)	files	blank	comment	code	Zen Doom (4d2877f)	files	blank	comment	code
C	329	37986	40769	198641	C	147	15445	12312	58477
C/C++ Header	223	5647	7973	24521	C/C++ Header	136	2834	4562	9250
Meson					Meson	1	13	7	227
make	19	258	14	1072	make
CMake	16	98	258	858	CMake	1	1	0	76
Objective-C	5	303	196	789	Objective-C
Python	5	276	228	709	Python	1	15	32	57
Nix					Nix	1	0	0	18
XML	2	3	2	614	XML
YAML	4	28	3	296	YAML
m4	1	40	4	246	m4
Bourne Again Shell	4	3	3	32	Bourne Again Shell	1	0	0	6
Dockerfile	1	11	8	20	Dockerfile
TNSDL	1	1	0	11	TNSDL
Sum	626	45186	49487	230396	Sum	307	18527	16914	70267

Building

git clone https://github.com/ranguli/mindoom
cd doom
nix-shell shell.nix
meson build
ninja -C build

Release Roadmap

• v0.0.7: The refactor, comment, and log release
  • Start doing static analysis and get to cleaning. This will be a huge undertaking, likely spanning multiple releases.
  • Add comments and documentation to whatever we refactor.
  • Add debug logging to whatever we refactor.
• v0.0.6:
  • Remove WAD merging (a la DeuTex)
  • Remove textscreen and endoom.
• v0.0.5:
  • Remove DeHackEd
• v0.0.4:
  • Remove all references to non-DOOM v1.9 in the code.
• v0.0.3:
  • Rebrand/re-reference everything internally from Chocolate Doom to Mindoom.
  • Remove Windows-specific code
  • No support for real OPL hardware (just the emulation)
• v0.0.2:
  • Remove GUS emulation
  • Remove music packs
  • Remove native MIDI playback
  • Remove fluidsynth music playback
  • Remove timidity support
  • Only support/emulation of OPL3 / Soundblaster.
• v0.0.1:
  • Remove CMake build system
  • Remove Autotools build system
  • Remove codebases for Strife, Hexen, and Heretic
  • Remove packaging and distribution code
  • Misc. repository cleanup