Descent (Visual Studio)

A cleaned-up copy of Parallax Software's Descent 1 (v1.5) source release, reorganized so it can be opened and worked on as a modern CMake / Visual Studio project. The original release notes and license are in docs/readme.txt; the code may only be used for non-commercial purposes.

The code compiles and links for 32-bit and 64-bit Windows, with all of the original assembly rewritten in C. It opens an SDL2 window for the graphics, keyboard, mouse, sound effects and music, and a console window that shows the debug output the original sent to a monochrome monitor. Joystick and networking are not done yet. See docs/porting-notes.md.

Layout

Path	Contents
include/	Headers shared between modules, grouped below
source/main/	The game (descent), grouped below
source/editor/	The level editor (built into the game with DESCENT_EDITOR=ON)
source/2d/	2D graphics library (gr)
source/3d/	3D rendering pipeline (3d)
source/texmap/	Texture mapper (texmap)
source/bios/	Keyboard, mouse, joystick, timer, DPMI and IPX (io)
source/fix/, source/vecmat/, source/div/	Fixed-point math, vectors and matrices, divide overflow handling
source/cfile/, source/iff/, source/mem/, source/misc/	File access, IFF images, memory and error helpers
source/ui/	The editor's user interface toolkit (ui)
source/pslib/	Compressed library archiver and its cflib/readfile libraries
source/platform/	SDL2 window, display, keyboard, mouse, sound and music backend (platform)
source/compat/, include/compat/	Replacements for Watcom/DOS headers and runtime functions
source/tools/	hogfile, lbmcomp and xcolor data tools
data/	editdata.exe, a self-extracting archive of the editor's data files
docs/	Original readme, build variant notes, porting notes

Each library keeps the name of the .lib file the original makefiles produced. Headers used by only one module live next to its sources.

The library directories under source/ are the directories of the original makefiles. The game itself was one flat directory of about 150 files; it is now split by subsystem, each .c file with its .h:

source/main/	Contents
core/	Startup, main loop, level sequencing, options, players' save files, missions, demos, version ids
data/	Bitmap and sound tables, the pig file, texture caching, polygon models, animations, fonts
world/	Mine geometry and segments, level loading and saving, walls, triggers, fuel centers, reactor, collision tracing
objects/	Objects, physics, collisions, weapons, powerups, explosions, hostages, players
ai/	Robot AI, pathfinding, robot definitions
render/	Mine renderer, automap, cockpit gauges, HUD, lighting, terrain and exit sequence
menus/	Menus, controls setup, credits, briefings, high scores, kill matrix
net/	IPX and serial/modem multiplayer
sound/	Sound effects and music
devices/	Head-mounted displays, 3D glasses, arcade and CD-ROM hooks

include/	Contents
2d/	Graphics library, palettes, PCX/IFF/RLE bitmaps
3d/	3D pipeline and texture mapper
math/	Fixed-point math, vectors and matrices
bios/	Keyboard, mouse, joystick, timer, DPMI, IPX, mono debug output
cfile/	File and library archive access
misc/	Errors, memory, basic types, argument parsing
ui/	Editor UI toolkit
platform/	SDL2 backend interface
compat/	Watcom/DOS header replacements

Every group directory is on the include path, so the sources still use plain #include "gr.h" as the originals did.

Generating a Visual Studio solution

The game needs SDL2, and libADLMIDI for the music. The easiest way to get them is vcpkg, which comes with Visual Studio 2022: the vcpkg.json manifest makes CMake fetch and build both automatically.

cmake -S . -B build -G "Visual Studio 17 2022" ^
    -DCMAKE_TOOLCHAIN_FILE=%VCPKG_ROOT%/scripts/buildsystems/vcpkg.cmake

That makes a 64-bit build; add -A Win32 for a 32-bit one. Without vcpkg, download the SDL2 VC development package from https://github.com/libsdl-org/SDL/releases and pass -DSDL2_DIR=<path>/cmake instead of the toolchain file; build libADLMIDI (https://github.com/Wohlstand/libADLMIDI) and pass -DlibADLMIDI_DIR=<prefix>/lib/cmake/libADLMIDI, or -DDESCENT_MUSIC=OFF to build without music. The build copies SDL2.dll next to descent.exe.

libADLMIDI is licensed in parts under the GPL and LGPL, so a descent.exe built with it carries those terms on top of the Parallax license.

Run descent.exe from the directory holding the game data (descent.hog, descent.pig): it opens them from the current directory. For Visual Studio, pass -DDESCENT_DATA_DIR=<that folder> when generating the solution and the debugger will start the game there.

Options:

• DESCENT_EDITOR (OFF): build the level editor into the game. Editor builds define EDITOR and leave RELEASE and NDEBUG off, as the original editor variant did.
• DESCENT_TOOLS (ON): build the data tools.
• DESCENT_MUSIC (ON): play the music with libADLMIDI.
• DESCENT_DATA_DIR (empty): the game data folder, used as the Visual Studio debugger's working directory.