VulkanTron

A cinematic lightcycle arena built on GLTron's faithful direct-Vulkan port. Version 0.3.0 introduces Obsidian: a dark arena with luminous cycle silhouettes, cyan and amber architecture, new energy trails and impacts, approximate floor reflections, and bloom confined to each player's view.

Obsidian in VulkanTron 0.3.0, captured from the running game.

VulkanTron retains the original game rules, AI, controls, menus, cameras, and local multiplayer layouts. Classic and faithful artpacks remain selectable, with the original models, effects and music available. SDL3 handles windows, input, controllers, and audio. The renderer uses Vulkan directly; it does not use SDL_GPU or an OpenGL driver.

The preserved OpenGL remaster is included as a comparison executable. The initial simplified Vulkan arena is now a separate development tool, vulkantron-lab; the normal vulkantron executable runs the complete game.

Version 0.2.0 completed the faithful full-game port on the tested Linux system. Its native OpenGL/Vulkan comparison covered original and faithful artpacks, with documented coplanar depth differences in three explosion fixtures. The 0.3.0 Obsidian build passed 21 Release and 21 sanitizer tests, native X11/Wayland arena captures, and installed gameplay/audio checks. The original artpack also passed the strict 39-scene renderer comparison. Obsidian's reflection treatment is an artistic approximation, and its bloom is limited to the game views. See the renderer architecture, development plan, and faithful verification and Obsidian verification for scope and evidence. Linux is the tested platform; other operating systems require their own ports and verification.

Build and play

Required: a C99/C++20 compiler, CMake 3.21 or newer, Ninja, pkg-config, SDL3 3.2 or newer, Vulkan headers and loader, glslc, spirv-val, libpng, zlib, and libmikmod. Lua 4.0.1 is bundled. The shared build also needs OpenGL development files for the retained reference executable.

The graphics baseline is Vulkan 1.3 with dynamic rendering and synchronization2. The faithful renderer uses a depth/stencil attachment and swapchain transfer support. Classic smooth lines use the optional line-rasterization extension; unsupported requested features produce a clear error. The development target is the NVIDIA GeForce GTX 1660. Broader GPU support requires separate testing.

On Arch Linux, shaderc supplies glslc, spirv-tools supplies spirv-val, and vulkan-validation-layers supplies the optional Khronos validation layer.

./run-vulkantron.sh

The helper configures the release preset, builds the full game, and runs it. It honors VULKAN_SDK; it also recognizes the optional user-local headers at ~/.local/opt/vulkan-headers/1.4.357.0 on the development machine. For a regular SDK installation, the equivalent commands are:

cmake --preset release
cmake --build --preset release
./build/release/bin/vulkantron

Use the original menus to start a game and configure controls, artpacks, music, effects, cameras, and one-, two-, or four-player layouts. Useful options:

./build/release/bin/vulkantron --help
./build/release/bin/vulkantron --obsidian
./build/release/bin/vulkantron --validation
./build/release/bin/vulkantron -i -8

--validation requires the Khronos validation layer and fails explicitly if it is unavailable. -i -8 requests a 1280×720 window; the desktop may constrain its actual size. In game, F5 saves preferences, F11 saves BMP, and F12 saves PNG. --obsidian selects the arena and its bundled soundtrack for this session; F5 makes that selection persistent. The artpack and soundtrack menus can select the classic or faithful presentation at any time.

Default first-player controls are A/S to turn, E to boost, and Q/W to glance. Existing saved bindings take precedence. Use arrows and Enter in menus, Space to pause, Escape to return through menus, and F10 to cycle cameras. F1/F2/F3/F4 select single, stacked, four-way, or automatic views. Player count and all bindings remain configurable through the original menus. Mouse Y uses normal direction by default. Game > Play Settings > Invert Mouse Y switches to the original inverted direction immediately. Quit through the main menu to save the choice, or press F5 while playing or paused.

App-menu installation and preferences

After a full release build, install a separate user-local copy and launcher:

python3 tools/install_vulkantron_launcher.py --select-obsidian

The installer requires Python 3.11 or newer and desktop-file-validate. It installs under ~/.local/opt/vulkantron, adds ~/.local/bin/vulkantron, and creates the VulkanTron application entry with its own icon. It verifies installed content and preserves previous versions. A fresh launcher profile selects Obsidian and its default soundtrack. --select-obsidian also selects these in an existing VulkanTron profile: it first saves a timestamped .gltronrc.pre-obsidian-*.bak beside the profile, then atomically appends only the artpack and soundtrack choices. Existing controls and other settings are preserved. Omit the flag to retain an existing profile's current selections.

Preferences default to ~/.config/vulkantron/.gltronrc; screenshots default to ~/.local/state/vulkantron/screenshots. The corresponding XDG environment variables are honored. VulkanTron does not import or overwrite the remaster's profile. Advanced overrides are:

• VULKANTRON_DATA_DIR: directory containing art, data, music, and scripts.
• VULKANTRON_CONFIG_DIR: directory for .gltronrc.
• VULKANTRON_SCREENSHOT_DIR: screenshot directory.
• VULKANTRON_SHADER_DIR: directory containing the compiled faithful shaders.

GLTRON_DATA_DIR remains supported for shared test assets; VULKANTRON_DATA_DIR takes precedence. Profiles use VulkanTron's variables above. Installed executables find assets and shaders relative to their location and can run from another working directory.

Tests and renderer comparison

cmake --build --preset release
ctest --preset release
cmake --preset asan
cmake --build --preset asan
ctest --preset asan

The suite covers original gameplay, cameras, local layouts, input, settings, assets, audio, and dynamic trails. Vulkan-specific tests cover matrix and light state, geometry recording, texture versions and mip uploads, readback packing, and frame capture/lifetime behavior. CPU-only tests do not certify GPU output. The sanitizer preset enables AddressSanitizer and UndefinedBehaviorSanitizer; whole-program leak checking is separate.

For a real desktop comparison, build both native harnesses and capture the same production game with a fixed clock and seed. The image checker additionally needs NumPy and Pillow; see tools/renderer-check-requirements.txt:

cmake --preset release -DGLTRON_BUILD_NATIVE_TESTS=ON
cmake --build --preset release
python3 tools/check_vulkantron_faithful.py \
  --opengl build/release/vulkantron-reference-smoke \
  --vulkan build/release/vulkantron-faithful-smoke \
  --assets . --output /tmp/vulkantron-comparison --driver x11

The output directory must be new. The checker first requires repeated OpenGL runs to match exactly, then compares game state, visual state, and full-size images across renderers. It records real window transitions, settings roundtrips, Vulkan validation, and diagnostic differences. Image metrics still require visual review. --driver wayland tests native Wayland separately.

Run the OpenGL reference with ./build/release/bin/gltron. Its original instructions are retained in the faithful README. That executable uses the original GLTron profile unless GLTRON_CONFIG_DIR is set. Reference-only builds can set -DVULKANTRON_BUILD_DIRECT_RENDERER=OFF.

Learning renderer development

The architecture guide follows production draw calls through the state recorder to Vulkan textures, pipelines, synchronization, and presentation. The adapter evaluates the classic vertex pipeline on the CPU and submits its output through Vulkan. It is a specific implementation of this game's drawing needs, not a general OpenGL replacement or a universal engine. Future optimization should preserve the same reference fixtures and be justified by measurements.

The earlier lab remains available after a full build:

./build/release/bin/vulkantron-lab --demo --overview --validation
./build/release/bin/vulkantron-lab --self-test

Its simplified visuals and controls are development aids. The full game's menus and original presentation live in vulkantron.

Credits and license

GLTron was created by Andreas Umbach and its original contributors. Original artwork, models, fonts, and audio retain their authorship. See asset provenance, the original README, and the retained in-game credits.

The program is distributed under the GNU General Public License, version 2 or later, without warranty; see COPYING. Bundled Lua retains its separate copyright and permission notice. VulkanTron is a fan project; no official TRON affiliation is claimed. Renderer work does not transfer ownership of the original game's assets.

Obsidian's authored visuals have their own asset record.