OXCE Realistic Lighting

OXCE Realistic Lighting

Test builds of OpenXcom Extended with an experimental Realistic Lighting pipeline.

Forum thread Source code

Latest download

Extended 8.6.1 + Realistic Lighting
Extended-8.6.1-realistic-lighting-c477bb375.zip
commit c477bb375 · uploaded 10 May 2026
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About this build

This is a test build of OpenXcom Extended (OXCE) with an experimental Realistic Lighting pipeline on top: LOS-traced light propagation, additive RGB tint per tile, per-corner light mixing for floors and walls, modder-tunable per-source colour / radius / intensity / litChance / offset, dithering, perceptual palette snap, and a small ambient sky-tint pass. The master switch is on by default in this build - turning it off restores byte-equivalent vanilla OXCE behaviour.

Installing

  1. Unzip the archive somewhere writable (not inside Program Files unless you are happy running as administrator - OpenXcom writes a log file alongside the executable).
  2. Copy your X-COM: UFO Defense data files into the UFO/ subdirectory. At minimum the UFO/ folder needs GEODATA, GEOGRAPH, MAPS, ROUTES, SOUND, TERRAIN, UFOGRAPH, UNITS (plus optional UFOINTRO). See UFO/README.txt for full details.
  3. (Optional) If you also have X-COM: Terror From The Deep, copy its data files into the TFTD/ subdirectory the same way. See TFTD/README.txt.
  4. Run openxcom.exe. The user / config / save folder is auto-created at %USERPROFILE%\Documents\OpenXcom\.

Lighting options

In-game: Options -> Advanced -> OXCE -> Battlescape category. Master switch:

Realistic Lighting (default YES)

The master gate. NO = vanilla OXCE. YES = LOS-traced light propagation, additive RGB mixing, and inverse-square clamped falloff.

Sub-options (only honoured when Realistic Lighting is on):

Allow modded lights (default YES)

When on, mods that ship light: { color: ..., source: ..., ... } blocks override the auto-derived colour and radius. When off, the engine derives colours from the sprite alone.

Smooth lighting (default YES)

When on, floor and wall tiles linearly interpolate between per-corner light values for smoother lighting gradients across the map.

Dithered lighting (default 2: Floyd-Steinberg)

0 = none, 1 = ordered Bayer, 2 = Floyd-Steinberg error diffusion. Reduces banding by introducing noise to the lighting blends.

Bundled mods

The standard/ folder ships two new mods you can enable from the in-game Mod Manager (Mods on the main menu):

Both mods only have a visible effect when the Realistic Lighting master switch is on.

Lighting sandbox

A playground for testing the Realistic Lighting blending mechanics is available here: Lighting Sandbox

Reporting issues

This is a development branch, not an upstream release. The primary place to report problems is the forum thread. For code-level bugs you can also raise an issue on the lewster32/OpenXcom fork on GitHub - not the OpenXcom Extended or OpenXcom upstream issue trackers.

Restoring vanilla behaviour

If anything looks visually wrong, try toggling Realistic Lighting to Off in Options -> Advanced -> OXCE -> Battlescape. With the master switch off this build is a clean OXCE binary that ignores all of the new code paths. If a problem still reproduces with the master switch off, that is an unrelated regression - please report it with that detail included.

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