Material Parameters

Most users never touch this. The plugin ships the fog material (M_Main_Fog_Volume) already wired to the Fog Manager. This page is the reference for anyone building a custom fog material or curious how the manager talks to the shader.

How it works

The Fog Manager creates a dynamic instance of Fog Material at BeginPlay and adds it as a post-process blendable. Each frame it sets a small set of named parameters on that instance: the local player’s position and view, plus the fog’s configuration. The material reads those names to draw the darkness and carve out lit areas.

That means the contract is the parameter names. A custom fog material must expose these exact names, or the manager’s updates land nowhere.

Configuration parameters

Set once at BeginPlay from the Fog Manager’s settings.

Parameter	Type	Source / meaning
MapSize	Scalar	The manager’s Map Size. Converts world units into map (UV) space.
IsMapCentered	Scalar (bool)	The manager’s Is Map Centered (1 = centered on origin).
CharacterVisibilityRadius	Scalar	The manager’s Character Visibility Radius. The lit radius around the player.
FloorMap	Texture	The baked Floor Map Texture, when one is assigned. White is lit-able ground, black is permanently dark.

Per-frame player parameters

Updated every tick from the local player’s tracker.

Parameter	Type	Meaning
CharacterUVLocation	Vector	Player position in map space, using Map Size.
CharacterUVLocationFixed	Vector	Player position in map space using the baseline 3000 scale, kept alongside the above for the material’s sampling.
CharacterForwardDirection	Vector	The player’s forward direction (x, y), used for field-of-view cones.
CharacterFOVCosHalfAngle	Scalar	Cosine of half the tracker’s Field Of View Angle. -1 when the angle is 360 (omnidirectional), so the cone test always passes.

Beacons

Beacon positions and field-of-view data are gathered every frame into arrays on the Fog Manager (BeaconLocationsAndSizes, where each entry is x, y, z, radius, and a parallel BeaconFOVData of forwardX, forwardY, cos(halfFOV), unused). These are exposed to Blueprint and routed to the material through the beacon render target (RT_Beacon_Locations) by the plugin’s Blueprint layer rather than as individual named scalars. If you build a custom material, reuse that beacon pipeline rather than re-deriving it.

Renaming breaks the link

If you rename any of the parameters above in a custom material, the manager will keep writing to the old names and the effect will silently stop updating. Keep the names identical, or update the manager’s material setup to match.

Keep MapSize consistent everywhere

Map Size and Is Map Centered show up on the Map Baker, the Fog Manager, and here in the material. All three must agree, otherwise lit areas drift out of alignment with the baked floor. See The Fog Manager.