Vision Occluders

By default a lit circle is a clean radius: the player sees everything around them out to the visibility radius. Vision occluders break that up. Add one to a wall, rock, or building and it casts a vision-blocking shadow, so the area behind it stays in fog even when it is inside the radius.

This is what makes peeking around corners and ambushes work: an enemy hiding behind a wall is not revealed until the player can actually see past it.

Add an occluder

1. Add a BP_Vision_Occluder component (a Blueprint subclass of UVisionOccluderComponent) to the actor that should block sight, for example a wall blueprint or a static-mesh actor.

   

2. Make sure the occluder mesh has collision. The shadow is built from the geometry that blocks the line of sight; no collision means nothing to block.

3. Place the occluder so it sits flat on the ground. Occluders cast their shadow from ground level, so a mesh floating above the floor leaves a gap that light leaks through, and one sunk into the floor can cause shadow artifacts.

   

Requirements

Occluders depend on a rendering feature that is off by default:

Custom Depth-Stencil Pass must be enabled

Occluders use the Custom Depth-Stencil Pass to cast their shadows. Enable it in Project Settings -> Rendering -> Postprocessing -> Custom Depth-Stencil Pass (set it to Enabled with Stencil). If occluders cast no shadow at all, this is almost always why.

The VISION_OCCLUDER tag

Occluder actors carry the tag VISION_OCCLUDER. This is the contract the rest of the system uses to tell occluders apart from ordinary geometry: the Fog Manager’s Get All Non Occluding Actors returns everything without that tag, so the shadow and baking pipeline knows which actors should not block vision. The BP_Vision_Occluder setup applies the tag for you; leave it in place.

Static cover is cheapest

Occluders are most efficient on static cover (walls, buildings) that does not move. Use them for the level’s permanent geometry and rely on beacons and the player’s own sight for moving units.