How to Fix Flicker Where Two Lights Overlap from Conflicting Additive Contributions

Two lights piled on the same surface can flicker when their additive output and shadow maps fight at the overlap. Trimming redundant lights and fixing shadow settings on both stabilizes the surface.

How to fix it

1. Remove redundant overlapping lights

If two lights cover nearly the same area, merge them into one. Redundant overlap is the cleanest thing to eliminate and removes the conflict entirely.

2. Fix shadow bias on both lights

Mismatched or too-tight shadow bias on overlapping shadow casters causes per-frame disagreement; set consistent, slightly larger bias on both so their shadows do not fight.

3. Clamp extreme intensities

Very bright overlapping lights amplify tiny precision differences into visible flicker; clamp or lower their intensity so the sum stays in a stable range.

4. Reduce shadow-caster overlap

Limit how many of the overlapping lights cast realtime shadows; fewer overlapping shadow maps means fewer chances for a frame-to-frame mismatch.

Catching the ones you can't reproduce

The hardest version of this to fix is the one you can't reproduce — it only happens on a player's hardware, OS, driver, or save state, under conditions that simply aren't present on your machine. A report that says “it crashed” or “it froze” gives you nothing to act on, so the bug survives release after release while quietly costing you players.

Automatic error capture closes that gap. Each failure arrives with its full stack trace, the device and OS, the build number, and a breadcrumb trail of what the player did right before it broke, so even a failure you have never seen becomes a specific, reproducible issue. Fold identical failures into one signature ranked by how many players each hits, and your worklist sorts itself worst-first instead of arriving as a stream of vague complaints.

This is where a tool like Bugnet earns its place. Its SDK captures every error automatically with the full stack trace plus device, OS, memory, build, and game-state context, folds duplicates into one grouped issue with an occurrence count, and ties each to the build it first appeared on — so you fix the problem that hurts the most players first and confirm it is gone when its signature disappears from the next release.