What causes shadow acne on large flat surfaces?

Shadow acne appears when a surface self-shadows due to depth-map quantization, and large flat areas hit at grazing light angles show the most because the depth error spans many texels.

How do I catch this when it only happens for some players?

Capture it automatically from the player's device with the full stack trace, the device and OS, the build, and a breadcrumb trail of what they did. That turns a vague complaint into a specific, reproducible issue you can fix without owning the hardware it happens on.

How to Fix Shadow Acne on Large Flat Surfaces

Quick answer: Add a slope-scaled (normal) bias that scales with the angle between surface and light, raise shadow resolution, and use front-face or mid-point depth in the shadow pass.

Shadow acne is a surface shadowing itself from depth-map error. A slope-scaled bias plus higher resolution stops the moire pattern on big flat surfaces without lifting contact shadows.

How to fix it

1. Add slope-scaled normal bias

Use a normal/slope-scaled bias that increases offset at grazing angles, where acne is worst, instead of a large flat depth bias that causes peter-panning.

2. Raise shadow resolution

Higher shadow map resolution shrinks each texel's world footprint, so the depth quantization that causes acne becomes too small to see on flat surfaces.

3. Use front-face or mid-point depth

Rendering the shadow pass with front-face culling or mid-point depth moves the comparison plane off the lit surface, removing most self-shadowing acne.

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.

Ship the fix, watch the signature disappear from the next build. That's how you know it's really gone.