Why don't multiple decal projectors stack visually?

Decal blend defaults to Replace on alpha, so a later decal hides earlier. Switch to Premultiply Alpha or Additive blend, and use Decal Projector Sort Order to layer.

Per-projector integer; higher draws over lower at the same position. Use to ensure blood splat over scorch mark, etc.

Performance with many decals?

DBuffer is more efficient than Screen Space when many decals overlap. Switch in URP/HDRP if your scene has 50+ overlapping decals.

Fix: Decal Materials Don't Stack

Quick answer: Decal Material blend = Premultiply Alpha. Set Decal Projector Sort Order per layer.

Bullet hole + blood splat at same spot. Only the last applied shows. Default Replace blend overwrites.

The Fix

Decal Material (Shader Graph):
  Surface Type:          Transparent
  Blend Mode:            Premultiply Alpha

Decal Projector:
  Sort Order:            1     // blood = 2; bullet hole = 1
  Decal Layer:           Default Decal Layer 0

Premultiplied alpha lets multiple decals contribute their color × alpha. Sort Order resolves z-fight at the same position.

Verifying

Place two decals overlapping. Both visible, blended. Without fix: only one shows.

“Premultiply blend. Sort layered.”

Related Issues

For URP decal on skinned, see URP decal. For SubGraph property, see SubGraph.

Premultiply. Sort. Stack.