Why does my 2D wall shadow appear on both sides?

ShadowCaster2D's polygon may be wound the wrong way, or Self Shadows is on causing the wall to cast onto itself. Reverse the polygon vertex order or disable Self Shadows.

What does Use Renderer Silhouette do?

Replaces the manual polygon with the SpriteRenderer's silhouette. Easier for static art; less control. Use the polygon for hand-tuned shadows where the sprite shape doesn't match the gameplay-relevant geometry.

How does Light Order affect shadows?

Lights at higher Order render after lower; both contribute to the shadow stack. For a single light per scene, Order is irrelevant; for layered light setups, ordering controls which casts what.

Fix: Unity ShadowCaster2D Double-Sided Light Bleeds Through

Quick answer: Disable Self Shadows on the ShadowCaster2D so the wall doesn’t shadow itself. Reverse the shape vertex winding if shadow casts the wrong direction. Use Renderer Silhouette for sprite-shaped shadows.

Wall casts shadow correctly on the dark side and also on the lit side. Two reasons: Self Shadows on, or polygon wound wrong.

The Symptom

2D Light scene; walls show shadow on both sides instead of just the back side. Or the wall itself appears unlit.

The Fix

ShadowCaster2D Inspector:
  Use Renderer Silhouette:  true     # for sprite-shaped
  Self Shadows:             false    # wall doesn't darken itself
  Casts Shadows:            true

Self Shadows on means the wall’s own surface evaluates as “in shadow,” making it appear dark. Off lets the lit side stay lit.

Polygon Winding

If using a manual Shape Path, Unity expects clockwise winding (in screen space). Reverse with the toggle in the editor or by editing the path. Wrong winding casts shadow into the wall instead of away from it.

Verifying

Place a Light 2D and a wall. Wall should be lit on the side facing the light, dark on the back, and the back should cast a shadow further into the world. Both-side shadow = Self Shadows on; backwards shadow = winding wrong.

“Self Shadows off. Right winding. Walls light correctly.”

Related Issues

For 2D Light volume intensity, see volumetric shadow. For URP 2D Light bake, see 2D Light bake.

No self-shadow. Right winding. Light correct.