# Layer post

per-CanvasLayer post-processing (bloom the world, keep the HUD crisp).

```{raw} html
<a class="example-run-button" href="../demos/features_2d_layer_post.html">▶ Run in browser</a>

```

**Tags:** `2d` `bloom` `post-processing` `canvaslayer`

A CanvasLayer can carry its own ``environment`` (a WorldEnvironment), so its post
effects apply to that layer's band ONLY. Here the game-world layer blooms while the
HUD layer on top stays crisp -- the classic "glow the world, not the UI" case, with
no manual masking. A layer with no ``environment`` is the shared/global path and
costs nothing (the feature is zero-cost when unused).

What to look for:
  - The world layer's bright shapes GLOW (its environment enables bloom).
  - The HUD layer's panel + text are CRISP (no environment -> no post on that band).
  - Toggle the world layer's bloom with B to compare.

Controls:
    B       - Toggle the world layer's bloom
    Escape  - Quit

Run: uv run python examples/features/2d/layer_post.py

## Source

```{literalinclude} ../../examples/features/2d/layer_post.py
:language: python
:linenos:
```