# Bloom 2D

glow on a pure-2D scene via WorldEnvironment.

```{raw} html
<a class="example-run-button" href="../demos/features_2d_bloom.html">▶ Run in browser</a>

```

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

A 2D-only scene (no 3D) opts into bloom by adding a WorldEnvironment with
``bloom_enabled = True``. Its 2D content is composited through the HDR lane + bloom
with a linear tonemap, so bright shapes glow while flat art keeps its authored
colour (no tonemap crush). With no WorldEnvironment a 2D scene renders flat as
before, at zero cost.

What to look for:
  - The bright stars/bars BLOOM (soft halo) when bloom is on.
  - The dark background bars stay their authored colour (below the threshold).
  - Lowering the threshold makes more of the scene glow; raising it restricts the
    glow to the brightest pixels.

Controls:
    B            - Toggle bloom
    Up / Down    - Raise / lower bloom threshold
    Left / Right - Decrease / increase bloom intensity
    Escape       - Quit

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

## Source

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