# Planar water

a Gerstner sea reflecting the world above it with a true mirror.

```{raw} html
<a class="example-run-button" href="../demos/features_3d_planar_water.html">▶ Run in browser</a>

```

**Tags:** `3d` `water` `planar-reflection` `mirror` `refraction`

Standard WaterSurface3D refraction + depth-fade + foam, but the reflection is a
real planar mirror instead of the environment cubemap. A PlanarReflection3D sits
on the water plane and re-renders the scene above it every frame; assign it to
``WaterSurface3D.reflection`` and the surface samples that live capture (rippled
by the waves, Fresnel-blended against the refraction below) so the coloured
pillars and the spinning cube appear inverted in the water and track the world in
the same frame. Contrast with water.py (cubemap/sky reflection): a planar mirror
is exact for the flat surface and shows the actual scene geometry, not an
approximation.


Usage:
    uv run python examples/features/3d/planar_water.py

## Source

```{literalinclude} ../../examples/features/3d/planar_water.py
:language: python
:linenos:
```