# Objective
Add random sampling for the `Annulus` primitive. This is part of ongoing
work to bring the various `bevy_math` primitives to feature parity.
## Solution
`Annulus` implements `ShapeSample`. Boundary sampling is implemented in
the obvious way, and interior sampling works exactly as in the
implementation for `Circle`, using the fact that the square of the
radius should be taken uniformly from between r^2 and R^2, where r and R
are the inner and outer radii respectively.
## Testing
I generated a bunch of random points and rendered them. Here's 1000
points on the interior of the default annulus:
<img width="1440" alt="Screenshot 2024-05-22 at 8 01 34 AM"
src="https://github.com/bevyengine/bevy/assets/2975848/19c31bb0-edba-477f-b247-2b12d854afae">
This looks kind of weird around the edges, but I verified that they're
all actually inside the annulus, so I assume it has to do with the fact
that the rendered circles have some radius.
5dbd827728