# Objective
#17404 reworked the `Segment2d` and `Segment3d` types to be defined by
two endpoints rather than a direction and half-length. However, the API
is still very minimal and limited, and documentation is inconsistent and
outdated.
## Solution
Add the following helper methods for `Segment2d` and `Segment3d`:
- `from_scaled_direction`
- `from_ray_and_length`
- `length_squared`
- `direction`
- `try_direction`
- `scaled_direction`
- `transformed`
- `reversed`
`Segment2d` has a few 2D-specific methods:
- `left_normal`
- `try_left_normal`
- `scaled_left_normal`
- `right_normal`
- `try_right_normal`
- `scaled_right_normal`
There are now also `From` implementations for converting `[Vec2; 2]` and
`(Vec2, Vec2)` to a `Segment2d`, and similarly for 3D.
I have also updated documentation to be more accurate and consistent,
and simplified a few methods.
---
## Prior Art
Parry's
[`Segment`](https://docs.rs/parry2d/latest/parry2d/shape/struct.Segment.html)
type has a lot of similar methods, though my implementation is a bit
more comprehensive. A lot of these methods can be useful for various
geometry algorithms.
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Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Greeble <166992735+greeble-dev@users.noreply.github.com>
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