# Quadratic curves

HTML: [altophp.com/bezier/curves/quadratic](https://altophp.com/bezier/curves/quadratic/)

A quadratic Bézier curve has a start point, one control point, and an end
point. Use it for a simple arc controlled by one handle or when preserving an
SVG `Q` segment.

<img src="../assets/quadratic-curve.svg" alt="A quadratic Bézier curve" width="240" height="200" />

## Create a curve

`QuadraticCurve` accepts its three points in path order:

```php
<?php

require __DIR__.'/vendor/autoload.php';

use Alto\Bezier\Point;
use Alto\Bezier\QuadraticCurve;

$curve = new QuadraticCurve(
    new Point(10, 170),
    new Point(140, 20),
    new Point(230, 170),
);

echo $curve->pointAt(0.5).PHP_EOL;
```

The midpoint is:

```text
(130, 95)
```

The public properties `p0`, `p1`, and `p2` retain the original points. They map
directly to `M 10 170 Q 140 20 230 170` in an SVG path.

The [shared operations](https://altophp.com/bezier/operations.md) cover splitting, length, orientation,
and intersections.

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Previous: [Curves](https://altophp.com/bezier/curves.md)
Next: [Cubic curves](https://altophp.com/bezier/curves/cubic.md)

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ALTO\BEZIER: [altophp.com/bezier](https://altophp.com/bezier/)
ALTO(PHP): [altophp.com](https://altophp.com/)