Cubic curves

A cubic Bézier curve has a start point, two control points, and an end point. Its two handles control the departure and arrival directions independently. It also maps directly to an SVG C segment.

Create a curve

CubicCurve accepts its four points in path order:

<?php

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

use Alto\Bezier\CubicCurve;
use Alto\Bezier\Point;

$curve = new CubicCurve(
    new Point(10, 160),
    new Point(60, 20),
    new Point(180, 20),
    new Point(230, 160),
);

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

The midpoint is:

(120, 55)

The public properties p0 through p3 retain the original points. They map to M 10 160 C 60 20 180 20 230 160 in an SVG path.

See Recipes for converting SVG coordinates and producing constant-speed motion.