import { distanceBetween } from "flo-vector2d";


/**
 * Returns the curve length of the given line within the specified parameter
 * interval.
 * 
 * @param interval the paramter interval over which the length is 
 * to be calculated (often `[0,1]`)
 * @param ps a linear bezier curve given by an ordered array of its control
 * points, e.g. `[[0,0],[1,1]]`
 * 
 * @internal
 */
 function lengthBez1(
		interval: number[],
		ps: number[][]): number {

	const [t1,t2] = interval;

	const [[x0, y0], [x1, y1]] = ps;

	const p1 = [x0 + t1*(x1 - x0), y0 + t1*(y1 - y0)];
	const p2 = [x0 + t2*(x1 - x0), y0 + t2*(y1 - y0)];

	return distanceBetween(p1,p2);
}


export { lengthBez1 }