thi-ng/umbrella

import type { ReadonlyVec } from "@thi.ng/vectors";
import type { DrawCommand, PolylineOpts } from "./api.js";
import { DOWN, MOVE, PEN, UP } from "./commands.js";

/**
 * Takes an array of 2D points and yields an iterable of {@link DrawCommand}s.
 * The drawing behavior can be customized via additional {@link PolylineOpts}
 * given.
 *
 * @remarks
 * The resulting command sequence assumes the pen is in the **up** position at
 * the beginning of the line. Each polyline will end with a {@link UP} command.
 *
 * @param pts
 * @param opts
 */
export function* polyline(
    pts: ReadonlyVec[],
    opts: Partial<PolylineOpts> = {}
): IterableIterator<DrawCommand> {
    if (!pts.length) return;
    const { speed = 1, onlyGeo = false, delayDown, delayUp, down } = opts;
    if (onlyGeo) {
        for (let p of pts) yield MOVE(p, speed);
        return;
    }
    yield MOVE(pts[0]);
    if (down !== undefined) yield PEN(down);
    yield DOWN(delayDown);
    for (let i = 1, n = pts.length; i < n; i++) yield MOVE(pts[i], speed);
    yield UP(delayUp);
    // reset pen to configured defaults
    if (down !== undefined) yield PEN();
}