Method sampleAt

src/main/java/field/graphics/FLine.java:1361–1365

returns a position on this line that's `alpha` along it: specifically when `alpha=0` then we're at the start of the line, when `alpha=0.5` then we are in the middle, when `alpha=1.0` we're at the end.

(double alpha)

	/**
	 * returns a position on this line that's `distance` along it: specifically when `distance=0` then we're at the start of the line, when `alpha=0.5` then we are in the middle, when
	 * `distance=line.length()` we're at the end.
	 */
	public Vec3 sampleAtD(double distance) {
		FLinesAndJavaShapes.Cursor c = cursor();
		c.setD(distance);
		return c.position();