Shape.js: A regular shape drawing class. #es6 #module #microlibrary

Shape.js

/*******************************************************************************
 ******************************* ES6 Shape Class *******************************
 *******************************************************************************
 * v0.1
 *******************************************************************************
 * A class that draws regular shapes of a given size with an arbitrary number of
 * sides. Also supports rotation and translation (even after the shape has been
 * created).
 *
 * 
 *
 * This class was originally written on Codepen. Links:
 * 
	* Codepen: https://codepen.io/sbrl/details/EPQbQo/
	* Blog post: (coming soon!)
 *
 * This class depends on the vector class that I wrote earlier. Link:
 *
	* https://gist.github.com/sbrl/69a8fa588865cacef9c0
 * 
 * Bug reports can be made as a comment on this gist, or
 * sent to <[email protected]>. Alternatively, you can tweet
 * me at @SBRLabs.
 *******************************************************************************
 * Author: Starbeamrainbowlabs <[email protected]>
 *
 * Changelog:
	* v0.1: Initial revision.
 * 
 */

class Shape
{
	constructor(pos, sides, radius, rotation)
	{
		this.position = pos;
		this.rotation = (typeof rotation == "number") ? rotation : 0;
		this.radius = radius;
		this.sides = sides;
		
		this.points = [];
		
		this.recalculatePoints();
	}
	
	get firstPoint()
	{
		return this.points[0];
	}
	
	get lastPoint()
	{
		return this.points[this.points.length - 1];
	}
	
	// From http://stackoverflow.com/a/7198179/1460422
	recalculatePoints()
	{
		this.points = [];
		for(let n = 0; n < this.sides; n++)
		{
			this.points.push(new Vector(
				this.radius * Math.cos(Math.PI*2 * (n / this.sides) + this.rotation - Math.PI/2) + this.position.x,
				this.radius * Math.sin(Math.PI*2 * (n / this.sides) + this.rotation - Math.PI/2) + this.position.y
			));
		}
	}
	
	rotate(rotation, absolute)
	{
		if(!absolute)
			this.rotation += rotation;
		else
			this.rotation = rotation;
		
		this.recalculatePoints();
	}
	
	translate(vector, absolute)
	{
		if(!absolute)
			this.position.add(vector);
		else
			this.position = vector;
		
		this.recalculatePoints();
	}
	
	lines(context, sidelimit)
	{
		for(let i = 0; i < this.points.length; i++)
		{
			context.lineTo(this.points[i].x, this.points[i].y);
			
			if(typeof sidelimit == "number" && i >= sidelimit - 1)
				return;
		}
		context.lineTo(this.points[0].x, this.points[0].y)
	}
}