How to draw a polygon using EaselJS?

Question

There are Shape.graphic methods to draw circles and rectangles easily, but no obvious method to draw polygons such as hexagons and polygons? How do you draw them using EaselJS?

Answer 1

I was surprised this functionality was missing, so I went ahead and wrote it.

(createjs.Graphics.Polygon = function(x, y, points) {
    this.x = x;
    this.y = y;
    this.points = points;
}).prototype.exec = function(ctx) {
    var start = this.points[0];
    ctx.moveTo(start.x, start.y);
    this.points.slice(1).forEach(function(point) {
        ctx.lineTo(point.x, point.y);
    });
    ctx.lineTo(start.x, start.y);
}
createjs.Graphics.prototype.drawPolygon = function(x, y, args) {
    var points = [];
    if (Array.isArray(args)) {
        args.forEach(function(point) {
            point = Array.isArray(point) ? {x:point[0], y:point[1]} : point;
            points.push(point);
        });
    } else {
        args = Array.prototype.slice.call(arguments).slice(2);
        var x = null;
        args.forEach(function(val) {
            if (x == null) {
                x = val;
            } else {
                points.push({x: x, y: val});
                x = null;
            }
        });
    }
    return this.append(new createjs.Graphics.Polygon(x, y, points));
}

This will add a drawPolygon() method to the graphics object that can be called in 3 ways.

Points as separate arguments drawPolygon(x, y, p1x, p1y, p2x, p2y, ...)

Points as an array of arrays drawPolygon(x, y, [[p1x, p1y], [p2x, p2y], ...])

Points as an array of objects drawPolygon(x, y, [{x:p1x,y:p1y}, {x:p2x,y:p2y}, ...])

Eg:

poly1.graphics.beginFill("Red").drawPolygon(0,0,10,10,10,40,40,30,60,5,30,0);
poly2.graphics.beginFill("Green").drawPolygon(0,0,[[10, 10], [10, 40], [40, 30], [60, 5], [30,0]]);
poly3.graphics.beginFill("Blue").drawPolygon(0,0,[{x:10,y:10}, {x:10,y:40}, {x:40,y:30}, {x:60,y:0}]);

See a working fiddle at https://jsfiddle.net/k3rgk11e/2/

Answer 2

The simplest way is to draw a PolyStar

JS Code:

x=60, y=60, size=20, sides=3, angle=0;

polygon = new createjs.Shape();
polygon.graphics.beginFill("black").drawPolyStar(x, y, size, sides, 0, angle);

myCanvas.addChild(polygon);

Result:

_{Change the value of sides for making any polygon. You may also rotate the shape using angle.}

Answer 3

Actually its very simple, one just needs to use the method moveTo and lineTo. An example to draw a simple triangle,

var polygon = new createjs.Shape();
polygon.graphics.beginStroke("black");
polygon.graphics.moveTo(0, 60).lineTo(60, 60).lineTo(30, 90).lineTo(0, 60);

And come to think of it, there is no need of a drawPolygon method. It won't be used that extensively in my opinion.

Answer 4

There is a drawPolyStar method, which you can use to draw geometric shapes. http://www.createjs.com/Docs/EaselJS/classes/Graphics.html#method_drawPolyStar

Anything irregular you can use the Shape lineTo and moveTo methods as mentioned by @quik_silv earlier (remember to begin a stroke or fill first before drawing).

3rd party tools can export more complex shapes, such as Flash CC (using the Toolkit for CreateJS, or the new Canvas document). The DrawScript plugin for Illustrator makes it really easy to export Illustrator paths to CreateJS, including the compact format. http://drawscri.pt/

Cheers.