Sketch demo

example.js

var COLOURS = [ '#60F0C0', '#FF360E', '#F0D442' ];
var radius = 0;

var demo = Sketch.create({

	container: document.getElementById( 'container' ),
	autoclear: false,

	setup: function() {
		console.log( 'setup' );
	},

	update: function() {
		radius = 2 + Math.abs( Math.sin( demo.millis * 0.003 ) * 50 );
	},

	// Event handlers

	keydown: function() {
		if ( demo.keys.C ) demo.clear();
	},

	// Mouse & touch events are merged, so handling touch events by default
	// and powering sketches using the touches array is recommended for easy
	// scalability. If you only need to handle the mouse / desktop browsers,
	// use the 0th touch element and you get wider device support for free.
	touchmove: function( e ) {

		for ( var i = demo.touches.length - 1, touch; i >= 0; i-- ) {

			touch = demo.touches[i];

			demo.lineCap = 'round';
			demo.lineJoin = 'round';
			demo.fillStyle = demo.strokeStyle = COLOURS[ i % COLOURS.length ];
			demo.lineWidth = radius;

			demo.beginPath();
			demo.moveTo( touch.ox, touch.oy );
			demo.lineTo( touch.x, touch.y );
			demo.stroke();
		}
	}
});

demo.start();