code/test/JavaScript/0050966_sensePi.js

	(function(){
		var strokeColor = [ 'rgba(89,48,27,1)','rgba(223,134,74,1)', 
							'rgba(76,31,115,1)','rgba(204,95,211,1)', 
							'rgba(4,100,102,1)','rgba(26,228,225,1)', 
							'rgba(2,64,144,1)','rgba(0,128,254,1)', 
							'rgba(51,75,40,1)','rgba(148,194,99,1)'];
		
		var canvas = document.getElementById("canvas");	
		var ctx = canvas.getContext('2d');
		var startAngles = [], endAngles = [], nextAngles = [];
		var xc, yc, innerCircleRad, outerCircleRad;
		var toValue, fromValue, steps = 1000, piIndex;
		

		function draw(){
			if (canvas.getContext){
				canvas.width = window.innerWidth;
	    		canvas.height = window.innerHeight;
	    		xc = (canvas.width/2);
	    		yc = (canvas.height/2);
	    		innerCircleRad = getRad(10);
				outerCircleRad = getRad(15);

	    		drawOuterCircle(xc, yc, outerCircleRad);
	    		drawText();
	    		fromValue = pi[0];
	    		piIndex = 1;
				setInterval(drawLines,100);					
			}
		}

		function getRad(r){
			if(canvas.height < canvas.width){
				return (yc - (canvas.height/r)) ;
			}else{
				return (xc - (canvas.width/r)) ;
			}
		}

		function xParametricCoord(xc, r, angle){
			return xc + r * Math.cos(angle); 
		}

		function yParametricCoord(yc, r, angle){
			return yc + r * Math.sin(angle);
		}

		function degreesToRad(degrees){
			return (degrees * Math.PI / 180);
		}

		function radToDegrees(rad){
			return (rad * 180 / Math.PI);
		}

		function drawText() {
		    ctx.fillStyle = 'white';
		    ctx.font = "10pt Roboto";
		    var xt, yt, segmentMed;
	    	textCircleRad = getRad(25);
	    	for(var i=0; i<10; i++){
	    		segmentMed = (startAngles[i] + endAngles[i])/2;
	    		xt = xParametricCoord(xc-10, textCircleRad, segmentMed);
	    		yt = yParametricCoord(yc+7, textCircleRad, segmentMed);
	    		ctx.fillText("//"+i, xt, yt);
	    	}
		}

		function drawInnerCircle(xc, yc, innerCircleRad){
			ctx.beginPath();
			ctx.lineWidth = 2;
			ctx.strokeStyle = 'black';
			ctx.arc(xc,yc,40,0,Math.PI*2,true);
			ctx.moveTo(xc+innerCircleRad,yc);
			ctx.arc(xc,yc,innerCircleRad,0,Math.PI*2,true);
			ctx.stroke();
		}

		function drawOuterCircle(xc, yc, outerCircleRad){
			var sectionRad = degreesToRad(36);
			var gapRad = degreesToRad(3);
			var startAngle = gapRad, endAngle;
			for(var i=1; i<=10; i++){
				endAngle = (i*sectionRad);

				ctx.beginPath();
				ctx.lineWidth = 5;
				ctx.strokeStyle = strokeColor[i-1];
				ctx.arc(xc, yc, outerCircleRad, startAngle , endAngle, false);
				ctx.stroke();

				ctx.beginPath();
				ctx.strokeStyle = 'black';
				ctx.arc(xc, yc, outerCircleRad, endAngle, endAngle+gapRad, false);
				ctx.stroke();

				startAngles.push(startAngle);
				nextAngles.push(startAngle);
				endAngles.push(endAngle);
				startAngle = endAngle+gapRad;
			}
		}

		function getNextSequentialAngle(value){
			var nextAngle = nextAngles[value];
			var spacingRatio = 0.005;
			if((nextAngles[value] + spacingRatio) < endAngles[value]){
				nextAngles[value] = nextAngles[value] + spacingRatio;
			}else{
				nextAngles[value] = startAngles[value]+ 0.002;
			}
			return nextAngle;
		}

		function getNextRandomAngle(value){
			return ((Math.random() * startAngles[value]) + endAngles[value]);
		}


		function drawLines(){
			if (canvas.getContext){
				var x0, y0, x1, y1, fromValueNextAngle, toValueNextAngle;
				if(piIndex <= steps){
					ctx.save();
					toValue = pi[piIndex];

					fromValueNextAngle = getNextSequentialAngle(fromValue), toValueNextAngle = getNextSequentialAngle(toValue);
					x0=xParametricCoord(xc, innerCircleRad, fromValueNextAngle);
					y0=yParametricCoord(yc, innerCircleRad, fromValueNextAngle); 
					x1=xParametricCoord(xc, innerCircleRad, toValueNextAngle); 
					y1=yParametricCoord(yc, innerCircleRad, toValueNextAngle);

					console.log("pi");

					ctx.beginPath();
					ctx.strokeStyle = strokeColor[toValue];
					ctx.lineWidth = 1;
					ctx.moveTo(x0, y0);
					ctx.quadraticCurveTo(xc, yc, x1,y1);

					ctx.stroke();
					ctx.restore();
					fromValue = toValue;
					piIndex++;
				}
			}
		}

	draw();	
})();