//IFS
//(c) 2011 by Tomasz Lubinski
//www.algorytm.org

/* Render area coordinates */
var minX = -8.0;
var maxX =  8.0;
var minY = 11.0;
var maxY = -5.0;

/* Render area size */
var width = 0;
var height = 0;
var ratioX;
var ratioY;

/* IFS data */
var a = [];
var b = [];
var c = [];
var d = [];
var e = [];
var f = [];
var p = [];

/* current point */
var x, y;

/* Number of points */
var pointsNum = 10000000;

/* Fractal image */
var data;
var imageData;
var canvas;
var ctx;

/* add new function to IFS */
function addFunction(paramA, paramB, paramC, paramD, paramE, paramF, paramP)
{
	a.push(paramA);
	b.push(paramB);
	c.push(paramC);
	d.push(paramD);
	e.push(paramE);
	f.push(paramF);
	p.push(paramP);
}

/* removes all functions */
function clearFunctions()
{
	a = [];
	b = [];
	c = [];
	d = [];
	e = [];
	f = [];
	p = [];
}

/* render Fractal */
function renderFractal()
{
	canvas = document.getElementById("canvas");
	ctx = canvas.getContext("2d");

	// read the width and height of the canvas
	width = canvas.width;
	height = canvas.height;

	// create a new pixel array
	data = new Array(width * height);
	imageData = ctx.createImageData(width, height);
	
	ratioX = (maxX - minX) / width;
	ratioY = (maxY - minY) / height;
	
	/* Clear data */
	for (var i=0; i<width*height; i++)
	{
		data[i] = 0;
	}
	
	currentPointsNum = 0;
	x = 0;
	y = 0;
	calculateFractal();
}

/* calculate Fractal */
function calculateFractal()
{
	/* Calculate data */
	for (i=0; i<pointsNum; i++)
	{
		/* Choose random function */
		r = Math.random();
		curr = 0;
		prob = 0;
		for (j=0; j<p.length; j++)
		{
			prob += p[j];
			if (prob > r)
			{
				curr = j;
				break;
			}
		}
		
		/* Perform calculation */
		xtmp = a[curr]*x + b[curr]*y + e[curr];
		ytmp = c[curr]*x + d[curr]*y + f[curr];
		x = xtmp;
		y = ytmp;
		
		/* Draw point */
		pointX = Math.floor((x - minX)/ratioX);
		pointY = Math.floor((y - minY)/ratioY);
		data[pointY*width+pointX]++;
	}
	
	/* Check range */
	biggest = data[0];
	for (var i=1; i<width*height; i++)
	{
		if (data[i] > biggest)
		{
			biggest = data[i];	
		}
	}	
	
	/* Generate image */
	for (var i=0; i<height; i++)
	{
		for (var j=0; j<width; j++)
		{
			index = (i*width+j)*4;
			imageData.data[index+3] = 0xff;
			if (data[j+i*width] > 0) 
			{
			        level = (Math.log(data[j+i*width])/Math.log(biggest))*0xff;
				imageData.data[index+0] = 0x80-level/2;
				imageData.data[index+1] = 0xff-level;
				imageData.data[index+2] = 0x80-level/2;
			}
			else
			{
				imageData.data[index+0] = 0xff;
				imageData.data[index+1] = 0xff;
				imageData.data[index+2] = 0xff;
			}
		}
	}	
	
	// copy the image data back onto the canvas
	ctx.putImageData(imageData, 0, 0);
}