/**
 * Chaikin's Algorithm
 * By Raphael Rouvinov-Kats
 * 
 * Implements Chaikin's Algorithm
 * http://graphics.cs.ucdavis.edu/education/CAGDNotes/Chaikins-Algorithm/Chaikins-Algorithm.html
 * */

var depth = 3;
var point_r = 2;
var control_points = [];

var draw = function() {
    background(255, 255, 255);
    // draw raw lines
    stroke(0, 0, 0);
    strokeWeight(0.5);
    for (var i = 0; i < control_points.length - 1; i++) {
        line(control_points[i][0], control_points[i][1],
             control_points[i+1][0], control_points[i+1][1]);
    }
    
    // draw points
    strokeWeight(0);
    fill(0, 0, 0);
    for (var i = 0; i < control_points.length; i++) {
        ellipse(control_points[i][0], control_points[i][1], point_r*2, point_r*2);
    }
    
    // calculate points of curve
    var old_points = control_points;
    var new_points;
    for (var i = 0; i < depth; i++) {
        new_points = [];
        for (var j = 0; j < old_points.length-1; j++) {
            var x1 = old_points[j][0];
            var y1 = old_points[j][1];
            var x2 = old_points[j+1][0];
            var y2 = old_points[j+1][1];
            new_points.push([x1*0.75 + x2*0.25, y1*0.75 + y2*0.25]);
            new_points.push([x1*0.25 + x2*0.75, y1*0.25 + y2*0.75]);
        }
        old_points = new_points;
    }
    
    strokeWeight(0.5);
    stroke(255, 0, 0);
    for (var i = 0; i < new_points.length - 1; i++) {
        line(new_points[i][0], new_points[i][1],
             new_points[i+1][0], new_points[i+1][1]);
    }
    strokeWeight(1);
};

var mouseClicked = function() {
    control_points.push([mouseX, mouseY]);
};