ex6_Harmonograph.pyde

# Writing the harmonograph program. check out http://www.walkingrandomly.com/?p=151 for different designs

def setup(): 
    size(600,600)
    noStroke()
def draw():
    background(255) 
    translate(width/2,height/2)
    t= 0 
    points = []
    
    while t<1000:
        points.append(harmonograph(t))
        t+=0.01
    
    #go through points list and draw lines between them
    for i,p in enumerate(points):
        stroke(255,0,255) #red+blue
        if i < len(points) - 1:
            line(p[0],p[1],points[i+1][0],points[i+1][1]) 
    
    
def harmonograph(t):
    a1=a2=a3=a4 = 150
    f1,f2,f3,f4 = 2.01,3,3,2
    p1,p2,p3,p4 = -PI/2,0,-PI/16,0 
    d1,d2,d3,d4 = 0.00085,0.0065,0,0 
    x = a1*cos(f1*t + p1)*exp(-d1*t) + a3*cos(f3*t + p3)*exp(-d3*t)
    y = a2*cos(f2*t + p2)*exp(-d2*t) + a4*sin(f4*t + p4)*exp(-d4*t)
    return [x,y]