ex6_Spirograph.pyde

# Spirograph. Change the radius of circle 2 and proportion value to draw different designs. (change time variable to see the differences.)

r1 = 300.0 #radius of big circle 
r2 = 40.0 #radius of circle 2
r3 = 5.0 #radius of drawing "dot" #location of big circle:
x1 = 0
y1 = 0
t = 0 #time variable
prop = 1.5 #proportion variable
points = [] #empty list to put points in

def setup(): 
    size(600,600)
def draw():
    global r1,r2,x1,y1,t,prop,points
    translate(width/2,height/2) 
    background(255)
    noFill()
    #big circle
    stroke(0) 
    ellipse(x1,y1,2*r1,2*r1)
    
    x2 = (r1-r2)*cos(t)
    y2 = (r1-r2)*sin(t)
    ellipse(x2,y2,2*r2,2*r2)
    
    x3 = x2+prop*(r2-r3)*cos(-((r1-r2)/r2)*t)
    y3 = y2+prop*(r2-r3)*sin(-((r1-r2)/r2)*t)
    fill(255,0,0)
    ellipse(x3,y3,2*r3,2*r3)
    
    #add points to list
    points = [[x3, y3]] + points[:2000]
    for i,p in enumerate(points): #go through the points list
        if i < len(points)-1: #up to the next to last point 
            stroke(0,0,255) #draw red lines between the points 
            line(p[0],p[1],points[i+1][0],points[i+1][1])
    
    t+=0.5