# Dilation

#### Posted December 14, 2015

#### by Lensyl Urbano

A quick program that animates scaling (dilation) of shapes by scaling the coordinates. You type in the dilation factor.

*dilation.py*

from visual import * #axes xmin = -10. xmax = 10. ymin = -10. ymax = 10. xaxis = curve(pos=[(xmin,0),(xmax,0)]) yaxis = curve(pos=[(0,ymin),(0,ymax)]) #tick marks tic_dx = 1.0 tic_h = .5 for i in arange(xmin,xmax+tic_dx,tic_dx): tic = curve(pos=[(i,-0.5*tic_h),(i,0.5*tic_h)]) for i in arange(ymin,ymax+tic_dx,tic_dx): tic = curve(pos=[(-0.5*tic_h,i),(0.5*tic_h,i)]) #stop scene from zooming out too far when the curve is drawn scene.autoscale = False # define curve here shape = curve(pos=[(-1,2), (5,3), (4,-1), (-1,-1)]) shape.append(pos=shape.pos[0]) shape.color = color.yellow shape.radius = 0.1 shape.visible = True #dilated shape dshape = curve(color=color.green, radius=shape.radius*0.9) for i in shape.pos: dshape.append(pos=i) #label note = label(pos=(5,-8),text="Dilation: 1.0", box=False) intext = label(pos=(5,-9),text="> x", box=False) #scaling lines l_scaling = False slines = [] for i in range(len(shape.pos)): slines.append(curve(radius=shape.radius*.5,color=color.red, pos=[shape.pos[i],shape.pos[i],shape.pos[i]])) #animation parameters animation_time = 1. #seconds animation_smootheness = 30 animation_rate = animation_smootheness / animation_time x = "" while 1: #x = raw_input("Enter Dilation: ") if scene.kb.keys: # event waiting to be processed? s = scene.kb.getkey() # get keyboard info #print s if s <> '\n': x += s intext.text = "> x "+x else: try: xfloat = float(x) note.text = "Dilation: " + x endpoints = [] dp = [] for i in shape.pos: endpoints.append(float(x) * i) dp.append((endpoints[-1]-i)/animation_smootheness) #print "endpoints: ", endpoints #print "dp: ", dp for i in range(animation_smootheness): for j in range(len(dshape.pos)): dshape.pos[j] = i*dp[j]+shape.pos[j] rate(animation_smootheness) if slines: for i in range(len(shape.pos)): slines[i].pos[1] = vector(0,0) slines[i].pos[-1] = dshape.pos[i] for i in range(len(shape.pos)): dshape.pos[i] = endpoints[i] slines[i].pos[-1] = dshape.pos[i] for i in range(len(shape.pos)-1): print shape.pos[i], "--->", dshape.pos[i] except: #print "FAIL" failed = True intext.text = "> x " x = ""

**Citing this post**: **Urbano**, L., 2015. Dilation, Retrieved November 18th, 2017, from *Montessori Muddle*: http://MontessoriMuddle.org/ .**Attribution (Curator's Code )**: Via: ᔥ Montessori Muddle; Hat tip: ↬ Montessori Muddle.