Bezier demo for DrawBot

bezier_drawbot.py

def lerp(v1, v2, t):
    return v1 + t * (v2 - v1)

def lerpPoint(p1, p2, t):
    return lerp(p1[0], p2[0], t), lerp(p1[1], p2[1], t)

def circle(p, r):
    x, y = p
    d = r * 2
    oval(x - r, y - r, d, d)

Variable([dict(name="t", ui="Slider", args=dict(minValue=0, value=0, maxValue=1))], globals())

p1 = (100, 100)
p2 = (256, 662)
p3 = (686, 620)
p4 = (880, 184)

m1 = lerpPoint(p1, p2, t)
m2 = lerpPoint(p2, p3, t)
m3 = lerpPoint(p3, p4, t)
mm1 = lerpPoint(m1, m2, t)
mm2 = lerpPoint(m2, m3, t)
bp = lerpPoint(mm1, mm2, t)

stroke(0)
for p in [p1, p2, p3, p4]:
    circle(p, 4)

line(p1, p2)
line(p2, p3)
line(p3, p4)
line(m1, m2)
line(m2, m3)
line(mm1, mm2)
circle(bp, 6)