### Coffee Stain

Like the one on your desk

```Canvas.setpenopacity(.1)

turtles = []

resolution = 100
steps = 200
wigglyness = 0.75

for (j = 0; j < resolution; j++) {
turtle = new Turtle()
turtle.penup()

outwardness = staincurve(j / resolution)
turtle.goto(offset, 0)

turtle.pendown()
turtles.push(turtle)
}

accum1 = 0
accum2 = 0
accum3 = 0

function walk(i) {
progress = i / (steps - 1)
originalAmount = progress < 0.5 ? progress * 2 : (1 - progress) * 2
originalAmount = Math.pow(originalAmount, 0.75)

accum1 += (Math.random() * 2 - 1) * wigglyness
accum2 += (Math.random() * 2 - 1) * wigglyness
accum3 += (Math.random() * 2 - 1) * wigglyness
randWalk1 = Math.abs(accum1 + accum3)
randWalk2 = Math.abs(accum2 + accum3)

j = 0
for (turtle of turtles) {
outwardness = j / resolution

randLow = -Math.min(randWalk1, randWalk2)
randHigh = Math.max(randWalk1, randWalk2)

outwardness = staincurve(outwardness)

x = Math.cos(Math.PI * 2 * progress) * radiusWithOffset
y = Math.sin(Math.PI * 2 * progress) * radiusWithOffset

turtle.goto(x, y)
j++
}

console.log("i " + i + ": " + (i < steps))

return i < steps - 1
}

function staincurve(x) {
outside = 0.5 - Math.pow(1 - x, 2)
inside = Math.pow(x, 2)
return x < 0.5 ? inside : outside
}

function lerp(a, b, amount) {
return (1 - amount) * a + amount * b
}```