Function main

src/gamesbyexample/ulamspiral.py:14–43

()

DOT_SIZE = 4

def main():
    turtle.bgcolor('#353337') # Use a dark background color.
    turtle.pencolor('#CCCCCC') # The spiral is a light gray color.

    # (!) Comment this next line to draw the spiral.
    turtle.penup()
    turtle.forward(SPACING) # 1 is not prime, so skip
    turtle.left(90)
    turtle.dot(DOT_SIZE) # 2 is prime, so make a dot
    turtle.forward(SPACING)
    turtle.left(90)

    currentNumber = 3 # This is the number we test for primality.
    spiralSideLength = 3
    while currentNumber < 40000:
        # We draw two sides before increasing the spiral side length:
        for i in range(2):
            for j in range(spiralSideLength):
                divs = amountOfDivisors(currentNumber)
                currentNumber += 1

                if divs == 0:
                    # Mark the prime number
                    turtle.dot(DOT_SIZE, '#76b7eb')
                turtle.forward(SPACING)
            turtle.left(90)
        spiralSideLength += 1

    turtle.update() # Finish drawing the screen.
    turtle.exitonclick() # When user clicks on the window, close it.


def amountOfDivisors(number):