Fills

Filling in Python Turtle uses the functions turtle.begin_fill() and turtle.end_fill(). TurtleThread uses a very similar approach!

Using begin_fill() and end_fill()

When you wish to begin filling a shape, use the begin_fill(...) function. The function accepts a Fill object, which determines how the shape is to be filled.

The easiest method to fill is to use the begin_fill() and end_fill() functions without any parameters. TurtleThread will automatically find an optimal angle to fill the polygon for you.

import turtlethread

t = turtlethread.Turtle()

# Simply call the begin_fill() function without any parameters!
t.begin_fill() 

# Draw a triangle
with t.running_stitch(25):
    for i in range(3):
        t.forward(100)
        t.right(120)

# You must call the end_fill() function, or the shape will not be filled!
t.end_fill()

t.fast_visualise(scale=2) # fast_visualise because fills can take a long time 

Hollow fills

Sometimes, it may be desirable to create a ‘hollow’ shape, or in other words, a filled polygon with some sections within cut out. In this case, a hollow fill can be used.

To create a hollow fill, trace the outline of the overall shape first. Then using a jump stitch, jump to the location within the shape where you wish to ‘cut out’ the filling. Thereafter, trace the outline of the inner ‘hole’ using any regular stitch.

import turtlethread

t = turtlethread.Turtle()

# The close=False argument must be passed for hollow fills!
t.begin_fill(closed=False)

# Draw a large square
with t.running_stitch(25):
    for i in range(4):
        t.forward(200)
        t.left(90)

# Use a jump stitch to 'jump' to the inner part of the filled shape
with t.jump_stitch():
    t.forward(50)
    t.left(90)
    t.forward(50)
    t.right(90)

# Draw the inner square
with t.running_stitch(25):
    for i in range(4):
        t.forward(100)
        t.left(90)

t.end_fill()

t.fast_visualise() # fast_visualise because fills can take a long time 

ScanlineFill

For more control over the fill, you may pass a Fill into the begin_fill() function. As of now, the only Fill available is the ScanlineFill. It accepts an angle argument, which sets the direction of the fill. Alternatively, the string 'auto' may be passed to the angle argument to allow TurtleThread to automatically decide a direction.

It is recommended that angle should be set manually for better performance.

import math
import turtlethread
from turtlethread import fills

t = turtlethread.Turtle()

# If the string 'auto' is passed to ScanlineFill, it will automatically try multiple angles and choose the one that
# minimizes the number of jump stitches.
t.begin_fill(fills.ScanlineFill("auto")) 

with t.running_stitch(25):
    for i in range(3):
        t.forward(100)
        t.right(120)

t.end_fill()

# You can also choose an angle (in radians) and pass it to ScanlineFill.
t.begin_fill(fills.ScanlineFill(math.pi/6)) 

# Draw another triangle
t.right(180)
with t.running_stitch(25):
    for i in range(3):
        t.forward(100)
        t.right(120)

t.end_fill()

t.fast_visualise() # fast_visualise because fills can take a long time