This program uses two subroutines, one for a rectangle and one for a circle, to demonstrate how to use subroutines to separate the detail of the code from the logic, and how to be efficient by re-cycling your code.
The pupil worksheet has the code for creating a rectangle and a circle function, and the challenge is to draw a face.
Note: It is very important that you don't name your circle subroutine "circle" because that is the name of the built in turtle command, and python will get upset.
A subroutine which draws a rectangle, which can be used several times.
# using subroutines to draw shapes
# this is the magic library which allows us
# to easily draw on the screen
from turtle import *
# this subroutine draws a rectangle of size 100 X 150
def myRect():
forward(100)
left(90)
forward(150)
left(90)
forward(100)
left(90)
forward(150)
left(90)
# set it to draw quickly
speed(0)
# start on the left of the screen
up()
goto(-300,0)
down()
# here is where we use it
myRect()
# and again
up()
forward(120)
down()
myRect()
Now the subroutine is adapted so it takes parameters for its colour and size.
# using subroutines to draw shapes
# this is the magic library which allows us
# to easily draw on the screen
from turtle import *
# this subroutine draws a rectangle of size 100 X 150
def myRect(w,h,c):
color(c)
begin_fill()
forward(w)
left(90)
forward(h)
left(90)
forward(w)
left(90)
forward(h)
left(90)
end_fill()
# start on the left of the screen
up()
goto(-300,0)
down()
# here is where we use it
myRect(100,200, "red")
# and again
up()
forward(120)
down()
myRect(200,30, "green")
Another subroutine added, this time to add a circle.
# using subroutines to draw shapes
# this is the magic library which allows us
# to easily draw on the screen
from turtle import *
# this subroutine draws a rectangle of size 100 X 150
def myRect(w,h,c):
color(c)
begin_fill()
forward(w)
left(90)
forward(h)
left(90)
forward(w)
left(90)
forward(h)
left(90)
end_fill()
# draw a circle radius r, colour c
def myCircle(r,c):
color(c)
begin_fill()
circle(r)
end_fill()
# a big pink circle
up()
goto(0, -300)
down()
myCircle(300,"pink")
# a purple square
up()
goto(-200,-200)
down()
myRect(400,400,"purple")
# a black circle
up()
goto(0,-200)
down()
myCircle(200,"black")
Note that colours used can be names, but they can also be any valid HTML colour code, such as "#CCCCCC" - which is a nice grey colour. The # needs to be inside the string (e.g. color("#FF0C49") )
There is a big list of HTML colours here on the W3 Schools site.
Garden Design: Drawing a picture
The code for this program draws a garden, with subroutines that draw flowers, a lawn and a shed, and using randomness to position the flowers. Some aspects are not finished off, so pupils have to adapt some of the subroutines, and also to add others of their own. The final extension, putting in a pond and stopping the flowers appearing in the water, is quite challenging.
There is quite a lot of code, but the bits which the pupils need to change are at the bottom, identified with comments.
It might be helpful to explain how to position elements of the flower using by adding and taking from the X,Y co-ordinates of the flower's position using the diagram here.
This is the starter code which the pupils need to download.
from turtle import *
import random
#===================================
# draws a rectangle
#===================================
def draw_rectangle(x,y,w,h,colour):
up()
goto(x,y)
down()
fillcolor(colour)
begin_fill()
for i in range(2):
forward(w)
left(90)
forward(h)
left(90)
end_fill()
#===================================
# draws a triangle
#===================================
def draw_triangle(x,y,b,h,colour):
up()
goto(x,y)
down()
fillcolor(colour)
begin_fill()
goto(x + b/2, y - h)
goto(x - b/2,y - h)
goto(x,y)
end_fill()
#===================================
# draws a regular polygon
#===================================
def draw_polygon(x,y,sides,size,colour):
up()
goto(x,y)
down()
fillcolor(colour)
begin_fill()
angle = 360 / sides
for i in range(sides):
forward(size)
left(angle)
end_fill()
#===================================
# draws a circle
#===================================
def draw_circle(x,y,radius,colour):
up()
goto(x,y+radius)
down()
dot()
up()
goto(x,y)
down()
fillcolor(colour)
begin_fill()
circle(radius)
end_fill()
#===================================
# This makes the first type of flower
#===================================
def flower(x,y):
down()
draw_rectangle(x,y,5,30,"brown") # a brown stem
draw_circle(x-5,y + 10,5,"green") # two green leaves
draw_circle(x+10,y + 10,5,"green")
draw_circle(x+2,y+20,10,"pink") # pink petals
draw_circle(x+2,y+25,5,"red") # red middle
up()
goto(x,y)
#===================================
# YOU CHANGE THIS
# to make the second type of flower
#===================================
def flower2(x,y):
draw_circle(x,y,10,"grey")
#===================================
# YOU CHANGE THIS
# to make the third type of flower
#===================================
def flower3(x,y):
draw_circle(x,y,10,"grey")
#===================================
# YOU CHANGE THIS
# This makes a shed that needs improvement
#===================================
def shed(x,y,w,h,):
draw_triangle(x,y,w,h/2,"brown")
draw_rectangle(x - w/2 +10,y-h,w -20,h/2,"brown")
#===================================
# YOU ADD YOUR TREE HERE
#===================================
choice = numinput("Choose", "Enter 1,2 or 3 to test your flower functions, 4 for the shed, or 0 draw the garden")
if choice == 1:
flower(0,0)
elif choice == 2:
flower2(0,0)
elif choice == 3:
flower3(0,0)
elif choice == 4:
shed(0,0,300,200)
else:
# speed as fast as possible
speed(0)
# set the whole screen colour
bgcolor("orange")
# draw the lawn
draw_rectangle(-300,-200,600,400,"#CCFF11")
# draw the shed
shed(-30,350,300,200)
# this makes it do 10 flowers
for i in range(10):
# choose a random place to put it
pos_x = random.randint(-300,300)
pos_y = random.randint(-200,100)
# choose what type it should be
flower_type = random.randint(1,3)
# chose a different function for each type
if flower_type == 1:
flower(pos_x,pos_y)
elif flower_type == 2:
flower2(pos_x,pos_y)
elif flower_type == 3:
flower3(pos_x,pos_y)
Example code with all the challenges competed.
from turtle import *
import random
hideturtle()
#===================================
# draws a rectangle
#===================================
def draw_rectangle(x,y,w,h,colour):
up()
goto(x,y)
down()
color(colour)
begin_fill()
for i in range(2):
forward(w)
left(90)
forward(h)
left(90)
end_fill()
#===================================
# draws a triangle
#===================================
def draw_triangle(x,y,b,h,colour):
up()
goto(x,y)
down()
color(colour)
begin_fill()
goto(x + b/2, y - h)
goto(x - b/2,y - h)
goto(x,y)
end_fill()
#===================================
# draws a regular polygon
#===================================
def draw_polygon(x,y,sides,size,colour):
up()
goto(x,y)
down()
color(colour)
begin_fill()
angle = 360 / sides
for i in range(sides):
forward(size)
left(angle)
end_fill()
#===================================
# draws a circle
#===================================
def draw_circle(x,y,radius,colour):
up()
goto(x,y)
down()
color(colour)
begin_fill()
circle(radius)
end_fill()
#===================================
# This makes the first type of flower
#===================================
def flower(x,y):
down()
draw_rectangle(x,y,5,30,"brown") # a brown stem
draw_circle(x-5,y + 10,5,"green") # two green leaves
draw_circle(x+10,y + 10,5,"green")
draw_circle(x+2,y+20,10,"pink") # pink petals
draw_circle(x+2,y+25,5,"red") # red middle
up()
goto(x,y)
#===================================
# YOU CHANGE THIS
# to make the second type of flower
#===================================
def flower2(x,y):
up()
goto(x,y)
down()
# set a thick green line
color("green")
width(4)
left(60)
# draw some stems
for i in range(3):
forward(30)
backward(30)
left(30)
# then the petals on top
width(1)
draw_circle(x+5, y+50,10,"red")
draw_circle(x+2, y+45,5,"blue")
up()
# point back the way we started
setheading(0)
#===================================
# YOU CHANGE THIS
# to make the third type of flower
#===================================
def flower3(x,y):
up()
goto(x,y)
down()
draw_circle(x,y,8,"blue")
# set a thin green line
color("green")
width(2)
setheading(30)
# choose a random angle
angle = random.randint(10,15)
# draw some stems
while heading() < 150:
forward(40)
fillcolor(random.choice(["red","yellow","orange"]))
begin_fill()
circle(5)
end_fill()
# color("green")
backward(40)
left(angle)
setheading(0)
#===================================
# YOU CHANGE THIS
# This makes a shed that needs improvement
#===================================
def shed(x,y,w,h,):
draw_triangle(x,y,w,h/2,"grey")
draw_rectangle(x - w/2 +10,y-h,w -20,h/2,"brown")
# draw a set of windows
for i in range(30,180,30):
draw_rectangle(x - w/2 + i,y-h + 30,26,50,"#FFCCFF")
# draw the door
draw_rectangle(x +w/2 - 60 ,y-h,40,h/2 - 10,"#CC0066")
#===================================
# YOU ADD YOUR TREE HERE
#===================================
def tree(x,y):
draw_rectangle(x-5,y,10,100, "brown")
draw_triangle(x,y+100,100,50,"green")
draw_triangle(x,y+120,100,50,"green")
draw_triangle(x,y+140,100,50,"green")
choice = numinput("Choose", "Enter 1,2 or 3 to test your flower functions, 4 for the shed, 5 for the tree, or 0 draw the garden")
if choice == 1:
flower(0,0)
elif choice == 2:
flower2(0,0)
elif choice == 3:
flower3(0,0)
elif choice == 4:
shed(0,0,300,200)
elif choice == 5:
tree(-30,0)
else:
# speed as fast as possible
speed(0)
# set the whole screen colour
bgcolor("orange")
# draw the lawn
draw_rectangle(-300,-200,600,400,"#336633")
# draw the shed
shed(-30,350,300,200)
# some trees
tree(200,190)
tree(300,190)
tree(320,190)
tree(260,180)
tree(230,170)
# a pond
draw_circle(100,-200,50,"#66CCFF")
draw_circle(150,-180,50,"#66CCFF")
draw_circle(180,-170,50,"#66CCFF")
draw_circle(200,-180,50,"#66CCFF")
draw_circle(175,-160,30,"#336633")
numflowers = int(numinput("Choose","How many flowers would you like?"))
# this makes it do 10 flowers
for i in range(numflowers):
# choose a random place to put it
pos_x = random.randint(-300,300)
pos_y = random.randint(-200,100)
# check to see if it would be in the pond. If so
# put it in the island
if pos_x > 75 and pos_y < -130:
pos_x = 175 + random.randint(-10,10)
pos_y = -130 + random.randint(-10,10)
# choose what type it should be
flower_type = random.randint(1,3)
# chose a different function for each type
if flower_type == 1:
flower(pos_x,pos_y)
elif flower_type == 2:
flower2(pos_x,pos_y)
elif flower_type == 3:
flower3(pos_x,pos_y)
