Drawing with the Pen
Barb Ericson
Georgia Tech
June 2011
Project Description
• We will create a
spider sprite and have
it draw with the Pen
blocks
– We will teach it to draw a
square
– And make a flower out of
many squares
Big Picture
• Delete the cat
• Program the
sprite
sprite
– To draw a square
• Paint the sprite
when it receives
that you will draw
a square
with
– A spider
message
– And a flower out
of many squares
Delete cat sprite
• To delete the cat
– Click the scissors
– Click the cat
• Or right click on
the cat and select
delete
Draw the sprite
• Click on the star
with a
paintbrush
– Under the stage
view
Using the paint program
• Click on the
ellipse tool
– Click the filled
circle
– Pick the color
– Click and drag to
draw a circle
Draw legs for the spider
• Use the line tool
to draw legs
– Click on the line
tool icon
– Pick the color
for the legs
– Click and drag to
draw
Draw a head and eyes
• Use the ellipse
tool to draw a
head and eyes
– Click "undo" if
you make a
mistake
– Click "OK" when
done
Grow or shrink sprite
• You can change the
size of the sprite
– Click on the arrows
pointing out icon to
grow it and arrows
pointing in to shrink
– Then click on sprite
Programming Steps
• When the green • How do you draw
flag is clicked do
a square?
all set-up
– Repeat 4 times
– Clear the
drawing area
– Draw a square
• Move 50 steps
• Turn 90 degrees
Set-up
• When the green
flag is clicked Control
– Clear the drawing
area – in Pen
– Put the pen down –
also in Pen
Draw a Square
• Repeat 4 times –
Control
– Move 10 steps –
Motion
• Change to 50
– Turn – Motion
• Change to 90
Drawing many squares
• We can draw a
flower by
drawing many
squares
– And turning
between them
Breaking this into pieces
• Use broadcast
and receive to
make reusable
parts
– drawSquare
– drawSquareFlower
Challenge
• Add other shapes
– Triangle
• Add a way to clear the drawing
– When you press a key
• Add a variable to control the width of
the square
– You can even make this a slider
Connection to Art
• Piet Mondrian made
modern art with just
black lines and solid
colors
– Can you do something
like this?
– Try setting the pen
width and color