Drawing with the PenDrawing with the PenBarb EricsonBarb EricsonGeorgia TechGeorgia Tech

June 2011June 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

sprite• Paint the sprite

that you will draw with– A spider

• Program the sprite– To draw a

square when it receives a square 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 flag is clicked do all set-up– Clear the

drawing area– Draw a square

• How do you draw a square?– Repeat 4 times

• 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– drawSquareFlow

er

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