Operation Manual

A beginner’s guide to Scratch
47
1. Moving the
red car
Hang on a second! Every time the red touches the blue dot, “score” is changed
to “score + 1”. If you are good at maths that should set the alarm bells ringing!
How can something be itself plus one?
Don’t worry; programmers often do this. Remember that a variable is not a
number; it is a container that can store numbers. We can do a sum with the
number and put the result back into the same container.
To see a working example of the Prancing Pony game, open
RPiScratch/Projects/prancing_pony.
Racing game
RESOURCES: The sprite “red_car” and the background “track”.
THE AIM OF THE GAME: A two-player game. Each player controls a racing car
around a track. If the car goes off the track, it crashes. The first one over the line
is the winner.
There are five tasks to program for each car:
1. Line cars up on the starting line.
2. Set the cars in motion.
3. Crash the car if it leaves the track.
4. Declare the first car over the line as the winner.
5. Oh, yes – and the players have to be able to control the cars!
Notes:
Tip...
Remember, to
stop everything
moving so that
you can sample
the colour of girl’s
top with the
eye-dropper tool,
hit the red “stop
scripts” button.
If you can’t find
the girl sprite,
have a look in the
bottom-left
corner. She may
have run off to
hide there when
you dragged your
mouse to the
Script tab.
Start off with a green-flag event. When the flag is clicked, the car to should:
n switch to “costume1”
n position itself at the coordinates x: 35 y: 130
n point itself to the right (direction 90)