This document provides instructions for creating a basic racing game in Scratch. It describes how to:
1) Draw a racetrack backdrop and race car sprite.
2) Code the car to move using arrow keys and turn left and right.
3) Add a speed variable to slow the car when off the track.
4) Draw start/finish line sprites to mark laps and code lap counting.
5) Add options like timing races and power-up boosts.
2. Getting Started
Log in to Scratch, then go into your projects and
create a new project. Name it something along the
lines of “Racing Game” so you and other people know
what it is.
3. Making a Racetrack
Click the “Paint new backdrop” button in the bottom left of the screen to open a
window where you can draw a racetrack. While drawing, make sure you are
always in “Vector Mode”, otherwise, click “Convert to Vector” Keep one main
color as the color of the racetrack, we will use this color to check what the car is
touching later on.
4. Making a Car
Next, right click on the cat and click delete. Click on the “Paint new sprite”
button and draw a racecar. Make sure the car isn’t too small to see well or
too big to fit on the track and make it face right. Once you are done drawing,
click the “Set costume center” button at the top right of the screen and make
sure the black + lines up with the center of your sprite.
5. Making the Car Move
To make the car move, we need to drag some blocks to
make some code. In the scripts tab of your car, use the
blocks on the left of the screen to make this piece of code.
Each colored piece can be found in the different colored
sections on the left. To change “key ‘space’ pressed?” to
up arrow, click on the black arrow next to the name of the
key to choose the key you want.
6. Making the Car Move
Right click on the top of the group of code and click
duplicate. Then, attach the new group of code to the
bottom of the first group. Change “up arrow” to “down
arrow” and turn right to turn left.
7. Making the Car Move
To finally let the car move, make a new piece of code with a start block and a
forever loop. Next, drag the code you put together before into the forever loop.
Now, hit play and use the arrow keys to drive the car.
+ =
8. Variables
Variables store information that we can use throughout the
game. For this game, we are going to use a variable
named speed to change the speed of the car.
9. Using Speed
We want the car to slow down when it is driving off-road. To do this, we are
going to make a new script that sets the normal speed when the game starts.
The script then checks if the car is touching the road using if/else and a color
sensor, and if it is not, changes the speed to the lower number. We also need
to add speed into the movement code where 10 and -10 used to be, and
multiply speed by -1 to make the car move backwards for down
arrow.
10. Laps
Draw a new sprite that can serve as a start line for your race. Make it just wide
enough to cover the track left to right. Duplicate the sprite, and put the copy on
the other side of the track. If you like, you can make the start line look different
from the midpoint line by coloring it differently.
11. Laps
To make the laps work, we need to add 3 pieces of code to the two different lap
parts. We need a new variable and to use broadcasts which send messages to
the other sprites.
12. Starting the Game
Drag the player just behind - but not touching the start line.
After this, if you drag in the block, it will have
the x and y of the car filled in automatically. We put this
extra piece of code on the player in order to make it start at
the start line at the beginning of each game.
13. Timed Games
To add a timed option to the race, add this code to the stage. This code asks
the amount of time you want to race for, and if you enter “forever” or “Forever”,
it doesn’t time you. The driving script on the car must also be changed,
replacing the When Green Flag Clicked with When I Receive “Start”.
14. Boosts
In order to add a boost
power up, a new sprite must
first be drawn. These two
scripts will then need to be
added to the new sprite in
order to make the boost
spawn, stay for 3 seconds,
and disappear. The Boost
variable must also be made.
15. Boosts
Some code on the player must also be changed in order to make the boost
work. The code on the left must be changed to look like the code on the right
allowing the player to activate the boost by pressing space.
