Introduction to Computer Science with Scratch and App Inventor

Interacting with Other Sprites
So far we have used the if block to let the user control the actions of our sprite, but we can also use the
if block to make different sprites interact with each other. First I need to add a second sprite to my
program. Scripts are sprite-specific. Every new sprite will need its own script(s) to tell it how to
behave.
Now I have two sprites – a dinosaur and a bowl of
cheesy poofs.
I can control my dinosaur using the arrow keys on
the keyboard using the script I wrote before.
Let’s try to make the dinosaur eat the cheesy poofs!
First, we need to move the dinosaur to the cheesy
poofs – that is easy to do using the arrow keys
The second step is to write a script so that we know
when the dinosaur arrives at the cheesy poofs.
When the dinosaur gets to the cheesy poofs, we
want to make them disappear so that it looks like
they’ve been gobbled up.
Let’s write a script for the cheesy poofs that makes it look like the dinosaur is eating them. First, to
detect when the dinosaur gets to the cheesy poofs we can use an if block. What should the condition
be? Luckily, one of the sensing blocks will tell us when two sprites are touching each other. Here, we
want to pick the condition “if touching sprite1” since the dinosaur is sprite1.
Check down here to see what each sprite is named.
You can change the name of your sprites if you like.
mbrace Game Development Workbook Page 18