Page 251 - Scratch Programming Playground

this platform should be low enough that the cat could hit
its head on it. If it can’t, then redraw the platform a little bit
lower.

Save Point

Click the green flag to test the code so far. Make the cat
jump under the low platform. Notice that when the Cat sprite
touches the platform, it ends up above the platform. this is the
bug we need to fix. Click the red stop sign.

8. Add the Ceiling Detection Code

the problem with the
code is in the custom
handle ground block.
this code always assumes
the Cat sprite is falling
from above, and if the
Cat sprite is touching the
Ground sprite, it should
be lifted above it. the
Ground sprite represents
any solid part that the cat
can’t move through, includ-
ing ceilings. We need to
change the code so that if the Cat sprite is jumping up when
it touches the Ground sprite, the cat stops rising because it
bumps its head. We know the Cat sprite is moving upward
when its y velocity is greater than 0. So let’s edit the custom
handle ground block to add a new Boolean input named
moving up.
a Boolean is a true or false value. We use a Boolean
input because we need to know if y velocity is greater than 0
when the handle ground block is first called. this true or

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