Page 78 - Learn To Program With Scratch

multiple sprites. The change volume by block reduces or increases the vol-
ume by the number you enter. Negative numbers make sounds softer, while
positive numbers make them louder. You can even show a sprite’s volume
on the Stage by checking the box next to the volume block. These blocks
are handy if you want to change the volume based on how close a sprite is
to a target (as in a treasure-hunt game) or make parts of a song louder than
others. You can also use these blocks to simulate an orchestra by playing
different instruments (with different loudness levels) simultaneously.

try it out 3-5
VolumeDemo .sb2 The file VolumeDemo.sb2 simulates a cat walking into a forest . The application
uses the change volume by command to make the cat's sound fade away as
it goes deeper into the woods . Come up with some ideas to make this simulation
more real and try to implement them .

Setting the Tempo

The last three blocks in the Sound palette are related to the tempo, or
speed, at which drums and notes are played. Tempo is measured in beats
per minute (bpm). The higher the tempo, the faster the notes and drums
will play.
Scratch lets you choose a specific tempo with the set tempo to bpm
command. You can also tell a sprite to speed up or slow down the tempo by
a certain amount with the change tempo by command. If you want to see a
sprite’s tempo on the Stage, check the box next to the tempo block.

try it out 3-6
TempoDemo .sb2 Open the file TempoDemo.sb2 and run it to see the set tempo to bpm and
change tempo by commands in action .

Scratch Projects

The commands in the Looks and Sound palettes will help you add lots of
nifty effects to your applications. In this section, we’ll put everything we’ve
learned so far in this chapter together to create animated scenes of a per-
son dancing and some fireworks. This should help you review some of the
new command blocks and give you more practice with creating a complete
Scratch project.

56 Chapter 3
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