Page 61 - Learn To Program With Scratch

condition happens, the wait until block will let the script move on to
execute the if/then block. The details for creating the wait until block
are illustrated in Figure 2-20.

 Drag the wait until block from the
Control palette.
Drag the or block (from the Operators
 palette) and drop it over the hexagonal
slot.
Drag the touching block (from the
Sensing palette) and drop it over the
 first slot in the or block. Click the down
arrow and select Player from the drop-
down menu.
Drag the greater than (>) block (from the
 Operators palette) and drop it over the
second slot in the or block.
Drag the timer block (from the Sensing
 palette) over the first slot in the > block.
Type the number 3 in the second slot as
shown.
Figure 2-20: Building the wait until block in the script of Figure 2-18

n o t e Blocks inside the if/then block will only run if the condition you specify in the header
of the if/then block is true. Chapter 6 explains this block in detail, but for now, you
know enough to use it to add your own touches to a program.

If the player touches the bag, the commands inside the if/then block
will run. In that case, the play sound block will make a WaterDrop noise, and
the change score by 1 block (in the Data palette) will add 1 to the score.
The game is now complete. Click the green flag to test your creation!

Scr atch’S timer
Scratch maintains a timer that records how much time has passed since Scratch
was started . When you start Scratch in a Web browser, the timer will be set
to 0, and it will count up by tenths of a second as long as you keep Scratch
open . The timer block (in the Sensing palette) holds the current value of the
timer . The checkbox next to the block allows you to show/hide the block’s
monitor on the Stage . The reset timer block resets the timer to 0, and the
time starts ticking up again immediately . The timer continues to run even when
the project stops running .

Catching Apples
CatchApples_ Consider the Catching Apples game shown in Figure 2-21. In this game,
NoCode .sb2 apples appear at random horizontal positions at the top of the Stage at ran-
dom times and fall to the ground. The player has to move the cart to catch
the apples before they touch the ground, and each apple is worth 1 point.

Motion and Drawing 39

www.it-ebooks.info