Page 86 - Programming the Raspberry Pi Getting Started with Python

Note that because the condition for the if is so long, we use the line-continuation command (\) to
break it into two lines.
The function check_for_catch adds 1 to the score if the raspberry has fallen as far as the spoon
(raspberry_y >= spoon_y) and the x position of the raspberry is between the x (left) position of the
spoon and the x position of the spoon plus 50 (roughly the width of the business end of the spoon).
Regardless of whether the raspberry is caught, the score is displayed using the display function.

The check_for_catch function is also added into the main loop as one more thing we must do each
time around the loop.
The ‘display’ function is responsible for displaying a message on the screen.

You write text on the screen in pygame by creating a font, in this case, of no specific font family

but of a 36-point size and then create a text object by rendering the contents of the string message
onto the font. The value (10, 10, 10) is the text color. The end result contained in the variable text
can then be blitted onto the screen in the usual way.

Timing
You may have noticed that nothing in this program controls how fast the raspberries fall from the sky.
We are lucky in that they fall at the right sort of speed on a Raspberry Pi. However, if we were to run
this game on a faster computer, they would probably fly past far too fast to catch.
To manage the speed, pygame has a built-in clock that allows us to slow down our main loop by just
the right amount to perform a certain number of refreshes per second. Unfortunately, it can’t do
anything to speed up our main loop. This clock is very easy to use; you simply put the following line
somewhere before the main loop:

This creates an instance of the clock. To achieve the necessary slowing of the main loop, put the
following line somewhere in it (usually at the end):

In this case, we use a value of 30, meaning a frame rate of 30 frames per second. You can put a
different value in here, but the human eye (and brain) do not register any improvement in quality
above about 30 frames per second.
Lots of Raspberries
Our program is starting to look a little complex. If we were to add the facility for more than one
raspberry at this stage, it would become even more difficult to see what is going on. We are therefore

going to perform refactoring, which means changing a perfectly good program and altering its
structure without changing what it actually does or without adding any features. We are going to do
this by creating a class called Raspberry to do all the things we need a raspberry to do. This still
works with just one raspberry, but will make working with more raspberries easier later. The code
listing for this stage can be found in the file 08_05_rasp_game_refactored.py. Here’s the class
definition: