Lesson 5

Download and extract the image files below.

img.zip

Decomposition

What are the components of the “Gem Catching” game?
How does the player interact with the game?
Can we make this game with our existing knowledge?
What is missing?
What could we add to make the game more interesting?

Functions

A function defines a procedure that we “call” to execute at a different location in our program. In Python, functions start with the def keyword to signify the definition of a new function, followed by the function name, the function arguments, and the code that we want the function to execute.

For example:

def create_gem():
    window.create_sprite(Gem)

The `Scheduler` Class

Pycat includes a Scheduler class to call a function repeatedly at a fixed time interval. For example, if we want to execute our create_gem function every second, we can write:

from pycat.core import Scheduler

Scheduler.update(create_gem, 1)

The `Sprite`’s `delete()` method

To delete a sprite from the window, use the delete() method.

if self.is_touching_sprite(cat):
    self.delete()

Randomization

You can use the random module to generate random numbers.

from random import randint
randint(1, 5)

The Sprite class also has a method to set a sprite’s position to a random x-y location in the window.

def on_create(self):
    self.goto_random_position()