Lesson 9 : Game Design Python 101

Learning Target:​
I can create a sprite to represent the player, apply coding concepts to clone, loop through a list, and more, in order to program a basic game with just a couple of sprites, one of which is controlled by keyboard input.

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What Is a Sprite?

Most games have ​

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that perform actions on the screen.

We call these characters sprites. Sprites can move around the screen and ​

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. A sprite might include the player character, coins for the player to collect, and ​

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for the player to avoid. Or they can be decorations, like the ​

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of the game.Let's look at how we can create and clone sprites with the Turtle module.

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Creating a Sprite with Turtle

When working with Python's Turtle module, you can use a ​

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. In your Asteroids game, for example, the ship and the rocks were all sprites represented ​

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So you can just ​

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using ​

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as we've done before.

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Setting a Sprite's Initial Values

You can set the sprite's ​

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so that it looks and behaves exactly as you want.

Often you'll want to use the ​

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commands so that the sprite doesn't leave a trail and moves as fast as possible, ​

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Clone the Prototype

Once you've created one sprite and set its initial values in a way that you like, you can ​

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of the sprite by ​

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In this way, your original sprite acts like ​

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Any clones of the original will​

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In the example we create a prototype called sprite, then make two clones of it called actor1 and actor2 using the ​

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method.

I copied the code on the lesson sheet. Then modified it to clone turtles.
Then I assigned two different colors. Success! "Check Code" says I was successful.

Teacher's Answer:

Multiple Choice

What is a sprite?

• A sprite is a graphical representation of an object

• A sprite is a function

• A sprite is a game

• A sprite is a string

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What Are Game Loops?

Most games consist of a ​

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that are repeated constantly as the game is played.

These steps often include tasks like:

Setting and updating ​

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(their location, whether to show or hide each sprite, and so forth)

Checking on important ​

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(such as whether the game has been won or lost)

This is called a game loop. Let's see how ​

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.

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A Function That Calls Itself: Game Loop Basics

We can implement a game loop using ​ a ​

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. You'll use an update function that sets a timer that calls itself ​

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This creates a cycle in which the update( ) function is called ​

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, on a regular interval. This process of a function calling itself is a concept called ​

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This is the big idea behind the game loop.

You'll need to call the ​

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function for the first time to kick off the cycle.

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This example shows the code to set up a game loop that updates​

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. Click Run to see the output. The background may appear to ​

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, but the loop is setting the ​

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every second.

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Another Game Loop

This example is similar to the previous one, except the ​

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now switches the background to a random color ​

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.

Press​

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and see the background switch color.

​Define an update( ) function and call it to kickstart the loop.

Perform actions with the sprite in the game loop to do something interesting. Need ideas? You might change the pen's color, clone a sprite, or change the shape of a sprite.

Do It Yourself

This code has a sprite, but not much else. Try to write a game loop of your own.

Teacher's
Answer:

Multiple Choice

What is the interval of this game loop?

• Every 10 seconds

• Every 1000 seconds

• Every 1 second

• It does not loop

​More on Lists

To make more advanced games, you'll need to learn more about lists.

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Looping

The ​

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provides an effective way to loop through every entry ​

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in Python. You can provide a list to a "for" loop ​

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. Each time the "for" loop runs, the counter variable will be set ​

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Drag and Drop

Append

To add more ​

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to the list, you can use the ​

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method. Check it out:

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items

list.append( )

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Insert

Another important method is ​

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. It lets you insert an entry at any ​

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in a list. Any entries at that location or after it will be pushed up one index.

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insert( )

index

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Pop

Pop( ) ​

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at any index on the list. It returns the value at the entry​

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.

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removes an entry

it removes

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In

in is another ​

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when you're using lists. It checks if an element is ​

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and returns True or ​

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.

Drag these tiles and drop them in the correct blank above

useful tool

currently in a list

False

Let's try out all these new tools in an application. You will be given a randomly generated unsorted list.

Can you use all the list methods you just learned to sort a list of numbers from least to greatest?

​Coding Challenge: Sort a List

​Here are the steps:

• You must loop through each index of the list. For each index:

  • Loop through all earlier indices.

  • If the value at an earlier index is greater than the value at the current index:

    • Pop the value at the current index

    • Insert the popped value into the earlier index

    • Stop looking though the earlier indexes

​Teacher's
Answer

Multiple Choice

Select correct answer:

Multiple Choice

Select correct answer:

Multiple Choice

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More on Dictionaries

To make more advanced games, you'll also need to know some ​

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for manipulating dictionaries.

Keys, Values, Items

The dictionary is a ​

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that consists of key-value pairs. You can examine each component of a dictionary separately or as ​

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:

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The data returned by the values( ), keys( ), and items( ) commands cannot be edited. To change the data in a dictionary, you'll need some different commands.

Looping

You can ​

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through a dictionary in ​

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ways.

​Teacher's
Answer

Multiple Choice

Select correct answer:

• apple

• banana

• cherry

• Dictionaries require a number as a key

Multiple Choice

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