Summary

Things You Have Learn Today

1. How to create a single costume sprite
2. Three types of events
   • when_game_start
   • when_this_sprite_clicked
   • when_backdrop_switched
3. Flow Control
   • Using loops with yield
   • Using if/else with Boolean variables (hexagon blocks)
4. Shared Variables (and the display)
5. Backdrop & Sound
6. Most of the functions that correspond to a Scratch block except
   • Those that reference to other sprites (day 2)
   • The other events that hasn’t been mentioned yet (day 3)

Yet to Learn

• Sprites with multiple costume
• Blocks that references to another sprite (such as is_touching)
• Other events

Exercises: Improve the Game

1. Add a targeting crosshair to the cursor

Easy - LV1

• Put the crosshair image to the asset folder
• Create the sprite with the image and import it to main.py
• Add a when_game_start event, with a forever loop:
  • Move the sprite to the cursor
  • Yield for one frame (or 1/60 second)
• Optional: Bring the sprite to the front layer in the when_game_start event before the loop

Optional: Add these two lines on the top of `main.py` to hide the mouse

import pygame
pygame.mouse.set_visible(False)

Outcome

2. Add visual and audio effects for clicking the friend

Easy - LV1

• Put a audio file to the asset folder
• Add a when_this_sprite_clicked event for the friend
  • Play the sound
  • In a repeat (for) loop, flash the friend by showing and hiding it.

Outcome

3. Add words at the end of the game

Intermediate - LV2

• Create an image with the word “You Lose” or “Game Over” using Piskel
• Create a sprite with the image and hide it on game start
• Show the sprite when the game switch to the backdrop "lose"

Outcome

4. Spin the enemy when clicked

Hard - LV3

To spin the enemy, you need to increment the enemy’s direction inside the repeat loop of the when_this_sprite_clicked event.

However, we already have a forever loop that continuously changes the enemy’s direction to control its movements. This will intervene the spinning of the enemy.

Therefore, you need to create a shared variable to tell your forever loop not to change the enemy’s direction when you are spinning the enemy.

Detailed Instruction

• Create a shared variable "spinning", default to False
• In the when_this_sprite_clicked event,
  • Set "spinning" to True
  • Turn the enemy by incrementing the direction inside the repeat loop (for loop)
  • Set "spinning" back to False
• In the event where you move the enemy
  • If "spinning" is True, do not run point_towards_mouse and the related logics.

Outcome

5. Add a perk that you can click to slow down the enemy

Hard - LV3

• Create a sprite when the any desired image
• Create a shared variable called "speed_multiplier", default to 1.0
• In a when_this_sprite_clicked event
  • Hide the sprite
  • Move the sprite to a random location
  • Multiply "speed_multiplier" by 0.9
• In a when_game_start event, with a forever loop
  • Yield for a random amount of time
  • Show the sprite
• In the event where you move the enemy
  • Multiple the enemy’s speed by "speed_multiplier"

Outcome