Getting Started with 2D Games Using Pyxel (Part 5): Creating Characters with Classes

Source: Dev.to

Characters that appear in a game are commonly referred to as sprites.
In this chapter we will use classes to prepare a common base class for sprites.

You might feel that “classes sound difficult…” at first, but for now the goal is simply to treat a character as a single reusable component.

The complete code is shown at the end of this article.

1. Prepare the Sprite Module

Create a new file named sprite.py and place it in your working folder.
The folder structure should look like this:

# Folder structure
working_folder/
 ├─ main.py
 ├─ sprite.py   # sprite module
 └─ shooter.pyxres

2. Create a Common Sprite Base Class

In sprite.py define a class named BaseSprite. This class will serve as the common base class for all sprites.

# sprite.py (excerpt)

import pyxel
import math
import random

class BaseSprite:
    def __init__(self, x, y, w=8, h=8):
        """Constructor"""
        self.x = x          # X coordinate
        self.y = y          # Y coordinate
        self.w = w          # Image width
        self.h = h          # Image height

    def update(self):
        """Update logic"""
        pass

    def draw(self):
        """Drawing logic (implemented in subclasses)"""
        pass

3. Create the Player Class

Add a ShipSprite class to sprite.py. This class inherits from BaseSprite and will be used to create the player character.

# sprite.py (excerpt)

# …previous code…

class ShipSprite(BaseSprite):
    def __init__(self, x, y):
        """Constructor"""
        super().__init__(x, y)

    def draw(self):
        """Drawing logic"""
        pyxel.blt(
            self.x, self.y, 0,
            0, 0,
            self.w, self.h, 0
        )  # Ship

4. Use the Player Class

We will integrate the player class inside the Game class in main.py in three steps.

4‑1. Initialize the Player

Create a player object in the constructor of the Game class.

# main.py (excerpt)

# Initialize the player (placed near the bottom‑center of the screen)
self.ship = sprite.ShipSprite(W / 2, H - 40)

4‑2. Update the Player

Update the player object in the update() method of the Game class.
(At this stage the player does not move yet.)

# main.py (excerpt)

# Update the player
self.ship.update()

4‑3. Draw the Player

Draw the player object in the draw() method of the Game class.

# main.py (excerpt)

# Draw the player
self.ship.draw()

Complete Code

Below is the full code with all features implemented so far.

sprite.py

import pyxel
import math
import random

class BaseSprite:
    def __init__(self, x, y, w=8, h=8):
        """Constructor"""
        self.x = x          # X coordinate
        self.y = y          # Y coordinate
        self.w = w          # Image width
        self.h = h          # Image height
        self.vx = 0         # Velocity (X direction)
        self.vy = 0         # Velocity (Y direction)

    def update(self):
        """Update logic"""
        self.x += self.vx   # Move in X direction
        self.y += self.vy   # Move in Y direction

    def draw(self):
        """Drawing logic (implemented in subclasses)"""
        pass

class ShipSprite(BaseSprite):
    def __init__(self, x, y):
        """Constructor"""
        super().__init__(x, y)

    def draw(self):
        """Drawing logic"""
        pyxel.blt(
            self.x, self.y, 0,
            0, 0,
            self.w, self.h, 0
        )  # Ship

main.py

import pyxel
import math
import random
import sprite   # Import the sprite module

W, H = 160, 120

# Game
class Game:
    def __init__(self):
        """Constructor"""

        # Initialize score
        self.score = 0

        # Initialize player
        self.ship = sprite.ShipSprite(W / 2, H - 40)

        # Start Pyxel
        pyxel.init(W, H, title="Hello, Pyxel!!")
        pyxel.load("shooter.pyxres")
        pyxel.run(self.update, self.draw)

    def update(self):
        """Update logic"""

        # Update player
        self.ship.update()

    def draw(self):
        """Drawing logic"""
        pyxel.cls(0)

        # Draw score
        pyxel.text(
            10, 10,
            "SCORE:{:04}".format(self.score),
            12
        )

        # Draw player
        self.ship.draw()

def main():
    """Main entry point"""
    Game()

if __name__ == "__main__":
    main()

When you run this program, the result will look like this:

Coming Up Next…

Thank you for reading this chapter. The next title will cover … (continue as needed).

e is “Let’s Move the Character.”

See you next time!