Sparkles

This game demonstrates how to have objects that:

• Have a velocity and deceleration

• Move at an angle using sine and cosine

DataclassesDictionaries

from designer import *
from dataclasses import dataclass
import math
import random

# Determines how fast the sparkles slow down
DECELERATION = .5
# Determines how big the spark is
SPARK_SIZE = 5

@dataclass
class Spark:
    """
    Sparks are little circles with an angle and velocity
    """
    image: DesignerObject
    velocity: float

@dataclass
class World:
    """
    The world is composed of just sparks. We could have used
    a list directly as our World, but its conventional to always
    have a World class, in case you want to add more things
    to your world later in development!
    """
    sparks: list[Spark]


def create_world() -> World:
    """ Creates a world without any sparks """
    return World([])


def create_spark(x: int, y: int) -> Spark:
    """ Create a single spark of a rainbow color """
    # Pick a random color from among choices
    color = random.choice(['red', 'yellow', 'orange', 'blue', 'green', 'purple'])
    spark_image = circle(color, SPARK_SIZE)
    # Partially transparent
    spark_image.alpha = .5
    # Rotate randomly 360 degrees
    spark_image.angle = random.randint(0, 360)
    # Move to the mouse location
    spark_image.x = x
    spark_image.y = y
    # Random velocity between 7 and 10
    velocity = random.randint(7, 10)
    # Actually make the Spark
    return Spark(spark_image, velocity)


def make_sparks(world: World):
    """ Make a new spark where ever the mouse is """
    # Get the current mouse x/y
    x = get_mouse_x()
    y = get_mouse_y()
    # Create spark at that location
    world.sparks.append(create_spark(x, y))


def move_sparks(world: World):
    """ Move each spark according to its velocity and angle """
    # For each spark
    for spark in world.sparks:
        # Get the velocity
        velocity = spark.velocity
        # Calculate their angle in radians (0 to 2pi)
        angle = math.radians(spark.image.angle)
        # Increase X by cosine of the angle times velocity
        spark.image.x += math.cos(angle) * velocity
        # Decrease Y by sine of the angle times velocity
        spark.image.y -= math.sin(angle) * velocity
        # Decrease velocity by the deceleration amount
        spark.velocity -= DECELERATION


def delete_stopped_sparks(world: World):
    """ Filter out all sparks that aren't moving """
    kept = []
    # Go through all the sparks
    for spark in world.sparks:
        # Is the spark still moving?
        if spark.velocity > 0:
            # Keep this spark
            kept.append(spark)
    # Update sparks list with our kept list
    world.sparks = kept

# Bind the events
when('starting', create_world)
when('updating', make_sparks)
when('updating', move_sparks)
when('updating', delete_stopped_sparks)
# Start the animation!
start()