python_objects_2.py

# Example for interactivedatascience.courses
# Simulation of bouncing balls with user interaction.
# License: BSD-3-Clause
# Author: A Samuel Pottinger

import sketchingpy
import time

WIDTH = 500  # pixels
HEIGHT = 400  # pixels


class Ball:

    def __init__(self, position_x, position_y, velocity_x, velocity_y):
        self.position_x = position_x
        self.position_y = position_y
        self.velocity_x = velocity_x
        self.velocity_y = velocity_y
    
    def reverse_x(self):
        self.velocity_x = self.velocity_x * -1

    def reverse_y(self):
        self.velocity_y = self.velocity_y * -1

    def update(self, duration, mouse_x, mouse_y):
        self.position_x = self.position_x + self.velocity_x * duration
        self.position_y = self.position_y + self.velocity_y * duration

        if self.position_x > WIDTH:
            self.position_x = WIDTH
            self.reverse_x()
        elif self.position_x < 0:
            self.position_x = 0
            self.reverse_x()

        if self.position_y > HEIGHT:
            self.position_y = HEIGHT
            self.reverse_y()
        elif self.position_y < 0:
            self.position_y = 0
            self.reverse_y()

        if self.get_is_near_mouse(mouse_x, mouse_y):
            if self.get_hit_mouse_in_direction(self.position_x, mouse_x, self.velocity_x):
                self.reverse_x()
            elif self.get_hit_mouse_in_direction(self.position_y, mouse_y, self.velocity_y):
                self.reverse_y()
    
    def get_is_near_mouse(self, mouse_x, mouse_y):
        x_near = abs(mouse_x - self.position_x) < 10
        y_near = abs(mouse_y - self.position_y) < 10
        return x_near and y_near
    
    def get_hit_mouse_in_direction(self, coordinate, mouse, velocity):
        if mouse > coordinate and velocity > 0:
            distance = mouse - coordinate
            return distance < 10
        elif mouse < coordinate and velocity < 0:
            distance = mouse - coordinate
            return distance > -10
        else:
            return False


class Simulation:
    
    def __init__(self):
        self.balls = [
            Ball(WIDTH / 2, HEIGHT / 2, -10, -10),
            Ball(WIDTH / 2, HEIGHT / 2, -10, 10),
            Ball(WIDTH / 2, HEIGHT / 2, 10, 0)
        ]
        self.last_time = time.time()

    def update(self, mouse_x, mouse_y):
        new_time = time.time()
        duration = new_time - self.last_time
        self.last_time = new_time

        for ball in self.balls:
            ball.update(duration, mouse_x, mouse_y)


sketch = sketchingpy.Sketch2D(WIDTH, HEIGHT)
simulation = Simulation()

def update_and_draw_balls(self):
    mouse = sketch.get_mouse()
    mouse_x = mouse.get_pointer_x()
    mouse_y = mouse.get_pointer_y()

    simulation.update(mouse_x, mouse_y)

    for ball in simulation.balls:
        sketch.draw_ellipse(ball.position_x, ball.position_y, 2, 2)

sketch.on_step(update_and_draw_balls)
sketch.show()