How to prevent fast moving objects passing through statics when calculating pi with colliding blocks

Question

I am trying to implement a similar program to the following in Python using Pymunk and Pyglet. My current implementation works well at low velocities however at high speeds the block can pass through the static wall. This because in 1/60s clock cycle the block moves further than the thickness of the wall. I have seen others solve this by having a limiting speed however in my case this would not work as the velocity is important to calculate the value for PI. I would like to know if there is any way of preventing this from happening.

import pyglet
import pymunk


class Block:
    """
    The class for a block
    Mass: the mass the block
    X: Initial x position
    Y: Initial y position
    PhysSpace: The physics space to add items to
    RenderBatch: Batch to add block to
    """

    def __init__(self, Mass, X, Y, PhysSpace, RenderBatch):
        # Create body with given mass and infinite moment of inertia
        self.Body = pymunk.Body(Mass, pymunk.inf)
        # Set Body's position
        self.Body.position = X, Y
        # Create shape for body
        BodyShape = pymunk.Poly.create_box(self.Body, size=(50, 50))
        # Define shapes elasticity
        BodyShape.elasticity = 1
        # Add block to the physics space
        PhysSpace.add(self.Body, BodyShape)

        # Import block image
        BlockImg = pyglet.image.load('res/sqr.png')
        # Set anchor point of image to be the centre
        BlockImg.anchor_x = BlockImg.width // 2
        BlockImg.anchor_y = BlockImg.height // 2
        # Create sprite for block
        self.BlockSprite = pyglet.sprite.Sprite(BlockImg, x=self.Body.position.x, y=self.Body.position.y,
                                                batch=RenderBatch)

    def update(self):
        # Set the position of the sprite to be equal to the position of the physics body
        self.BlockSprite.position = self.Body.position

    def give_velocity(self, velocity):
        # Set velocity of the body
        self.Body.velocity = (velocity, 0)


class Simulation(pyglet.window.Window):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)

        # Set background to be clear
        pyglet.gl.glClearColor(1, 1, 1, 1)
        # Set clock speed
        pyglet.clock.schedule_interval(self.update, 1/60)

        # Create batch to draw all the graphics with
        self.Batch = pyglet.graphics.Batch()

        # Create Title Label
        self.TitleLabel = pyglet.text.Label(text='Block Collision Simulator', x=self.width / 2, y=self.height - 20,
                                            batch=self.Batch, anchor_x='center', anchor_y='center', font_size=24,
                                            color=(0, 0, 0, 255))
        self.Counter = -2
        self.CounterLabel = pyglet.text.Label('Counter = 0'.format(self.Counter), x=self.width / 2, y=self.height - 60, anchor_x='center',
                                              anchor_y='center', font_size=24, color=(0, 0, 0, 255), batch=self.Batch)

        # Initiate space for Physics engine
        self.Space = pymunk.Space()
        self.Handler = self.Space.add_default_collision_handler()
        self.Handler.begin = self.coll_begin

        # Create the ground in physics engine
        Ground = pymunk.Poly.create_box(self.Space.static_body, size=(self.width, 20))
        Ground.body.position = self.width / 2, 10
        self.Space.add(Ground)

        # Create the sprite for the ground
        GroundImg = pyglet.image.load('res/ground.png')
        self.GroundSprite = pyglet.sprite.Sprite(GroundImg, x=0, y=0, batch=self.Batch)

        # Create Wall in physics engine
        Wall = pymunk.Poly.create_box(self.Space.static_body, size=(20, self.height))
        Wall.body.position = 10, self.height / 2
        Wall.elasticity = 1
        self.Space.add(Wall)

        # Create the sprite for the wall
        WallImg = pyglet.image.load('res/wall.png')
        self.WallSprite = pyglet.sprite.Sprite(WallImg, x=0, y=0, batch=self.Batch)

        self.BlockRight = Block(10000, 2 * (self.width / 3), 45, self.Space, self.Batch)
        self.BlockRight.give_velocity(-100)

        self.BlockLeft = Block(1, self.width / 3, 45, self.Space, self.Batch)

        pyglet.app.run()

    def coll_begin(self, arbiter, space, data):
        self.Counter += 1
        if self.Counter > 0:
            self.CounterLabel.text = 'Counter: {}'.format(self.Counter)
        return True

    def on_draw(self):
        self.clear()
        self.Batch.draw()

    def update(self, dt):
        self.Space.step(dt)
        self.BlockRight.update()
        self.BlockLeft.update()

Answer 1

One way is as you write to limit the velocity. Another way is to call the step function with a smaller dt. (On the same note, you should almost always use a fixed value for the dt, that will help to keep the simulation stable).

One way to use smaller dt is to call the step function multiple times for each call to the update function. So you can try something like this:

def update(self, dt):
    for _ in range(10):
        self.Space.step(dt/10)
    #self.Space.step(dt)
    self.BlockRight.update()
    self.BlockLeft.update()