How to add moving platforms in PyGame

Prerequisite: Drawing in Pygame

In this article, we will learn how we can add moving platforms to our game using PyGame in Python.

Creating a Platform

We can easily create any type of platform in pygame using the draw( ) method. For this, we will create react with specific width and height using the draw.rect() function.

Syntax: pygame.draw.rect(surface, color, rect, width)

Parameters:

• surface : Here we can pass the surface on which we want to draw our rectangle.
• color : Here we can pass the color for our rectangle.
• rect : Here we can pass the rectangle, position, and dimensions.
• width : Here we can pass the line thickness. we can also create a solid rectangle by changing the value of this width parameter.

Code:

Python3

# Importing the pygame module
import pygame
from pygame.locals import *

# Initiate pygame and give permission
# to use pygame's functionality
pygame.init()

# Create a display surface object
# of specific dimension
window = pygame.display.set_mode((600,600))

# Creating a new clock object to
# track the amount of time
clock = pygame.time.Clock()

# Starting coordinates of the platform
x = 100
y = 150

# Creating a rect with width
# and height
rect = Rect(x, y, 200, 50)

# Creating a boolean variable that
# we will use to run the while loop
run = True

# Creating an infinite loop
# to run our game
while run:

    # Setting the framerate to 30fps
    clock.tick(30)

    # Drawing the rect on the screen using the
    # draw.rect() method
    pygame.draw.rect(window, (255, 0, 0),rect)

    # Updating the display surface
    pygame.display.update()

    # Filling the window with white color
    window.fill((255,255,255))

Output:

Moving the Platform

To move the platform we can create a velocity variable with some numeric value and we can add that velocity to the x coordinate of our platform. After that, we will multiply the velocity variable with -1 if its x coordinate is less than 100 or greater than or equal to 300.

Code:

Python3

# Importing the pygame module
import pygame
from pygame.locals import *

# Initiate pygame and give permission
# to use pygame's functionality
pygame.init()

# Create a display surface object
# of specific dimension
window = pygame.display.set_mode((600,600))


# Creating a new clock object to
# track the amount of time
clock = pygame.time.Clock()

# Variable to store the
# velocity of the platform
platform_vel = 5

# Starting coordinates of the platform
x = 100
y = 150

# Creating a rect with width
# and height
rect = Rect(x, y, 200, 50)

# Creating a boolean variable that
# we will use to run the while loop
run = True


# Creating an infinite loop
# to run our game
while run:

    # Setting the framerate to 30fps
    clock.tick(30)

    # Multiplying platform_vel with -1
    # if its x coordinate is less than 100
    # or greater than or equal to 300.
    if rect.left >=300 or rect.left<100:
        platform_vel*= -1

    # Adding platform_vel to x
    # coordinate of our rect
    rect.left += platform_vel

    # Drawing the rect on the screen using the
    # draw.rect() method
    pygame.draw.rect(window, (255,   0,   0),rect)

    # Updating the display surface
    pygame.display.update()

    # Filling the window with white color
    window.fill((255,255,255))

Output:

Adding Player Sprite and Collision

Now we are going to add our player and collision between our player and platform. For this, we are using colliderect() method.

Syntax: pygame.Rect.colliderect(rect1 , rect2)

Parameters: It will take two rects as its parameters.

Returns true if any portion of either rectangle overlap.

If the player is colliding with the platform then we will set the coordinate of player bottom equal to the top of the platform and then we will add the platform velocity. We are also creating a gravity variable.

Code:

Python3

# Importing the pygame module
import pygame
from pygame.locals import *

# Initiate pygame and give permission
# to use pygame's functionality
pygame.init()

# Create a display surface object
# of specific dimension
window = pygame.display.set_mode((600,600))

# Creating a new clock object to
# track the amount of time
clock = pygame.time.Clock()

# Variable to store the
# velocity of the platform
platform_vel = 5

# Starting coordinates of the platform
x = 100
y = 150

# Starting coordinates for
# player sprite
player_x = 180
player_y = 0

# Creating a new variable
# for gravity
gravity = 8

# Creating a new rect for player
player_rect = Rect(player_x, player_y, 50, 50)

# Creating a rect with width
# and height
rect = Rect(x, y, 200, 50)

# Creating a boolean variable that
# we will use to run the while loop
run = True

# Creating an infinite loop
# to run our game
while run:

    # Setting the framerate to 30fps
    clock.tick(30)

    # Multiplying platform_vel with -1
    # if its x coordinate is less than 100
    # or greater than or equal to 300.
    if rect.left >=300 or rect.left<100:
        platform_vel*= -1

    # Checking if player is colliding
    # with platform or not using the
    # colliderect() method.
    # It will return a boolean value
    collide = pygame.Rect.colliderect(rect, player_rect)

    # If player is colliding with
    # platform then setting coordinate
    # of player bottom equal to top of platform
    # and adding the platform velocity
    if collide:
        player_rect.bottom = rect.top
        player_rect.left += platform_vel

    # Adding platform_vel to x
    # coordinate of our rect
    rect.left += platform_vel

    # Adding gravity
    player_rect.top += gravity

    # Drawing the rect on the screen using the
    # draw.rect() method
    pygame.draw.rect(window, (255,   0,   0),rect)

    # Drawing player rect
    pygame.draw.rect(window, (0,   255,   0),player_rect)

    # Updating the display surface
    pygame.display.update()

    # Filling the window with white color
    window.fill((255,255,255))

Output: