How to fix Type Error in Pygame: TypeError: unsupported operand type(s) for +=: 'int' and 'pygame.math.Vector2'

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I am trying to build the border for my pygame (by following a youtube tutorial) and I've encountered an error that I need help to understand. I've tried to fix it but the error remains. Here is my code:

import pygame, sys, time, random, colorsys, math
from pygame.math import Vector2
from pygame.locals import *


def main():
    x = 100
    y = 100
    velocity = 0
    acceleration = 0.1

    # Initialize the pygame
    pygame.init()

    # Create the screen
    DISPLAY = pygame.display.set_mode((500, 400), 0, 32)

    # Title and Icon
    pygame.display.set_caption('Dragon')
    icon = pygame.image.load('dragon.png')
    pygame.display.set_icon(icon)

    velocity = pygame.Vector2()
    velocity.xy = 3, 0

    WHITE=(255, 255, 255)
    BLUE=(0, 0, 255)

    DISPLAY.fill(WHITE)


    while True:
        keys = pygame.key.get_pressed()
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                pygame.quit()
                sys.exit()
        DISPLAY.fill((255, 255, 255))
        pygame.draw.rect(DISPLAY, BLUE, (x, y, 50, 50))
        x += velocity.x
        if x + 50 > DISPLAY.get_width():
            velocity.x = -3
        if x < 0:
            velocity.x = 3
        y += velocity
        velocity += acceleration
        if keys[pygame.K_a]:
            velocity = -3
        pygame.display.update()
        pygame.time.delay(10)
main()

And when I click run, the error is:

 line 51, in <module>
 main()
 line 45, in main
    y += velocity
TypeError: unsupported operand type(s) for +=: 'int' and 'pygame.math.Vector2'
pygame python
2 Answers

You can greatly simplify the code by using pygame.math.Vector2 objects for position, velocity and acceleration:

position = pygame.Vector2(100, 100)
velocity = pygame.Vector2(3, 0)
acceleration = pygame.Vector2(0, 0.1)

The position is changed by the velocity and the velocity is changed by the acceleration:

position += velocity
velocity += acceleration

Complete example:

import pygame, sys

def main():
    position = pygame.Vector2(100, 100)
    velocity = pygame.Vector2(3, 0)
    acceleration = pygame.Vector2(0, 0.1)

    # Initialize the pygame
    pygame.init()

    # Create the screen
    DISPLAY = pygame.display.set_mode((500, 400), 0, 32)

    # Title and Icon
    pygame.display.set_caption('Dragon')
    icon = pygame.image.load('dragon.png')
    pygame.display.set_icon(icon)

    WHITE = (255, 255, 255)
    BLUE = (0, 0, 255)

    clock = pygame.time.Clock()
    run = True
    while run:
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                run = False
            if event.type == pygame.KEYDOWN:
                if event.key == pygame.K_a:
                    velocity.y = -3            

        position += velocity
        velocity += acceleration
        if position.y + 50 > DISPLAY.get_height():
            position.y = DISPLAY.get_height() - 50
        if position.x + 50 > DISPLAY.get_width():
            position.x = 0

        DISPLAY.fill(WHITE)
        pygame.draw.rect(DISPLAY, BLUE, (round(position.x), round(position.y), 50, 50))
        pygame.display.update()
        clock.tick(100)

    pygame.quit()
    sys.exit()
main()
user_55777650

You have two mistakes in these lines:

        y += velocity
        velocity += acceleration

y is an int, velocity is a pygame.math.Vector2 and acceleration is a float.

I think you would like to have e.g.

        y += velocity.y
        velocity.y += acceleration

Pro tip: Use pygame.math.Vector2 for position, velocity and acceleration to allow code like:

>>> dt = 0.1
>>> position = pygame.math.Vector2(0, 0)
>>> velocity = pygame.math.Vector2(3, 0)
>>> position += dt * velocity
>>> position
<Vector2(0.3, 0)>
user_121185460
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