python - PYGAME - Move Character with Vector

Question

I am teaching myself pygame and am looking at making my character able to rotate and then move in the direction they are facing.

I can do the rotation but cannot get the character to move in the direction the image is then facing.

The code is on Trinket HERE

class Bob(pygame.sprite.Sprite):
  def __init__(self, color , height , width):
    super().__init__()
    self.image = pygame.Surface([width , height])
    self.image.fill(BLACK)
    self.image.set_colorkey(BLACK)
    
    #Loading the image for the character
    self.img = pygame.image.load("char.jfif")
    #creating a copy of the image
    self.img_orig = self.img.copy()
    #defining the starting angle of the character image
    self.angle = 0
    
    self.velocity = 5
    self.rect = self.img_orig.get_rect()
    
  def moveLeft(self):
    self.angle += 1
    self.img = pygame.transform.rotate(self.img_orig, self.angle)
      
  def moveRight(self):
    self.rect.x += self.velocity
    if self.rect.x > 485:
      self.rect.x = 485

while run:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            run = False
            
    keys = pygame.key.get_pressed()
    if keys[pygame.K_UP]:
      pSprite.moveForward()
    if keys[pygame.K_DOWN]:
      pSprite.moveDown()
    if keys[pygame.K_LEFT]:
      pSprite.moveLeft()
    if keys[pygame.K_RIGHT]:
      pSprite.moveRight()

    #---- Game Logic Here
    
      
    #--- Drawing Code Here
    #Reset the screen to blank
    screen.fill(BLUE)
    #Draw Play Area
    
    #Draw Sprites
    screen.blit(pSprite.img,(pSprite.rect.x, pSprite.rect.y))

Answer 1

You can use pygame's Vector2 class instead of calculating the position of your sprite yourself.

I also suggest to let the sprite itself handle its movement instead of doing so in the main loop and using a clock for constant framerates and easy control of the speed of your sprites.

You also probably want to use an image format with alpha channel (like PNG).

Here's a simple example:

import pygame

class Actor(pygame.sprite.Sprite):
    def __init__(self, pos, *grps):
        super().__init__(*grps)
        self.image = pygame.image.load('char.png').convert_alpha()
        self.image_org = self.image.copy()
        self.rect = self.image.get_rect(center=pos)
        self.pos = pygame.Vector2(pos)
        self.direction = pygame.Vector2((0, -1))
        
    def update(self, events, dt):
        pressed = pygame.key.get_pressed()
        
        # if a is pressed, rotate left with 360 degress per second
        if pressed[pygame.K_a]: self.direction.rotate_ip(dt * -360) 
        # if d is pressed, rotate right with 360 degress per second
        if pressed[pygame.K_d]: self.direction.rotate_ip(dt *  360)

        # check if should move forward or backward
        movement = 0
        if pressed[pygame.K_w]: movement =  1
        if pressed[pygame.K_s]: movement = -1
        movement_v = self.direction * movement
        if movement_v.length() > 0:
            movement_v.normalize_ip()
            # move 100px per second in the direction we're facing
            self.pos += movement_v * dt * 100
        
        # rotate the image
        self.image = pygame.transform.rotate(self.image_org, self.direction.angle_to((0, -1)))
        self.rect = self.image.get_rect(center=self.pos)
        

def main():
    pygame.init()
    screen = pygame.display.set_mode((600, 480))
    sprites = pygame.sprite.Group()
    Actor((100, 100), sprites)
    clock, dt = pygame.time.Clock(), 0
    while True:
        events = pygame.event.get()
        for e in events:
            if e.type == pygame.QUIT:
                return
        screen.fill('grey')
        sprites.draw(screen)
        sprites.update(events, dt)
        pygame.display.flip()
        dt = clock.tick(60) / 1000
main()

char.png