pygame sprite wall collision

Question

I am working on a platform game in python and pygame. The entire code can be found at \"https://github.com/C-Kimber/FBLA_Game\". The issue I am having is with the collision

Answer 1

The easiest way to handle collisions with walls is to move the player rect or sprite along the x-axis first, check if it collides with a wall and then set its self.rect.right = wall.rect.left if it's moving to the right or self.rect.left = wall.rect.right if it's moving to the left. Afterwards you do the same with the y-axis. You have to do the movement separately, otherwise you wouldn't know the direction and how to reset the position of the rect.

import pygame as pg
from pygame.math import Vector2


class Player(pg.sprite.Sprite):

    def __init__(self, x, y, walls):
        super().__init__()
        self.image = pg.Surface((30, 50))
        self.image.fill(pg.Color('dodgerblue1'))
        self.rect = self.image.get_rect(center=(x, y))
        self.pos = Vector2(x, y)  # Position vector.
        self.vel = Vector2(0, 0)  # Velocity vector.
        self.walls = walls  # A reference to the wall group.

    def update(self):
        self.pos += self.vel
        self.wall_collisions()

    def wall_collisions(self):
        """Handle collisions with walls."""
        self.rect.centerx = self.pos.x
        for wall in pg.sprite.spritecollide(self, self.walls, False):
            if self.vel.x > 0:
                self.rect.right = wall.rect.left
            elif self.vel.x < 0:
                self.rect.left = wall.rect.right
            self.pos.x = self.rect.centerx

        self.rect.centery = self.pos.y
        for wall in pg.sprite.spritecollide(self, self.walls, False):
            if self.vel.y > 0:
                self.rect.bottom = wall.rect.top
            elif self.vel.y < 0:
                self.rect.top = wall.rect.bottom
            self.pos.y = self.rect.centery


class Wall(pg.sprite.Sprite):

    def __init__(self, x, y, w, h):
        super().__init__()
        self.image = pg.Surface((w, h))
        self.image.fill(pg.Color('sienna1'))
        self.rect = self.image.get_rect(topleft=(x, y))


def main():
    screen = pg.display.set_mode((640, 480))
    clock = pg.time.Clock()

    all_sprites = pg.sprite.Group()
    walls = pg.sprite.Group()

    wall = Wall(100, 200, 300, 30)
    wall2 = Wall(230, 70, 30, 300)
    walls.add(wall, wall2)
    all_sprites.add(wall, wall2)

    player = Player(300, 300, walls)
    all_sprites.add(player)

    done = False

    while not done:
        for event in pg.event.get():
            if event.type == pg.QUIT:
                done = True

        keys = pg.key.get_pressed()
        if keys[pg.K_w]:
            player.vel.y = -3
        elif keys[pg.K_s]:
            player.vel.y = 3
        else:
            player.vel.y = 0
        if keys[pg.K_a]:
            player.vel.x = -3
        elif keys[pg.K_d]:
            player.vel.x = 3
        else:
            player.vel.x = 0

        all_sprites.update()
        screen.fill((30, 30, 30))
        all_sprites.draw(screen)

        pg.display.flip()
        clock.tick(30)


if __name__ == '__main__':
    pg.init()
    main()
    pg.quit()

Answer 2

elif self.rect.top <= block.rect.bottom and self.rect.top >= block.rect.bottom - 15:  # Moving up; Hit the bottom side of the wall
        self.rect.top = block.rect.bottom
        self.yvel = 0

Shouldn't yvel be set to a positive number to make it go up?

Answer 3

Thank you to user sloth! The question he linked gave me some much needed clarity. It took me a bit but I implemented it. I created a function for the collision.

def wallColl(self, xvel, yvel, colliders):
    for collider in colliders:
        if pygame.sprite.collide_rect(self, collider):
            if xvel > 0:
                self.rect.right = collider.rect.left
                self.xvel = 0
            if xvel < 0:
                self.rect.left = collider.rect.right
                self.xvel = 0
            if yvel < 0:
                self.rect.bottom = collider.rect.top
                self.onGround = True
                self.jumps = 3
                self.yvel = 0
            if yvel > 0:
                self.yvel = 0
                self.rect.top = collider.rect.bottom

And then I call them in my update function.

def update(self):
    self.rect.x += self.xvel
    # self.walls is an array of sprites.
    self.wallColl(self.xvel, 0, self.walls) 

    self.rect.y -= self.yvel
    self.onGround = False
    self.wallColl(0, self.yvel, self.walls)

    self.wallCollisions()
    if self.otherplayers != None:
        self.playerCollisions()

    # Gravity
    if self.onGround == False:
        self.yvel-=.0066*self.mass

    self.boundries(highbound, lowbound, leftbound, rightbound)
    self.down = False

The actual useage in my game makes usability near perfect. Not 100% though, this is not a perfect answer.