How i can remove the black background on my sprite sheet in pygame

Question:

I’m trying to learn how use sprite sheets on pygame , and on my first try my sprite for some reason have a black background , i don’t know how i can fix this problem , i alredy put 000 on the color key but when i do this the sprite be all buggy

import pygame


class Spritesheet(pygame.sprite.Sprite):
def __init__(self, filename, *groups):
    super().__init__(*groups)
    self.filename = filename
    self.spritesheet = pygame.image.load(filename).convert()

def get_sprite(self, x, y, w, h):
    sprite = pygame.Surface((w, h))
    sprite.set_colorkey(( 0 , 0 , 0))
    sprite.blit(self.spritesheet, (0, 0), (x, y, w, h))
    return sprite

    pass

colorkey 0 0 0

colorkey with any number

Asked By: Juw

||
Source

Answers:

Do not set the color key and remove the line:

sprite.set_colorkey(( 0 , 0 , 0))

But use convert_alpha() instead of convert()

self.spritesheet = pygame.image.load(filename).convert()

self.spritesheet = pygame.image.load(filename).convert_alpha()

The pygame documentation notes that:

The returned Surface will contain the same color format, colorkey and alpha transparency as the file it came from. You will often want to call convert() with no arguments, to create a copy that will draw more quickly on the screen.
For alpha transparency, like in .png images, use the convert_alpha() method after loading so that the image has per pixel transparency.

So if you call convert(), the alpha information per pixel is lost and the image is given an opaque background.

When you blit the image on a new surface, the target surface must provide a per pixel alpha format. Create a surface with an alpha channel per pixel using the SRCALPHA flag:

sprite = pygame.Surface((w, h))

sprite = pygame.Surface((w, h), pygame.SRCALPHA)

Spritesheet class:

class Spritesheet(pygame.sprite.Sprite):
    def __init__(self, filename, *groups):
        super().__init__(*groups)
        self.filename = filename
        self.spritesheet = pygame.image.load(filename).convert_alpha()

    def get_sprite(self, x, y, w, h):
        sprite = pygame.Surface((w, h), pygame.SRCALPHA)
        sprite.blit(self.spritesheet, (0, 0), (x, y, w, h))
        return sprite

Also see:

Answered By: Rabbid76

What happened?

Assuming your sprite (although you not yet posted the original file sprite.png) uses an Alpha-Channel for transparency, like similar image of Boyfriend of Friday Night Funkin:

Boyfriend image transparent

You apparently set the colorkey to a color which is present in the sprite (black with RGB 0,0,0).

See the PyGame docs on set_colorkey:

Set the current color key for the Surface. When blitting this Surface onto a destination, any pixels that have the same color as the colorkey will be transparent. The color can be an RGB color or a mapped color integer. If None is passed, the colorkey will be unset.

Thus all the contours (eyes, lips, hears, grid on the microphone, key-laces), which were drawn in black in your sprite, disappeared in new alpha-blended transparency.

You could try any other dominant color of your sprite, like red or white as colorkey and see what else disappears. Or you could set the colorkey to None to unset it.

Extending the Sprite class

Maybe you can gain additional advice on extending the pygame.sprite.Sprite class for your game-objects like explained in Real Python’s PyGame tutorial series:

Erase background with a special color

And for the background eraser to make unimportant parts transparent, this Thread in Python Forum recommends the a rare special color like pink:
Loading images, transparency, handling spritesheets (part 2)

Answered By: hc_dev