Transparent Sprites in Pygame - python

I'm working on some Python code that uses Pygame, trying to display a small sprite (a ball) on top of a background. I have that part working, but I'm trying to get the background of the ball sprite to be transparent so it doesn't show up as a "ball within a black square" sprite, but instead shows up with the black pixels not being blitted to the display surface.
Here is my code:
# For sys.exit()
import sys
# Pygame imports
import pygame
from pygame.locals import *
# Initialize all the Pygame Modules
pygame.init()
# Build a screen (640 x 480, 32-bit color)
screen = pygame.display.set_mode((640,480))
# Create and Convert image files
# Use JPG files for lots of color, and use conver()
# Use PNG files for transparency, and use convert_alpha()
background = pygame.image.load("bg.jpg").convert()
ball = pygame.image.load("ball.png").convert_alpha()
ball.set_colorkey(-1, RLEACCEL) # Use the upper-left pixel color as transparent
# The main loop
while True:
# 1 - Process all input events
for event in pygame.event.get():
# Make sure to exit if the user clicks the X box
if event.type == QUIT:
pygame.quit()
sys.exit()
# 2 - Blit images to screen (main display window)
screen.blit(background, (0,0))
x,y = pygame.mouse.get_pos()
x = x - ball.get_width()/2
y = y - ball.get_height()/2
screen.blit(ball, (x,y))
# 3 - Update the main screen (redraw)
pygame.display.update()
I must be making an obvious mistake, but I can't figure it out. Calling ball.set_colorkey(-1, RLEACCEL) should pick up the color of the upper-left corner of the ball sprite (which happens to be black) and use that as the pixel color "not to blit". Am I missing a step?
Thanks for your help.

There's per-pixel alpha, colorkey alpha, and per-surface alpha. You're asking for colorkey.
When you call convert_alpha() it creates a new surface for per-pixel alpha.
And from set_colorkey
The colorkey will be ignored if the Surface is formatted to use per pixel alpha values.
So: Load image with .convert() Since you want to use a color key. Then call set_colorkey.
Also, I saw nothing in the docs about passing "-1" as first argument to set_colorkey.
That's probably from a tutorial, which has a load_image function to grab the topleft pixel's color value.

How is your image created?
Pygame transparecy for blitting should work if your "ball.png" file i s a ball on transparent background, and not a ball on a black square.
That said, from Pygame's surface documentation for "set_colorkey":
"The colorkey will be ignored if the Surface is formatted to use per pixel alpha values. The colorkey can be mixed with the full Surface alpha value."
So, the idea of colorkey is to use it when yiour image does not have per pixel alpha - and you are just ensuring it does have when you call "convert alpha". Also, I saw nothing in the docs about passing "-1" as first argument to set_colorkey.
In short: My advice is to use proper transparent images to start with - and forget about "convert", "convert_alpha", "set_colorkey" and so on. If you have some reason for not using per pixel alpha from the PNG file, then check this answer a the right way to do it (and even for one reason not to want per pixel alpha when blitting to the screen):
PyGame: Applying transparency to an image with alpha?

Related

pygame rect argument being raised despite no rect being used [duplicate]

I would like to know how to draw images using pygame. I know how to load them.
I have made a blank window.
When I use screen.blit(blank, (10,10)), it does not draw the image and instead leaves the screen blank.
This is a typical layout:
myimage = pygame.image.load("myimage.bmp")
imagerect = myimage.get_rect()
while 1:
your_code_here
screen.fill(black)
screen.blit(myimage, imagerect)
pygame.display.flip()
import pygame, sys, os
from pygame.locals import *
pygame.init()
screen = pygame.display.set_mode((100, 100))
player = pygame.image.load(os.path.join("player.png"))
player.convert()
while True:
screen.blit(player, (10, 10))
pygame.display.flip()
pygame.quit()
Loads the file player.png.
Run this and it works perfectly. So hopefully you learn something.
Images are represented by "pygame.Surface" objects. A Surface can be created from an image with pygame.image.load:
my_image_surface = pygame.load.image('my_image.jpg')
However, 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.
Use the appropriate conversion method for best performance:
image_surface = pygame.load.image('my_image.jpg').convert()
alpha_image_surface = pygame.load.image('my_icon.png').convert_alpha()
A Surface can be drawn on or blended with another Surface using the blit method. The first argument to blit is the Surface that should be drawn. The second argument is either a tuple (x, y) representing the upper left corner or a rectangle. With a rectangle, only the upper left corner of the rectangle is taken into account. It should be mentioned that the window respectively display is also represented by a Surface. Therefore, drawing a Surface in the window is the same as drawing a Surface on a Surface:
window_surface.blit(image_surface, (x, y))
window_surface.blit(image_surface,
image_surface.get_rect(center = window_surface.get_rect().center))
Minimal example:
import pygame
pygame.init()
window = pygame.display.set_mode((300, 300))
clock = pygame.time.Clock()
pygameSurface = pygame.image.load('apple.png').convert_alpha()
run = True
while run:
clock.tick(60)
for event in pygame.event.get():
if event.type == pygame.QUIT:
run = False
window.fill((127, 127, 127))
window.blit(pygameSurface, pygameSurface.get_rect(center = window.get_rect().center))
pygame.display.flip()
pygame.quit()
exit()
pygame.image.load is bale to load most images. According to the documentation the following formats are supported: JPG, PNG, GIF (non-animated), BMP, PCX, TGA (uncompressed), TIF, LBM (and PBM), PBM (and PGM, PPM), XPM.
If you want to use images in PyGame that are loaded with other libraries, see:
PIL and pygame.image
How do I convert an OpenCV (cv2) image (BGR and BGRA) to a pygame.Surface object
For information on loading Scalable Vector Graphics (SVG) files, see:
SVG rendering in a PyGame application
Loading animated GIF files is presented at:
How can I load an animated GIF and get all of the individual frames in PyGame?
How do I make a sprite as a gif in pygame?
Or see how to load NumPy frames:
Pygame and Numpy Animations
After using blit or any other update on your drawing surface, you have to call pygame.display.flip() to actually update what is displayed.

Why isn't the surface showing the updated position of the game piece? [duplicate]

I would like to know how to draw images using pygame. I know how to load them.
I have made a blank window.
When I use screen.blit(blank, (10,10)), it does not draw the image and instead leaves the screen blank.
This is a typical layout:
myimage = pygame.image.load("myimage.bmp")
imagerect = myimage.get_rect()
while 1:
your_code_here
screen.fill(black)
screen.blit(myimage, imagerect)
pygame.display.flip()
import pygame, sys, os
from pygame.locals import *
pygame.init()
screen = pygame.display.set_mode((100, 100))
player = pygame.image.load(os.path.join("player.png"))
player.convert()
while True:
screen.blit(player, (10, 10))
pygame.display.flip()
pygame.quit()
Loads the file player.png.
Run this and it works perfectly. So hopefully you learn something.
Images are represented by "pygame.Surface" objects. A Surface can be created from an image with pygame.image.load:
my_image_surface = pygame.load.image('my_image.jpg')
However, 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.
Use the appropriate conversion method for best performance:
image_surface = pygame.load.image('my_image.jpg').convert()
alpha_image_surface = pygame.load.image('my_icon.png').convert_alpha()
A Surface can be drawn on or blended with another Surface using the blit method. The first argument to blit is the Surface that should be drawn. The second argument is either a tuple (x, y) representing the upper left corner or a rectangle. With a rectangle, only the upper left corner of the rectangle is taken into account. It should be mentioned that the window respectively display is also represented by a Surface. Therefore, drawing a Surface in the window is the same as drawing a Surface on a Surface:
window_surface.blit(image_surface, (x, y))
window_surface.blit(image_surface,
image_surface.get_rect(center = window_surface.get_rect().center))
Minimal example:
import pygame
pygame.init()
window = pygame.display.set_mode((300, 300))
clock = pygame.time.Clock()
pygameSurface = pygame.image.load('apple.png').convert_alpha()
run = True
while run:
clock.tick(60)
for event in pygame.event.get():
if event.type == pygame.QUIT:
run = False
window.fill((127, 127, 127))
window.blit(pygameSurface, pygameSurface.get_rect(center = window.get_rect().center))
pygame.display.flip()
pygame.quit()
exit()
pygame.image.load is bale to load most images. According to the documentation the following formats are supported: JPG, PNG, GIF (non-animated), BMP, PCX, TGA (uncompressed), TIF, LBM (and PBM), PBM (and PGM, PPM), XPM.
If you want to use images in PyGame that are loaded with other libraries, see:
PIL and pygame.image
How do I convert an OpenCV (cv2) image (BGR and BGRA) to a pygame.Surface object
For information on loading Scalable Vector Graphics (SVG) files, see:
SVG rendering in a PyGame application
Loading animated GIF files is presented at:
How can I load an animated GIF and get all of the individual frames in PyGame?
How do I make a sprite as a gif in pygame?
Or see how to load NumPy frames:
Pygame and Numpy Animations
After using blit or any other update on your drawing surface, you have to call pygame.display.flip() to actually update what is displayed.

Append or insert random elements to my array [duplicate]

I would like to know how to draw images using pygame. I know how to load them.
I have made a blank window.
When I use screen.blit(blank, (10,10)), it does not draw the image and instead leaves the screen blank.
This is a typical layout:
myimage = pygame.image.load("myimage.bmp")
imagerect = myimage.get_rect()
while 1:
your_code_here
screen.fill(black)
screen.blit(myimage, imagerect)
pygame.display.flip()
import pygame, sys, os
from pygame.locals import *
pygame.init()
screen = pygame.display.set_mode((100, 100))
player = pygame.image.load(os.path.join("player.png"))
player.convert()
while True:
screen.blit(player, (10, 10))
pygame.display.flip()
pygame.quit()
Loads the file player.png.
Run this and it works perfectly. So hopefully you learn something.
Images are represented by "pygame.Surface" objects. A Surface can be created from an image with pygame.image.load:
my_image_surface = pygame.load.image('my_image.jpg')
However, 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.
Use the appropriate conversion method for best performance:
image_surface = pygame.load.image('my_image.jpg').convert()
alpha_image_surface = pygame.load.image('my_icon.png').convert_alpha()
A Surface can be drawn on or blended with another Surface using the blit method. The first argument to blit is the Surface that should be drawn. The second argument is either a tuple (x, y) representing the upper left corner or a rectangle. With a rectangle, only the upper left corner of the rectangle is taken into account. It should be mentioned that the window respectively display is also represented by a Surface. Therefore, drawing a Surface in the window is the same as drawing a Surface on a Surface:
window_surface.blit(image_surface, (x, y))
window_surface.blit(image_surface,
image_surface.get_rect(center = window_surface.get_rect().center))
Minimal example:
import pygame
pygame.init()
window = pygame.display.set_mode((300, 300))
clock = pygame.time.Clock()
pygameSurface = pygame.image.load('apple.png').convert_alpha()
run = True
while run:
clock.tick(60)
for event in pygame.event.get():
if event.type == pygame.QUIT:
run = False
window.fill((127, 127, 127))
window.blit(pygameSurface, pygameSurface.get_rect(center = window.get_rect().center))
pygame.display.flip()
pygame.quit()
exit()
pygame.image.load is bale to load most images. According to the documentation the following formats are supported: JPG, PNG, GIF (non-animated), BMP, PCX, TGA (uncompressed), TIF, LBM (and PBM), PBM (and PGM, PPM), XPM.
If you want to use images in PyGame that are loaded with other libraries, see:
PIL and pygame.image
How do I convert an OpenCV (cv2) image (BGR and BGRA) to a pygame.Surface object
For information on loading Scalable Vector Graphics (SVG) files, see:
SVG rendering in a PyGame application
Loading animated GIF files is presented at:
How can I load an animated GIF and get all of the individual frames in PyGame?
How do I make a sprite as a gif in pygame?
Or see how to load NumPy frames:
Pygame and Numpy Animations
After using blit or any other update on your drawing surface, you have to call pygame.display.flip() to actually update what is displayed.

Pygame - How to display multiple images - space invaders [duplicate]

I would like to know how to draw images using pygame. I know how to load them.
I have made a blank window.
When I use screen.blit(blank, (10,10)), it does not draw the image and instead leaves the screen blank.
This is a typical layout:
myimage = pygame.image.load("myimage.bmp")
imagerect = myimage.get_rect()
while 1:
your_code_here
screen.fill(black)
screen.blit(myimage, imagerect)
pygame.display.flip()
import pygame, sys, os
from pygame.locals import *
pygame.init()
screen = pygame.display.set_mode((100, 100))
player = pygame.image.load(os.path.join("player.png"))
player.convert()
while True:
screen.blit(player, (10, 10))
pygame.display.flip()
pygame.quit()
Loads the file player.png.
Run this and it works perfectly. So hopefully you learn something.
Images are represented by "pygame.Surface" objects. A Surface can be created from an image with pygame.image.load:
my_image_surface = pygame.load.image('my_image.jpg')
However, 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.
Use the appropriate conversion method for best performance:
image_surface = pygame.load.image('my_image.jpg').convert()
alpha_image_surface = pygame.load.image('my_icon.png').convert_alpha()
A Surface can be drawn on or blended with another Surface using the blit method. The first argument to blit is the Surface that should be drawn. The second argument is either a tuple (x, y) representing the upper left corner or a rectangle. With a rectangle, only the upper left corner of the rectangle is taken into account. It should be mentioned that the window respectively display is also represented by a Surface. Therefore, drawing a Surface in the window is the same as drawing a Surface on a Surface:
window_surface.blit(image_surface, (x, y))
window_surface.blit(image_surface,
image_surface.get_rect(center = window_surface.get_rect().center))
Minimal example:
import pygame
pygame.init()
window = pygame.display.set_mode((300, 300))
clock = pygame.time.Clock()
pygameSurface = pygame.image.load('apple.png').convert_alpha()
run = True
while run:
clock.tick(60)
for event in pygame.event.get():
if event.type == pygame.QUIT:
run = False
window.fill((127, 127, 127))
window.blit(pygameSurface, pygameSurface.get_rect(center = window.get_rect().center))
pygame.display.flip()
pygame.quit()
exit()
pygame.image.load is bale to load most images. According to the documentation the following formats are supported: JPG, PNG, GIF (non-animated), BMP, PCX, TGA (uncompressed), TIF, LBM (and PBM), PBM (and PGM, PPM), XPM.
If you want to use images in PyGame that are loaded with other libraries, see:
PIL and pygame.image
How do I convert an OpenCV (cv2) image (BGR and BGRA) to a pygame.Surface object
For information on loading Scalable Vector Graphics (SVG) files, see:
SVG rendering in a PyGame application
Loading animated GIF files is presented at:
How can I load an animated GIF and get all of the individual frames in PyGame?
How do I make a sprite as a gif in pygame?
Or see how to load NumPy frames:
Pygame and Numpy Animations
After using blit or any other update on your drawing surface, you have to call pygame.display.flip() to actually update what is displayed.

Make the background of an image transparent in Pygame with convert_alpha

I am trying to make the background of an image transparent in a Pygame script. Now the background in my game is black, instead of transparent. I read somewhere else that I could use convert_alpha, but it doesn't seem to work.
Here is (the relevant part of) my code:
import PIL
gameDisplay = pygame.display.set_mode((display_width, display_height))
img = pygame.image.load('snakehead1.bmp').convert_alpha(gameDisplay)
What am I doing wrong? Thanks in advance!
To make an image transparent you first need an image with alpha values. Be sure that it meets this criteria! I noticed that my images doesn't save the alpha values when saving as bmp. Apparently, the bmp format do not have native transparency support.
If it does contain alpha you should be able to use the method convert_alpha() to return a Surface with per-pixel alpha. You don't need to pass anything to this method; if no arguments are given the new surface will be optimized for blitting to the current display.
Here's an example code demonstrating this:
import pygame
pygame.init()
screen = pygame.display.set_mode((100, 100))
image = pygame.image.load("temp.png").convert_alpha()
while True:
screen.fill((255, 255, 255))
for event in pygame.event.get():
if event.type == pygame.QUIT:
quit()
screen.blit(image, (0, 0))
pygame.display.update()
And my image ("temp.png"):
If it doesn't contain alpha there are two easy fixes.
Save the image with a different file format, like png.
Use colorkeys. This works if you only need to remove the background. It is as easy as putting the line of code image.set_colorkey((0, 0, 0)), which will make all black colors transparent.

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