Pygame: key.get_pressed() does not coincide with the event queue - python

I'm attempting to work out simple controls for an application using pygame in Python. I have got the basics working, but I'm hitting a weird wall: I am using the arrow keys to control my character. If I hold down one arrow key, then hold down another arrow key (to move diagonally), the character moves as expected. However, if I release the second key that I pressed (while still holding down the first key), the character stops moving, even though I am still holding down that first key. Here is my simple movement code:
for event in pygame.event.get():
if event.type == QUIT:
pygame.quit()
sys.exit()
elif event.type == KEYDOWN:
if pygame.key.get_pressed()[K_LEFT]:
player.pos = (player.pos[0] - 2, player.pos[1])
if pygame.key.get_pressed()[K_RIGHT]:
player.pos = (player.pos[0] + 2, player.pos[1])
if pygame.key.get_pressed()[K_UP]:
player.pos = (player.pos[0], player.pos[1] - 2)
if pygame.key.get_pressed()[K_DOWN]:
player.pos = (player.pos[0], player.pos[1] + 2)
Now, I was naturally very confused by this. So I tried to print some lines to debug. In the top of the main control loop, I wrote:
print (pygame.key.get_pressed()[K_DOWN], pygame.key.get_pressed()[K_RIGHT])
print pygame.event.get()
...to output a tuple displaying the state of the down and right arrow keys, and then display the pygame event queue. My results baffled me even more. If I move the character diagonally down and right, pressing the down key first and then the right key, then release the right key to make it move simply downward, the character stops moving as before... but this is printed to the shell:
(1, 0)
[]
That is, when I release the right arrow key and still hold down the down arrow key, pygame.key.get_pressed() understands that the down arrow key is still being held down, but there is nothing in the event queue.
Also, earlier in the code (before the control loop) I am invoking
pygame.key.set_repeat(1, 2)
to make the character continue to move while the key is held down.
Any help will be appreciated! Thanks :)

For things like movement, you should not check for events (like KEYDOWN or KEYUP), but check every iteration of your mainloop if your movement keys are pressed (using get_pressed).
In your code, you check the pressed keys only if there's also a KEYDOWN event.
There are also some other things to consider:
You should seperate the key-mapping and the speed of your player, so it will be easier later on to change either of this.
You should determine a movement vector and normalize it first, since otherwise, if your vertical and horizontal movement speed is 10, your diagonal movement speed would be ~14.
Working example:
import pygame
pygame.init()
screen = pygame.display.set_mode((200, 200))
run = True
pos = pygame.Vector2(100, 100)
clock = pygame.time.Clock()
# speed of your player
speed = 2
# key bindings
move_map = {pygame.K_LEFT: pygame.Vector2(-1, 0),
pygame.K_RIGHT: pygame.Vector2(1, 0),
pygame.K_UP: pygame.Vector2(0, -1),
pygame.K_DOWN: pygame.Vector2(0, 1)}
while run:
for e in pygame.event.get():
if e.type == pygame.QUIT: run = False
screen.fill((30, 30, 30))
# draw player, but convert position to integers first
pygame.draw.circle(screen, pygame.Color('dodgerblue'), [int(x) for x in pos], 10)
pygame.display.flip()
# determine movement vector
pressed = pygame.key.get_pressed()
move_vector = pygame.Vector2(0, 0)
for m in (move_map[key] for key in move_map if pressed[key]):
move_vector += m
# normalize movement vector if necessary
if move_vector.length() > 0:
move_vector.normalize_ip()
# apply speed to movement vector
move_vector *= speed
# update position of player
pos += move_vector
clock.tick(60)

just use the events return data, instead of trying to poll, you're already checking if its a keydown event TYPE, now just interrogate the KEY index, like so:
for event in pygame.event.get():
if event.type == QUIT:
pygame.quit()
sys.exit()
elif event.type == KEYDOWN:
if event.key == K_LEFT:
player.pos = (player.pos[0] - 2, player.pos[1])
rest of code.....
also consider using a separate data structure to store the state of your controls, then just use the events to update that data structure. That will help make the controls a bit more flexible as you wont be relying on the event queue to cause your character to move, which in my experience causes problems like: not being able to push more than two buttons at a time, and odd delay or timing issues with character movements. so something like:
keystates={'up':False, 'down':False, 'left':False, 'right':False}
running=True
#start main pygame event processing loop here
while running:
for event in pygame.event.get():
if event.type == QUIT:
running=False
#check for key down events
if event.type == KEYDOWN:
if event.key == K_UP:
keystates['up']=True
if event.key == K_DOWN:
keystates['down']=True
if event.key == K_LEFT:
keystates['left']=True
if event.key == K_RIGHT:
keystates['right']=True
#check for key up events
if event.type == KEYUP:
if event.key == K_UP:
keystates['up']=False
if event.key == K_DOWN:
keystates['down']=False
if event.key == K_LEFT:
keystates['left']=False
if event.key == K_RIGHT:
keystates['right']=False
#do something about the key states here, now that the event queue has been processed
if keystates['up']:
character.moveUp() #or whatever your call for these are...
if keystates['down']:
character.moveDown()
if keystates['left']:
character.moveLeft()
if keystates['right']:
character.moveRight()
#gracefully exit pygame here
pygame.quit()

You are using event-based input , but in this case you want polling-based input. Then you don't mess with key-repeats.
import pygame
from pygame.locals import *
done = False
player.pos = Rect(0,0,10,10)
while not done:
for event in pygame.event.get():
# any other key event input
if event.type == QUIT:
done = True
elif event.type == KEYDOWN:
if event.key == K_ESC:
done = True
elif event.key == K_F1:
print "hi world mode"
# get key current state
keys = pygame.key.get_pressed()
if keys[K_LEFT]:
player.pos.left -= 10
if keys[K_RIGHT]:
player.pos.left += 10
if keys[K_UP]:
player.pos.top -= 10
if keys[K_DOWN]:
player.pos.left += 10
if keys[K_SPACE]:
print 'firing repeated gun'

My guess is that set repeat doesn't work the way that you think it will. Basically, after your second key goes up, the repeat doesn't happen. This would seem to make sense to me: open up a text editor and hold down the "A" key. "A"s will spill out across the screen. Then, press the "J" key with the "A" key still held down. The "A"s stop. That is a typical key repeat system.
I'm not sure using this "set_repeat" method is going to work out in the end anyway. Basically, any key that the player presses will now "repeat", even if they click "fire" or "jump".
As an alternative, try saving the state when the user presses or releases. Don't use the set_repeat, but do something like the following:
for event in pygame.event.get():
if event.type == QUIT:
pygame.quit()
sys.exit()
elif event.type == KEYDOWN:
if pygame.key.get_pressed()[K_LEFT]:
player.moving_left = True
if pygame.key.get_pressed()[K_RIGHT]:
player.moving_right = True
if pygame.key.get_pressed()[K_UP]:
player.moving_up = True
if pygame.key.get_pressed()[K_DOWN]:
player.moving_down = True
elif event.type == KEYUP:
if pygame.key.get_pressed()[K_LEFT]:
player.moving_left = False
if pygame.key.get_pressed()[K_RIGHT]:
player.moving_right = False
if pygame.key.get_pressed()[K_UP]:
player.moving_up = False
if pygame.key.get_pressed()[K_DOWN]:
player.moving_down = False
# Somewhere else in your game loop...
if player.moving_left:
player.pos[0] -= 2
if player.moving_right:
player.pos[0] += 2
if player.moving_up:
player.pos[1] -= 2
if player.moving_right:
player.pos[1] += 2

Related

Player not moving in pygame [duplicate]

This question already has answers here:
How to get keyboard input in pygame?
(11 answers)
How can I make a sprite move when key is held down
(6 answers)
Closed 2 years ago.
I created a program with pygame. The background and player are appearing but the player is not moving. The program is not giving any errors, can you help me? I am using python 3.8.6. Here is some of my code.
# Game Loop
running = True
while running:
for event in pygame.event.get():
player(playerX, playerY)
pygame.display.update()
# Movment
if event.type == pygame.KEYDOWN:
if event.key == pygame.K_a:
player_x_change -= 10
if event.key == pygame.K_d:
player_x_change += 10
if event.key == pygame.K_w:
player_y_change -= 10
if event.key == pygame.K_s:
player_y_change += 10
if event.type == pygame.KEYUP:
if event.key == pygame.K_a:
player_x_change = 0
if event.key == pygame.K_d:
player_x_change = 0
# Close the game
if event.type == pygame.QUIT:
running = False
Your code is just displaying the player, not moving him.
To move the player, you have, in a first step, to define a speed variable. Then you have to get the rectangle of your player. That will allow you to modify player position by using the speed variable you defined.
Also, if you want to move your player, you have to draw the background before drawing the player. Otherwise, every player you draw will not disappear.
And don't forget to define the game speed.
Code
#!/usr/bin/python3
import pygame
# set the game speed
delay = 10
screen = pygame.display.set_mode((800, 600))
# loading player image and get pos
player = pygame.image.load('pixel_ship_yellow.png')
player_pos = player.get_rect()
# define speed variable
speed = [1, 1]
while True:
for event in pygame.event.get():
if event.type == pygame.QUIT:
break
# drawing background
screen.fill((0,0,0))
# apply speed (position is automatically updated)
player_pos = player_pos.move(speed)
# drawing player
screen.blit(player, player_pos)
pygame.display.flip()
# set the game speed
pygame.time.delay(delay)
You need to check for the event when a user pressed a button to move the character and then update the players position. For example, here's checking if the player pressed the right arrow:
while running:
for event in pygame.event.get():
player(playerX, playerY)
pygame.display.update()
# checking if right arrow is being pressed
if events.type == pygame.KEYDOWN:
if events.key == pygame.K_RIGHT
# update players x position here to move right
# for example, player.x += 2
# Close the game
if event.type == pygame.QUIT:
running = False

I want my character to do something as long as I'm holding a button, then go back to normal once I let go of the button

I'm creating my first game. I'm working with Python and PyGame. So far everything has been going great, but I've ran into a problem that I can't seem to solve:
I want my character to do a certain movement as long as I'm pressing a button.
Normally when you want to make your character move, I would do
if event.type == pygame.KEYDOWN:
if event.key == pygame.K_SPACE:
With this, the character does something when you press space, but it only does it once if you HOLD space.
I thought I'd do this
if event.type == pygame.KEYDOWN:
while event.key = pygame.K_SPACE
But when I run this and press space, the program blocks, and I get the 'program isn't reacting' thing.
So, one last time. I want my character to do something when I hold space, and when I let go I want it to go back to how it was.
For example: My character is walking by default. When I hold space I want it to crawl for as long as I hold space. And then finally I want it to go back to normal walking once I let go of space.
Is this possible?
Set a state (spacePressed) if SPACE is pressed when the KEYDOWN event is received. Reset the state and rest the position of the character if the SPACE is released and KEYUP is received. Move the character dependent on spacePressed in the main application loop e.g.:
spacePressed = False
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_SPACE:
spacePressed = True
if event.type == pygame.KEYUP:
if event.key == pygame.K_SPACE:
spacePressed = False
# reset character
# [...]
if spacePressed:
# move character
# [...]
Another option is to use pygame.key.get_pressed() to get the pressed keys in the main application loop and reset the position of the character if the KEYUP event is received:
while run:
for event in pygame.event.get():
if event.type == pygame.QUIT:
run = False
if event.type == pygame.KEYUP:
if event.key == pygame.K_SPACE:
# reset character
# [...]
keys = pygame.key.get_pressed()
if keys[pygame.K_SPACE]:
# move character
# [...]

pygame moving left and right issue

I have started making something on pygame but I have encountered an issue when moving left or right. if I quickly change from pressing the right arrow key to pressing the left one and also let go of the right one the block just stops moving. this is my code
bg = "sky.jpg"
ms = "ms.png"
import pygame, sys
from pygame.locals import *
x,y = 0,0
movex,movey=0,0
pygame.init()
screen=pygame.display.set_mode((664,385),0,32)
background=pygame.image.load(bg).convert()
mouse_c=pygame.image.load(ms).convert_alpha()
m = 0
pygame.event.pump()
while 1:
for event in pygame.event.get():
if event.type == QUIT:
pygame.quit()
sys.exit()
if event.type==KEYDOWN:
if event.key==K_LEFT:
movex =-0.5
m = m + 1
if event.key==K_RIGHT:
movex=+0.5
m = m + 1
elif event.type == KEYUP:
if event.key==K_LEFT and not event.key==K_RIGHT:
movex = 0
if event.key==K_RIGHT and not event.key==K_LEFT:
movex =0
x+=movex
y=200
screen.blit(background, (0,0))
screen.blit(mouse_c,(x,y))
pygame.display.update()
is there a way I can change this so if the right arrow key is pressed and the left arrow key is released that it will go right instead of stopping?
P.S
I am still learning pygame and am very new to the module. I'm sorry if this seems like a stupid question but i couldn't find any answers to it.
Your problem is that when you test the KEYDOWN events with
if event.key==K_LEFT and not event.key==K_RIGHT:
you always get True, because when event.key==K_LEFT is True,
it also always is not event.key==K_RIGHT (because the key of the event is K_LEFT after all).
My approach to this kind of problem is to separate
the intent from the action. So, for the key
events, I would simply keep track of what action
is supposed to happen, like this:
moveLeft = False
moveRight = False
while True:
for event in pygame.event.get():
if event.type == QUIT:
pygame.quit()
sys.exit()
if event.type == KEYDOWN:
if event.key == K_LEFT: moveLeft = True
if event.key == K_RIGHT: moveRight = True
elif event.type == KEYUP:
if event.key == K_LEFT: moveLeft = False
if event.key == K_RIGHT: moveRight = False
Then, in the "main" part of the loop, you can
take action based on the input, such as:
while True:
for event in pygame.event.get():
...
if moveLeft : x -= 0.5
if moveRight : x += 0.5
the problem is that you have overlapping key features; If you hold down first right and then left xmove is first set to 1 and then changes to -1. But then you release one of the keys and it resets xmove to 0 even though you are still holding the other key. What you want to do is create booleans for each key. Here is an example:
demo.py:
import pygame
window = pygame.display.set_mode((800, 600))
rightPressed = False
leftPressed = False
white = 255, 255, 255
black = 0, 0, 0
x = 250
xmove = 0
while True:
window.fill(white)
pygame.draw.rect(window, black, (x, 300, 100, 100))
for event in pygame.event.get():
if event.type == pygame.KEYDOWN:
if event.key == pygame.K_RIGHT:
rightPressed = True
if event.key == pygame.K_LEFT:
leftPressed = True
if event.type == pygame.KEYUP:
if event.key == pygame.K_RIGHT:
rightPressed = False
if event.key == pygame.K_LEFT:
leftPressed = False
xmove = 0
if rightPressed:
xmove = 1
if leftPressed:
xmove = -1
x += xmove
pygame.display.flip()
One way could be to create a queue that keeps track of the button that was pressed last. If we press the right arrow key we'll put the velocity first in the list, and if we then press the left arrow key we put the new velocity first in the list. So the button that was pressed last will always be first in the list. Then we just remove the button from the list when we release it.
import pygame
pygame.init()
screen = pygame.display.set_mode((720, 480))
clock = pygame.time.Clock()
FPS = 30
rect = pygame.Rect((350, 220), (32, 32)) # Often used to track the position of an object in pygame.
image = pygame.Surface((32, 32)) # Images are Surfaces, so here I create an 'image' from scratch since I don't have your image.
image.fill(pygame.Color('white')) # I fill the image with a white color.
velocity = [0, 0] # This is the current velocity.
speed = 200 # This is the speed the player will move in (pixels per second).
dx = [] # This will be our queue. It'll keep track of the horizontal movement.
while True:
dt = clock.tick(FPS) / 1000.0 # This will give me the time in seconds between each loop.
for event in pygame.event.get():
if event.type == pygame.QUIT:
raise SystemExit
elif event.type == pygame.KEYDOWN:
if event.key == pygame.K_LEFT:
dx.insert(0, -speed)
elif event.key == pygame.K_RIGHT:
dx.insert(0, speed)
elif event.type == pygame.KEYUP:
if event.key == pygame.K_LEFT:
dx.remove(-speed)
elif event.key == pygame.K_RIGHT:
dx.remove(speed)
if dx: # If there are elements in the list.
rect.x += dx[0] * dt
screen.fill((0, 0, 0))
screen.blit(image, rect)
pygame.display.update()
# print dx # Uncomment to see what's happening.
You should of course put everything in neat functions and maybe create a Player class.
I know my answer is pretty late but im new to Pygame to and for beginner like me doing code like some previous answer is easy to understand but i have a solution to.I didn`t use the keydown line code, instead i just put the moving event code nested in the main game while loop, im bad at english so i give you guy an example code.
enter code here
while run:
clock.tick(60)
for event in pygame.event.get():
if event.type == pygame.QUIT or event.type == pygame.K_ESCAPE:
run = False
win.blit(bg, (0, 0))
pressed = pygame.key.get_pressed()
if pressed[pygame.K_LEFT]:
x -= 5
if pressed[pygame.K_RIGHT]:
x += 5
if pressed[pygame.K_UP]:
y -= 5
if pressed[pygame.K_DOWN]:
y += 5
win.blit(image,(x,y))
pygame.display.update()
pygame.quit()
This will make the image move rapidly without repeating pushing the key, at long the code just in the main while loop with out inside any other loop.

How do I make a game object move continuously as long as the key is pressed?

I am trying to make a game object (here, the welcome text) move as long as the key is pressed on the keyboard. But in this code of mine,
import pygame , sys
from pygame.locals import *
pygame.init()
WHITE = (255 , 255 , 255)
RED = (255 , 0 , 0)
DISPLAYSURF = pygame.display.set_mode((800 , 400))
pygame.display.set_caption('Welcome Tanks')
#render(text, antialias, color, background=None)
fontObj = pygame.font.SysFont('serif' , 40)
text = fontObj.render('Welcome Folks' , True , RED )
x = 150
y = 29
while True:
DISPLAYSURF.fill(WHITE)
DISPLAYSURF.blit(text ,(x , y))
for event in pygame.event.get():
if event.type == QUIT:
pygame.quit()
sys.exit(0)
elif event.type == KEYDOWN or event.type == KEYUP:
if event.key == K_ESCAPE:
pygame.quit()
sys.exit(0)
elif event.key == K_DOWN:
y += 15
elif event.key == K_UP:
y -= 15
elif event.key == K_RIGHT:
x += 14
elif event.key == K_LEFT:
x -= 15
else:
x = 150
y = 29
pygame.display.update()
The object moves only once, even though the key is continuously pressed for a long time. In other words, the object changes its position only once when the keyboard button is pressed. I want it to move continuously while I hold the key.
Which event should I look for instead of event.KEYDOWN?
I suggest you to use the key.get_pressed(), e.g.
while True:
DISPLAYSURF.fill(WHITE)
DISPLAYSURF.blit(text ,(x , y))
for event in pygame.event.get():
if event.type == QUIT:
pygame.quit()
sys.exit(0)
elif event.type == KEYDOWN or event.type == KEYUP:
if event.key == K_ESCAPE:
pygame.quit()
sys.exit(0)
if pygame.key.get_pressed()[K_LEFT]:
x -= 15
if pygame.key.get_pressed()[K_RIGHT]:
x += 14
if pygame.key.get_pressed()[K_UP]:
y -= 15
if pygame.key.get_pressed()[K_DOWN]:
y += 15
pygame.display.update()
pygame.key.get_pressed()
Returns a sequence of boolean values representing the state of every
key on the keyboard. Use the key constant values to index the array. A
True value means the that button is pressed.
Getting the list of pushed buttons with this function is not the
proper way to handle text entry from the user. You have no way to know
the order of keys pressed, and rapidly pushed keys can be completely
unnoticed between two calls to pygame.key.get_pressed(). There is also
no way to translate these pushed keys into a fully translated
character value. See the pygame.KEYDOWN events on the event queue for
this functionality.
Also you can take a look at doc
keyState = pygame.key.get_pressed()
Declare that, and then you use keystate:
if KeyState()[K_DOWN]:
y += 15
You could try:
if key.get_pressed()
down = True
while down = True:
y+= 15
Then get FPS clock so it does not just flow over the screen!

Python - Pygame - Learning get_pressed

I am learning python as well as pygame. I am struggling a bit with finding the issue in my code. When I hold down a key and press another key at the same time, and then let go of them in the same order I press them, it sometimes makes my little character move backwards in the opposite direction.
Here is my code that I am struggling with:
while running:
for event in pygame.event.get():
if event.type == KEYDOWN:
keystate = pygame.key.get_pressed()
if event.type == pygame.QUIT: # if user clicked close
running = False # flag done to exit this loop
# all game logic / controls should go below this comment
elif event.type == KEYDOWN:
if keystate[K_SPACE]:
print ('pressed space')
player.move_up = True
elif keystate[K_RIGHT]:
print ('pressed right')
player.move_right = True
elif keystate[K_LEFT]:
print ('pressed left')
player.move_left = True
elif event.type == KEYUP:
if keystate[K_SPACE]:
print ('released space')
player.move_up = False
elif keystate[K_RIGHT]:
print ('released right')
player.move_right = False
elif keystate[K_LEFT]:
print ('released left')
player.move_left = False
if player.move_up:
player.pos[1] -= 3
if player.move_up == False:
if player.pos[1] < ground_level:
player.pos[1] +=3
if player.move_right:
player.pos[0] += 5
if player.move_left:
player.pos[0] -= 5`
So far I don't have any actual physics, and he just flies around. But that's okay, I just want to iron out the issues that I am already having.
You never update keystate's value on a KEYUP event. Thus, it still has whatever values it had whenever the last KEYDOWN event fired.
To fix this, change this...
if event.type == KEYDOWN:
keystate = pygame.key.get_pressed()
to this:
if event.type in (KEYDOWN, KEYUP):
keystate = pygame.key.get_pressed()

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