I am developing a simple game in PyGame... A rocket ship flying around and shooting stuff.
Question: Why does pygame stop emitting keyboard events when too may keys are pressed at once?
About the Key Handling: The program has a number of variables like KEYSTATE_FIRE, KEYSTATE_TURNLEFT
, etc...
- When a
KEYDOWN
event is handled, it sets the coorspondingKEYSTATE_*
variable to True. - When a
KEYUP
event is handled, it sets the same variable to False.
The problem:
If UP-ARROW
and LEFT-ARROW
are being pressed at the same time, pygame DOES NOT emit a KEYDOWN
event when SPACE
is pressed. This behavior varies depending on the keys. When pressing letters, it seems that I can hold about 5 of them before pygame stops emitting KEYDOWN
events for additional keys.
Verification: In my main loop, I simply printed each event received to verify the above behavior.
The code: For reference, here is the (crude) way of handling key events at this point:
while GAME_RUNNING:
FRAME_NUMBER += 1
CLOCK.tick(FRAME_PER_SECOND)
#----------------------------------------------------------------------
# Check for events
for event in pygame.event.get():
print event
if event.type == pygame.QUIT:
raise SystemExit()
elif event.type == pygame.KEYDOWN and event.dict['key'] == pygame.K_UP:
KEYSTATE_FORWARD = True
elif event.type == pygame.KEYUP and event.dict['key'] == pygame.K_UP:
KEYSTATE_FORWARD = False
elif event.type == pygame.KEYDOWN and event.dict['key'] == pygame.K_DOWN:
KEYSTATE_BACKWARD = True
elif event.type == pygame.KEYUP and event.dict['key'] == pygame.K_DOWN:
KEYSTATE_BACKWARD = False
elif event.type == pygame.KEYDOWN and event.dict['key'] == pygame.K_LEFT:
KEYSTATE_TURNLEFT = True
elif event.type == pygame.KEYUP and event.dict['key'] == pygame.K_LEFT:
KEYSTATE_TURNLEFT = False
elif event.type == pygame.KEYDOWN and event.dict['key'] == pygame.K_RIGHT:
KEYSTATE_TURNRIGHT = True
elif event.type == pygame.KEYUP and event.dict['key'] == pygame.K_RIGHT:
KEYSTATE_TURNRIGHT = False
elif event.type == pygame.KEYDOWN and event.dict['key'] == pygame.K_SPACE:
KEYSTATE_FIRE = True
elif event.type == pygame.KEYUP and event.dict['key'] == pygame.K_SPACE:
KEYSTATE_FIRE = False
# remainder of game loop here...
For pressing this sequence:
a (down)
s (down)
d (down)
f (down)
g (down)
h (down)
j (down)
k (down)
a (up)
s (up)
d (up)
f (up)
g (up)
h (up)
j (up)
k (up)
Here is the output:
<Event(2-KeyDown {'scancode': 30, 'key': 97, 'unicode': u'a', 'mod': 0})>
<Event(2-KeyDown {'scancode': 31, 'key': 115, 'unicode': u's', 'mod': 0})>
<Event(2-KeyDown {'scancode': 32, 'key': 100, 'unicode': u'd', 'mod': 0})>
<Event(2-KeyDown {'scancode': 33, 'key': 102, 'unicode': u'f', 'mod': 0})>
<Event(3-KeyUp {'scancode': 30, 'key': 97, 'mod': 0})>
<Event(3-KeyUp {'scancode': 31, 'key': 115, 'mod': 0})>
<Event(3-KeyUp {'scancode': 32, 'key': 100, 'mod': 0})>
<Event(3-KeyUp {'scancode': 33, 'key': 102, 'mod': 0})>
<Event(2-KeyDown {'scancode': 36, 'key': 106, 'unicode': u'j', 'mod': 0})>
<Event(2-KeyDown {'scancode': 37, 'key': 107, 'unicode': u'k', 'mod': 0})>
<Event(3-KeyUp {'scancode': 36, 'key': 106, 'mod': 0})>
<Event(3-KeyUp {'scancode': 37, 'key': 107, 'mod': 0})>
Is this a common issue? Is there a workaround? If not, what is the best way to handle multiple-key control issues when using pygame?
Thanks!