Re: [pygame] Paralax snow flaks: Some tipps for enhancing the performance?

[Ludwig Auer <lu_lle@yahoo.de>]

Ok, I corrected that! But now another error occures:

  File "schneeflocken_dirty_rects.py", line 93, in ?
    main()
  File "schneeflocken_dirty_rects.py", line 74, in main
    screen.blit(background, dirty, dirty)
TypeError: invalid destination position for blit

Hmm, th thought that it was obvious, that "dirty, dirty" wasn't a valid  
destination for to blit sth.
So I changed

for i in dirty:
            screen.blit(background,dirty, dirty)
        old_dirty = dirty
        dirty = []

to

for i in dirty:
             
screen.blit(background,dirty.get_abs_offset(),dirty.get_rect())
        old_dirty = dirty
        dirty = []


But now I get this:

Traceback (most recent call last):
  File "schneeflocken_dirty_rects.py", line 93, in ?
    main()
  File "schneeflocken_dirty_rects.py", line 74, in main
    screen.blit(background,dirty.get_abs_offset(),dirty.get_rect())
AttributeError: 'list' object has no attribute 'get_abs_offset'

Sorry for the stupied Newbie Questions....

thanks, Ludwig


Am Dienstag, 04.05.04, um 00:31 Uhr (Europe/Berlin) schrieb Ian Sharkey:

> Just one little correction. Technically, 'dirty' does contain a value  
> at that for loop, however, the interpreter believes that 'dirty' is a  
> local variable, separate from the globally defined one.
>
> Whenever an assignment to a variable takes place in a function, the  
> interpreter assumes that it is local, even if there is a global  
> variable that has the same name (and even if there is references to  
> the value that do _not_ write to it).
>
> Changing main() like so:
>
> def main():
>  global dirty  # reference the global dirty variable
>  frames=0
>  ...  #etc
>
> should do the trick.
>
> - Ian
>
> > From: Ricardo Jamin <ricardo@jaminphotography.com>
> > Reply-To: pygame-users@seul.org
> > To: pygame-users@seul.org
> > Subject: Re: [pygame] Paralax snow flaks: Some tipps for enhancing  
> > the performance?
> > Date: 3 May 2004 12:06:26 -0000
> You guessed it right.
> the first time you call dirty in the main()
> > is in that for loop.  So there\'s no value in the variable yet, not  
> > even None.
>
> > By mischance the Interpreter splits out this:
> >
> >
> > File \"schneeflocken_dirty_rects.py\", line 69, in main
> >     for i in dirty:
> > UnboundLocalError: local variable \'dirty\' referenced before  
> > assignment
> >
> > Hmm, i don\'t really understand this error message. It means  
> > something like \"want\'s to deal with a variable which hasn\'t been  
> > declared yet\" ??? Hmm, i think will toy around with this problem a  
> > little bit!
> >
> > greets, Ludwig
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