Re: [pygame] possible to get rid of ghost image after rotating a line?

[tom arnall <kloro2006@xxxxxxxxx>]

Paul!

beautiful stuff. just what i needed.

thanks very much.

Tom Arnall

.....
âOnce you can accept the universe as matter expanding into nothing
that is something, wearing stripes with plaid comes easy.â Albert
Einstein




On 8/25/15, Paul Vincent Craven <paul@xxxxxxxxxxxxxxxx> wrote:
> I'm not sure why you are creating a new surface everytime. Or why you
> create one at all?
>
> Is this similar to what you are looking for?
>
> http://programarcadegames.com/python_examples/f.php?file=radar_sweep.py
>
> Paul Vincent Craven
>
> On Tue, Aug 25, 2015 at 3:57 PM, tom arnall <kloro2006@xxxxxxxxx> wrote:
>
>> I want to rotate a line around a point. The code that follows does
>> this, BUT when it draws a line, it leaves next to the line its ghost.
>> Is this a problem with pygame, or is there a change I can make in the
>> code which will make the problem go away?
>>
>>
>> import pygame, sys
>> from pygame.locals import *
>> import time
>>
>> pygame.init()
>>
>> #create a surface that will be seen by the user
>> screen =  pygame.display.set_mode((400, 400))
>>
>> #create a varible for degrees pf rotation
>> degree = 0
>> while True:
>>
>>     for event in pygame.event.get():
>>         # quit the game if escape is pressed
>>         if event.type == QUIT:
>>             sys.exit()
>>         elif event.type == KEYDOWN and\
>>                 event.key == K_ESCAPE:
>>             sys.exit()
>>
>>     #clear screen at the start of every frame
>>     screen.fill((40, 40, 40))
>>
>>     #create new surface with white BG
>>     surf =  pygame.Surface((1000, 5))
>>     surf.fill((255, 255, 255))
>>     #set a color key for blitting
>>     surf.set_colorkey((255, 0, 0))
>>
>>
>>     ##ORIGINAL UNCHANGED
>>     #where will the static image be placed:
>>     where = (0,200)
>>
>>     #draw surf to screen and catch the rect that blit returns
>>     blittedRect = screen.blit(surf, where)
>>
>>     ##ROTATED
>>     #get center of surf for later
>>     oldCenter = blittedRect.center
>>
>>     #rotate surf by DEGREE amount degrees
>>     rotatedSurf =  pygame.transform.rotate(surf, degree)
>>
>>     #get the rect of the rotated surf and set it's center to the
>> oldCenter
>>     rotRect = rotatedSurf.get_rect()
>>     rotRect.center = oldCenter
>>
>>     #draw rotatedSurf with the corrected rect so it gets put in the
>> proper
>> spot
>>     screen.blit(rotatedSurf, rotRect)
>>
>>     #change the degree of rotation
>>     degree += 5
>>     if degree > 360:
>>         degree = 0
>>
>>     #show the screen surface
>>     pygame.display.flip()
>>
>>     #wait 60 ms until loop restart
>>     pygame.time.wait(60)
>>
>


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