Thanks DR0ID.

Per pixel alpha, color key, and per surface alpha are all separate,
it's a SDL constraint.

I'll have to look into your script a bit more.  I think maybe the
rotate/rotozoom functions need some fixing for non 32bit per pixel
alpha.  I'm guessing that the blend modes for blit are ok.

Cheers,

On 8/10/07, DR0ID <dr0id@[...].ch>  wrote:
>  René Dudfield schrieb:
>  > Hi,
>  >
>  > DR0ID, do you have a script which demonstrates this bug?
>  >
>  > Or can you explain it further?
>  >
>  >
>  Hi
> 
>  there you have a script. Blendmodes only work with pygame1.8. Users
>  using pygame1.7 can start the script, but should not change the
>  blendmode pressing 'm'.
> 
>  Perhaps I have done something wrong, please correct any mistake you
>  find. Or perhaps I have forgotten an interesting case.
> 
>  Results:
> 
>  rotate() screws up on normals surfaces and surfaces with per surface alpha.
> 
>  rotozoom() screws up all except surfaces with per pixel alpha
> 
>  Blendmodes do not respect colorkey nor per pixel alpha. I do not know if
>  this is intentional.
> 
>  rotozoom fills the space in with black, therefore you will not see any
>  difference in blendmodes 'add' or 'sub' (because adding 0 or subtracting
>  0 gives the same number).
> 
>  An is there a reason why colorkey and per pixel alpha are mutual
>  exclusive? (is that a constraint from SDL?)
> 
>  ~DR0ID
> 
>  #Copyright 2006 DR0ID <dr0id@[...].ch> http://mypage.bluewin.ch/DR0ID
>  #
>  #
>  #
>  """
>  gradients demo
>  """
> 
>  __author__ = "$Author: DR0ID $"
>  __version__= "$Revision: 106 $"
>  __date__   = "$Date: 2007-08-09 17:43:42 +0200 (Do, 09 Aug 2007) $"
> 
> 
>  import pygame
>  import math
>  import random
>  import os
> 
> 
> 
> 
> 
> 
>  def main():
>          screen_size = (800,700)
>          size = 100 # size of the test surfaces
>          fill_color = (0,255,0)
>          num_table = (4, 4) # number of test surfaces per row/column
> 
>          pygame.init()
>          os.environ['SDL_VIDEO_CENTERED'] = '1'
>          screen = pygame.display.set_mode(screen_size, pygame.SRCALPHA)
>          bgd = pygame.Surface(screen.get_size())
>          bgd.fill((128,128,128))
>          screen.blit(bgd, (0,0))
>          font = pygame.font.Font(None, 30)
>          surfaces = []
> 
>          surfaces.append(pygame.Surface((size,)*2)) #normal surface
> 
>          colorkey = pygame.Surface((size,)*2)#colorkey
>          colorkey.set_colorkey((255,0,255))
> 
>          surfaces.append(colorkey) # colorkey
> 
>          surfaces.append(pygame.Surface((size,)*2).convert_alpha()) #alpha surface, per pix
el alpha
>  ##        surfaces[-1].set_colorkey((255,0,255))
>  ##        surfaces[-1].set_alpha(128)
>          surf_alpha = pygame.Surface((size,)*2)
>          surf_alpha.set_alpha(128)
>          surfaces.append(surf_alpha) #alpha surface, per pixel alpha
> 
>          for idx, surf in enumerate(surfaces):
>              surf.fill(fill_color)
> 
>          pygame.draw.circle(surfaces[1], (255,0,255), (20,20), size/2)
>          pygame.draw.circle(surfaces[2], (255,0,255,0), (20,20), size/2)
>  ##        pygame.draw.circle(surfaces[3], (255,0,255,0), (20,20), size/2)
> 
>          for idx in range(num_table[0]):
>              surfaces.append( pygame.transform.rotate(surfaces[idx], 30))
> 
>          for idx in range(num_table[0]):
>              surfaces.append( pygame.transform.rotozoom(surfaces[idx], 30,1))
> 
> 
> 
>          modes  = [0,1,2,3,4,5]
>          mode   = 0
> 
>          pygame.display.set_caption( "mode:"+str(modes[mode])+
>                                      "    keys: m"
>                                      )
>          running = True
>          changed = True
>          while running:
>              event = pygame.event.wait()
>              if pygame.QUIT==event.type:
>                  running = False
>              elif pygame.KEYDOWN == event.type:
>                  if event.key == pygame.K_ESCAPE:#pygame.K_ESCAPE == event.key:
>                      running = False
>                  elif event.key == pygame.K_m:
>                      mode += 1
>                      mode %= len(modes)
>                  changed = True
>              elif pygame.MOUSEBUTTONDOWN == event.type:
>                  if pygame.key.get_mods()&pygame.KMOD_CTRL:
>                      spoint = list(pygame.mouse.get_pos())
>                  else:
>                      epoint = list(pygame.mouse.get_pos())
>                  changed = True
> 
>              if changed:
>                  changed = False
>                  mode_str = ["normal", "add", "sub", "mult", "min", "max"]
>                  pygame.display.set_caption( "mode:"+mode_str[modes[mode]]+
>                                              " keys: m"
>                                              )
>                  screen.fill((50,50,50))
>                  screen.blit(bgd, (0,0))
> 
>                  #here blit the different surfaces
>                  distx = screen_size[0]/num_table[0]
>                  disty = screen_size[1]/num_table[1]
>                  idx = 0
>                  for y in range(0,600, disty):
>                      for x in range(0,800, distx):
>                          if idx<len(surfaces):
>                              if modes[mode]==0:
>                                  screen.blit(surfaces[idx], (x+50,y+50))
>                              else:
>                                  screen.blit(surfaces[idx], (x+50,y+50), None, modes[mode])
>                              idx += 1
> 
>                          # strings
>                          if y == 0:
>                              if x == 0:
>                                  tex = font.render('normal', 1,(255,255,255))
>                                  screen.blit(tex, (x+50, y))
>                              elif x == distx:
>                                  tex = font.render('colorkey', 1,(255,255,255))
>                                  screen.blit(tex, (x+50, y))
>                              elif x == 2*distx:
>                                  tex = font.render('per pixel alpha', 1,(255,255,255))
>                                  screen.blit(tex, (x+50, y))
>                              elif x == 3*distx:
>                                  tex = font.render('surface alpha 128', 1,(255,255,255))
>                                  screen.blit(tex, (x+20, y))
>                          if x == 0:
>                              if y == 0:
>                                  tex = font.render('no rotation', 1 , (255,255,255))
>                                  screen.blit(tex, (x, y+30))
>                              if y == disty:
>                                  tex = font.render('rotate()', 1 , (255,255,255))
>                                  screen.blit(tex, (x, y+30))
>                              if y == 2*disty:
>                                  tex = font.render('rotozoom()', 1 , (255,255,255))
>                                  screen.blit(tex, (x, y+30))
>                                  tex = font.render('press m to change blendmode: '+mode_str
[modes[mode]], 1 , (255,255,255))
>                                  screen.blit(tex, (screen_size[1]/3, screen_size[1]-50))
> 
> 
>                  pygame.display.flip()
> 
> 
>          pygame.quit()
> 
> 
> 
> 
> 
>  if __name__ == '__main__':
>      main()
>