UB BaseBitmap Alpha channels from file



  • THE POST BELOW IS MORE THAN 5 YEARS OLD. RELATED SUPPORT INFORMATION MIGHT BE OUTDATED OR DEPRECATED

    On 16/08/2007 at 11:11, xxxxxxxx wrote:

    User Information:
    Cinema 4D Version:   R9.5-R10 
    Platform:      Mac OSX  ; 
    Language(s) :     C++  ;

    ---------
    The only place that I have difficulties with alphas in image files is in XCode (UB). If the image is just loaded, the alphas are incorrect. My usual solution is to call:

    bitmap->RemoveChannel(bitmap->GetChannelNum(0));
    

    But this creates undesirable results as well - in UB. Works a spiff otherwise. Doesn't seem to be clear information on how to get at the actual alpha channels. You can get the count, get the internal, but with reading a file, how do you know which channels (by number) are the actual alpha channels, pray tell? Any suggestions?

    Thanks,



  • THE POST BELOW IS MORE THAN 5 YEARS OLD. RELATED SUPPORT INFORMATION MIGHT BE OUTDATED OR DEPRECATED

    On 17/08/2007 at 04:00, xxxxxxxx wrote:

    GetChannelNum() should always give you the alphachannel as you get an AlphaBitmap from it.

    What is exactly not working with it?

    If you have other layers than the primary color layer beside the alpha channels, you maybe should check if it´s a MultipassBitmap and cast accordingly? Maybe that gets rid of any problems as MultipassBitmap seems to have more specific functions concerning working with any type of layers.

    However, this is all just guessed. Haven´t tried it.



  • THE POST BELOW IS MORE THAN 5 YEARS OLD. RELATED SUPPORT INFORMATION MIGHT BE OUTDATED OR DEPRECATED

    On 19/08/2007 at 19:46, xxxxxxxx wrote:

    Well, what I'm getting is as expected. In UB versions, Loading PNG/PICT images via C4D's QuickTime support yields a 'ghosted' image when there is an alpha channel in the file. Removing the channel works - per se - but you get no alpha, just stark transitions due to the lack of alpha. This doesn't occur in non-UB versions (PPC Classic, Windows). Why the alpha is mistranslated in the UB support is beyond me - works fine in Classic MacOS and Windows 32-bit (in Windows 64-bit, I opt for libPng instead with no PICT support). This could be Cinema 4D and/or QuickTime (?).

    It is so frustrating not having consistent image support (simplistic (as it can be) 2D bitmaps) across systems. This all has nothing to do with QuickTime though (?) as I replaced all PNG support with libPng - but, ah, libPng doesn't support *all* possible PNG formats and a user is complaining about missing thumbnails. Can't win... I could spend money on a robust library - and pass the cost to users - naaah. ;)

    Thanks,


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