nanogui: Problem with GC_MODE
Subject:
Re: [nanogui] Problem with GC_MODE
From:
Carlo Zinato ####@####.####
Date:
26 Sep 2007 16:11:40 +0100
Message-Id: <46FA76A4.1020209@viscount.it>
Carlo Zinato ha scritto:
> Hi all,
>
> I'm using a truecolor 565 color framebuffer drawing graphics
> exclusively in black and white, i.e. with GrSetGCBackground(gc, WHITE)
> and GrSetGCForeground(gc, BLACK). Everything works fine in GR_MODE_COPY
> and GR_MODE_COPYINVERTED (involving only src graphic), but when I use
> any other mode which combines src and dst nothing is drawn. For example
> if I draw in GR_MODE_XOR mode a black box somewhere over a bigger black
> box nothing happens. Am I missing something?
OK, I misunderstood how GR_MODE works: I thought logical operations
consider foreground as 1 and background as 0. But they refer to actual
pixel colors, so in my case WHITE is 1 (pixel is 0xFFFF) and BLACK is 0
(pixel is 0x0000).
Solved problem inverting the logic (e.g. replaced GR_MODE_XOR with
GR_MODE_EQUIV).
Cheers,
Carlo
>
> Thanks in advande,
> Carlo
>
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