| From: | Lee Procter |
| Date: | 10 Aug 2001 at 12:15:01 |
| Subject: | Re: [amiga-c] "transparent" colors |
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--- "David McMinn" <dave@blitz-2000.co.uk>
> wrote:
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>--- In amiga-c@y..., Marcin Kielesi=F1ski <misterq@c...> wrote:<BR>
><BR>
>> "PDTA_MaskPlane (PLANEPTR) -- Pointer to a bit plane suitable for=
> <BR>
>> use with BltMaskBitMapRastPort(), or NULL if the picture has no<=
>BR>
>> transparent colours."<BR>
>>
>> My question is: what is a "transparent" colour?<BR>
>
>It depends on the image format I guess. ILBM's usually have colour 0
>as a transparent colour, so you'd get a mask which would only allow
>pixels with a non-zero palette index to pass through. I think you can
>set it to be any specific palette index with GIF's, so you'd get a
>mask which allows any other pixel to pass through. PNG is similar I
>think.
So how would you select which color is transparent, do you choose the colour index in hex, does it matter if it is 0x0C0 for a direct copy or does it need to be "inverted" or something? Sorry for the basic question but Datatypes are giving be a headache!
==
Lee Procter
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