Re: Mac 32 bit color depth?

[thierry(at)NOSPAM.rsinc.com (Thierry Faucounau)]

In article <3ABCE1F3.137D4AC2@home.com>, randall-frank@computer.org wrote

> Here he goes again...
> 
> <soapbox>

<snip>

> With the exception of a few (older) Macintosh gfx cards,

Ah, the old Apple 16/24 card, I remember it fondly...


<snip>

> </soapbox>
> 
> <blithering>
>         The real question is what abstraction of these 
> issues would be useful in IDL?  Source alpha is in Object
> Graphics already.  It does not require HW alpha plane support,
> and thus tends to be fairly universally supported by both 3D 
> and 2D APIs.  Destination alpha is supported in common 3D APIs 
> but not as many 2D APIs.  I have heard one request for destination
> alpha (wrt png) in the previous discussions, but would ask 
> seriously  how one intends to use the destination alpha 
> channel.  Given the complexities of pixel formats exposed 
> in DG already, I might question the value of exposing 
> another, especially given cross-platform issues.
> </blithering>
> 

The cross platform bit is indeed the killer in all likelyhood. In fact
only Mac X has native support for the Alpha component (it does use it for
transparency), classic Mac (for example) just ignores it and sometimes
deosn't even preserve it's value. The other platforms are even more
problematic.



> <IMHO>
>         In short, source alpha might be useful in DG
> (but can easily be done yourself in the existing API for
> many applications).

This is an interesting statement. Looking through the IDL docs it seems
you can specify source alpha in IDL GR1 using the CMYK color space but it
doesn't say much. Then again I could be reading it wrong, I often do.


> </IMHO>
> 
> > > In article <thierry-2203011142210001@dualpants.dev.rsinc.com>,
> > > thierry@NOSPAM.rsinc.com (Thierry Faucounau) wrote:
> 
> <insidejoke>
> Thierry, "dualpants.dev."?  My preference, of course, "nicepants.",
> the original :).

Yeah, guess all this Unix use has made me kind of functional. Should have
gone with muchopants or lotsapants.

> </insidejoke>
> 
<XInteranimate stuff>

> 
If it were possible to set the alpha component (a big if) my inclination
would be to just send those values as is to the underlying 2D system
(which most likely would ignore it). This has gotten pretty far afield
here. Randy, do you have an opinion as to what get_visual_depth should
return on the Mac? The actual depth or the IDL usable depth?

> 
> Man am I in a strange mood today... :)
> 
> rjf.

Must be the lack of electricity :)