Re: what's 32 bpp?

1999-02-09 Thread Dave Swegen 
On Mon, Feb 08, 1999 at 18:26 -0500, Branden Robinson wrote:
 On Mon, Feb 08, 1999 at 12:06:30PM -0800, Kenneth Scharf wrote:
  What happens in 32bpp??  I do not believe that video dac's are
  available wider than 8 bits.  If they are, are 3 10 bit dac's used,
  with the extra 2 bits thrown away?  Or is a 12 bit dac used for the
  green
  
  Or is this only a maping thing, 24 bits are used, and a whole byte is
  thrown away, but using 32bits per pixel cleans up the dma access some
  how?
 
 As far as I know, the latter is the case.
 
 Kind of a shame.  I wish the last 8 bits could be used for an alpha
 channel.

I seem to recall reading somewhere (I think it was in the xfree86 docs for
the matrox driver) that using 32bpp was faster than using 24bpp, probably
because it can blit stuff along a longword boundary...But what do I know?

Cheers
Dave

-- 
 Dave Swegen   | Debian 2.0 on Linux i386 2.2.1
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Re: what's 32 bpp?

1999-02-08 Thread Branden Robinson 
On Mon, Feb 08, 1999 at 12:06:30PM -0800, Kenneth Scharf wrote:
 What happens in 32bpp??  I do not believe that video dac's are
 available wider than 8 bits.  If they are, are 3 10 bit dac's used,
 with the extra 2 bits thrown away?  Or is a 12 bit dac used for the
 green
 
 Or is this only a maping thing, 24 bits are used, and a whole byte is
 thrown away, but using 32bits per pixel cleans up the dma access some
 how?

As far as I know, the latter is the case.

Kind of a shame.  I wish the last 8 bits could be used for an alpha
channel.

-- 
G. Branden Robinson  |   Human beings rarely imagine a god that
Debian GNU/Linux |   behaves any better than a spoiled child.
[EMAIL PROTECTED]   |   -- Robert Heinlein
cartoon.ecn.purdue.edu/~branden/ |


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