Overlay planes

[Thant Tessman]

In article <36536 at bu-cs.BU.EDU>, tjh at bu-cs.BU.EDU (Timothy Hall) writes:
> Real work question:
> 
> I am planning on porting a paint package to our 240 soon.  The package wants
> 8 bitplanes and the Iris 4sight manual tells me the max overlay planes I
> can get is 4.  (I don't need the window manager)  Now somewhere along the
> line I thought I heard the 240 has 96 bitplanes - 64 bits image buffer -
> 24 bit z-buffer and 8 bits of overlay.  So is my memory fading?  If not how
> do I get all 8 overlay planes?
> 
[the question I don't know how to answer deleted]
> 
> -Tim Hall
> Boston University Computer Graphics Lab
> tjh at bu-pub.bu.edu


Four bits are for overlay and four are for window I.D.  That's how the 
machine does arbitrarily shaped and/or overlaping windows in different
modes that can be independently swapped, all without any performance hit.

If you talk about what you need the 8 overlays for, somebody may have a
a better/workable solution.  (What machine had 24 bits of color AND 8 bits
of overlay?)

thant at sgi.com