Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!ames!sgi!thant@horus.sgi.com From: thant@horus.sgi.com (Thant Tessman) Newsgroups: comp.sys.sgi Subject: Re: Overlay planes Summary: 96 planes Message-ID: <40363@sgi.SGI.COM> Date: 16 Aug 89 16:12:02 GMT References: <36536@bu-cs.BU.EDU> Sender: daemon@sgi.SGI.COM Organization: Silicon Graphics, Inc., Mountain View, CA Lines: 26 In article <36536@bu-cs.BU.EDU>, tjh@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@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@sgi.com