Path: utzoo!mnetor!uunet!lll-winken!lll-lcc!lll-tis!ames!rutgers!princeton!phoenix!mjlarsen
From: mjlarsen@phoenix.Princeton.EDU (Michael J. Larsen)
Newsgroups: comp.sys.mac
Subject: Re: COLOR GRAPHICS on mac-II
Message-ID: <1606@phoenix.Princeton.EDU>
Date: 1 Feb 88 16:39:05 GMT
References: <659@ut-emx.UUCP> <323@bnl.ARPA>
Reply-To: mjlarsen@phoenix.Princeton.EDU (Michael J. Larsen)
Organization: Princeton University, NJ
Lines: 15

In article <323@bnl.ARPA> wishart@bnl.UUCP (james wishart) writes:
>
>I think a lot of people would like to know about a program to display (x,y,z) data in color coded maps, so please also post your responses to the net.
>Thanks,
>
Why not just set a character pointer variable "screen" to the upper left
hand corner of the screen and treat the screen as a long array?
E.g. screen = thePort->portBits.baseAddr (or something like that),
*(screen + y * 1024L + x) = color.  Note that on the MacII, each line is
1024 pixels wide (the rightmost 384 being off the screen).  Moreover,
all the data for a single pixel is clumped together.  Thus, for
instance, in 16 color mode, screen memory is arranged with two pixels
per byte, rather than in 4 separate planes with 8 quarter-pixels per
byte.

							-Michael Larsen