nanogui: Microwindows for Hercules
Subject:
RE: Microwindows for Hercules
From:
Greg Haerr ####@####.####
Date:
15 Jul 1999 16:48:12 -0000
Message-Id: <01BECEAE.D58CABF0.greg@censoft.com>
: I have examples on how to draw fast lines horizontal, vertical and
: (x1, y1) -> (x2, y2) using Bresenham.
: These are in a book in asm. so I don't know about their copyright but
: I think they are intended to be used, ie public domain.
: Bresenham on Hercules is a little tricky.
No need. MicroWindows handles the Bresenham algorithm in the mid
level code in devdraw.c. It uses successive calls to drawpixel to make it work.
In this way, people like you and me don't have to rewrite bresenham for every
card someone wants....
The fast line draw that we need is the one that calculates the
*bit* starting position in a starting scan line byte, and the end *bit* position.
The bits in between the begin and end are then filled with ones. For the bytes
inbetween, this is ridculously easy, just set them to 0xff. For the begin and
end, use a mask to set those bits...
: If I don't remember wrong, there are two buffers on a Hercules (2 * 32k mem)
: so you can even doublebuffer changes. Now that would be cool to work into
: the driver.
: If you other people fix it into working order, I can fix double buffering.
Neither nano-X or microwindows require or use double buffering currently,
This might be useful when bitblt is implemented though...
Greg
