[net.micro.amiga] Talkin' 'bout 399---400 dots

spencer@oberon.UUCP (Randy Spencer) (01/30/86)

I begin to see why it is that all this flaming goes on around here.

> I think I'm beginning to get the gist here. But you really can't exactly
> call that v400 resolution, can you? Vertical dots just aren't as *fine*
> as they would be if they weren't piled on top of each other. Which brings
> me to my second point: 400 vertical dots is what we're working with here,
> right? Not 399. Though most every interface to the bit map uses positions
> numbered 0 through 399, it doesn't mean there are 399 positions. Position
> 0 counts too- hence we have 400 positions. (Or am I still missing something?)

If you wish to create a drawing that has a very thing line, almost to
the point of obscurity, then yes, this isn't quite what you may be
looking for.

The point in creating higher resolution (to a great extent) is to
avoid the ugly stair stepping effect.  When you are drawing dots that
are two pixels high, but are only offset on the curve by one pixel you
have done a wonderful job of cleaning up the line with out surpassing
the resolving capabilities of the monitor (NTSC) by making the dot too
small.

As far as 400 vs 399, I want to assume that just after you sent the
message you checked your math again and this is no longer a point of
confusion, however, I will endever:

Remember, you are talking about placing dots of two pixels each.
There are 400 possible pixel positions.  Place down one pixel and you
have 399 other positions.  Place down the second of the two pixels and
you have 398.  That second pixel is the bottom pixel in your dot.
Since you will stop counting when the bottom pixel of your dot hits
the last line of the screen you have 398 more positions for the bottom
pixel (you are currently at the top position for the bottom pixel).
OK?  then it is simply 398 more pixels, plus the current pixel of the
current dot makes a 399 pixel resolution using the anti-stair stepping
and anti-flicker method.