2012/4/17 Máirín Duffy
<duffy@...2818...>
On Mon, 2012-04-16 at 12:47 +0200, Johan Engelen wrote:
> I guess you are using the "visual bounding box" (preferences -> tools).
I don't think I ever modified this so it must be the default setting?
Oddly, my 1 px line is at .00 x .00 coordinates when I turn on geometric
bounding box but the line is blurry / inbetween pixels. If I make the
coordinates .05 x .05 then the line is crisp. (?!)
I think I understand what's going on.. a square pixel is 1.0 pixels wide. For a one pixel wide line to be "pixel aligned", it should be centered on the pixel, meaning the line's middle needs to be at 0.5.
If you think of a pixel as being a square with corners at (0,0), (0,1), (1,1) and (1,0) then you can see that the coordinates of a line going through the centre of that pixel needs to be at 0.5.
I'll try to do some ascii art..
(0,1) (1,1) (2,1)
+-----------+-----------+
| | |
| a pixel | another |
| | pixel |
| | |
| | |
+-----------+-----------+
(0,0) (1,0) (2,0)
See how a line that's one pixel wide, if you want it to be drawn on just one pixel rather than overhanging across two pixels, needs to be through the centre of the pixels at x=0.5.
Cheers