Re: [AGG] Subpixel problem - 90/180 deg. lines

[Petr K. <kob...@gm...>]

Hi,

if you are drawing a line:

[10, 10] -> [100, 10]

and stroke it using 1 pixel width, then you are drawing the polygon:

[9.5, 9.5] [100.5, 9.5] [100.5, 10.5] [9.5 10.5].

To align the line, you should add the [.5 .5] to the line coordinates.

Best regards
Petr

On Mon, Mar 7, 2011 at 2:31 PM, Oyvind Idland <oyv...@gm...> wrote:
> When a line segment is 90 or 180 degrees (has same x or y), the subpixel
> logic makes the lines appear as 50% transparent and twice as fat as they
> should
> be. For example, the fill in this polygon is 1 pixel wide stroked lines:
>
> http://img233.imageshack.us/i/agg.png/
>
> Is there any way to ommit this, such as a stock conv_something<> ?
>
> If not, maybe a conv_round<> or something like that rounds of to whole
> pixels
> would be the way to go ?
>
>
> -- Oyvind
>
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