small lines beside roads

[kaputtnik]

Roads have small black lines on their edges which should be transparent. We had this already when i created the new roads but i found a workaround by giving problematic roads a width of 12 pixel instead of 10. See https://wl.widelands.org/forum/topic/1627/?page=2#post-12183

Now the roads have this small line again. Attached is a screenshot with current roads (12pixel). Mostly on roads in direction southeast have on both sides this small black line.

I checked also barbarian roads, but those do not have this line as much as empire roads have.

Next screenshot shows the situation when roads have a width of 10 pixel (the width used in program).

[kaputtnik (franku)]

Giving a width of 10 pixel to the roads, the line appears only at one side of them.

[kaputtnik (franku)]

The linked branch contains the 10 pixel roads

[GunChleoc (gunchleoc)]

I see lines in both screenshots, although 10px is a bit better.

[SirVer (sirver)]

tweaking the road is just treating the symptomps here. The culprit is that the texture atlas packs all graphics tightly and OpenGL is imprecise when sampling from the texture. Though we pixel perfectly request sampling, due to floating point and rounding, OpenGL sometimes does not sample perfectly in the middle of a pixel and then does interpolation. What you see here is the interpolation with the neighboring image in the texture atlas.

Fixing this will give each image in the atlas a padding of 1 transparent pixel that should fix that for good.

[GunChleoc (gunchleoc)]

Fixed in build19-rc1.