i thought about this problem, and its really bugging me, because ...
1. i want to use linear, it too nice to not use it
2. its perfect on preview
3. other programs use it
4. i want to use construct
consider this linear example
a 16 at 16 tilemap, about 76 frames
sprite tilemap imported from tiled (no plugins needed) hold mouse to move, mousewheel to zoom, starts at zoom 2
download and preview file / perfect no seams no bleeding, even when scaling / construct can
on export this happens, the actual background is showing thru = seams, ( no bleeding tho ) / construct can't
so as showed in my early version with the colors (modified export), its possible to have tiles perfectly aligned and no seams, so this means, whatever happens it is happening internally on the texturemap and not on the positioning of the tiles
ps: what you will have and always have is a little bit of blur from the surounding color but this is not an issue and almost not noticeable (well check the preview)
so its pretty clear to me that construct engine can display linear perfect, so its really a question what happens on export
for the bleeding there's the 1 pixel transparent gap, not actually a problem, but it needs adjustments, it must consider transparent space for two tiles and a setting for these transparent pixels
libgdx has its own texturepacker, there are the follow options, and i think the bleed one is actually another name for what extruding actually is
these are there standard settings:
paddingX The number of pixels between packed images on the x-axis. 2
paddingY The number of pixels between packed images on the y-axis. 2
bleed If true, RGB values for transparent pixels are set based on the RGB values of the nearest non-transparent pixels. This prevents filtering artifacts when RGB values are sampled for transparent pixels. true
edgePadding If true, half of the paddingX and paddingY will be used around the edges of the packed texture.
this makes sense, because linear will pick the surrounding pixels of the texture actually the subtexture, to make transition, and now the two tiles takes the transparent pixels of the 1px gap, that is why we see this obvious border around the tiles on export.
theres also an analogy between 3d models used in games, always padding between uv's and never stop your texture on the uv-border or you get the same black lines on your model
now for the c2 tilemap, if it would use the same texture method, it could still use the optimization, because again, the texture size is not changed, and there is no overlap.
so i hope you consider testing these settings out, i don't know if this is a convenient workaround, or easy coded, but its definitly worth trying something other engines are putting in and something where most of us are having trouble with, especially when you consider that on preview you could asume that everything is working fine...