Window resize artifacts

[AsuMagic]

I am currently working on a game project and I've encountered a problem when resizing the window.
I have a problem :


I use my custom sprite class with independant layers. These rely on VBOs. When I resize the window, they have one pixel (on texture size; when i use 2x zoom the issue is doubled) "imprecision" which makes them badly mix together.

It looks pretty subtle here but gets worse with view levels :
http://i.imgur.com/FxSVHiP.png
When you zoom in you can notice near the right of the boat, in the background layer, that the pixels are "inclinated" while they should be perfect vertical.
Similar problem : The main frame of the ship (not the sail) is offset by one from zero on the left if you look close enough.
Correct behavior (another window size) :
http://i.imgur.com/FFLIY3m.png

Code :
- Handling the window view : https://github.com/AsuMagic/game/blob/master/engine/engine.cpp#L32 (should be highlighting the right line if I haven't pulled a commit since you read this)
- Sprite code : https://github.com/AsuMagic/game/blob/master/engine/render/sprite.cpp (focus only on SpriteLayer methods)

There is another side problem : I use

Code: [Select]

view.zoom(1.f / static_cast<int>( view.getSize().x / (preferredWidth * map->getTilesize()) ));to set the view zoom as close as the preferred width (in tiles). But when the size is 3x, this also causes issues with tiles offsetting oddly. How can I get 3x zoom to work without this problem?

If that matters, I'm under Linux with proprietary nvidia drivers.

Thanks!