I am drawing another tree for the level 4, after that, I need to color one character and one background.
I have an old bug everywhere in the game with the sprites sheet, every object is bonded to another object in the sprite with no margin.
But when the images of the door are displayed at lower resolutions we can see a small vertical line belonging to the other object in the sprite sheet. This is due to the round error OpenGL do when reducing the size of the object. The solution is to add a small margin of 2 pixels each side of the object.
In this image, the margin is white because I converted the image to JPEG to improve loading time, in the original margin are transparent.
After doing all the generation of the sprite sheet for the first level, I have big PNG files and I need to compress them but most of the software out there to compress images files are in command lines and not multithreaded. And the GUI programs do not let enough options and are built around one optimizer. For the moment I use PNGGauntlet, I am building a small flexible program with Qt that can use any of the command line optimizers where the user can specify the options in an XML config file.