Optimize fillrate for atlas animations

Setup

Install Python. Tested on Python 3, but should also work with 2. Then:

pip install deftree Pillow

Usage:

python trim.py <path_to_project_root> <path_to_atlas_file> <path_to_output_directory>

This will output PNGs and an animations.lua in the output directory. To convert the existing sprite to an optimized one:

1. Delete all the animations in the atlas and add the new PNGs (just the frames, without any animation).

2. Require the animations.lua in any script being initialized at the same time or earlier as your sprite component (renaming it as .script and attaching it to a game object in the same collection as your sprite also works).

3. Make sure your sprite component is positioned at (0,0) with no rotation or scale within a parent game object itself at (x, y) with no rotation or scale, where (x, y) is the offset of the default animation's first frame. The position and scale of this game object will be controlled by the animation controller, so don't touch them from code.

4. Add the animation controller script (main/animations/sprite_animation.script) next to the sprite component and set the texture_id property to the name of your original atlas file.

5. Send the sprite_play_animation message to this script instead of play_animation to the sprite. Extra features are available (Read the code).