1) Straightened out a few kinks in the collision detection algorithm.
2) Converted the bounding boxes for detecting collisions into bounding polygons, so custom galaxies of any shape can be aligned in a variety of ways and not "squared off" as the old bounding rectangle method I used would have it.
3) Implemented elliptical galaxies.
4) Implemented random galaxy rotations--most noticeable with the ellipticals. Adds some variety to the layout.
In the picture below, the bright orange pixels are the bounding polygons for each galaxy--I turned them on in this run to observe. There are two large elliptical galaxies, two large spirals, one medium spiral, one small spiral, and about four tiny ellipticals. Note that not all ellipticals will look like footballs--I set their parameters to make them dramatically non-circular for testing reasons.
I'll maybe have one more post in the next day or two, then nothing until after Christmas. Enjoy!