[quote="Ashley":q0njyvcr]Grids of points can overlap with none of their points touching! All the points just fall in between the other points. It won't do at all! Collision polygons are the standard used by physics engines and other algorithms like lighting. We may as well use collision polygons and then you get your physics polygon automatically.[/quote:q0njyvcr]
Yeah, that might work. As well, it could certainly make shadows better-quality and, well, actually fit the shapes of the sprites rather than using the bounding box!
Also, speaking of lights, I imagine lights can be improved in some ways upon their implementation in C2, such as being able to replicate the effect of hanging a light above an object when in top-down view (to cast a shadow on the ground), and for light to either be sunlight (rays are parallel) or closer lights (which don't cast parallel light rays).
Anyway, collision polygons are a reasonable compromise, as they're used with physics anyway, and in some ways just as effective as per-pixel without being nearly as speed-dependent.