Tip: Layer 3 backgrounds and tides disappear when you hit a message box, so plan your level around that. For example, you can add a sublevel without layer 3 at the start/midpoint, and include your message there.
After my (not so) recent encounter with player hitboxes I decided to make a tool out of it... yeah.
Anyway, this allows you to easily modify the player's collision points as well as sprite hitboxes.
Changing collision points in the wrong way can easily cause glitches with the player's behaviour which may or may not be immediately noticeable
While there are template and interaction files included with the tool the included template patches only modify the interaction points/sprite hitboxes. They do NOT fix any of the side effects of moving the interaction points/sprite hitboxes that may or may not appear. Use at your own risk.
Don't use this if you don't know what you're doing
Just in case if someone else would apply a patch that edits an area this software would modify, causing glitches
Well, that would be true if my program would modify the rom. It doesn't though.
Everything the tool does is generate tables in smw's format and put it in a template file which you can easily modify without the source code.
The only hardcoded thing in this tool is the format of the tables and changing that is pointless as you'd have to rewrite the way smw expects the table and there's really no reason I could think of that anyone would want to do that.