I'm new to custom post types and such, so bear with me.
I've created a plugin for a custom post type, "patterns", that will allow users to upload patterns that are downloaded from a game. The game outputs all of the images at the same size, but some types of pattern contain four images.
What I would like to do is a) create a front-end upload form for users, so they don't have to go into the WP control panel, and b) have them select a category before anything else. Depending on the category they select, they will be allowed to upload ONE image, or FOUR.
For example, a clothing pattern contains four images, while a sign pattern contains one. If the user selects the "clothing" category when uploading patterns, they should be required to upload four images. If they select the "signs" category, they are only allowed to upload one image.
I'm not sure, logistically, how this should work—as I said, I'm new(ish) to WordPress and very new to custom post types.