Hey, fellow GMS devs!

A few weeks ago I posted about Spritely, a tool that we made for batch operations on sprites (like autocropping and "bleed") before importing them into Gamemaker.

We've been experimenting with using gradient maps to make it easy to batch-create recolored assets, which ended with updating Spritely to accommodate that. This might be useful to others, so I wanted to share it here.

If you aren't familiar with gradient maps, the idea is this: you start with a grayscale image, and then map positions along the intensity scale to colors. A gradient is computed between each pair of mapped colors you defined, so that any intensity value in your image can be automatically mapped onto a color. (Photoshop, Clip Studio Paint, and presumably many other graphics applications provide gradient mapping tools.)

This way you can have one grayscale image and a collection of gradient maps, and then create new, colored images for each map. You can use this to batch-create new sprites for each map, or to make skins in applications like Spine.

Spritely has a new command spritely skin that takes a file describing your gradient maps, plus all your images, and creates recolored versions of all images. The original images don't even have to be grayscale to work -- Spritely will convert each pixel to grayscale before applying the gradient map.

The README has all the details.