The formulas that ship with PM are very basic. So why not share some of your own that you think may be beneficial for other people?
I’ll start. Paint Single Color mode is nice, but what if you need to stamp brushes in different colors that still have the shading (or the closest approximation of it using your palette) of the original? This is similar to how grayscale brushes work in software like Photoshop.
The way it works, is that it first averages all RGB channels (which makes it workable with any brush, not just ones that were made with it in mind), then it multiplies colors of each channel by the foreground color, then it divides everything by 255, otherwise it wouldn’t work as everything would come out white.
These are brush formulas for both RMB and LMB (made it so it works with the bg color as well):
And here it is in action:
As you can see, in case of the first image, I’ve used 3 pixel-wide grayscale brush to make cracks. Then I’ve used the brick as a brush to make the second brick, the green one. I didn’t have to change anything other than the drawing color to make both happen.
Please share your formulas as well!