Merging two textures with jaggedness

Hi,

I would like to merge two textures, and by that I mean imagine two 512x512 textures, overlapping by 100pixels. However I would like the overlap to be jagged rather than a fully merged composite. I hope I have explained that well enough (imagine ink running down a piece of frosted glass, it wouldn't run down in a straight line, there would be fronds or tendrils of ink reaching into the glass below).

A little like this (best I could find)


How could such a jagged overlap be achieved?

Rock

If you're talking about doing it in-world, you'd need one of the textures to be partially transparent. Put the jaggedness into one texture's alpha channel, and then put that texture on a surface very placed very slightly in front of the other. 0.002 meters or so should do the trick.

If you're asking how to do it in Photoshop, use a layer mask. Masks works exactly like alpha channels, except they only affect one layer (or one group of layers), rather than affecting the whole image. Anywhere you paint black on a mask will cause the same area of its layer to disappear. Anywhere you paint white on the mask will cause that part of the layer to be visible. Anywhere you paint gray on the mask will cause that part of the layer to be translucent (the darker the gray the more transparent, the light there more opaque).

As for creating the jaggedness itself, there are any number of ways to do that. You could paint it by hand with an ordinary hard brush, you could use a more spattered brush for a less delibarate look, you could apply a bit of noise followed by a motion blur to part of the mask, etc., etc., etc. As with anything else in Photoshop, the possibilities are endless for how you could proceed.