How can I have 2 different images seamlessly tile with each other?

Question

If I Google for "seamless tile" I can find many great answers to create a single image that will seamlessly tile with itself. GIMP even has a filter that will automatically make an image seamless in 1 click, and it works surprisingly well.

But for my game, I would like not only 1 image to tile with itself. But I would like to have different variations of that tile, so the whole texture looks less boring. I want, for example, 10 different grass textures, 10 different dirt textures. Not only should grass01 tile seamlessly with grass01. But grass01 should tile seamlessly with grass02 and dirt08.

One great example of a game that does this is Starcraft. Even the original Starcraft from 1998 has this system where they have multiple grass textures that all seamlessly tile with each other. How do they do that?

Answer 1

Basically, I think what you do is first of all create a tile for each of your terrain types that seamlessly tiles with itself. As you said there are many tutorials available on how to do this.

Once you have those tiles, you can draw variants as well as transitions between different types of terrain by modifying copies of them. The only thing you need to make sure to avoid is changing the borders of the image, since you need those to seamlessly connect to neighbouring tiles.

Of course, when you're drawing transition tiles, you may start with a tile that has half of it filled with each type of terrain and then you need to make it look good. In this process you'll often end up modifying the edges a bit anyway where the terrains meet up. However, transition tiles are quite specific cases so you only need to make sure these sides still connect seamlessly to only a handful of other tiles.