http://i.imgur.com/3o92hxG.png - As you can see in this screenshot, I have a weird problem with some of my landscape layers. The ‘mud’ layer and ‘rock’ layer blen in squares with each other. They interract correctly with everything else though.
http://i.imgur.com/ERbcZ5l.png - here you can see my landsace layers, they are pretty simple, so I have no idea why this is happening.
I need an advice - how could I fix this?
I believe this to be an issue with the falloff of your brush and the strength of your tool. I ran a test and found that if you have the tool strength set to 1.0 and your falloff to 0 it creates a more jagged edge. This is due to the vertices in your landscape. When you paint with full strength the information is sent to the nearest vertex.
I took a screenshot of my experiment. The one on the top left is with the tool strength set to 1.0 and the falloff to 0. The one on the top right is a tool strength of 1 but with around .9 falloff. The bottom is with a tool strength of .1 and a fall off of .99. So, play with these values and see what kind of results you can come up with.