How to have different materials assigned to same mesh gradate into each other (without using a mapping node) I would like to be able to assign grass and dirt to certain parts of the mesh and have them gradate into each other instead of having a hard edge, just like in this video: 

https://www.youtube.com/watch?v=ilmS_CeKCuo

The plugin shown in the video itself is not available to be downloaded. I was wondering if there was another way I could achieve the same effect.

(edit)

I'm including an image to describe exactly what I'm trying to achieve. In the video, the blender user has a plugin which allows him to assign the textures to the faces, and the textures gradate automatically. I heard that this was possible without the use of the plugin, but I wasn't sure how to achieve it.
You can use vertex colors. If you paint a mask in black and white in Vertex Paint mode(ctrl+tab -> Vertex Paint) and then mix your desired shaders or textures using vertex color node, the textures will blend gradually:



You can make various gradients from a lot of things with nodes so this is probably not the only solution. I would recommend not to limit yourself by excluding usage of any nodes such as mapping node when working with your materials for no reason. It's usually best to use all the tools available to you.