First download this file: texturemasks.zip
These files are the masks we are going to use to break up our different texture layers. As you can see they are called bottomlayer_XX, middlelayer_XX and toplayer_XX, where XX is the size of the walkable part of your area.
I'll assume you know how YATT works (there's a website) and how to make a heightmap (but check out the programs Leveller, GeoControl and World Machine if you need an editor).
Let's assume you are making a 16x16 area. Start YATT and import your heightmap in the usual way. On the Settings Browser:
click on 3. Texturemaps. This opens the Texturemap collection screen:
Press the "Add" button and import the file bottomlayer_16x16.bmp. Assign a texture to it and leave the Map Generation Rules section blank. Press "Add" again and import middlelayer_16x16.bmp. Assign another texture. At this stage it doesn't matter what it is as long as it is different to the first layer. Repeat the same process for the toplayer. You should now have something similar to the pic above. Bottomlayer on row 0, middlelayer on row 1 and toplayer on row 2. Press OK and on the Settings Browser set Texture Overflow Action to "Merge".
Now continue creating your area as normal. What you will get is three layers of textures in the new area that are broken up by the texure noise masks:
Now, the fun thing about this is that if you choose the "paint terrain" tool and move it over the main toolset window the three textures appear at the bottom of the Terrain/Texturing window. Click on any of the textures to highlight it and then press the swapper button. You can now globally change that texture for another one. Two things to watch out for; first make sure you do not have the "select terrain" tool highlighted or you will just get the texture replaced in one 4x4 meta-tile and secondly don't use the same texture twice or one of your layers will be deleted and you will have to start again. The way I have made the masks means that the bottom layer has least effect, and is quite patchy and the other layers are more prominent. I tend to use the middle layer for my main texture, say grass, toplayer for dirt, for example, and the bottomlayer for patchy areas of rock/mud or whatever.
There are 82 textures in the toolset, so by my reckoning that's about 531360 possible permutations. Should keep you going for a bit!
TnD
