So I figured I would start the blog with something that people may find useful. A quick little tutorial on vertex blending in UDK.
Vertex blending is a process that blends two different textures on a mesh based on the vertex colors of that mesh. Obviously, you need two textures to start with, but you can always use more if you want. But for this example, I'm just going to keep it simple.
The first node that you'll need to use to blend these textures is a lerp node. If you're going to use the search function, the full name is Linear Interpolate. Or you can press L and click the mouse as a shortcut. The Lerp node has three different inputs. A and B are for the textures that need to be plugged in, and the Alpha slot is where you determine what channel you need to paint on in order to blend the textures.
Now is when we determine the channel needed to paint on. In order to do this, you need to use a Vertex Color node, and take one of the output channels on the node and plug it into the alpha slot in the Lerp node. In this case I just chose the red channel because it's the first one, but you can use any of the four available channels.
Now just plug it in, and do the same process for any other maps you may have. Make sure you use the same channel for all of these and that each texture plugs into the same Lerp input. This is the most basic example of a blend texture.
Here is the blend texture so far. Very basic with just a standard smooth transition. Next, we'll add a blend mask to give the transition some variation.
This is the node structure for the blend mask. For this example, the blend mask is just a simple clouds texture from photoshop. For this, you need to take a multiply node and plug your texture and whatever channel you want to use from a vertex color node into it. Make sure the texture is in the A slot. Then, plug your multiply node into the A slot of an add node and plug the same channel color from the vertex color node into the B slot. Then plug the add node into a Constant Clamp node, and finally, plug the Constant Clamp node into the alpha slots of the original Lerp nodes. This will get rid of the original vertex color nodes but that's ok because it's replaced by the vertex color node used to multiply and add over the blend mask.
To start changing the vertex colors, click on the paintbrush in the sidebar of UDK to open up the Mesh Paint menu. In order to paint, check whatever color you used in your material, and then use a combination of ctrl click and ctrl + shift click to add and bring back your blended texture. Just note, that because this is all based on vertices, the more vertices in the mesh, the more crisp the blend will be.
Now as you can see, with that blend mask, the transition has much more variation. Well, that's it really, I hope this helped some people, and sorry if you have a hard time understanding some of the things I'm explaining, it's my first walkthrough ;). Hopefully I'll get better at explaining these things as I make more.
Vertex blending is a process that blends two different textures on a mesh based on the vertex colors of that mesh. Obviously, you need two textures to start with, but you can always use more if you want. But for this example, I'm just going to keep it simple.
The first node that you'll need to use to blend these textures is a lerp node. If you're going to use the search function, the full name is Linear Interpolate. Or you can press L and click the mouse as a shortcut. The Lerp node has three different inputs. A and B are for the textures that need to be plugged in, and the Alpha slot is where you determine what channel you need to paint on in order to blend the textures.
