This process show how to use RGB channels of the vertex paint from a modelisation to mix together some materials, under Blender. This is perfect to break the repetition of repeatable textures.

Theory :

On a sufficietly rich wireframe object we use a nodal material. From ther we want to separate R, G and B values of the vertex color to blend 4 materials. See Blender material nodes for more informations on nodal materials under Blender.

Ordering sequence :

First, create an object with sufficient wire to hold gradients, if necessary.

Unwrap UV for the object(see Blender UV Maps if necessary - for simple objects just use Mesh> UV Unwrap> Unwrap with the object selected in edition mode  - TAB - ).

Then we must create all the materials that will be used on the object (Color map, normal map, spec map, etc...).

In this example we will use 3 materials (even if it's possible do it with 4 materials)

Use simple objects (cube/speres) with the "invisible" tag ennabled in the game engine (F4 > Look for the "invisible" button in the button pannel). Save these objects and materials in an other file (named "materials.blend" by example) to create the singles simples materials upside. Then give to all these objects a group ("Materials", to be original !).

Finally, link the group in the working file (File > Append or Link with the "Link" option selected, navigate until the file "materials.blend" created before, enter in the file by double cliking it > Groups > select the group named "Materials" that we created precedently), then add the objects groupped in the scene (space bar > add > <name of the group> -> "Materials" for us).

Select the initial object, give it a nodal material ("Nodes" button in the material). In the nodal editor create the following nodes :

N.B : It is possible to genericise the nodes in an external linked file, as we did for the materials.

Set the working view in "textured" mode, enventually set the game engine on GLSL materials.

Get in "vertex paint" mode

Using the colors in the paint window under the "Editing" button (F9) it's now possible to create a paint that blends materials together...

 

 

 

       ==> Blend File : Vertex_Paint.rar  <==