How to use multiple textures for an actor?

I have a block with multiple materials, each material corresponds to a texture. How do i show it in an actor?
In vtk8.1.2,I cannot get the number of texture unit that hardware support without class vtkOpenGLHardwareSupport.(there is no class vtkOpenGLHardwareSupport in vtk 8.1.2)
How to implement multiple textures on an actor? how to define which patches use the specified texture?

You can use vtkProperty::SetTexture

but I do not know how to set a specific cell in vtkCellArray use a specific texture.
Each cell only use one texture,but cell array will use several texture.
Is there any example for me refer to?

How many different texture do you have?
Maybe you could split your polyData in order to have one actor per texture.

most time there are two textures.
I could use vtkAppendPolydata to append all the polydata,but i do not know how to map polydata and texture.