Mutable allows to use multiple UV channels in the Materials of the Customizable Objects. This way, the texture parameters used in several UV channels can be used inside Mutable to create customizations. The resulting materials from the Mutable Instances still have the UV channels used in the Customizable Object.
= How to use them?
In order to use multiple UV channels inside Mutable, we must configure the material graph and all the nodes related to the textures that affect the used UV channels.
(WARNING) These textures must be declared as texture parameters inside the material graph, so they are exposed in the Mutable graph.
Also, these textures must have a TexCoord node in the material graph to indicate which UV layout we are going to use. {F422879}
The following is a list of the nodes that are involved in the use of multiple UV channels in a Customizable Object and the way they must be set.
==Material node
In the Node Properties tab of this node, we can decide which texture parameters are exposed to the node. The selected ones will appear in the "Images" array inside "Customizable Object".
(IMPORTANT) Each texture parameter must have assigned the proper channel in the "UVLayout" parameter.
{F422501}
==Skeletal Mesh node
The Skeletal Mesh node will show, with yellow connections, all the UV channels from each section and LOD of the mesh. Mesh Layout nodes will be connected to these yellow connections of the Skeletal Mesh.
==Mesh Layout node
As explained in the [[ mutable/unreal-engine-4/user-documentation/texture-layouts | reference page of the Mesh Layout node ]] and in the [[ mutable/unreal-engine-4/user-documentation/nodes/mesh-layout/ | Texture Layouts page ]], this node allows to organize the UV islands of a mesh in blocks and define a size in relation to other Child Object layouts.
In case of needing Mesh Layouts for an UV channel, all the previous UV channels must have their own Mesh Layout node assigned.
**Example: **//If a Skeletal Mesh with 4 UV channels is used (0, 1, 2 and 3) and a Mesh Layout for the channel 3 is needed, the channels 0, 1 and 2 will also need a Mesh Layout each one. If, in this Skeletal Mesh, only channel 1 needs a Mesh Layout node, channel 0 must have its own as well and Mesh Layouts in channels 2 and 3 would be optional. //
==Edit Material node
It is possible to edit texture parameters from a Customizable Object with an Edit Material node in a Child Object. Edit Material node lets you select which UV channel is edited.
In the Node Properties tab of this node, there is a parameter called "Layout" with a drop-down menu. In this menu the UV channel can be selected. Once selected, the layout and the blocks from the Mesh Layout node will appear.
(IMPORTANT) The selected Layout must match the channel of the texture to be edited in the node.
{F422503}
==Remove Mesh Blocks node
It is also possible to decide from which UV Layout we want to remove blocks. This node has the same approach as the Edit Material node.
==Texture Project node
In the Node Properties tab of this node there is a menu called "Layout" that allows the selection of an specific UV Layout. The selected layout will be the one where the projection will happen.