Material slots

IntermediateArtistProgrammer material slots. For example, the second material slot in this model specifies the material for the visor and the shoulder and chest plate stripes. By changing the material in this slot, we change the material used in these parts of the model. .fbx, .obj, etc). You can’t edit material slots in Game Studio; you can only change which materials are used in each slot.

Set materials on a model

You can change the materials a model uses in two places:

• Materials properties of the model itself:

  Note

  This affects every instance of this model.
• model component of an entity or prefab: this instance or prefab.

  Meshes and material slots

  Models imported from modeling software can contain meshes. Meshes can share materials via material slots. The association between a mesh and a material slot is defined in the model source file. You can’t change these associations in Game Studio, but you can change them in code at runtime. To change the association between a mesh and a material, use:

  MyModelComponent.Model.Meshes[submeshIndex].MaterialIndex = materialIndex;

  To change or add a material to the list of materials:

  MyModelComponent.Materials[ExistingOrNewMaterialIndex] = myMaterial;

  Merging meshes

  When Xenko draws a model with meshes, it performs one GPU draw call for each mesh. By default, to improve performance, at build time, Xenko merges meshes that share materials. In the example above, there are five meshes and five draw calls. After merging, there are three meshes and three draw calls.

  Note

  When Xenko merges meshes, it merges the vertex and index buffers. This means you can’t draw the meshes separately at runtime, and you can’t change the original mesh position (transformation matrix). The meshes become a single mesh with a single material and a single transformation matrix (relative to the model).

  Note

  When Xenko merges meshes, it changes the draw order of elements. In the case of transparent materials, this can produce different results.

  Note

  physics collider from a model, Xenko builds separate convex hulls for each mesh in the model. If the meshes are merged, only one mesh remains per material, so convex hulls are also built from merged meshes.

  Disable mesh merging

  You might want to disable mesh merging if you want to:
• animate a mesh
• change the material of a mesh at runtime To disable mesh merging on a model:
• Select the model you want to disable mesh merging for.
• Property Grid, disable Merge meshes.

  Disable merging for specific meshes

  nodes.
• Select the model that contains the meshes.
• Property Grid, under Skeleton, make sure the model has a skeleton associated with it. Animation.
• Asset View, select the skeleton.
• Property Grid, under Nodes, select the nodes that correspond to the meshes you don’t want to merge.

  Tip

  To see which nodes correspond to which mesh, open the model source file in a modeling application such as Maya.

  Note

  Make sure you don’t disable nodes that are animated at runtime.

  See also

• Material maps
• Material attributes
• Material slots