Level of Detail - anticto/Mutable-Documentation GitHub Wiki

Why use multiple levels of detail

The reasons to use levels-of-detail (LODs) in Mutable are the same reasons you would use them for other game assets: memory usage, processor performance and loading time. In Mutable you can take advantage of its procedural construction of characters to optimize even more by creating specific diagrams for each LOD. This way, you can have objects like the base character body that follow the usual LOD optimization, by simply lowering the polycount and texture sizes on each LOD, but you can also go beyond this and define different construction process for each LOD using cheaper operations as the object is further away.

As an example lets imagine a character bracelet. In the top LOD used during close-ups, the bracelet has its own mesh and complex materials with physics animation. For the second LOD it may be simplified by replacing it with a rigid mesh with a single material directly skinned to the arm bone. The third LOD may be just a texture patch on the arm (if the bracelet is big enough). In the fourth LOD it may have disappeared completely. You can define all this cases in different diagrams using the same parameters, so if the bracelet color was customizable, you could see it change on every LOD.

Defining the levels of detail of a component

The LODs can be defined in the different nodes in the graph. The most important location is the Mesh Component node. The number of LODs specified in this node, will limit the maximum LODs that can be defined in that component. This means that Add To Mesh Component nodes will only generate as many LODs as its parent Mesh Component node. Finally, if a LOD pin has no connections, it means that that LOD will not have geometry (unless automatic LODs are used, see section below).

The engine-side LOD properties that control how the LOD is selected, are just the standard Unreal Engine properties. They are copied from the Reference SkeletalMesh object, so you can easily set them up there. Please note that this means that the Reference SkeletalMesh object must have LODs.

Finally you can find more LOD settings in the the Object Properties tab.

Automatic level of detail

Since customizable objects may become very big, there is a way to simplify the generation of LODs without having to multiply all the nodes. This method can be enabled by choosing the right option for the Auto LOD Strategy field in Mesh Component node. See that node form more information.