Rebel Fork Framework
Model Resource

Model contains vertex and index buffers used to render static geometries. Model also contain Skeleton for skeletal animation and some extra metadata.

Note: Model contains prepared data ready for rendering. Use ModelView to access model data in easy-to-use format.

Model is stored in the file system as *.mdl file which contains main data and optional *.xml auxiliary file which contains arbitrary metadata.

Data Layout

Vertex and Index Buffers

Model contains arbitrary amount of VertexBuffer-s and IndexBuffer-s of arbitrary format.

Model contains BoundingBox in model space which will be used for spatial queries.

Vertex Morphs

Model may contain arbitrary amount of morphs.

Morph is an update to a subset of vertices in one or more VertexBuffer-s. Morph may additively modify position, normal and/or tangent of vertices. Morphs are applied to geometry in AnimatedModel.


Model contains exactly one Skeleton. For static models Skeleton is empty and is usually ignored.

Skeleton is an array of Bone-s.

Every Bone has its name, initial transform and parent bone.

Also, Bone should contain either bounding box or bounding sphere in order to contribute to the bounding box of AnimatedModel.


Geometries are what actually defines how Model will be rendered.

Model is split into one or more "submodels", where each "submodel":

  • has its own independent set of LODs;
  • has geometry center in model space used to calculate LOD distance;
  • has optional mapping of bone indices (from bone index in vertex to bone index in skeleton);
  • may be assigned with unique Material during rendering.

Geometry is the specific LOD of specific "submodel". Example layout of geometries in the Model:

| |LOD #0|LOD #1|LOD #2|...| |-|-|-|-|-| |**Batch #0**|Geometry #0|Geometry #1|| |**Batch #1**|null|Geometry #2|Geometry #3|...| |**Batch #2**|Geometry #4|Geometry #5|Geometry #5| |**...**|...|...|...|...|

Every Geometry references one or more VertexBuffer of the Model and at most one IndexBuffer. Geometry never stores actual vertices or indices.

Geometry also defines the range of vertices/indices to be rendered and primitive type used.


Usually metadata is up to user, but there's a couple of values with special meaning:

Name Type Description
LightmapSize IntVector2 Size of the region in lightmap texture required to fit all object lightmaps with specified LightmapDensity.
LightmapDensity float Number of lightmap texels per unit, assuming that the object takes LightmapSize texels of lightmap texture.
LightmapSharedUV bool Whether the object uses the same lightmap UVs for all its LODs.