There are two parts: root classes and element classes.

Root Classes

The Alien root classes represent the roots in the document where the elements are stored. The memory allocation function Alloc*() must be overriden.

The following root classes exist:

Root Class	Description
AlienRootObject	Contains scene objects.
AlienRootLayer	Contains scene layers.
AlienRootMaterial	Contains scene materials.
AlienRootRenderData	Contains scene render data.

Root Elements

The Alien element classes represent the different elements in the document (objects, materials, layers, etc.). Data saving/loading is handled through the overridden classes.

Element building for the external application with the specific data happens in the Execute() method. If false is returned the load operation will go one level deeper to the next cache. The Execute() method must always be overridden. See Polygon and Object Caches.

Examples of alien elements:

class AlienLayer : public LayerObject
class AlienNullObjectData : public NodeData
class AlienForegroundObjectData : public NodeData
class AlienBackgroundObjectData : public NodeData
class AlienFloorObjectData : public NodeData
class AlienSkyObjectData : public NodeData
class AlienEnvironmentObjectData : public NodeData
class AlienFFDObjectData : public PointObjectData
class AlienPolygonObjectData : public PolygonObjectData
class AlienCameraObjectData : public CameraObjectData
class AlienPrimitiveObjectData : public NodeData
class AlienSplineObject : public SplineObject
class AlienLightObjectData : public LightObjectData
class AlienInstanceObjectData : public NodeData
class AlienXRefObjectData : public NodeData
class AlienBoolObjectData : public NodeData
class AlienExtrudeObjectData : public NodeData
class AlienDeformerObjectData : public NodeData
class AlienSkyShaderObjectData : public SkyShaderObjectData
class AlienCAJointObjectData : public JointObjectData
class AlienCASkinObjectData : public SkinObjectData
class AlienMaterial : public Material
class AlienBaseMaterial : public BaseMaterial
class AlienRenderData : public RenderData

It is recommended to use the provided alien_def.h from commandline example.