Ogre 3D File Format

OGRE 3D files are XML files use to store 3D model information. Tools such as Maya, 3D Max facilitate users to export file into OGRE 3D file format. Following files contain different information about model.

1. .mesh.xml File : This file contains the information of mesh’s  contains the information of geometry for a visible object in a 3D application. A mesh is a set of triangles, and usually has a texture. To load a mesh in your application you need to create an entity, where as entity is an instance of mesh. An entity can be any object from real world having some state, actions and behavior.  A mesh loaded in your application will load default material. You can use material to change object shape. Multiple entities can be created from the same mesh.
2. 

   Skeleton Information in a human pose

   .sekeleton.xml File : Contain bone information mostly entity required to animate. Skeletal animation works by having a collection of ‘bones’ which are actually just joints with a position and orientation, arranged in a tree structure. Lets consider the human model, the wrist joint is a child join of the elbow  and elbow is  the child of the shoulder joint. Moving or rotating the shoulder automatically moves the elbow and wrist because of  this hierarchy. Every vertex in a mesh is assigned to one or more bones which affects position when the bone is moved or rotated. If a vertex is assigned to more than one bone, then weights must be assigned to determine how much each bone affects the vertex (actually a weight of 1.0 is used for single bone assignments). Weighted vertex assignments are especially useful around the joints themselves to avoid ‘pinching’ of the mesh in this region.

3. .material File : .material file used to store surface information of a mesh. A material determines how the surface of a mesh will appear after being rendered. You can e.g. assign textures, set colours, enable lighting or shadow-receiving as well as assigning shader.
4. .scene File : .scene file is also a xml file format, which is  used to set up a scene. It does not contain any mesh or texture information. It just contains the elements that describes the scene.

References

[1] Ogre 3D website, http://www.ogre3d.org/, Accessed on 21/04/2014

[2] JMonkeyEngine website, http://jmonkeyengine.org/, Accessed on 21/04/2014