# Blender to Ogre Exporter

Blender is an open source 3D content creation suite for modeling, animation, rendering and video post production. The Blender to Ogre Exporter is a python script to run directly within Blender. Currently it supports the export of

- mesh objects with vertex colours, multiple materials, uv textures and blend modes,
- armature keyframe animations.

## Installation

The script needs access to standard Python modules not shipped with Blender. Consult the Blender documentation at www.blender.org how to incorporate Python with Blender.

- Copy the script either into ".blender/scripts" or the user defined scripts directory.
- In the "Scripts Window" run "Scripts -> Update Menus".

## Basic Usage

- In the "3D View" select the objects you want to export.
- In the "Scripts Window" run "Scripts -> Export -> Ogre XML".
- Choose your export options.
- Press the "Export" button.

You will get a detailed log of the export process. Use the OgreXmlConverter of your Ogre installation to convert the generated XML files to binary .mesh and .skeleton files.

Screenshot of the exporter interface.

### Options

Material File
  The name of the material script file that will be generated.
Game Engine Materials
  Export materials as diplayed in the game engine. Materials are exported as displayed in the rendered results on default.
Export Armature
  Export armatures and armature animations.
World Coordinates
  Export objects in world coordinates instead of object coordinates.
Coloured Ambient
  Use scaled diffuse colour as ambient colour instead of scaled white. This does only work for materials for which TexFace is not set.
Mesh Scale Factor
  All meshs and bones are scaled on export by this factor.
RotX
  Angle of an additional rotation around the x-axis of all objects on export. This rotation is applied first. Set it to -90 degrees to map Blender's up-vector (z-direction) to Ogre's default up-vector (y-direction).
RotY
  Angle of an additional rotation around the y-axis. This rotation is applied second, after RotX.
RotZ
  Angle of an additional rotation around the z-axis. This rotation is applied third, after RotY.
Animation settings of
  Choose an object from the list of all objects selected for export. The animations that will be exported for that object are then displayed in the scroll area below. Each animation correspond to one line.
  Action name
    The name of the Blender action.
  Start frame (Sta:)
    Start frame of the animation.
  End frame (End:)
    End frame of the animation.
  Animation export name
    The animation name in the exported Ogre file.
  Delete
    Removes the animation from export.
  Add
    Add another animation to be exported.
Update
  Updates the list of all objects selected for export from the currently selected objects in the "3D View". Also updates the list of possible actions, deletes animations for removed actions and sets default animations for new actions.
Use Pose Sampler
  The exporter has two modes of operation when converting Blender armature action animations to Ogre skeleton animations. When Use Pose Sampler button is not pushed in (not enabled) the animations will be sampled using ipo curves (pre-blender 2.40). Sampling ipo curves does not take into acount bones setup using IK (Inverse Kinemetics) or constraints so the exported animation will not be a true representation of the animation as rendered in Blender with IK and constraints. With Blender 2.41 and above, the exporter can use Blender Pose Sampling so that the exported animation to Ogre will be identical to the Blender animation even if IK and contraints are used on the bones of the armature.
Mesh Path
  Mesh and Skeleton files of the exporter are written into this directory. Mesh files are named after the mesh object name in Blender with suffix ".mesh.xml". Skeleton files are named after the armature object name in Blender with suffix ".skeleton.xml".
Material Path
  The material file generated by the exporter is written into this directory.
Export
  Export all objects in the list of objects selected for export.
Quit
  Exit from the export script.

The script loads and saves its options to a text buffer "ogreexport.cfg" inside the current .blend file. You can disable this behaviour by changing the script variable KEEP_SETTINGS to 0.

If the OGRE_XML_CONVERTER script variable is set to the OgreXMLConverter executable, the converter is called on the exported XML files.

## Specifics

### Mesh

The script supports sticky and per face vertex uv coordinates, smoothed and non-smoothed normals, vertex colours. Each rectangle face is automatically converted into two triangle faces in the exported mesh. The exporter defaults to using 16 bit indices but if the submesh vectex count exceeds the 16 bit limit then 32 bit indices are used.

The script does not support subdivision surface (SubSurf) options. To export a SubSurf object, you have to convert it into a Mesh object, "Object -> Convert Object Type... -> Mesh (keep original)".

The script does not support the "Double Sided" mesh option, use the "Two Sided" face option instead.

### Material

In contrast to Ogre, Blender treats material, uv texture and blend mode separately. Also Blender distinguishs between material appearance in the game engine and material appearance in the rendered results.

#### Game Engine Materials

The material name has to be unique. Therefore, the name of the exported material consists of Blender's material name (if any), the face blend mode and texture file name (if any). If vertex colours are defined, a postfix "/VertCol" is appended. Also, if the two-sided face option is set, "/TWOSIDE" is appended.

If a material is assigned to face, only the properties that affect the appearance in the game engine are exported. These are the "Col" and "Spe" colours, the "Amb", "Spec" and "Hard" factors and the "VCol Paint" and "TexFace" options.

Textures assigned with the UV/Image Editor are exported. Note that material image textures, which can be exported as rendering engine materials, give you more control over filtering and texture address modes.

Blender's face settings affect the mesh appearance only in the game engine. The properties exported by the script are marked green.

#### Rendering Engine Materials

The name of the exported material is the same as in Blender. If the "Two Sided" face option is set, the suffix "/TWOSIDE" is appended. If the "TexFace" material option is set, the suffix "/TEXFACE" and the name of the texture image that is assigned with the UV/Image Editor is appended. The "Two Sided" face option has no effect in Blender's rendering results and is evaluated on export for convenience only.

Blender's material settings that affect the exported Ogre material are marked green.

The script exports image textures with "Map Input" set to "UV" and "Map To" set to "Col" and optional "Alpha". The supported image options are marked green.

InterPol | MipMap | resulting filtering
--- | --- | ---
yes | yes | trilinear
yes | no | linear linear none
no | yes | bilinear
no | no | none

### Armature

You must have no more than four weighted bone assignments per mesh vertex. If you have more, the script will eliminate the lowest weighted assignments and renormalise the other weights. All vertices must be assigned to at least one bone.

Armature animations are exported based upon keyframe ranges and action names. You can choose any frame as start and end frame of an animation. The script will automatically insert keyframes at the start and end of the exported animation and reverse the exported animation if the end frame is lesser than the start frame. In order to export armature animations of a mesh you don't have to select the armature separately.

The script will evaluate action constraints if the Use Pose Sampler button is pressed.

Ogre does not inherit parent bone scaling by default.

The animation speed in the export in terms of frames per second is taken from the corresponding scene render button.

Blender's format setting that affect the exported Ogre animation is marked green.