blender2ogre

• License: GNU LGPL
• Ogre forum thread

This versions requires Blender 2.8+. For Blender 2.7x: use the 2.7x-support branch

Index

• Installing
• Updating to new versions
• Video Tutorials
• Exporting Meshes
  • Materials
  • Blender Modifiers Support
  • Mesh triangulation issues
  • OgreNext Tips
• Importing Meshes
• Additional Features
  • Merge Objects on export
  • External OGRE Materials
  • Console Export
  • Exporting Custom Vertex Groups
  • Exporting Custom Normals
  • Exporting Skeletal Animations
  • Exporting Particle Systems
  • Exporting Shape (or Pose) Animations
  • Exporting Node Animations
  • Exporting for Physics
  • Exporting Vertex Colors
  • Exporting SkyBoxes
  • Level of Detail (LOD)
  • Mesh Previewer
• About
• Authors

Installing

1. Copy the io_ogre folder into the $BLENDER_DIR/scripts/addons folder.
2. Enable the addon in Blender: Edit menu > Preferences > Add-ons. Search for 'ogre' and click the box up the top left.
3. Configure the plugin before the first run.
   • Set the correct path to OGRETOOLS_XML_CONVERTER
     • for Ogre (v1): path should point to OgreXMLConverter.exe. This can be found in the Ogre SDK
     • for OgreNext (v2): path should point to OgreMeshTool.exe. This can be found in the OgreNext SDK
   • OPTIONAL Set MESH_PREVIEWER to a path pointed to ogre-meshviewer.bat. This can be found in OGRECave/ogre-meshviewer
   • Make sure that USER_MATERIALS isn't set to a directory like "C:\". The addon scans this path recursively and will crash when it hits a path it doesn't have permissions for.

NOTE: Installing Blender using Ubuntu Snap package or Fedora Flatpak will lead to the following error: cp: cannot create directory '/snap/blender/3132/3.4/scripts/addons/io_ogre': Read-only file system (see: Installing on Ubuntu 20.04 and Blender 3.4.1. #169)

There are two possible solutions:

• After downloading the blender2ogre repo, uncompress it somwhere and then compress the io_ogre folder as a .zip file. Go to Edit -> Preferences (CTRL-ALT-U) -> Add-ons -> Install... and then select the file io_ogre.zip
• Copy the io_ogre folder into the folder: ~/.config/blender/3.4/scripts/addons/ (where 3.4 is the Blender version)

Updating to new versions

If you are upgrading from a previous version of blender2ogre and having problems, you may want to delete your old .json config file from $BLENDER_DIR/config/scripts/io_ogre.json and restart blender.

Video Tutorials

• General Usage
• Animations
• Meshmoon: Video and text instructions on how to install and use blender2ogre addon

Exporting Meshes

To export a blender model: File Menu > Export > Ogre3D (.scene & .mesh).

If the menu button is greyed out (or you get this error: RuntimeError: Operator bpy.ops.ogre.export.poll() failed, context is incorrect), then make sure there is an active object selection in the blender Node tree (Scene collections) first. The active object selection is when there is an object with a yellow outline (in contrast to the orange outline of the passive selected objects)

• If you have OGRETOOLS_XML_CONVERTER set to "OgreXMLConverter.exe" path, then the export dialogue will display options relevant to the Ogre (v1) mesh format.
• If you have OGRETOOLS_XML_CONVERTER set to "OgreMeshTool.exe" path, then the export dialogue will display options relevant to the OgreNext (v2) mesh format.

Check out all the exporter and importer options in the Options Document

Materials

Materials will be exported as OGRE 1.x material files or as OGRE Next material.json files as required.

OGRE 1.x Materials

Materials are exported as RTSS OGRE 1.x materials (unless "Fixed Function Parameters" is selected). The following textures are exported: Base Color, Metallic and Roughness, Normal Map and Emission. Baked Ambient Occlusion is not supported for the moment.

Your material will be best exported if you follow the GLTF2 guidelines: glTF 2.0 - Exported Materials. Except for the Emission texture, where the Emission input of the Principled BSDF node is used as the Emission texture.

A good example of how the material should be setup for best results is the "Damaged Helmet" model found here: https://github.com/KhronosGroup/glTF-Sample-Models/tree/master/2.0/DamagedHelmet

OGRE Next JSON Materials

The current OGRE Next JSON exporter only explicitly supports a metalness workflow, however it will attempt to export materials not following that workflow regardless and may produce passable results.

For materials using metalness it expects a single image with the blue channel containing the metalness map and the green channel containing the roughness map fed into the Principled BSDF via a Separate RGB node. Not following this convention will print a warning to the console and the exported materials will likely not appear correctly when rendered.

There are numerous features in the Ogre Next JSON format that are not directly supported, see the Materials JSON notes for details.

Blender Modifiers Support

Blender has some very useful modifiers, and most of them are supported by blender2ogre but not all of them. Check out the Blender Modifiers Support Page to check out the list and also some recommendations about them.

Mesh triangulation issues

If you are seeing some issues with the mesh triangulation (like visible triangles in your shading), check the Mesh Triangulation README to learn more about the subject and how to work around it.

OgreNext tips

If you do want to export in the OgreNext (v2.) format, make sure in the Export dialogue > General Settings > Mesh Export Version is set to V2. The following parameters are a good starting point to get a model exported to an Ogre mesh:

• General
  • Mesh export version: v2
• Materials
  • Export materials: ticked
• Armature
  • Armature animation: ticked
• Mesh
  • Export mesh: ticked
  • Edge lists: un-ticked
  • If your model's materials contain normal mapping:
    • Tangents: "generate with parity"
    • Else Tangents: "none"
  • Optimise Vertex buffers for shaders: ticked
  • Vertex buffer options: puqs

You can check the arguments passed to OgreMeshTool.exe in the Blender console. (Window Menu > Toggle System Console)

Blender will export the material format in an Ogre (V1) format. This is not compatible with OgreNext (V2.*). You should manually convert them to a material.json file. See the Ogre Wiki: HLMS Materials for more information.

Importing Meshes

As of blender2ogre version 0.8.2, the Kenshi Importer has been integrated into blender2ogre with the following features:

• Import mesh from .xml as well as .mesh files
• Import whole .scene files (as of version 0.8.5) with all its objects
• Option to be able to merge imported submeshes or keep them separate
• Parsing/Conversion of materials into Blender (just create a Principled BSDF material and add a texture with the proper UV mapping)
• Importing of Poses
• Importing of Skeletons works for the most part, but Ogre skeletons conventions are not like Blenders (see: How to get bone's vector and bone's length?)
• Importing of Animations work, but depends on the skeleton which sometimes doesn't get correctly imported
• As of Blender 4.1+, it is now possible to drag and drop files of types: .xml, .mesh or .scene and import them automatically. (https://docs.blender.org/api/4.1/bpy.types.FileHandler.html)

NOTE: Orientation of the imported mesh is assumed to be xz-y (Ogre default), the blender2ogre Axis Swapping option does not work for the importing process.

Additional Features

Merge Objects on export

You might have hundreds of objects, which you want to keep separate but have them in one .mesh on export. For this create a new collection (M) named merge.<yourname>. The output will be a single <yourname>.mesh file. Alternatively link the collection.

NOTE: The origin of the resulting merged object will be that of the last object you added to the collection (although when reloading the blend file, this order will be lost). To have control over the precise location of where the merged objects' origin will be, use the dupli_offset property of the collection. Setting any value other than the default (0, 0, 0) will result in a mesh with the origin set to that value. For example:

Instancing and DotScene Plugin

As of OGRE 1.13 a new feature has been added to the DotScene Plugin where it now accepts the static / instanced keywords for entities. (for more information read the DotScene Plugin README).

To use this feature create a new collection (M) names as static.<Group Name> or instanced.<Instance Manager Name> and blender2ogre will automatically add the corresponding attribute to the exported entities in the Scene. This feature goes hand in hand with Exporting Particle Systems to create vegetation, debris and other static objects in your scene.

External OGRE Materials

You might already have some materials in OGRE that you do not want to export. Prefix them with extern.<yourname> and the sub-entity will have the material name set, but the material is not exported. The following material 'vertexcolor' can be defined in your OGRE project:

Console Export

You might have several blender files in your project you want to export to Ogre. Do this by hand? NO! You can do better! Here is how you can export a scene with blender2ogre.

blender test.blend -b --python-expr "import bpy;bpy.ops.ogre.export(filepath='test.scene')"

Exporting Custom Vertex Groups

As shown in the picture below, you can now export SubEntities that contain a user-defined amount of faces.

You simply call your vertex group with the prefix ogre.vertex.group.<yourname> and access it in Ogre similar to the following:

void example(const Ogre::Entity * entity)
{
    auto collision = entity->getSubEntity("collision");
    auto mesh = collision->getSubMesh();
    VertexData * data = nullptr;
    if (!mesh->useSharedVertices) {
        data = mesh->vertexData;
    } else {
        data = mesh->parent->sharedVertexData;
    }
    auto pos_cursor = data->vertexDeclaration->findElementBySemantic(Ogre::VES_POSITION);
    auto vbuffer = data->vertexBufferBinding->getBuffer(pos_cursor->getSource());
    auto ibuffer = mesh->indexData->indexBuffer;

    uint16_t * indices = static_cast<uint16_t*>(ibuffer->lock(Ogre::HardwareBuffer::HBL_READ_ONLY));
    float * vertices = static_cast<float*>(vbuffer->lock(Ogre::HardwareBuffer::HBL_READ_ONLY));
    float * v;
    int count = mesh->indexData->indexCount;
    int stride = vbuffer->getVertexSize() / 4;
    for (int i = 0; i < count; i+=3) {
        uint16_t a = indices[i], b = indices[i+1], c = indices[i+2];
        pos_cursor->baseVertexPointerToElement(vertices + a * stride, &v);
        Vector3 va(v);
        pos_cursor->baseVertexPointerToElement(vertices + b * stride, &v);
        Vector3 vb(v);
        pos_cursor->baseVertexPointerToElement(vertices + c * stride, &v);
        Vector3 vc(v);
        // do something with your triangle here
    }
    ibuffer->unlock();
    vbuffer->unlock();
}

The vertex group will get the material name 'none' so you might want to add the following script:

material none {
    technique {
        pass {
           // ...
        }
    }
}

Exporting Custom Normals

Custom Split Normals is a way to tweak the mesh shading by pointing normals towards directions other than the default, auto-computed ones. It is mostly used in game development, where it helps counterbalance some issues generated by low-poly objects (the most common examples are low-poly trees, bushes, grass, etc. and the ‘rounded’ corners). Check out the Custom Normals README to learn more about Custom Normals in Blender.

Exporting Skeletal Animations

Skeletal Animation refers to the technique of using bones to deform a mesh as if the mesh were the skin. This kind of animation is commonly used to animate characters in video games. Check out the Skeletal Animations README to see how to create and export an animated mesh.

Exporting Particle Systems

A common technique for laying out random objects on a scene in Blender is to use the Particle System. Check out the Particle System README to see how to create and export a scene where the trees, foliage and rocks are distributed randomly using a particle system.

Exporting Shape Animations

Shape (or Pose) Animations allow animating different poses, a technique commonly used to do face animations. Check out the Shape Animations tutorial to see how to create some poses and animate them. Then you can use blender2ogre to export the poses and animations into a .mesh file.

Exporting Node Animations

Node Animations are a way to have scripted node animations in your Ogre application. Check out the Node Animations tutorial to see how to create some animations for a couple of different scenarios.

Exporting for Physics

Check out the Exporting for Physics tutorial to see some techniques and optimizations when exporting collision meshes for Physics Engines

Exporting Vertex Colors

blender2ogre can import and export Vertex Colors, a way to assign colors to your mesh by vertex. It is also possible to asign alpha values to each vertex for transparency or other uses. Check out the Vertex Colors tutorial to see how to create the Vertex Colors in Blender and how to export them.

Exporting SkyBoxes

blender2ogre can generate SkyBoxes from HDRi Maps and export them in a format that can be used in OGRE, that is a Cube Map. Check out the SkyBoxes tutorial to see how to create import the Environment Map in Blender and how to export it.

Level of Detail (LOD)

Level of Detail or LOD is an optimization technique supported by OGRE, where meshes that are far away from the camera are replaced by meshes with lower vertex count. Because you can get away with less detailed models when they are in the distance this optimizacion technique is very common, especially in games. With blender2ogre there are three ways to generate LOD levels for a mesh:

• OgreMesh Tools: This method uses the tool OgreMeshUpgrader to automatically generate the LOD levels for the mesh by removing edges. This allows only changing the index buffer and re-use the vertex-buffer (storage efficient)
• Blender: This method uses Blenders "Decimate" Modifier to automatically generate the LOD Leves by collapsing vertices. This can result in a visually better LOD, but needs different vertex-buffers per LOD
• Manual: This metod requires that the user manually creates the additional LOD levels for the mesh. The meshes should be called [base mesh]_LOD_1, [base mesh]_LOD_2, etc. This method gives better control over the resulting LODs.

For the Manual method it is currently not possible to manually set the distances for each LOD, but it is possible to have different materials for each LOD level.

Mesh Previewer

If MESH_PREVIEWER is set, a button will appear allowing you to preview your mesh in Ogre3D. If the button isn't there, the path is invalid. This only works for Ogre (V1) meshes. The button is located here:

About

The original version of this was a single monolithic Python file. This is not maintainable and contains a tremendous amount of bugs. There was the need to export Blender model to OGRE from the console, thus I rewrote the whole script and split it into several files. It has been well-tested on Linux 64-bit and should work with others.

Authors

This Blender addon was made possible by the following list of people. Anyone can contribute to the project by sending bug reports and feature requests here. Naturally, the most welcome contribution is actual code via pull requests. If you are planning to implement something "big", it's a good practice to discuss it in the issue tracker first with other authors. So that there is no overlap with other developers or the overall roadmap.

• Git Contributors
• Brett
• S. Rombauts
• F00bar
• Waruck
• Mind Calamity
• Mr.Magne
• Jonne Nauha aka Pforce
• vax456
• Sybren Stüvel

Additionally, the following companies have supported/sponsored the development efforts.

• Adminotech Ltd.