Ultimate 3D model file export plugin

The Ultimate 3D model file export plugin for Blender gives you the possibility to export models directly from Blender 2.44 (in later releases it may or may not work) to the Ultimate 3D model file format (*.u3d), which can be used with the 3D engine Ultimate 3D. If you are interested in using the Ultimate 3D model file format for one of your own Ultimate 3D independent applications have a look at its chunk descriptions. The format is a quite simple binary format and it is well-documented, so you may find it interesting. A viewer for *.u3d files is also available. The use of the export plugin is quite simple. This document will describe the process in detail.

Installing the plugin

The installation of the plugin is very simple. The download contains a *.py file. This is a python script, which is the export plugin. Copy it to %BlenderInstallationDirectory%\.blender\scripts. After that you need to restart Blender (or you can just let it search for new scripts, if you know where that option is). The menu File->Export should contain an entry called "Ultimate 3D model file format (*.u3d)" now. If so the installation has succeeded. If the plugin does not work the reason usually is that it uses several Python modules, which do not come with Blender, to handle texture files. In this case it will say "Python script error: check console". To fix this go to Python.org to download Python. This will fix the problem.

The abilities of the exporter

The export plugin is quite versatile and should offer enough features for most purposes. It can export the following data:

Mesh objects, including vertex normals, vertex texture coordinates and painted skin weights. If you are using envelopes for your skin weights that is no problem. All you need to do to create painted skin weights from envelopes is selecting the geometry, going into weight painting mode, selecting one bone after the other and pressing "W" for each of them. This will apply the bone envelopes to the vertex groups.
Material objects with ambient, diffuse, emissive and specular color and up to eight textures. If there are multiple textures Ultimate 3D will always use a multiplicative texture operation to combine them. All used textures will be copied to a directory called "gfx" at the path to which the model gets exported.
Armature objects with an arbitrary number of actions effecting them and with constraints. The actions will be placed one after the other in the animation of the Ultimate 3D model file. Their frame numbers can be written to a file and get output to the console.

Usually this is all data a game developer needs, but Blender can handle a lot of additional information, which can not be exported with this plugin. I want to state some things that can not be exported explicitly here:

Envelopes and the skin weights that result from them. See above for an explanation on how to get them converted to painted skin weights.
Most material properties, like special effect settings.
Object animations. Only the animations of armatures can be exported.
Most modifiers. The only exception are modifiers that actually change the data of the mesh. To be on the save side you should apply all modifiers before exporting.
Special objects like particle systems, camera objects and light objects.
And a lot more. Blender has way too many features to list everything that is not supported.

Exporting models

Exporting models with the plugin is an easy and fast process. Before exporting you should make sure that you want to export only information that can be exported (see above). If so just choose the exporter from Blender's list. A small pop up with five options will appear. Here is a list of the options and their meaning:

Selection only
If this option is enabled the plugin will export only objects that are currently selected. This is useful if your model contains many components that are not meant to be exported, e.g. older versions of the model on other layers. The exporter will behave as if all objects, despite those that are selected were deleted. If it is disabled all objects in the current scene will be exported (default). Layers do not have any effect.

Animation
If this option is enabled the plugin will export armatures (default), otherwise it will simply ignore them completely. Skin weights will not be exported either.

Constraints
If this option is enabled an alternative technique will be used to export armature animations (default). This technique works with constraints. Otherwise the animation will be exported by exporting the Ipo curves of the actions. This is recommended if you are not using constraints. If this option is enabled, it may happen that the interpolation between rotation keys does not work correctly in the exported model.

Remove double vertices
If this option is enabled the plugin will avoid exporting identical vertices twice. If it is not checked one vertex will be exported for every vertex of each face, so e.g. if your model is made up of 300 triangles there will be 900 vertices. For this reason enabling this will usually reduce the vertex count by more than 50%. Anyway it is by default not checked, since it takes quite a lot of computing time. If it is enabled exporting will take a while.

Action list
If this option is enabled a list of the actions with their corresponding frame values will be exported to a text file. The file will have the same name as the model file, but .txt as file ending instead of .u3d. The exported file contains information about one action per line. Every line starts with the name of the action in quotation marks. Next there is the first frame of the action and after that there is the last frame of the action. If this information is disabled you can get the same information from the console window.

If you are done setting the options click OK. Then a file selection window will pop up. Simply chose the file you want to export to and click "Export *.u3d model". You will not be warnt if you try to overwrite an existing file. If everything works out fine you will see a small pop up message, telling you that exporting has succeeded. If it has not succeeded check the console window for more information.

Contact

If anything is going wrong with the exporter please read this document first. Make sure that the information you want to export can be exported and that you have selected the right options. If it is still not working there are several possibilities to report this. The easiest way is to post a report on the Ultimate 3D Community. Alternatively you can contact me by email at admin@Ultimate3D.org or through the contact form on Ultimate3D.org. I am thankful for any bug report. Just make sure that you include the relevant information. What is not working, what is the console output and which Blender version are you using? It is also very helpful if you include the blender file in the bug report. You can rely on the fact that I will not use it for anything other than debugging purposes.

Last updated: 19th of August 2008