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114 lines
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4.4 KiB
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##################
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Native Mesh Format
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This article explains how to export a model from Blender to OpenMW using the OSG model format.
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Starting with OpenMW version 0.38 we can utilize the OSG native model format.
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The OSG model format doesn't yet support all the features that NIF's support,
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but works for basic models. For more details on the format, refer to
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`this forum post <https://forum.openmw.org/viewtopic.php?f=20&t=2949&p=35514#p35514>`_.
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Previously, NIF files were the only way to get models into the game.
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Unfortunately, the NIF format is proprietary, bloated,
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and the available exporters are not in great shape.
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For example, the Blender NIF exporter currently only works with the very old Blender 2.49.
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Prerequisites
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#############
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- OpenMW 0.38 or later
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- Blender 2.60 or later
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- OSG exporter add-on for Blender
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- A Blender model you would like to export
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Installing the exporter
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#######################
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#. Download the
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`OSG export script
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<https://github.com/openmw/osgexport/blob/release/blender-2.5/build/osgexport-0.14.2.zip?raw=true>`_
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#. Open Blender and go to File -> User Preferences
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#. Select Add-ons -> Install from File, then select the downloaded `.zip`
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#. Enter "osg" into the search bar, then tick the checkbox next to the add-on to enable it
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#. Now click Save user setting so the exporter stays enabled when you re-start Blender
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You can now export your models using the OSG model (osgt) entry in the File -> Export menu.
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Model's location
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################
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The model needs to be at 0,0,0 coordinates in Blender,
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as this is where its origin will always be when exported.
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If the model is offset from 0,0,0 in Blender,
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it will be offset from its origin in the exported file as well.
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Model's rotation
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################
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- Blender's Z axis is up axis in OpenMW
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- Blender's Y axis is front axis in OpenMW
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- Blender's X axis is left-right axis in OpenMW
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- Visual rotation is taken into account when exporting
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Model's scale
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#############
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Blender:OpenMW model scale is 70:1,
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which means 70 Blender units (BU) translate into 1m in OpenMW.
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Using this scale, any models you make will fit with the existing ones.
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The scale does not need to be applied,
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the exporter will always use the visual scale of the model.
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However, 70 is an odd number to work with so here's an alternative workflow:
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- In Blender, use a scale of 1BU = 1m which is a nice scale and ratio to work with.
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Have all models use this scale.
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- Before exporting a model, scale it up by a factor of 70.
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- After exporting, undo the model's scale change and continue working as normal
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(in the future a preferable way would be to apply the scale through the exporter)
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Putting the model in-game
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#########################
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Place the exported model in the Meshes sub-folder of a data folder recognized by the game,
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e.g. the Morrowind Data Files folder, or the local data folder.
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Place all required textures in the Textures sub-folder.
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Now start OpenMW-CS, create a new addon file
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and you should see your mesh in the Assets -> Meshes table.
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Go ahead and make some object use your mesh.
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You can now preview by right clicking on the object -> Preview to see what the mesh will look like.
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Converting the model to binary
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##############################
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When the model behaves to our liking,
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we can think about converting it from the "osgt" text format to the "osgb" binary format
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so that it's smaller in size - and thus faster to load.
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To do this, simply invoke the osgconv tool.
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This tool should be included with your distribution of OpensceneGraph.
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`osgconv -O WriteImageHint=UseExternal model.osgt model.osgb`
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Of course, you can convert the binary model back to text format as well:
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`osgconv -O WriteImageHint=UseExternal model.osgb model.osgt`
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Note the use of `-O WriteHint=UseExternal` option.
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Enabling this option is desirable because it keeps the textures as external file references,
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rather than embedding the textures within the model file.
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Embedded textures have disadvantages such as being hard to inspect,
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and impossible to share between model files.
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Using shaders/normal maps
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#########################
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See :ref:`OSG Native Files`
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Conclusion
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##########
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These are the basics of getting a textured, static model from Blender into the game.
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In the future, we will want a way to add texture animations,
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skeletal animations, separate collision shapes,
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and some other features that are currently only available via NIF files.
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We will likely add these features to the native OSG format after OpenMW 1.0. |