This class can export an Open Inventor scenegraph to a U3D file. U3D files can be used to import a 3D scene into a PDF file. For a simple PDF export, see SoToPDFAction.

U3D is a much simpler format than the Open Inventor scene graph and limits what can be exported.

Limitations of U3D:

• Cameras

  • Multiple cameras are ignored, only the main scenegraph is exported (no legends, logos...).

  • PoViews (PoSceneView, PoView, PoBaseView) are not supported.

• Lights

  • Lights affect the whole scenegraph no matter where they are placed in the scenegraph.

  • Per-vertex lighting is precomputed with default lights.

  • Two-sided lighting is not supported. Incorrect normals will result in black triangles. However note that the end user can enable two sided rendering in the Acrobat Reader preferences dialog under the "3D & Multimedia" tab.

• Lines

  • Line width is not supported.

  • Per-vertex coloring and lighting are not supported on lines.

  • Precision issue on line vertices. Point locations may drasticaly diverge from orginal. Since this problem increases with the number of vertices per shape, try to split lines into smaller shapes.

• MeshVizXLM

  • Enhanced coloring (MoMaterial) is not supported.

  • Fading threshold (MoDrawStyle) is not supported.

  • Polygon offset is not supported, so rendering cells with both faces and edges may result in depth buffering problems in the Adobe viewer.

• Miscellaneous

  • FXViz representations are not supported.

  • Engines are ignored.

  • Dragger shapes are not exported.

• Points

  • Coloring is not supported on points.

• Rendering

  • Modeling clipping (SoClipPlane) is ignored.

  • Drawstyle is ignored.

  • Screen-aligned rendering (SoText2, SoBillboard, etc) is not supported.

• Text

  • Text2 and textured Text3 are converted into polygonal Text3.

• Textures

  • Only MODULATE and REPLACE texture models are supported.

  • Only REPEAT and CLAMP texture wraps are supported.

  • Multitexturing is not supported.

• Transparency

  • Transparency is exported, but Adobe Reader's transparency algorithm is limited. Solid objects, MeshVizXLM mesh skin for example, can be handled correctly by Open Inventor's SORTED_PIXELS_BLEND algorithm, but are not (in general) handled correctly by Adobe Reader (as of version 10.1 anyway).

• VolumeViz

  • VolumeViz representations are not supported, except orthoslice, obliqueslice and volumeskin.

  • VolumeViz slices are exported with their current LOD (NB: LOD is minimal if the node has never been rendered).

  • LDM volumes with overlap of zero will not export correctly (gaps between tiles will be visible.

  • ROIs are ignored.

  • Lighting on VolumeViz slices is not supported.

  • VolumeViz slices are exported as simple RGBA textures (no colormap), which impacts visual quality (as if useRGBA field set)

Tips

• Node names

  • Node names are exported for SoSeparator and SoShape, as well as all derived classes. These names will appear in the "Model Tree" in Acrobat Reader. The end user can set visibility, render mode, etc for each object. You can also use these names in JavaScript functions that manipulate the model in the PDF file.

  • Separator nodes with no assigned name will appear in the tree as "Group-XXX" and Shape nodes with no assigned name will appear in the tree as "Model-XXX", where "XXX" is the address of the node (just to make the name unique).

  • Names in the U3D file must be unique. Nodes with duplicate names will have a numeric value automatically appended to their name.

• Lights: Lights in the scene graph will be exported. However note that the viewer's headlight will be exported as a directional light with a fixed position (it will not automatically rotate with the camera). If Acrobat Reader finds lights in the U3D file it will use those lights. So it may be better to export without lights and also to turn off the viewer's headlight before exporting to U3D. Note that one of the lighting options in Acrobat Reader is a headlight (that rotates with the camera).

• Camera: If the action finds a camera in the scene graph, that camera will define the default view for the model in the PDF file. Therefore if you apply the action to a Separator above the viewer's camera, the exported model will be displayed with the current on-screen view.

• Background color: You can export a background color using an SoGradientBackground node. The exported color will be the average of the color0 and color1 fields. However you can also change the background color using Adobe Acrobat Pro after inserting the U3D file in a PDF.

• Two sided rendering: If the back faces of your geometry are black when displayed in Acrobat Reader, you may want to advise your users to enable the two sided rendering option in Reader's Preferences dialog under the "3D & Multimedia" tab.

• Tools:

  • You can use the commercial tool Adobe Acrobat Pro to create and modify PDFs with embedded U3D content. Adobe calls this content "3D annotations".

  • You can also use open source tools like pdflatex, with the movie15 package, to create a PDF file with embedded 3D from a LaTeX source file.

Use case

SoSeparator root = new SoSeparator();
...
SoToU3DAction u3dAction = new SoToU3DAction();
bool result = u3dAction.OpenFile( "output.u3d" );
if ( !result )
{
  // Report error
}
u3dAction.Apply( root );
result = u3dAction.CloseFile();
if ( !result )
{
  // Report error
}

Warning

• On some platforms, some applications may encounter problems loading, displaying an error message like: "IFXOSFileIterator.ProcessDir: error opening /usr/local/u3d/lib/Plugins/ No such file or directory". In this case, declare the environment variable U3D_LIBDIR (UNIX only) and set it with the path to the Open Inventor libraries ($OIVHOME/lib).

• It is now possible to specify a directory name which will contain the U3D plug-ins by setting the environment variable U3D_PLUGINS_DIRNAME for instance: "U3DPlugins". Important: This is not a path to the directory. Moreover this directory must remain in the same folder as IFXCore.so/dll.

• By default this action always uses the alternate representation of an SoNode derived class (if one exists).

• The U3D_LIBDIR path is limited to 103 characters, path plus filename. If this length is exceeded, an error message is outputed and U3D library is not loaded.

Reference