This Converter reads and writes models in the OpenFlight format as defined by MultiGen. It adds one entry to the conversion lists:

OpenFlight *.flt

Geometry
In general, polygonal geometry is translated. Splines, fonts, etc. are not translated.

Hierarchies of objects are translated. Each group or switch becomes an object or a hierarchy of objects. All level of detail groups are translated as separate objects on import. Level of detail objects are always imported.

When exporting, each object becomes its own group, in a hierarchy if necessary. Additional groups may be created to insure the preservation of hierarchy.

Material attributes
When importing OpenFlight files, polygons are assigned colors from the color palette in the file, including packed colors but not per-vertex colors. Interchange materials are created from the color and any material or texture palette descriptions.

When exporting to OpenFlight format, up to 512 or 1024 colors will be added to the color palette, depending on the version of file you want to create.

Descriptions of each surface are also assigned to material palette entries, translating diffuse, ambient and specular color. Vertex texture UV coordinates are translated. Default vertex normals are created based on the face's original orientation.

Each texture-mapped material becomes an entry in the texture palette. Filenames in the texture palette have their extension changed to ".rgb".

On export, if a polygon's material is double-sided, the polygon is given the "solid" attribute. Similarly, wireframe polygons are given the "closed wireframe" attribute.

Options dialog

Release 11 compatible sets whether the exported file uses the old integer-based style of representing polygons as used in version 11 and earlier releases, or the newer and more compact style of vertex table with floating point coordinates. With "Release 11 compatible" checked, the geometry's will be scaled into integer values, which can lead to loss of precision and altered geometry. By default, this is not checked and an OpenFlight version 15.2 file is created.

Make point normals selects whether points will be created that contain explicit normals. Until Interchange supports the preservation of per-vertex normals, this normal will be generated by duplicating the polygon's implicit outward normal.

Scale factor, when checked, resizes the geometry by the given scale factor upon export.

Texture filename case adjusts the case of the texture filename path when exporting to OpenFlight. This can aid the process of moving image maps to an SGI.

For example, when converting a 3D Studio object with a texture map called "ROUGH.GIF" to OpenFlight format, the texture filename reference is "ROUGH.rgb" if Original case is selected, "ROUGH.RGB" if Uppercase is selected, and "rough.rgb" if Lowercase is selected. You will need to convert the texture map from GIF to .rgb format and place it in the texture map directory for your application.

Background
OpenFlight software is made by:
MultiGen, Inc.
550 South Winchester Blvd., Suite 500
San Jose, CA 95128
(408) 261-4100
(408) 261-4101 FAX
www.multigen.com