G3DViewer is a GTK+ compatible 3D file viewer that can display multiple types of file formats in a visually appealing manner.
Aside from its comprehensive file format support, G3DViewer also comes with several handy features. It has a wireframe mode, texture support (new in 0.1.99.1), and the ability to change the background color. However, its specular lighting feature isn't as nice as it could be at the moment.
To run G3DViewer, you'll need to have one of the following combinations: GTK+ 2.x and GtkGLExt 1.0 (recommended), GTK+ 2.x and GtkGLArea 2.0 (1.99), or GTK+ 1.2 and GtkGLArea 1.x. Please note that support for Gtk+ 1.2 and for GtkGLArea will probably be removed in the next major version (0.3.0). You'll also need an OpenGL implementation, such as MesaGL. While hardware 3D acceleration is supported, it's not necessary. You can use G3DViewer even on a slow machine without hardware acceleration.
The latest stable release of G3DViewer (version 0.2.0) contains all the changes introduced in the preview releases (0.1.99.x). This includes bug fixes and cleanup, texture support, and new and improved plugins. Meanwhile, the development release (version 0.2.99.4) addresses some issues, such as missing thumbnailer files in the previous version's tarball.
Overall, if you're searching for a flexible 3D file viewer for your GTK+ environment, G3DViewer is worth a try. Its support for various file types and nifty features can make it a useful tool for various tasks.
Version 0.2.99.4: N/A