K-3D is the free-as-in-freedom 3D modeling, animation, and rendering system
for GNU/Linux, Posix, and Win32 operating systems. K-3D features a robust,
object-oriented plugin architecture, designed to scale to the needs of
professional artists, and is designed from-the-ground-up to generate
motion-picture-quality animation using RenderMan-compliant render engines.
We strongly recommend the Aqsis render engine for use with K-3D.

K-3D allows you to create and edit documents in multiple realtime OpenGL
solid, shaded, texture-mapped views. You can even model, animate, and interact
with animations while they play back for maximum productivity!

WWW: http://www.k-3d.org/