Octaviz is a visualization system for Octave. It is a wrapper that makes all VTK classes accessible from within Octave using the same object-oriented syntax as in C++ or Python. It also provides high-level functions for 2D and 3D visualization. Using those functions, most common visualization tasks (3D surface plots, contour plots, meshes, etc.) can be accomplished without any knowledge about VTK.
QuesoGLC is a free implementation of the OpenGL Character Renderer. The OpenGL Character Renderer (GLC) is a state machine that provides OpenGL programs with character rendering services including scale and rotate text and draw text using lines, filled triangles, or bitmaps. QuesoGLC is based on the FreeType library, provides Unicode support, and is designed to be easily ported to any platform that supports both FreeType and the OpenGL API.
Fandango is a GL-rendered, Python-scripted CAD program. The low-level functionality is programmed in C++, and then the relevant functions are exposed to Python and used as building blocks for more functions. Currently the memory core allows lines, triangles, line strips, and triangle strips. Texture, blending, and lighting can be switched on and off from a command line.