Togl is a Tk widget for OpenGL rendering. Togl was originally based on OGLTK, written by Benjamin Bederson at the University of New Mexico. Togl's main features are: * unifies Microsoft Windows, X11 (Linux/IRIX/...), and Mac OS X Aqua support * support for requesting stencil, accumulation, alpha buffers, etc. * multiple OpenGL drawing windows * simple stereo rendering support * simple, portable font support * color-index mode support including color allocation functions * overlay plane support * OpenGL extension testing from Tcl * Tcl Extension Architecture (TEA) 3 compliant Togl does almost no OpenGL drawing itself, instead it manages OpenGL drawing by calling various Tcl commands (a.k.a., callback functions). Those commands can be C functions that call OpenGL (in)directly or another Tcl package (e.g., Tcl3D).