Togl is a Tk widget for OpenGL rendering. Togl is based on OGLTK, originally written by Benjamin Bederson at the University of New Mexico (who has since moved to the University of Maryland). Togl adds the new features: - color-index mode support including color allocation functions - support for requesting stencil, accumulation, alpha buffers, etc - multiple OpenGL drawing widgets - OpenGL extension testing from Tcl - simple, portable font support - overlay plane support Togl allows one to create and manage a special Tk/OpenGL widget with Tcl and render into it with a C program. That is, a typical Togl program will have Tcl code for managing the user interface and a C program for computations and OpenGL rendering. Togl is copyrighted by Brian Paul (brian_paul@avid.com) and Benjamin Bederson (bederson@cs.umd.edu). See the LICENSE file for details.