BRL-CAD , originally by Mike Muuss , is a powerful cross-platform open-source CAD/solid-modeling system that featues interactive geometry editing, high-performance ray-tracing for rendering and geometric analysis, image and signal-processing tools, a system performance analysis benchmark suite, libraries for robust geometric representation, with more than 20 years of active development.
To provide for the construction of realistic models of complex objects from a ralttively small set of "primitive shapes", BRL-CAD employs the basic Boolean operations of union, subtraction, and intersection, and assigns reals-world material attributes.
The Multi-Device Geometry Editor, comprised of over 100K lines of application logic in Tcl/Tk/Itcl/Itk/Iwidgets, is the heart of BRL-CAD, and its GUI is the primary user interface to the system. It calls into Tcl from C for nearly all tasks, including event handling, logging, I/O, and other operations. Both the large red window and the smaller rendering window have graphics contexts implemented via Tk C API, with the larger one providing a custom interactive 3D environment using Tk Pixmap and the smaller displaying an asynchronous incrementally rendered (ray traced) 2D image using Tk_PhotoImageBlock. There’s also dozens of complex/custom dialogs, windows, and other elements not shown. 1 .
Since 1979, the U.S. Army Research Laboratory has been developing and distributing the BRL-CAD constructive solid geometry (CSG) modeling package for a wide range of military and industrial applications. The package includes a large collection of tools and utilities including an interactive geometry editor, raytracing and generic framebuffer libraries, a network-distributed image-processing and saignal-processing capability, and an embedded scripting language.