SolveSpace is a parametric 3d CAD program, intended primarily for mechanical drawing.

Lines and curves may be specified in terms of their relationship (for example, distance, or angle, or projected distance, or other more complicated quantities) with other lines and curves in the drawing. A constraint solver determines the geometry of these lines and curves in terms of the specified constraints.

These entities may be exported in various formats (PDF, EPS, SVG, DXF, ...). The entities may also be extruded or revolved to form three-dimensional shells, modeled here as rational polynomial (NURBS) surfaces trimmed by rational polynomial curves, or as triangle meshes. Boolean union and difference operations may be performed on these shells. The resulting shells may be exported, for example as an STL file to a 3d printer, or as a STEP file to other CAD or CAM software.

The program is written in a subset of C++, with heavy use of OpenGL. Roughly 1500 lines of code depend on Win32, and specific features depend on libpng and the 3Dconnexion ("SpaceNavigator") controller library. The program's user interface, the geometric constraint solver itself, and the surface operations are implemented within this project, in roughly 33k lines of code.