## Assigning the GCE geometric solver

Within the C3D geometric kernel, the three-dimensional geometric solver
has an internal technical designation -- GCM (***G**eometric
**C**onstraint **M**anager*). The **GCM\_** prefix in the names of
functions and data structures means that they are related to the
three-dimensional solver API. The GCM component calculates the position
and coordinates of geometric objects that satisfy a predefined set of
constraints and dimensions, ensuring the integrity of the geometric
model of an application. The GCM geometric solver is used with such
geometric objects as a point, line, plane, circle, sphere, cylinder,
cone, toroid, or their combination in rigid sets (**Cluster**).
Positions of geometric objects may be subject to dependencies in the
form of constraints from a predefined set of types, including logical
constraints: parallelism, perpendicularity, tangency, coincidence,
coaxiality, symmetry and various dimensions in distance and angle
measurement units.

The core functionality of the geometric solver GCM is available via the
**gcm_api.h** header file. The application interacts with the constraint
solver based on simple C++ data structures; all these structures are
declared in the **gcm_types.h** file.