## Assignment of GCE Geometric Solver

The 2D solver included in C3D geometry core is called GCE. This is an
internal name given for technical purposes, it is an *abbreviation of
Geometric* *Constraint Engine*. GCE is a component of C3D Solver module
that has another component, namely three-dimensional mating solver
(GCM). The main purpose of the GCE component is to satisfy the system of
constraints for geometric objects of flat drawing (sketch). The
following flat geometric objects can be a subject of GCE calculations: a
point, line, circle, ellipse, spline or parametric curve. Users can add
links to them in the form of constraints selected from a given set of
types, including the following logic constraints: parallelism,
perpendicularity, tangency, point on curve, symmetry, and also various
types of dimensional constraints that define the distances, lengths and
angles. The solver can also work with curves that have ends (bounded
curves), for example, line segments and circular arcs.

All functions of the GCE geometric solver are available via the
**gce_types.h** and **gce_api.h** header files, they contain a set of
simple data structures and functions. The solver type system reflects
the main concepts required to define geometric constrain problem for a
drawing and manipulate the states of geometric objects. The problem
domain of the geometric solver includes such concepts, as geometric
solver, geometric constraint, dimension, constraint system, numeric
variable, etc. The application interacts with the constraint solver
based on simple C++ data structures, all these structures are declared
in **gce_types.h** file.