LEDAS Ltd :: products & solutions :: LGS 2D

Products & solutions

In October, 2011 the intellectual property rights for the flagship LEDAS products has been acquired by Menhirs NV, the parent company of Bricsys NV. In the framework of this deal, LEDAS became an authorized reseller of its former products and in coordination with Bricsys is ready to provide various services on maintenance, integration as well as related software development. At the same time, the sold IP can be considered as an additional proof of the LEDAS team competence, experience, and ability to provide high level and unique software development service in the domain of science-intensive software engineering.


LGS 2D is a computational engine aimed at two-dimensional parametric sketching and drawings in CAD and other computer graphics systems. It is also suitable for other 2D applications that require parametric connections or constraints between geometrical objects in 2D planes.

LGS 2D is used on its own as software component, or together with LGS 3D solver and/or C3D modeling kernel. The 2D and 3D versions of LGS have similar APIs and so they provide a complete parametric solution for all of the functions necessary in CAD/CAM/CAE systems – from 2D sketching to history-free parametric 3D modeling, assembly design, kinematic simulation, and more.

As a cross-platform software package, LGS 2D runs on all 32- and 64-bit versions of Windows, as well as Linux, *BSD, AIX, HP-Unix, Sun Solaris, Mac OS X, and so on. It is coded in C++, and because its API declarations are in pure C, it is easily integrated in a broad range of software applications.

LGS 2D Features

LGS 2D supports the creation and modification of geometric models through explicit or implicit constraints. Models are made from geometric objects, such as points, lines, circles, arcs, ellipses, NURBS curves, and user-defined curves. These objects may be fixed in the absolute coordinate system, or relative to each other; if the latter, then the calculations of LGS 2D are carried out through so-called rigid sets of objects.

LGS 2D provides geometric and dimensional constraints. Logical constraints between geometric objects consist of coincidence, parallelism, tangency, concentricity, and more; dimensional constraints specify required values for given distances, angles, and radii. To solve constraints, LGS 2D moves and rotates objects into position, taking care to minimize the number of transformations from the initial configuration.

LGS 2D supports user-defined variables, algebraic and black-box equations, and tabular constraints. These can be arbitrarily mixed with geometric dimensions. LGS 2D processes all constraints simultaneously, and so it solves cyclic dependencies between constraints. Both under-constrained and over-constrained models are solved efficiently. Additional functions in LGS 2D include dynamic constraint solving while dragging an object, optimization of goal functions with respect to constraints, redundant/inconsistent constraint diagnostics, and pattern constraints.

Sample Code

A sample sketching application shows developers how to implement different kinds of technical sketches. Lege'n'd 2D is available as a free download, and can be used by anyone to test the functions, performance, and robustness of LGS 2D. It is created using the Open CASCADE open-source application framework, and the source code is available upon special request. An additional module is available for trimming geometry. LGS Profiles is fully integratable with LGS 2D, and is available for separate licensing.


LEDAS spent the decade 2001-2011 developing LGS 2D. When it sold the product to Bricsys in 2011, LEDAS became a value-added reseller of LGS 2D. We are ready to provide software development and consulting services for integrating and tuning LGS 3D, as well as applications on which it is based.

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