From Russia with CAD
Press-releases      14 Dec 2009

LEDAS Enhances Parametric Drawings with Updated 2D Geometric Constraint Solver

Implement powerful parametric CAD/CAM/CAE drawing functions faster and cheaper than ever before with version 3.0 of LGS 2D geometric constraint solver

Novosibirsk, Russia, December 14, 2009 – LEDAS Ltd., an independent provider of variational design tools, component technologies, and software development services for the CAD/CAM/CAE/PLM market, today announced version 3.0 of its LGS 2D geometric constraint solver. As a core component of parametric drawing applications, LGS 2D allows users to express design intent through geometric constraints and driving dimensions applied to 2D points, lines, curves, and other elements of sketches and drawings.

Since its first release in 2004, the LGS 2D software component has been licensed and embedded by several CAD/CAM/CAE vendors into parametric drawing applications. In five years, LEDAS has released eight intermediate versions of LGS 2D.

New Features in LGS 2D 3.0

Version 3.0 of LGS 2D adds support for NURBS curves, equal curvature geometric constraints, memory management, and many additional improvements.

Wing design with NURBS in Legend 2D powered by LGS 2D verison 3.0

NURBS (non-uniform rational B-spline) curves are commonly used in computer-aided design and computer graphics applications. Previous versions of LGS 2D supported NURBS curves, but required that they be evaluated on the application side. Whereas application developers before had to implement callback functions to regenerate the shapes of curves, they will now find that working with NURBS curves is as easy as working with lines and circles in LGS 2D 3.0. The application simply calls the spline creation function, passing all needed parameters (algebraic degree, control points, knots and weights), and then the solver evaluates the spline. This new feature reduces the software development cycle and shortens the time to market for a new parametric drawing application.

An even greater advantage to using the new NURBS curves support is the significant performance improvement. The derivatives of NURBS evaluation functions needed for numerical methods of constraint solving are now expressed analytically and computed by the solver.

Version 3.0 supports a new form of geometric constraint, equal curvature. It is useful for parametric drawing applications that require smooth (G2) tangencies between curves. In this case, application developers create both tangency and equal curvature constraints between two curves (or between a curve and a circle or a line) and then make the corresponding "help" parameters equal.

Version 3.0 allows application developers to define custom sets of memory management tools for controlling and optimizing memory use. This new feature is critical for applications that deal with large drawings, which are typically composed of thousands of geometric elements.

LGS 2D 3.0 also contains many other improvements, such as alignments for tangency constraints with curves, versioning for binary dump, and journaling enhancements. Several bugs in the autoconstraining function have been fixed, and issues reported by LEDAS customers have been resolved.

"LGS 2D is used by our customers to implement powerful parametric drawing functions, which are compatible with the capabilities of mainstream MCAD systems, but at an affordable price," said Dmitry Ushakov, Director of Product Management, LEDAS Ltd. "Our new version 3.0 is another significant step towards this direction: it introduces new functions aimed at supporting advanced user requirements yet shortening the application development time."

An integration module has also been created, which allows version 3.0 of LGS 2D to be used with applications based on DWGdirect of the Open Design Alliance (ODA). This integration module was developed jointly by LEDAS and the ODA, and it provides DWGdirect-based applications with support for constraints contained in the DWG 2010 file format.

About LGS Software

The LGS 2D and 3D geometric constraint solvers are used as parametric engines for 2D sketching and drawing, history-free 3D modeling, assembly design, motion analysis, and other geometric modeling applications. LGS 2D and 3D are cross-platform software packages running on 32- and 64-bit versions of Windows, Linux, Mac OS X, *BSD, AIX, HP-UX, Sun Solaris, and other OSes. Coded in C++, LGS 2D and 3D have a C-style API for easy integration into a broad range of software applications using a variety of wrappers, such as .NET, Java, and C++.

LGS 2D/3D supports the creation and modification of geometric models by means of explicit or implicit constraints. (Geometric objects include points, lines, circles, planes, cylinders, spheres, parametric curves, surfaces and swept surfaces.) Objects can be fixed in the absolute coordinate system or relative to each other. Supported geometric constraints include logical constraints between geometric entities (coincidence, parallelism, tangency, and so on), and dimensional constraints that specify the required values for distances, angles, or radiuses. LGS 2D/3D moves and rotates objects to positions that satisfy all constraints, yet minimizes transformations from initial configurations. Other LGS functions implement advanced features of CAD/CAM/CAE systems, such as diagnostics of over- and under-defined parts of models, engineering variables and equations, "help" points, and tolerance management.

Sample applications named "Lege’n’d 2D/3D" are available for free download from the LEDAS Web site. These representative examples show the kinds of 2D sketches and 3D assemblies made possible by LGS. The applications can be used by anyone to test the functionality, robustness, and performance of LGS 2D/3D. The sample applications were created with the Open CASCADE open-source application framework, and their source code is available to all licensees.

To learn more about LGS 2D/3D, visit the LEDAS Web site at


LEDAS Ltd. is an independent software development company founded in 1999. It is based in the Novosibirsk Scientific Centre at (Akademgorodok), the Siberian Branch of the Russian Academy of Science. A leader in constraint-based technologies, LEDAS is a well-known provider of computational software components for PLM (Product Lifecycle Management) solutions: geometric constraint solvers for CAD/CAM/CAE, optimization engines for project management, work scheduling and meeting planning as well as interval technologies for knowledge-based engineering and collaborative design.

The company also provides comprehensive services for PLM markets, including software development, consulting, reselling, education, and training.

More information about LEDAS is available at

LGS is a trademark of LEDAS Ltd. Any other trademarks are the property of their respective owners.

Press Contact

LEDAS Marketing Department
phone: +7 383 3356 504 / fax: +7 383 3356 256

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