在FreeCAD中，借助于Boost Signals2实现了业务层、显示层的分层，但整个FreeCAD Gui层却采用了Coin3D进行渲染，很难在这方面进行扩展。

相较之下，在SALOME中，可以为不同的Module指定特定的ViewModel，支持OpenGL、OCC、VTK、Plot2D、Qt Graphics View等多种渲染方式。

Ref. from GoF's Design Patterns

Structuring a system into subsystems helps reduce complexity. A Common design goal is to minimize the communication and dependencies between subsystems. One way to achive this goal is to introuduce a facade object that provides a single, simplified interface to the more general facilities of a subsystem.

结合FreeCAD与SALOME的优缺点，在Acise中采用了如下的View Model。

参考资料

• Erich Gamma. Design Patterns:elements of reusable object-oriented software. Addison Wesley, 1994.
• Joseph Ingeno. Software Architect's Handbook. Packt Publishing, 2018.

网络资料

FreeCADhttps://www.freecad.org/

SALOMEhttps://www.salome-platform.org/

Boosthttps://www.boost.org/