The technology behind this methodology is experiencing substantial improvement. With some of the CAD systems out there that are based on this technology it is now possible to parametrically control models and assemblies – without recording modeling history in an ordered way. The term “parametric modeling” can no longer be used to describe history-based modeling. Parametric modeling can be done with or without history.
The benefits include the fact that with the direct modeling methodology there is no need to plan ahead. Users can create and manipulate geometry anyway possible. Relations and constraints (design intent) can be added on the fly as need. There is no need for strict and consistent modeling practices. It simply makes no difference how you come up with the geometry. And it can work on any geometry; 2D, 3D wires, surfaces, and solids, regardless of where it comes from or how it was created. With direct modeling, geometry is the master, rather than the proprietary history tree.
In the past there were several areas where history-based modeling and the ordered model provided many advantages over history-free direct modeling. One of those areas was in regards to the development and management of family , or variant parts. The ordered structure made it relatively simple to represent a part in several slightly different states or configurations. With adherence to modeling standards and careful development of the 3D history-based model, the model can be “programmed” to support the family variants simply by changing a parameter.
Below is a video of doing something similar with history-free direct modeling using the PTC Creo product “Creo Elements/Direct Modeling” (“CoCreate” or “SolidDesigner” for the old guys like me.)
In this case I am starting with an IGES file just to highlight the fact that with the direct modeling methodology, it makes no difference where or how the geometry came into existence, or if proper methods were used in creating it. Perhaps this is an example of a model coming from a supplier that uses a different CAD tool. In this scenario we need to add some design intent to the model so that we can represent other variants that may be required of this part. With traditional history-based modeling this would require a model rebuild.
Perhaps in another video I can show you how the assembly configuration can actually be used to drive the configuration of this part.
Imagine a design process that does not involve planning ahead, ordered models, model rebuilds, strict modeling practices, proprietary data, regeneration failures and the mind-numbing web of relationships and references. Well, it’s not too far away.