3D Modeling

[bryn]

Hi

I managed to implement a MESH_MANAGER with the help of Eric (thanks!).

While implementing this, I found the api: "logical MESH_MANAGER::need_edge_grading(double &mu)". According to the documentation, it is possible to set the grading (default 2.0).

Is it possible to set the grading in a "simpler" way, e.g. via facet_options? Or should I create my own mesh manager, which overrides this function to set the grading "mu"?

Thanks & best regards

Bryn

[asdf]

Hi Bryn

Two things:

1)  The grading functionality has been deprecated for years.   I am not sure if it does anything when you use it in the mesh manager.  (Have you any comments in this regard?)

2)  Could you briefly discuss what the requirement for mesh grading is?

thanks

Eric

[bryn]

Hi Eric

Regarding you question (2):

I am currently trying to facet the faces of a body, such that different faces (or edges) have different edge length requirements.

Two faces with very different edge length requirements, seem to lead to poor grading in the mesh element size.

I would be interested in any possibility to control/improve this in ACIS.

Thanks

Bryn

[asdf]

Hi Bryn

I think the main grading control in facet options is max edge length.

There is a way to control facet settings on a per face basis.  It used to be the default way to control settings.  There is an attribute called a REFINEMENT.  It has fields for all of the basic faceter controls plus some deprecated stuff.  The documentation for refinements is at http://doc.spatial.com/index.php/Refinements and http://doc.spatial.com/index.php/Facet_Options#Facet_Options_vs_Refinements.

To sum it up: you can put refinements on FACEs, LUMPs, SHELLs, and BODYs.  The refinement that applies to an element is the one lowest on the topological hierarchy (so refinements on FACEs trump everything, next SHELLs, next LUMPs, ...).  To have the faceter pay attention to refinements you need to use facet_options_expert with the tolerance specification mode set to look at the refinement.  I think what you want with grading is different max triangle edge lengths per FACE (which we can do easily).  EDGEs will should have the max edge length equal to the minimum of the max edge lengths for the incident FACEs.  

Please let me know if you have further questions in this regard.  Right now we don't have a max edge length control per edge which would allow you to force the faceter to put short EDGE facets on a particular EDGE.  

It is possible, but even more complex, to install EDGE facets yourself and force the faceter to use the EDGE discretisation you chose.  (The data structure for these is called AF_POINT).  This is a fairly low level trick and can really mess things up.

Eric