Macro TNP Solution

Description


This is solution for Topological Naming Problem example described at the page: Topological Naming Problem

If you build object at another object, and also with Sketch it is straightforward to solve, because you know two things:


 * 1) Points from Sketch is always part of the face below
 * 2) The Sketch and the face below are in the same plane

To solve Topological Naming Problem problem you can:

Store the key before any operation:

You need only store the key before any operation. For this example described at Topological Naming Problem page the object is at XY plane. So, I use Z axis value from Sketch BoundBox center:

Next search all faces for the stored key:

After the resize I search all faces for the stored key. Because if the Sketch and Face were at the same plane XY. The Z axis value was the same for both. At the PartDesign you cannot move 3rd Pad above the 2nd Pad, to have gap between, this is single object, the next Pad with the Sketch always will be touching the face. At the new face the Z axis value always will be the same with the stored key. So, return the face index. Nothing more to be done.

Final steps

At the end I assign the new face to the Sketch and recompute. To be honest, the most difficult part was to assign the face to Sketch.Support, for me the syntax is mind-blowing ;-)

Code for the example
File for testing has been uploaded at FreeCAD forum: TNP.FCStd.

THE Solution
This code above shows how to solve the example from Topological Naming Problem described at: Topological Naming Problem but exactly the same rules you can use to solve other problems. The approach is simple:


 * 1) Store the key before any operation
 * 2) Search for the key after operation

The specific implementation may be different. In this example the plane is XY, but you can do exactly the same for other axes. Also you can choose other key. At Woodworking project I make many operations at non-existing objects, so I had to solve the Topological Naming Problem many times.

Here I change Cube objects into PartDesign Thickness objects:



At this example below I change Cubes into PartDesign Chamfers, so I had to store key for edges:



This example below is little more complicated because as you see at the GUI screen, the references to the object and face changes automatically. But also to make a hole I call function defined in my library not directly in the tool. So, I had to use small trick with selection and deselection, to get new reference:

There are many such problems when programming in FreeCAD, but they can all be solved in a similar way. I hope, it helps.