Modifying Rounds

Some modifications fail because the entire round chain (along with all chains required to be removed by the modification) are all included in the modification. In some cases, parts of the chain (or others, even far away ones) are restricted by surrounding geometry and the modification fails. To make modifications more robust, they are localized to the selected piece of the round.

For this to work, the ends of the localized section need to be "auto-capped". In other words, they need to be able to be closed off by a plane triangular face, essentially normal to the last-visited construction edge. The following example illustrates this.

The radius is going to be increased at the selected edge.

Localizing means that the round pieces on either side of the edge are removed first. For this to work, the ends of the removed pieces need to be "capped" with a triangular face or be the start or end point of the round chain. These end conditions are necessary to rebuild the new variable round between the ends.

An end cap is shown in the example below.

The Localized round can then be reconstructed with the modified radius as shown below.

The image below shows an example where capping the end is difficult. The red circles highlight points where there is ambiguity for capping. It's difficult to construct a capping face normal to the construction edge. With Localization, the modification will fail if either of these edges is an end of a modified piece of the round. Without Localization, the modification would include these areas and the modification would fail.

In order to remove a round for modification, the side faces need to be able to Extend up and form a sharp edge as shown below.

In some cases, extra surface patches can cause ambiguous situations where the sharp edge cannot be determined and the round cannot be removed for modification. The image below is an example of a round that cannot be removed because of face extension ambiguity.