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SPAkern Global Function api_get_modified_faces

Finds faces that have been deleted, created, or modified since a particular DELTA_STATE.

Role: This routine is intended to find lists of faces that have been created, deleted, or modified between the (input) start DELTA_STATE and the current DELTA_STATE of the history stream that contains that state.

For the purposes of this API, a face is not considered modified if its associated attributes or bounding box changes, but it is considered modified if one of its "contained" entities is modified. These contained entities are its SURFACEs, LOOPs, COEDGEs, EDGEs (and associated curves) and VERTEXes (and associated points).

The intended use of this API is to allow customers to avoid refaceting faces which can be determined (by examining the HISTORY_STREAM) to be unchanged since the start DELTA_STATE. Because of this, the algorithm to identify "modified" faces is conservative: whenever it is unclear whether a change recorded in the history stream actually affected a face in a manner which requires refaceting, that face is included in the "modified" list. This ensures that all faces which require refaceting will be included at one of the lists, at the expense of introducing occasional "false positives" into the "modified" list.

This API clears the deleted, created, and modified lists before writing to them (it overwrites them).

Errors: Roll back state not on history stream main branch.

Effect: Read-only

Journal: Not Available

Parameters:

ds

start state.

deleted_faces

deleted since start.

created_faces

created since start.

modified_faces

modified since start.

ao

acis options.

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