Component:GGCM-ACIS
From DocR23
GGCM-ACIS Bridge
The GGCM/ACIS Bridge (or GA_bridge) is a functionality provided by Spatial to access the GGCM constraint solver from within an ACIS application. The GGCM constraint solver provides a way for applications to specify a set of constraints between geometric entities and solves them to give a set of modifications to the geometry which satisfies the constraints. When used with ACIS, much of the functionality between the geometry and the GGCM workspace can be handled by the GGCM/ACIS Bridge as shown in the figure.
The definitions of the geometry and its position are all stored in the ACIS ENTITYs and the modifications are done by the bridge using standard ACIS functions. This means that for adding "simple" constraints, the application only needs to define the constraints and call the solve function. The GGCM/ACIS Bridge, therefore, supplies a set of functions to support the addition and solving of GGCM "simple" constraints together with the ability to extend the workspace to contain additional constraints added directly by the application.
Topics
GGCM Concepts
- Main article: GGCM Concepts
GGCM uses terminology proper of a constraint manager and different to that one used in ACIS. This section summarizes all the concepts used and how they apply to the bridge.
General Considerations
The GGCM documentation gives a full description of the functionality of the GGCM and the interfaces it supports. This section contains some other notes which may also be useful:
Simple Constraints Usage
The selection object types that can be used in a simple constraint depend on the objects in the constraint. For example, you can set a distance constraint from a point to line, but not to a curve; you have to be more specific for a curve and select the center (GGCM_csel_centre) or an end point (GGCM_csel_1st_endpoint).
Distance Constraints
From the GGCM documentation on simple distance constraints:
- If the constraint is defined between a line and a plane, there must also be an angle constraint with required value π/2 defined on the same pair of entities.
- If the constraint is defined between two planes, there must also be an angle constraint with the required value 0 or π defined on the same pair of entities.
Limitations
GGCM does not support partial ellipses; therefore, these are disabled for input from ACIS. The workaround is to use a full ellipse and then determine which piece to use afterward. Similarly, the positioning of the seam vertex on an ellipse (if there is one) is arbitrary and it is, therefore, not possible to add constraints to it using the GGCM/ACIS Bridge.
