Method for modifying a piece of 3D geometry
A three-dimensional solid geometry modeling method is described that can move or modify any piece of solid or surface geometry, such as a protrusion or depression, when faces are changed in a way that is not obvious or predictable from the original data. The method involves a combination of local changes and a context-based process that uses simplification, detaching, modification, and reattaching algorithms. The method is invoked automatically when a modeling tool (such as Move or Pull) is used to move or modify a piece of geometry. During the movement or modification, the geometry reflects the changes dynamically as the user interacts with the modeling tool. When performing the modification, simplification of the faces and edges can be manually or automatically invoked.
1. A method of interactively modifying a feature of interest attached to a CAD object when it is moved relative to the CAD object, such that the feature of interest is maintained and adapted to geometry changes during non-local movements, the method comprising:
a feature of interest attached to a first boundary representation CAD object within a three dimensional modeling space, wherein the feature of interest forms at least part of an intersection between the first boundary representation CAD object and a second boundary representation CAD object;
receiving a command from a user to reposition the feature of interest relative to the first boundary representation CAD object, and determining an updated position of the feature of interest;
generating, in real-time, a modified feature of interest based on the updated position of the feature of interest relative to the first boundary representation CAD object, wherein the feature of interest is modified in response to the updated position, such that the modified feature of interest continues forming at least part of the intersection between the first boundary representation CAD object and the second boundary representation CAD object, and wherein the modified feature of interest has a different number of faces and edges; and
redisplaying the first boundary representation CAD object and the modified feature of interest within the three dimensional modeling space for further real-time interactive modifications by the user.
2. The method of claim 1 , wherein the modified feature of interest is attached to the first boundary representation CAD object with an attachment detail, and wherein the attachment detail is at least one of a fillet, a round, and a chamfer.
3. The method of claim 2 , wherein the attachment detail is maintained throughout the intersection of the first boundary representation CAD object and the second boundary representation CAD object when the feature of interest is modified.
4. The method of claim 1 , wherein generating a modified feature of interest comprises:
gathering a plurality of neighboring faces of the feature of interest into a group;
comparing, using a tolerance, the group of neighboring faces with a planar face; and
replacing the group of neighboring faces with the planar face when the tolerance is met.
5. The method of claim 4 , further comprising:
point-wise sampling each of the neighboring faces in the group and comparing each face to an analytic surface; and
converting at least one face from the group of neighboring faces to an analytic surface.
6. The method of claim 5 , further comprising:
at least one of moving and rotating a converted face to make it co-planar with a second converted face from the group of neighboring faces.
7. The method of claim 1 , wherein generating a modified feature of interest based on the updated position of the feature of interest relative to the first boundary representation CAD object comprises:
extending the feature of interest to generate an extended feature of interest;
computing a plurality of intersection loops between the first boundary representation CAD object and the extended feature of interest;
retaining, from the plurality of intersection loops, the intersection loops that are similar to the feature of interest; and
modifying the feature of interest using the retained intersection loops.
8. The method of claim 1 , further comprising:
simplifying the feature of interest.
9. The method of claim 1 , wherein generating the modified feature of interest is performed without recording history information.
10. The method of claim 1 , further comprising:
determining if it is possible to modify the feature of interest, and only receiving a command from a user to reposition the feature of interest relative to the first boundary representation CAD object when it is determined that it is possible to modify the feature of interest.
11. A system for interactively modifying a feature of interest attached to a CAD object when it is moved relative to the CAD object, such that the feature of interest is maintained and adapted to geometry changes during non-local movements, the method comprising:
a feature of interest attached to a first boundary representation CAD object within a three dimensional modeling space, wherein the feature of interest forms at least part of an intersection between the first boundary representation CAD object and a second boundary representation CAD object;
a graphical user interface receiving a command from a user to reposition the feature of interest relative to the first boundary representation CAD object, and determining an updated position of the feature of interest;
a module generating, in real-time, a modified feature of interest based on the updated position of the feature of interest relative to the first boundary representation CAD object, wherein the feature of interest is modified in response to the updated position, such that the modified feature of interest continues forming at least part of the intersection between the first boundary representation CAD object and the second boundary representation CAD object, and wherein the modified feature of interest has a different number of faces and edges; and
the graphical user interface redisplaying the first boundary representation CAD object and the modified feature of interest within the three dimensional modeling space for further real-time interactive modifications by the user.
12. The system of claim 11 , wherein the modified feature of interest is attached to the first boundary representation CAD object with an attachment detail, and wherein the attachment detail is at least one of a fillet, a round, and a chamfer.
13. The system of claim 12 , wherein the attachment detail is maintained throughout the intersection of the first boundary representation CAD object and the second boundary representation CAD object when the feature of interest is modified.
14. The system of claim 11 , wherein the module generating a modified feature of interest comprises:
gathering a plurality of neighboring faces of the feature of interest into a group;
comparing, using a tolerance, the group of neighboring faces with a planar face; and
replacing the group of neighboring faces with the planar face when the tolerance is met.
15. The system of claim 14 , further comprising modules for:
point-wise sampling each of the neighboring faces in the group and comparing each face to an analytic surface; and
converting at least one face from the group of neighboring faces to an analytic surface.
16. The system of claim 15 , further comprising modules for:
at least one of moving and rotating a converted face to make it co-planar with a second converted face from the group of neighboring faces.
17. The system of claim 11 ,
the module generating a modified feature of interest based on the updated position of the feature of interest relative to the first boundary representation CAD object comprises modules for:
extending the feature of interest to generate an extended feature of interest;
computing a plurality of intersection loops between the first boundary representation CAD object and the extended feature of interest;
retaining, from the plurality of intersection loops, the intersection loops that are similar to the feature of interest; and
modifying the feature of interest using the retained intersection loops.
18. The system of claim 11 , further comprising modules for:
simplifying the feature of interest.
19. The system of claim 11 , wherein generating the modified feature of interest is performed without recording history information.
20. The system of claim 11 , further comprising modules for:
determining if it is possible to modify the feature of interest, and only receiving a command from a user to reposition the feature of interest relative to the first boundary representation CAD object when it is determined that it is possible to modify the feature of interest.