Method for Immediate Boolean Operations Using Geometric Facets
AssigneeNature Simulation Systems Inc.
InventorShangwen Cao
Life of this patent
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Abstract
A method for performing Boolean operations using a computer to create geometric models from primary geometric objects and their facets, comprises calculating intersection lines of facets, splitting facets through which the intersection lines pass, determining each facet is obvious or obscure, and regrouping the facets to form one or more geometric objects. This method does not utilize the most popular data structures CSG and B-REP in CAD/CG/Solid Modeling systems, but has the advantages of both CSG and B-REP: easy to implement and flexible.
Claims20
A method that performs immediate Boolean Operations using geometric facets implemented in a computer system and operating with a computer, the method comprising:
- mapping rendering facets to extended triangles that contain neighbors;
- searching for the first pair of triangles that hold a start point of an intersection line by detecting whether two minimum bounding boxes overlap and performing edge-triangle intersection;
- extending the intersection lines until they get closed by searching neighboring triangles;
- splitting triangles through which intersection lines pass;
- Regrouping facets, deleting, and reserving triangles according to Boolean operation types;
- and mapping extended triangles to rendering facets.
A computer software or hardware system that performs immediate Boolean operations using rendering facets of geometric objects, the system comprising:
- a computer with input devices for entering data and commands, and a display device showing user interface, geometric objects, and additional data, having a medium storing geometric data and instructions that make up of a software system, or having a microchip or integrated circuit embedding partially or totally the instructions, and a processor that executes these calculations:
- creating, modifying or loading primary geometric objects including swept and extruded ones and relocating them at different positions or orientations with input devices of the computer;
- selecting two of the geometric objects;
- mapping rendering facets to extended triangles that contain neighbors;
- searching for the first pair of triangles that hold a start point of a intersection line by detecting whether two minimum bounding boxes overlap and by performing edge-triangle intersection;
- extending the intersection lines until they get closed when searching neighboring triangles;
- splitting facets through which intersection lines pass;
- Regrouping facets, deleting, reserving, and merging facets according to Boolean operation types;
- and mapping extended triangles to rendering triangles.
Dependencies are inferred from the claim text.