Feature operations using selective Boolean
Biplab Sarkar, Navin Pai, Sunit Mangalvedhekar · 1997
This paper presents techniques required in a generic boundary representation based solid modeler to implement ctficient feature operations.Boolean operators' like union.difference or intersection cannot be used directly t'or most of the profile-based feature operations described here.Using profiles drawn by the user on identified reference planes.these feature operations either add or remove material by extruding, revolving or sweeping the profiles in a very local region of the base solid based on some user definedf~crrurr-~~re,2f criteria.Typically a sufficiently large tecmhry .solid(a protofeature according to some authors') is created from the given profile.The secondary solid (tool) adds or removes volume from the base solid (blank) using a Selective Boolean algorithm.Two techniques have bern described in this paper to perform the Boolean operation selectively: (a) Generate the whole intersection graph between the tool and the blank and manipulate it by deleting or modifying intersection edges.(b) Selectively intersect faces of interest between the tool and the blank and generate the intersection graph incrementally by marching over the intersection edges as they are generated.Both these methods selectively manipulate the intersection graph between the base and the secondary solids resulting in a Selective Boolean.