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A
bump refers to any feature that is "Booleaned" onto/into a larger entity. With this definition, holes are considered to be bumps.
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When an application needs to create an array of identical bumps, such as a two-dimensional array of spherical bumps upon a planar substrate, it is obviously wasteful to perform the Boolean operation that creates the bump more than once. The results of the repeated Booleans are guaranteed to be identical, except for a simple transformation. The use of
ACIS patterns avoids such redundant calculations, by performing the Boolean operation before applying the pattern to one face (or loop) of the resulting bump.
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When applying a pattern to a bump, apply it to the highest-level entity associated with the bump. For example, if one creates a hollow shell within a block by subtracting a sphere, apply the pattern to the shell, not to the face owned by the shell.
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In the case in which a bump consists of multiple faces and loops, only one entity belonging to a bump needs to be specified when applying the pattern, as
ACIS automatically generates the others.
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When applying a pattern to a bump consisting of multiple faces, make sure that the face used to identify the bump will make the determination of the bump's extent unambiguous. For example, consider a hole with a raised face above a surrounding substrate. If the programmer uses the hole's inner face to identify the bump, it is not clear whether the bump is to include the raised face, or if the raised face is instead to be considered part of the substrate on which the bump is to be repeated. To make sure that the raised face is considered as part of the bump, the programmer should that face instead of the inner face to identify the bump.
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