Negative 3D Geomsets (NGMSET) and Negative Primitives

A NGMSET is a grouping of negative 3D primitive elements which are used to represent holes or end preparations for structural items. It specifies the dimensions, orientation and obstruction geometry of each negative primitive. The attributes of NGMSETs are the same as those of their positive equivalents (refer to 3D Geomsets (GMSET) and 3D Geomset Primitives).

The Negative Geomset defines the symbol that is drawn for a particular Component by Paragon (and Model) and also defines the obstruction geometry of the Component for use when checking for clashes.

Each symbol is built up from a combination of the following negative primitives:

• NSBO - negative rectangular box

• NBOX - negative boxing

• NSCO - negative cone

• NLCY - negative cylinder

• NSCY - negative cylinder

• NSSL - negative slope bottomed cylinder

• NLPY - negative pyramid

• NSCT - negative circular torus

• NSRT - negative rectangular torus

• NLSN - negative snout

• NSSP - negative sphere

• NTUB - negative tubing

• NSEX - negative user-defined extrusion

• NSRE - negative solid of revolution

• NSRU - negative ruled surface

Negative Primitives have the same attributes as the corresponding positive primitives, with the addition of the NAPP (Negative APPlies to) attribute, which controls whether the negative primitive is removed from the item itself, or the attached or owning item. The allowed values are:

The positive values can be additively combined so that the hole will be created in more than one item. For example,

NAPP=6 means that the volume will be removed from the item itself and the item's hierarchical owner.

NAPP=7 will remove the negative from the attached, the hierarchical owner, and itself (all the options)

The following table shows what Attached and Owner mean for items whose geometry is defined by components of NGMSets. The same rules apply to negatives owned by TMPLATES defining these items' geometry.

For example, if a SUBJoint references a NGMSet which contains an NSBOX with NAPP=1, the NSBOX will be removed from the Subjoint’s attached SCTN.

A Fixing is acting as a Fitting if its Catalog item is an SFIT or for template defined Fixings if it is not attached (by its CREF) to a GENSEC or SCTN.

A Fixing is acting as a Joint if its Catalog item is a JOIN or for template defined Fixings if its CREF references a GENSEC or SCTN.

When a component negative of a NGMS (or a TMPL) used by a FIXING is set to negate from self (NAPP=4) then the negative will apply both to the FIXING itself but also any owning FIXING (this is the case if a component of a compound FIXING). A similar operation does not occur on compound owners (CMFI, CMPF, SCOJ) of sub joints and sub fittings (SUBJ, SBFI) and is an example of inconsistent behaviour.

NAPP = -1 - is the Default.

This is a default setting which causes different behaviour when the negative is used in a joint, to when it is used in a fitting component.

For Joint like elements it is equivalent to NAPP = 1.

Negatives of PJOI, SJOI, SUBJ, and FIXINGs acting as Joints negate from its attached SCTN or GENSEC. Compound joint (SCOJ) negatives act in the same way but, of course, never have an attached element. FIXINGs acting as compound joints do have a CREF and can themselves be attached as well as owning attached subsidiary joints (i.e. FIXINGS).

For Fitting like elements it is equivalent to NAPP = 2

Negatives of FITT, PFIT CMPF COFIT CMFI and FIXINGs acting as Fittings negate from their PANEL/SCTN/GENSEC owner in the hierarchy (which is not necessarily its direct owner!).