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BRL-CAD
BRL-CAD User Commands

# r

Creates a region with the specified region_name.

        r

        region_name
        operation object

## DESCRIPTION

Creates a region with the specified region_name. The region is constructed using the list of Boolean operations and objectpairs. The operators are represented by the single characters +, -, and u for intersection, subtraction, and union, respectively. The object associated with each operator may be a combination or a primitive shape. No parentheses or any grouping indication is allowed in the `r` command. The operator hierarchy for the `r` command has been established through the ancestry of BRL-CAD and does not conform to accepted standards (see the `c` command for a more standard implementation). Intersection and subtraction operations are performed first, proceeding left to right; then union operations are performed. BRL-CAD regions are special cases of BRL-CAD combinations and include special attributes. Default values for these attributes may be set using the `regdef` command. As new regions are built, the default ident number gets incremented. If region_name already exists, then the operation/object pairs get appended to its end.

## EXAMPLES

The example shows the use of the `r` command to create a region consisting of two parts unioned together.

### Create a region using operations and object pairs.

mged>`r new_region u shape1 - shape2 u shape3 + group4`

Creates a region named new_region that consists of two parts unioned together. The first part is shape1 with shape2 subtracted. The second part is the intersection of shape3 and the combination group4.

## AUTHOR

BRL-CAD Team

## BUG REPORTS

Reports of bugs or problems should be submitted via electronic mail to <devs@brlcad.org>, or via the "cadbug.sh" script.