MGED CMD nmg

This page contains the design document for an enhancement or feature. The design should be considered a work in progress and may not represent the final design. As this is a collaborative design, contributions and participation from other developers and users is encouraged. Use the discussion page for providing comments and suggestions.

nmg design

Syntax

nmg object subcommand [suffix]

Arguments

object

Name for the primitive that you want to operate on.

subcommand

Command specified to alter an NMG object. Each has it's own set of arguments.

Subcommands

mm

Creates a new NMG model structure and fills the appropriate fields. The result is an empty model.

cmface

Generates a manifold face in the first encountered shell of the NMG object. Vertices are listed as the suffix and define the winding-order of the face. Faces require at least three specified vertices, each specified by three coordinates. In addition to creating a face, the subcommand will join edges of the new face with dangling edges of other faces in the same shell. This makes it easier for the application to generate topologically correct, closed, manifold objects.

kill V

Removes the vertexuse and vertex geometry of the selected vertex (via its coordinates). When specifying vertex to be removed, user generally will display vertex coordinates in object via the MGED command labelvert. Note: vertex selection via their index number is not currently supported.

For example:

mged> labelvert myobj

mged> nmg myobj kill V 0.0 2.537 1.289

kill F

Removes the faceuse and face geometry of the selected face (via its index). When specifying the face to be removed, user generally will display face indices in object via the MGED command labelface.

For example:

mged> labelface myobj

mged> nmg myobj kill F 14

move V x_initial y_initial z_initial x_final y_final z_final

Moves an existing vertex specified by the coordinates x_initial y_initial z_initial to the position with coordinates x_final y_final z_final.

For example:

mged> nmg myobject move V 1.0 1.0 1.0 2.0 2.0 2.0

make V vertex-list

Creates a new vertex and shell for all vertices, using the vertex-list.

For example:

mged> nmg myobject make V 0 0 0 0 1 0 1 1 0 1 0 0 1 0 1 0 0 1 0 1 1 1 1 1

make F face-list

Creates face(s) in first encountered region and shell. General usage is to first label vertices with their index number using labelvert -i.

For example:

mged> labelvert -i myobject

mged> nmg myobject make F 4 5 6 7 F 0 1 6 5 F 1 2 7 6 F 2 3 4 7 F 0 5 4 3

Note: index numbers may change after 'make F' command. Thus, execute labelvert witht the -i option before each use of 'make F'.

Return Value(s)

No Return Values for this command.

Description

The "nmg" command is a command for creating, adding geometry, and manipulating NMG objects in BRL-CAD. All operations are result in the addition of manifold geometry to the object.

Example(s)

mged> nmg cube mm

Creates an empty NMG object.

mged> nmg cube cmface 0 0 0 0 1 0 1 1 0 1 0 0

Creates 1st face of a six-sided cube.

mged> nmg cube cmface 1 0 1 0 0 1 0 1 1 1 1 1

Creates 2nd face of a six-sided cube.

mged> nmg cube cmface 0 0 0 0 1 0 0 1 1 0 0 1

Creates 3rd face of a six-sided cube.

mged> nmg cube cmface 0 1 0 1 1 0 1 1 1 0 1 1

Creates 4th face of a six-sided cube.

mged> nmg cube cmface 1 1 0 1 0 0 1 0 1 1 1 1

Creates 5th face of a six-sided cube.

mged> nmg cube cmface 0 0 0 0 0 1 1 0 1 1 0 0

Creates 6th face of a six-sided cube.

See Also

NMG Editing project idea page

put for use with NMG objects

brep command

Wikipedia article on polygon mesh