2.2 Vertex Commands

The following commands are available on the Geometry/Vertex subpad.

Symbol	Command	Description
	Create Vertex	Creates a real vertex at any specified location, a real or virtual vertex on an edge or face, a virtual vertex associated with a volume, or a real or virtual vertex at the intersection of two edges
	Slide Virtual Vertex	Changes the position of a virtual vertex along the edge or face upon which it was created
	Connect Vertices Disconnect Vertices	Connects real and/or virtual vertices; disconnects vertices that are common to two or more entities
	Modify Vertex Color Modify Vertex Label	Changes a vertex color; changes a vertex label
	Move/Copy Vertices Align Vertices	Moves and/or copies vertices; aligns vertices and connected geometry
	Convert Vertices (Nonreal to Real)	Converts non-real vertices to real vertices
	Summarize Vertices Check Vertices Query Vertices Total Entities	Displays vertex summary information; checks validity of vertex topology and geometry; opens a vertex query list; displays entity totals
	Delete Vertices	Deletes real or virtual vertices

2.2.1 Create Vertex

The Create Vertex command button allows you to perform the following operations.

Symbol	Command	Description
	Create Real Vertex	Creates a real vertex at any specified location
	Create Vertex on Edge	Creates a real or virtual vertex on an existing real edge
	Create Vertex on Face	Creates a real or virtual vertex on an existing real face
	Create Virtual Vertex on Volume	Creates a virtual vertex associated with an existing real volume
	Create Vertices at Edge Intersections	Creates real or virtual vertices at the intersections of two edges
	Create Real Vertex at Centroid	Creates a real vertex at the centroid of a volume, face, or edge
	Project Vertices on Edge	Projects one or more vertices onto an existing edge

Create Real Vertex

The Create Real Vertex operation (vertex create coordinates command) creates a real vertex at a specified location.

Using the Create Real Vertex Form

To open the Create Real Vertex form (see below), click the Create Real Vertex command button on the Geometry/Vertex subpad.

The Create Real Vertex form includes the following specifications.

Coordinate Sys.	specifies the coordinate system with respect to which the vertex position is specified. (See Section 2.1.3.)
Type
Cartesian Cylindrical Spherical	specifies the type of coordinate parameters to be used in creating the vertex.
Global | Local	specifies the location of the vertex with respect to either the Global or Local system.
Label	specifies a label for the new vertex. (See Section 2.1.1).

Create Vertex on Edge

The Create Vertex on Edge operation (vertex create onedge or vertex create vonedge command) creates a real or virtual vertex on an existing edge.

Specifying the Position Parameter, u

When you create a vertex on an edge, GAMBIT associates a position parameter, u, with the vertex creation point. The position parameter represents the fraction of total edge length measured from the start endpoint of the edge. For example, if you locate the creation point at the exact center of the edge, the value of u is 0.5.

The default value of u depends on the method used to specify the edge upon which the vertex is created. There are two ways to specify the edge:

• By means of the Edge list box
• By means of the mouse-by picking the edge from the model as displayed in the graphics window

If you specify the edge by means of the mouse, GAMBIT assigns a value of u corresponding to the exact point at which the edge was selected. For example, if you select the edge by picking a point 27.3% of the distance along the edge as measured from the start endpoint, GAMBIT assigns a value of u equal to 0.273. To reposition the vertex using the mouse, drag the vertex along the edge.

NOTE: When you pick the edge on which the vertex is to be created and release the mouse button, GAMBIT fixes the position of the vertex creation point. If you release the mouse button before the creation point is at the desired position, you can reposition the creation point in one of three ways: Input its u value Input its coordinates Repick the with the middle mouse button and drag the vertex creation point to the desired position

Using the Create Vertex on Edge Form

To open the Create Vertex on Edge form (see below), click the Create Vertex on Edge command button on the Geometry/ Vertex subpad.

The Create Vertex on Edge form includes the following specifications.

Edge	specifies the edge upon which the vertex is created.
Type:
Real	creates a real vertex.
Virtual	creates a virtual vertex.
U Value	specifies the value of the position parameter, u.
Coordinate Sys.	specifies the coordinate system with respect to which the vertex position is specified. (See Section 2.1.3.)
Type
Cartesian Cylindrical Spherical	specifies the type of coordinate parameters to be used in creating the vertex.
Global | Local	specifies the location of the vertex with respect to either the Global or Local system.
Label	specifies a label for the new vertex. (See Section 2.1.1.)

Create Vertex on Face

The Create Vertex on Face operation (vertex create onface or vertex create vonface command) creates a real or virtual vertex on an existing face.

Specifying the Position Parameters, u and v

When you create a vertex on a face, GAMBIT associates two position parameters, u and v, with the vertex creation point. The position parameters represent coordinates for a two-dimensional mapping of the creation point. The default values of u and v depend on the method used to specify the face upon which the vertex is created. There are two ways to specify the face:

• By means of the Face list box
• By means of the mouse-by picking the face from the model as displayed in the graphics window

If you specify the face by means of the mouse, GAMBIT assigns values of u and v corresponding to the point at which the face was selected. To reposition the vertex using the mouse, drag the vertex in any direction along the face.

NOTE: When you pick the face on which the vertex is to be created and release the mouse button, GAMBIT fixes the position of the vertex creation point. If you release the mouse button before the creation point is at the desired position, you can reposition the creation point in one of three ways: Input its u and v values Input its coordinates Repick the with the middle mouse button and drag the vertex creation point to the desired position

Using the Create Vertex on Face Form

To open the Create Vertex on Face form (see below), click the Create Vertex on Face command button on the Geometry/Vertex subpad.

The Create Vertex on Face form contains the following options.

Face	specifies the face upon which the vertex is created.
Type:
Real	specifies the creation of a real vertex.
Virtual	specifies the creation of a virtual vertex.
U Value	specifies the value of the position parameter, u.
V Value	specifies the value of the position parameter, v.
Coordinate Sys.	specifies the coordinate system with respect to which the vertex position is specified. (See Section 2.1.3.)
Type
Cartesian Cylindrical Spherical	specifies the type of coordinate parameters to be used in creating the vertex.
Global | Local	specifies the location of the vertex with respect to either the Global or Local system.
Label	specifies a label for the new vertex. (See Section 2.1.1.)

Create Virtual Vertex on Volume

The Create Virtual Vertex on Volume operation (vertex create vonvolume command) creates a virtual vertex associated with an existing volume.

Regardless of whether you specify the volume by means of the Volume list box or by means of the mouse, GAMBIT locates the vertex creation point in the center of the volume by default. To reposition the creation point, you must input its location coordinates.

GAMBIT does not require the new vertex to be located within the volume with which it is associated. Therefore, if you specify vertex coordinates that lie outside the volume, GAMBIT does not "snap" the vertex to the volume.

NOTE: You cannot use the mouse to create or relocate a virtual vertex associated with a volume.

Using the Create Virtual Vertex on Volume Form

To open the Create Virtual Vertex on Volume form (see below), click the Create Virtual Vertex on Volume command button on the Geometry/Vertex subpad.

The Create Virtual Vertex on Volume form contains the following options.

Volume	specifies the volume with which the created vertex is associated.
Coordinate Sys.	specifies the coordinate system with respect to which the vertex position is specified. (See Section 2.1.3.)
Type
Cartesian Cylindrical Spherical	specifies the type of coordinate parameters to be used in creating the vertex.
Global | Local	specifies the location of the vertex with respect to either the Global or Local system.
Label	specifies a label for the new vertex. (See Section 2.1.1.)

Create Vertices at Edge Intersections

The Create Vertices at Edge Intersections operation (vertex create edgeints command) creates real or virtual vertices at the points of intersection (or closest approach) between any two specified edges. Vertices created by means of this operation are not connected to either of the edges used to define the points of intersection.

The Create Vertices at Edge Intersections command requires the following input parameters:

• Two edges that define the points at which the vertices are to be created
• Tolerance value (optional)
• Vertex geometry type (optional)

Specifying the Edges

You can specify any combination of real and/or non-real edges to define the points of intersection (or closest approach) at which vertices are to be created. If you specify two edges that intersect or approach each other at more than one location, GAMBIT creates a separate vertex at each point of intersection or closest approach. The types of edges (real or non-real) used to define the points of intersection do not affect the types of vertices that result from the vertex creation operation (see below).

If you specify two edges that intersect or approach each other at or near the endpoint(s) of one of the edges, GAMBIT determines whether or not to create new vertices according to the following criteria (see Figure 2-26):

• If the endpoint of Edge 2 (as specified in the lower pick list on the Create Vertices at Edge Intersections form) lies on or near the body of Edge 1, GAMBIT creates a new vertex (see Figure 2-26(a)).
• If the endpoint of Edge 1 lies on or near the body of Edge 2, GAMBIT does not create a new vertex (see Figure 2-26(b)).

Figure 2-26: Create Vertices at Edge Intersections—Endpoint criteria

Specifying the Tolerance Option

The Create Vertices at Edge Intersections command can be used to create vertices for sets of edges that do not exactly intersect as long as the edges nearly intersect at their points of closest approach. Specifically, when you select the Tolerance option, GAMBIT creates vertices at the points of closest approach the distances between which are less than a given tolerance value.

GAMBIT provides two Tolerance options:

• Auto
• Manual

When you create vertices using edges that do not exactly inter­sect, GAMBIT locates the vertices on the edge specified in the Edge 1 pick-list box. For example, if you specify two non-intersecting edges, v_edge.5 and edge.17, as Edge 1 and Edge 2, respec­tively, and specify an appropriate Tolerance value, GAMBIT locates any created vertices on v_edge.5.

Specifying the Vertex Geometry Type

The Create Vertices at Edge Intersections command allows you to create real or virtual vertices regardless of whether the edges that define the points of intersection are, themselves, real or non-real. For example, it is possible to create a real vertex at the point of intersection between two virtual edges or between a real edge and a virtual edge.

• To create virtual vertices, select the Virtual option on the Create Vertices at Edge Intersections form.
• To create real vertices, deselect the Virtual option.

Using the Create Vertices at Edge Intersections Form

To open the Create Vertices at Edge Intersections form (see below), click the Create Vertices at Edge Intersections command button on the Geometry/Vertex subpad.

The Create Vertices at Edge Intersections form contains the following specifications.

Edge 1	specifies the first of two edges the intersection point(s) of which locate(s) the position of the created vertex (or vertices).
Edge 2	specifies the second of two edges the intersection point(s) of which locate(s) the position of the created vertex (or vertices).
Tolerance	specifies that vertices are created only where the distances of closest approach between the specified edges are less than a tolerance value. GAMBIT provides two Tolerance options: Auto—specifies that GAMBIT computes the tolerance based on an internal algorithm Manual—Allows you to specify a tolerance value (default = 10-6)
Virtual	specifies that all created vertices are virtual vertices.
Label	specifies a label for the first created vertex. (See Section 2.1.1.)

Create Real Vertex at Centroid

The Create Real Vertex at Centroid operation (vertex create centroid command) creates a real vertex at the centroid of a volume, face, or edge. To execute the operation, you must specify the entity (volume, face, or edge) at the centroid of which the vertex is to be created.

Using the Create Real Vertex at Centroid Form

To open the Create Real Vertex at Centroid form (see below), click the Create Real Vertex at Centroid command button on the Geometry/Vertex subpad.

The Create Real Vertex at Centroid form contains the following specifications.

Volume Face Edge	specifies the type of entity to be used in defining the vertex creation point.
Volume Face Edge	specifies the entity at the centroid of which the vertex is to be created.
Label	specifies a label for the created vertex. (See Section 2.1.1.)

Project Vertices on Edge

The Project Vertices on Edge operation (vertex create project command) creates real vertices that represent the projection of existing vertices onto an existing edge. The operation requires the following input specifications:

• One or more vertices (real or non-real) to be projected onto an existing edge
• The target edge (real or non-real) onto which the vertices are to be projected
• Split edge option

Specifying the Split edge option

Using the Project Vertices on Edge Form

To open the Project Vertices on Edge form (see below), click the Project Vertices on Edge command button on the Geometry/Vertex subpad.

The Project Vertices on Edge form contains the following specifications.

Vertices	specifies the vertices to be projected onto the edge.
Edge	specifies the edge onto which the vertices are to be projected.
Split edge	splits the target edge (using each of the created vertices).
Label	specifies a label for the first created vertex. (See Section 2.1.1.)

2.2.2 Slide Virtual Vertex

The Slide Virtual Vertex operation (vertex move virtual command) moves a virtual vertex that is hosted by an edge, face, or volume. You cannot move an edge- or face-hosted vertex to any position that does not lie on its host entity; however, you can move a volume-hosted vertex to any location inside or outside the volume.

NOTE: When you move a virtual vertex by means of the Slide Virtual Vertex operation, GAMBIT changes the shapes and positions of any higher-topology virtual entities to which the vertex is connected. For example, if you move a virtual vertex that constitutes one apex of a virtual pyramid, GAMBIT changes the shape of the pyramid to reflect the new position of the vertex.

Sliding a Vertex

The methods available for moving (sliding) a virtual vertex depend on its host entity type. For a volume-hosted vertex, you must specify the coordinates of the new vertex location. For an edge- or face-hosted vertex, GAMBIT provides three options for moving the vertex:

• Pick the vertex in the graphics window and drag it to a new location.
• Specify position parameters for the new location.
• Specify the coordinates of the new location.

Specifying the Move with links Option

You can use the Slide Virtual Vertex command to move a connecting vertex that results from a virtual edge-split operation (see "Split Edge," in Section 2.3.5, below). Doing so allows you to change the relative lengths of the two virtual edges created by the operation.

If the host edge for the vertex to be moved is part of a set of mesh-linked edges, GAMBIT allows you to specify whether or not to move the corresponding vertices for all linked edges in the set. The specification is made by means of the Move with links option on the Slide Virtual Vertex form, which operates as follows.

• If you select the Move with links option, GAMBIT moves the corresponding vertices for the other linked edges in the set. (For an exception to this behavior, see NOTE (1), below.)
• If you unselect the Move with links option, GAMBIT moves only the vertex specified for the slide operation.

Using the Slide Virtual Vertex Form

To open the Slide Virtual Vertex form (see below), click the Slide Virtual Vertex command button on the Geometry/Vertex subpad.

The Slide Virtual Vertex form includes the following specifications.

Vertex	specifies the vertex to be moved.
U Value	specifies the value of the position parameter, u (edges and faces).
V Value	specifies the value of the position parameter, v (faces only).
Coordinate Sys.	specifies the reference coordinate system for coordinate input values. (See Section 2.1.3.)
Type
Cartesian Cylindrical Spherical	specifies the type of coordinate parameters to be used in creating the vertex.
Global | Local	specifies the new location of the vertex with respect to either the Global or Local system.
Label	specifies a label for the vertex. (See Section 2.1.1.)
Move with links	moves all vertices on edges that are linked to the selected host edge.

2.2.3 Connect/Disconnect Vertices

The Connect/Disconnect Vertices command button allows you to perform two operations.

Symbol	Command	Description
	Connect Vertices	Connects coincident real vertices or creates virtual vertices that represent the connection of two or more existing vertices
	Disconnect About Real Vertex	Disconnects edges, faces, and/or volumes that share a common real vertex

The following sections describe the procedures and specifications required to execute the operations listed above.

NOTE: The Specify Color Mode command button on the Graphics/Windows Control toolpad allows you to display model colors based on entity connectivity rather than topology. For a description of the use of the Specify Color Mode command button, see the GAMBIT User's Guide, Section 3.4.2.

Connect Vertices

The Connect Vertices operation (vertex connect command) connects sets of two or more vertices. When you connect a set of vertices, GAMBIT replaces the vertices in the set with a single vertex.

NOTE: If any of the vertices to be connected are mesh-linked to other vertices in the model, GAMBIT preserves the mesh link(s) and assigns it/them to the single vertex that results from the connect operation.

To connect vertices, you must specify the following parameters:

• Two or more vertices to be connected
• The connection type

Specifying the Vertices to Be Connected

The vertices to be connected can be real or virtual, but they are subject to certain restrictions imposed by the connection type (see below).

Specifying the Connection Type

There are four types of vertex connection operations:

• Real
• Virtual (Forced)
• Virtual (Tolerance)
• Real and Virtual (Tolerance)

Specifying a Real Connection

The Real option allows you to connect coincident real vertices. When you connect real vertices and specify the Real option, GAMBIT deletes all but one of the specified vertices and connects the remaining real vertex to all higher topology associated with the deleted vertices.

NOTE: For the purpose of connecting vertices, GAMBIT defines coincidence with respect to a global tolerance value of 10-6.

As an example of the Real connection operation, consider the configuration shown in Figure 2-27, in which two real, unconnected edges are located such that two of their endpoint vertices (vertex.2 and vertex.3) are coincident.

Figure 2-27: Connecting vertices, Real option

If you connect vertex.2 and vertex.3 by means of the Real connection operation, GAMBIT deletes vertex.3 and redefines edge.2 such that its endpoints are vertex.2 and vertex.4. As a result, edge.1 and edge.2 share a common endpoint—that is, vertex.2—and are, therefore, connected.

Specifying a Virtual (Forced) Connection

The Virtual (Forced) option allows you to connect real or virtual vertices, regardless of their proximity to each other. When you connect vertices and specify the Virtual (Forced) option, GAMBIT replaces all of the specified vertices with a single virtual vertex. If a specified vertex constitutes the endpoint of an edge, GAMBIT overlays the edge with a virtual edge and positions the virtual edge according to the location of the new virtual vertex. If the edge is connected to a face and/or volume, GAMBIT overlays the face and/or volume with a corresponding virtual entity.

Specifying a Virtual (Tolerance) Connection

The Virtual (Tolerance) option allows you to specify that only those vertices that are near to each other to within a specified tolerance are connected. There are two ways to express the tolerance value:

• Tolerance
• Shortest Edge%

Specifying a Real and Virtual (Tolerance) Connection

When you specify the Real and Virtual (Tolerance) option, GAMBIT performs the following two operations in sequence:

1. Real connect operations for vertices that are coincident to within the global tolerance value
2. Virtual (Tolerance) connect operations for unconnected, specified vertices that are near to each other to within the user-specified tolerance

Preserving the First Vertex Location

If you connect a set of vertices using a Virtual (Forced), Virtual (Tolerance), or Real and Virtual (Tolerance) operation, you can specify the location of the resulting vertex by means of the Preserve first vertex location option. When you select the Preserve first vertex location option, GAMBIT places the vertex resulting from the connect operation at the location of the first vertex listed in the Vertices list.

As an example of the effect of the Preserve first vertex location option, consider the set of edges shown in Figure 2-28(a).

Figure 2-28: Effect of Preserve first vertex location option

If you connect vertex.1 and vertex.3 by means of either the Virtual (Forced) or Virtual (Tolerance) operation, the location of the created vertex (v_vertex.5) and shapes of the created edges (v_edge.3 and v_edge.4) depend on which original vertex is listed first in the Vertices list.

• If vertex.1 is listed first, v_vertex.5 is created at the original location of vertex.1 (see Figure 2-28(b)).
• If vertex.3 is listed first, v_vertex.5 is creatd at the original location of vertex.3 (see Figure 2-28(c)).

Using the Connect Vertices Form

To open the Connect Vertices form (see below), click the Connect command button on the Geometry/Vertex subpad.

The Connect Vertices form includes the following specifications.

Disconnect About Real Vertex

The Disconnect About Real Vertex operation (vertex disconnect command) disconnects entities that share a common vertex.

When you disconnect edges, faces, and/or volumes about a common vertex, GAMBIT creates a separate vertex for each entity to which the specified vertex is connected. As a result, the entities are disconnected and can be treated (for example, moved or aligned) independently with respect to each other.

As an example of the vertex disconnection procedure, consider the configuration shown in Figure 2-29, in which face.1 and edge.5 share a common vertex (vertex.4). If you disconnect the topology about vertex.4, GAMBIT creates a new vertex (vertex.6) that is coincident with vertex.4 and assigns it as an endpoint of edge.5. As a result, face.1 and edge.5 are disconnected from each other.

Figure 2-29: Disconnecting entities about a common vertex

NOTE: GAMBIT does not allow you to disconnect topology around a vertex that constitutes part of an individual face or volume. For example, you cannot disconnect edge.1 and edge.2 about vertex.1 in Figure 2-29, because vertex.1 constitutes one corner of a single topological entity—that is, face.1.

Using the Disconnect About Real Vertex Form

To open the Disconnect About Real Vertex form (see below), click the Disconnect command button on the Geometry/Vertex subpad.

The Disconnect About Real Vertex form includes only a list box that allows you to specify the vertex about which the topology is to be disconnected.

2.2.4 Modify Vertex Color/Label

The Modify Vertex Color/Label command button allows you to perform two operations.

Symbol	Operation	Description
	Modify Vertex Color	Changes the color of one or more vertices as displayed in the graphics window
	Modify Vertex Label	Changes a vertex label

The following sections describe the procedures and specifications required to execute the operations listed above.

Modify Vertex Color

The Modify Vertex Color operation (vertex modify command) changes the displayed color of one or more vertices. To modify the Geometry color specification on the Modify Vertex Color form, click the color bar located immediately to the right of the Geometry check box on the Modify Vertex Color form. When you do so, GAMBIT opens the Set Color form. The Set Color form allows you to select a color from a preset list of available colors. (See "Using the Set Color Form," below.)

Using the Modify Vertex Color Form

To open the Modify Vertex Color form (see below), click the Modify Color command button on the Geometry/Vertex subpad.

The Modify Vertex Color form includes the following specifications.

Vertices	specifies one or more vertices the color of which is to be modified.
Color:
Geometry	specifies modifying the color of the currently specified vertices.

Using the Set Color Form

To open the Set Color form (see below), click the Geometry color bar on the Modify Vertex Color form.

The Set Color form includes the following specifications.

Color name	specifies the color by name.
Colors:	allows you to select a color from a list of available colors. GAMBIT displays the currently selected color as a color band located immediately above the Colors: scroll list.

Modify Vertex Label

The Modify Vertex Label operation (vertex modify command) changes the label associated with any vertex.

Using the Modify Vertex Label Form

To open the Modify Vertex Label form (see below), click the Modify Label command button on the Geometry/Vertex subpad.

The Modify Vertex Label form includes the following specifications.

Vertex	specifies the vertex to be modified.
Label	specifies a new label for the vertex. (See Section 2.1.1).

2.2.5 Move/Copy/Align Vertices

The Move/Copy/Align Vertices command button allows you to perform two operations.

Symbol	Operation	Description
	Move/Copy Vertices	Moves and copies vertices
	Align Vertices	Aligns vertices and connected geometry with existing topological entities

The following sections describe the procedures and specifications required to execute the operations listed above.

Move/Copy Vertices

The Move/Copy Vertices operation (vertex copy, vertex move, vertex cmove, vertex reflect, vertex creflect, vertex scale, and vertex cscale com­mands) repositions and/or creates copies of vertices. For a description of the procedures and specifications required to move and/or copy entities, see "Moving an Entity" and "Copying an Entity," respectively, in Section 2.1.4.

Using the Move/Copy Vertices Form

To open the Move/Copy Vertices form (see below), click the Move/Copy command button on the Geometry/Vertex subpad.

For a complete description of the specifications available on the Move/Copy Vertices form, see "Using Move/Copy Forms" in Section 2.1.4.

Align Vertices

The Align Vertices operation (vertex align command) repositions a set of one or more vertices with respect to a set of translation, rotation, and plane-alignment vertices. When you align a vertex, GAMBIT translates the vertex according to the specifications on the Align Vertices form. You cannot rotate or plane-align a vertex because vertices are zero-dimensional entities. (For a general description of the procedure and specifications required to align an entity, see "Aligning an Entity," in Section 2.1.4.)

Using the Align Vertices Form

To open the Align Vertices form (see below), click the Align command button on the Geometry/Vertex subpad.

For a complete description of the specifications available on the Align Vertices form, see "Using Align Forms" in Section 2.1.4.

2.2.6 Convert Vertices (Nonreal to Real)

The Convert Vertices (Nonreal to Real) operation (vertex convert command) converts one or more non-real (faceted and/or virtual) vertices to real vertices. The topology and any existing mesh associated with the converted vertices are preserved in the conversion process.

Using the Convert Vertices (Nonreal to Real) Form

To open the Convert Vertices (Nonreal to Real) form (see below), click the Convert command button on the Geometry/Vertex subpad.

The Convert Vertices (Nonreal to Real) form includes the following specifications.

Vertices	specifies which non-real vertices are to be converted to real vertices.
All Pick	All specifies all vertices in the model. Pick specifies vertices selected by means of the Vertices list box.

2.2.7 Summarize/Check/Query Vertices and Total Entities

The Summarize/Check/Query Vertices and Total Entities command button lets you perform the following operations.

Symbol	Command	Description
	Summarize Vertices	Displays vertex summary information in the Transcript window
	Check Vertices	Checks the topological and geometrical validity of model vertices
	Query Vertices	Opens the vertex query list
	Total Entities	Displays in the Transcript window the total number of entities of one or more specified types

The following sections describe the procedures and specifications required to execute the operations listed above.

Summarize Vertices

The Summarize Vertices operation (vertex summarize command) displays vertex summary information in the Transcript window. The summary information includes the vertex name, mesh status, and the coordinates of the vertex relative to the global coordinate system.

Using the Summarize Vertices Form

To open the Summarize Vertices form (see below), click the Summarize command button on the Geometry/Vertex subpad.

The Summarize Vertices form includes the following specifications.

Vertices	specifies one or more vertices for which information is to be summarized in the Transcript window.
All Pick	All specifies all vertices in the model. Pick specifies vertices selected by means of the Vertices list box.

Check Vertices

The Check Vertices operation (vertex check command) assesses the topological and/or geometrical validity of vertices in the model and summarizes the results in the Transcript window.

When you execute the Check Vertices command, GAMBIT checks the model to determine its validity with respect to either or both of the following types of characteristics:

• Topology
• Geometry

NOTE (1): Failure of the topology and/or geometry check for any vertex in the model constitutes a serious problem for the model as a whole. GAMBIT does not currently include any tools that allow you to repair problems that cause failures of topology or geometry checks for vertices.

NOTE (2): GAMBIT can automatically check the validity of all input and output (created) entities for any geometry operation and display warning or error messages in the Transcript window for any entity that fails the check(s). The automatic-checking behavior is specified by means of the GEOMETRY.GENERAL.CHECK_LEVEL default variable, which can be set to any of the following values. 0—Do not automatically check input or output entities. 1—(Default) Automatically check output entities; display a warning message for any entity that fails the check(s). 2—Automatically check input and output entities; display a warning message for any entity that fails the check(s). 3—Automatically check input and output entities; display an error message and abort the operation.

Topology Check

Topological validity is an assessment of the underlying organization of the model—for example, the correct associations between a face entity and the edges that comprise its boundaries or between entities that are associated with each other by virtue of a virtual-geometry, guest-host relationship.

For any specified vertex, the Check Vertices topology check operation examines the model to ensure that the vertex meets the following criteria:

• Upper-topology edges associated with the vertex correctly reference the vertex.
• Any virtual entities that are guests of the vertex correctly reference the vertex as a host.

Geometry Check

Geometrical validity is an assessment of the model with respect to proximity and shape characteristics—such as the distances between connected edges and/or the mathematical continuity of model curves and surfaces. The Check Vertices geometry check criteria are as follows:

• All real vertices correctly reference the ACIS model.
• Any virtual-vertex hosts are of the correct type. For example, a virtual vertex formed by connecting two vertices must reference only the two vertices as hosts. Similarly, a virtual vertex defined on an edge, face, or volume must not be hosted by a vertex. (NOTE: The vertex geometry check operation also checks the validity of host geometry.)

Using the Check Vertices Form

To open the Check Vertices form (see below), click the Check command button on the Geometry/Vertex subpad.

The Check Vertices form includes the following specifications.

Vertices	specifies the vertices to be included in the checking operations.
All Pick	All specifies all vertices in the model. Pick specifies vertices selected by means of the Vertices list box.
Check Topology	specifies a topology check on the selected vertices.
Check Geometry	specifies a geometry check on the selected vertices.

Query Vertices

The Query Vertices operation (no corresponding command-line command) allows you to identify the locations and/or names of individual vertices or subsets of vertices in the model.

When you execute the Query Vertices command, GAMBIT opens the Query Vertices form, which lists all existing vertices in the model. You can use the Query Vertices form to identify individual vertices, one at a time, or subsets of vertices by means of a label filter.

Identifying Vertices

You can use the Query Vertices form to perform the following vertex identification tasks:

• Identify the location of a vertex with a known label
• Identify the label of a vertex with a known location

To identify the label of a vertex with a known location, select (pick) the vertex in the graph­ics window. GAMBIT highlights the vertex label in the query list.

Specifying a Label Filter

The Query Vertices form includes a Filter text box that allows you to quickly identify individual vertices or subsets of vertices the labels of which contain a common string. To identify an individual vertex, input its label in the Filter text box. To identify a subset of vertices, input the common string value and include one or more wildcard characters (*). (NOTE: In either case, you must press Enter to complete the Filter string input.)

For example, if you input the Filter string "vertex.2", GAMBIT high­lights only vertex.2 in the query list and graphics window. If you input the Filter string "vertex.2*", GAMBIT highlights all vertices the labels of which begin with "vertex.2"—that is, vertex.2, vertex.20, vertex.21, ..., vertex.29; vertex.200, vertex.201, ..., vertex.299, and so on.

Selecting the Labels Option

Using the Query Vertices Form

To open the Query Vertices form (see below), click the Query command button on the Geometry/Vertex subpad.

The Query Vertices form includes the following specifications.

Label Names	contains the names of all vertices currently existing in the model. Vertices corresponding to highlighted names are displayed in red in the graphics window.
Filter	specifies the filter text string.
Label	specifies that labels corresponding to highlighted vertex names are displayed in the graphics window.

Total Entities

The Total Entities operation (list totals command) displays in the Transcript window the total number of geometry and/or mesh entities that currently exist in the model. For example, if you select only the Geometry entities option on the Total Entities form and click Apply, GAMBIT displays in the Transcript window the total numbers of vertices, edges, faces, volumes, groups, and coordinate systems that currently exist in the model.

Using the Total Entities Form

To open the Total Entities form (see below), click the Total command button on the Geometry/Vertex subpad.

The Total Entities form includes two check boxes that allow you to specify the types of entities the totals of which are displayed in the Transcript window. It includes the following options.

• Geometry entities
• Mesh entities

2.2.8 Delete Vertices

The Delete Vertices operation (vertex delete command) deletes one or more vertices from the model. The operation is subject to the following restrictions:

• GAMBIT does not allow you to delete vertices that constitute parts of higher-topology entities. For example, you cannot delete a vertex that constitutes the endpoint of an edge or one corner of a volume.
• If you delete a virtual vertex that constitutes the connection of two or more real or virtual vertices, GAMBIT restores the real vertices when it deletes the specified vertex.

Deleting Virtual Vertices

If you delete a virtual vertex, GAMBIT deletes all virtual hierarchy that is associated with the vertex and is not associated with any other entities in the model.

Using the Delete Vertices Form

To open the Delete Vertices form (see below), click the Delete command button on the Geometry/Vertex subpad.

The Delete Vertices form includes the following specifications.

Vertices	specifies one or more vertices to be deleted.
All Pick	All specifies all vertices in the model. Pick specifies vertices selected by means of the Vertices list box.

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