Creating Vertices

The basic commands available for creating new vertices directly in Trelis are:

1. XYZ location: The simplest form of this command is to specify the XYZ location of the vertex. It can also be created lying on a curve or surface in the geometric model by specifying the curve or surface id; the position of the vertex will be the point on the specified entity which is closest to the position specified on the command. With all of these commands, the user is able to specify the color of the vertex.

To create a Vertex by specifying the XYZ location

  1. On the Command Panel, click on Geometry and then Vertex.
  2. Click on the Create action button.
  3. Select Coordinates from the drop-down menu.
  4. Enter in the appropriate values for X Coordinate, Y Coordinate and Z Coordinate.
  5. Select Curve or Surface from the Create On menu.
  6. Enter in the appropriate values for Curve ID or Surface ID. This can also be done using the Pick Widget function.
  7. Optionally, specify the color.
  8. Click Apply.

Create Vertex <x><y><z> [On [Curve | Surface] <id>] [Color <color_name>]

2. On Curve - Fraction: A vertex can be positioned a certain fraction of the arc length along a curve using the second form of the command.

To create a Vertex from the On Curve options

  1. On the Command Panel, click on Geometry and then Vertex.
  2. Click on the Create action button.
  3. Select On Curve from the drop-down menu.
  4. Enter in the appropriate value for Curve ID(s). This can also be done using the Pick Widget function.
  5. Select Fraction, Distance, Position, Close to Vertex, Segments or Midpoint from the Specify Location menu.
  6. Enter in the remaining appropriate information for this menu.
  7. Optionally, specify the color.
  8. Click Apply.

Fraction: Divides the selected curve into segments based on the fraction value entered and creates a vertex at the end of the first segment. Specify from which direction by seleting Start, End or Vertex. For example, create a vertex at .25 (1/4) the length of a curve.

Distance: Creates a vertex on the selected curve the specified number of units away from the starting point (start, end, vertex, curve and surface). For example, create a vertex a distance of 2 along a curve with length 5.

Position: Creates a vertex at the location entered into the X,Y and Z coordinates.

Close to Vertex: Creates a vertex on the selected curve at the closest point to a specified vertex.

Segments: Divides the selected curve into a specified number of segments and creates a vertex at each endpoint.

Midpoint: Creates a vertex at the Midpoint of the selected curve.

Vertex 3 in the following example was created with this command:

create vertex on curve 1 fraction 0.25 from vertex 1

Figure 1. Create Vertex a Fraction of the length of a Curve

On Curve - General: A more general purpose form of the command is also available for creating vertices on curves:

Create Vertex On Curve <id_list> { MIDPOINT | Start | End | Fraction <val 0.0 to 1.0> [From Vertex <id> | Start|End] | Distance <val> [From {Vertex|Curve|Surface} <id> | Start|End] | {{Close_To|At} Location {options} | Position <xval><yval><zval>|{Node|Vertex} <id>} | Extrema [Direction] {options} [Direction {options}] [Direction {options}] | Segment <num_segs> | Crossing {Curve|Surface} <id_list> [Bounded|Near] } [Color <color_name>]

It allows the vertex to be created at a fractional distance along the curve, at an actual distance from one of the curves ends, at the closest location to an xyz position or another vertex, or at a specified distance from a vertex, curve or surface. You can also preview the location first with the command Draw Location On Curve (where the rest of the command is identical to the Create Vertex form).

3. From Vertex: Create a vertex from an existing vertex.

Create Vertex from Vertex <id_list> [ On {Curve|Surface} <id> ] [Color <color_name>]

If 'on curve|surface' option is used, the vertex is positioned on that curve or surface. When the 'on curve|surface' is not used, the new vertex is positioned on the existing vertex.

4. At Arc: Another form simply creates vertices at arc or circle centers.

To create a Vertex in the Center of an Arc

  1. On the Command Panel, click on Geometry and then Vertex.
  2. Click on the Create action button.
  3. Select Arc Center from the drop-down menu.
  4. Enter in the appropriate value for Curve ID(s). This can also be done using the Pick Widget function.
  5. Optionally, specify the color.
  6. Click Apply.

Create Vertex Center Curve <id_list> [Color <color_name>]

5: At Intersection: The last form creates vertices at the intersection of two curves. If the bounded qualifier is used, the vertices are limited to lie on the curves, otherwise the extensions of the curves are also used to calculate the intersections. The near option is only valid for straight lines, where the closest point on each curve is created if they do not actually intersect (resulting in two new vertices).

To create a Vertex at an Intersection

  1. On the Command Panel, click on Geometry and then Vertex.
  2. Click on the Create action button.
  3. Select At Intersection from the drop-down menu.
  4. Enter in the appropriate values for Curve ID 1 and Curve ID 2. This can also be done using the Pick Widget function.
  5. Enter in any other appropriate settings from this menu.
  6. Optionally, specify the color.
  7. Click Apply.

Create Vertex AtIntersection Curve <id1> <id2> [Bounded] [Near] [Color <color_name>]