The Start and End Condition Menu appears in the Conversation bar frequently throughout spline creation. You can choose how to set the tangent vector at the end points of 2D and 3D splines to control the spline's shape. This menu does not appear with the Helical, 2D Closed, or 3D Closed options.

• You must indicate the node points of the spline and choose ACCEPT before the Start/End Condition Menu appears.

• Note that both the Start and End Condition menus are identical (displayed above as Start menu)

Natural

Automatically sets a curvature of zero to the appropriate end of the spline. This is the same as attaching the spline to the end point without applying any external forces. The ends are free.

Two Positions

This option specifies a tangent vector at a spline end point with two indicated positions.

1. Select Two Positions as the start and/or end condition.

2. Indicate the start position of the vector.

3. Indicate the end position of the vector. The two positions are projected to the spline's construction view. The distance between the two defined positions is the magnitude of the tangent vector. The direction between the first and second position sets the direction of the tangent vector.

4. Enter the vector magnitude.

End of Entity

This option specifies a tangent vector by using the tangency at the end of any existing curve, except circles.

1. Select End of Entity as the start and/or end condition.

2. Select an entity near its end point. The entity is projected to the spline's construction view before it calculates the tangent vector.

3. Enter the vector magnitude. The positive vector direction points away from the end of the selected entity closest to the cursor.

Tangent

This option allows you to enter the X and Y vector components, which determine the slope and magnitude of the tangent vector.

NOTE: If you set the View/World switch to View under Edit>Settings from the pull-down menu, the vector components are relative to the view coordinate axes. If you set it to World, the vector coordinates are relative to the world axes.

1. Select Tangent as the start and/or end condition.

2. Enter the X vector component.

3. Enter the Y vector component.

4. Enter the Z vector component. The Z vector component only appears when Tangent is used with 3D Open and 3D Auto.

Angle

Determines the direction of a tangent vector using the entered angle between the tangent vector and the positive X axis. Angle only appears on the Start/End Condition Menu when you create a 2D Open or 2D Auto spline.

1. Select Angle for the start and/or end condition.

2. Enter the angular value.

3. Enter the tangent vector magnitude.

NOTE: A temporary marker is placed at the appropriate end of the spline.