Selecting Implicit Elements

You can select the implicit elements using the Spline command. The implicit elements are specific to wireframe and surface elements, such as the axis of a cylinder, or the vertex of a cone for instance, participating in the creation of a feature yet not directly selectable as a separate element.

Before you begin: Create a 3D shape containing four points and a cylinder.
See Also
Creating Splines
Creating Cylindrical Surfaces
  1. From the Wireframe section of the action bar, click Spline and successively select the four points.
    The Spline Definition dialog box appears.
  2. Select Point.3 from the list, to impose a tangency constraint on this point.
    Note that you cannot select the cylinder's surface.
  3. Press and hold the Shift key, then move the pointer over the cylinder.
    The cylinder's axis is automatically detected as a selectable element to indicate a direction, and displayed.

  4. Click anywhere on the cylinder's surface, still holding the Shift key pressed down.
    The tangency constraint direction, based on the cylinder's axis, is displayed at the selected point.

  5. Click OK to create the spline tangent to the cylinder at the selected point.