Hull forms surfaces are complex shapes and defining them in a the 3D CAD environment can be difficult as interactive manipulating is generally restricted to two directions available in the mouse. In terms of the actual directions manipulated in the model, if no feature is provided points are manipulated in the direction of the screen plane or to a fix plane aligned with one of the axis. In the case of editing in the screen plane only, if the user wants to manipulate the model in one of the axis planes it is necessary to restrict the view to an x,y, y,z or xz view. When fairing the hull surface there is then a need to keep rotating the view to review to quality of the hull surface and then switch back to edit the points.

The Enhanced 3D Editing feature in PolyCAD aims to put the user in control of the edit plane, allowing points to manipulated in any plane regardless of the view (subject to practical limitation). This means that a hull form could be designed using an isometric view and still manipulate control points in the 2D axis planes, switching the edit plane at the touch of a button. Now the hull surface can be fair while viewing the surface in a direction that highlights the imperfections.

The Enhanced 3D Editing feature can be enabled from PolyCAD Options Panel -> Manipulation Options or controlled from the Status Bar. The Status Bar also displays displays the what edit planes are currently available, (Figure 1). Planes with too small angle to the view port direction cannot be used to prevent editing at infinity. The currently selected Edit Plane is displayed in the bottom right corner of the mouse cursor, (Figure 2). The Edit Plane can be toggled between those available using the Tab key.

Figure 1, Status Bar showing available Edit Planes.

  
Figure 2, the current edit plane direction is shown
in the bottom right corner of the mouse cursor.

When 3D Editing is enabled, except for when viewing x,y, y,z or x,z screen planes, planar editing is the default option. Once the mouse is left-clicked onto a control point, the 3D Edit icon frame is displayed showing the directions the point can be moved in, (Figure 3). The Edit Plane can be toggled between those available using the Tab key.

  
Figure 3, The 3D Edit icon frame for each edit plane.

While Planer editing mode, the edit direction can be restricted to one of the two axis directions by pressing Ctrl and the single axis Edit icon will be displayed about the control point, (Figure 4). The axis direction selected is dependent on the closest distance between the location of the control point on the axis and the world location of the mouse cursor.

  
Figure 4, the 3D Edit icon frame for axis directions.