Control Point Manipulation Techniques

Manipulation of control points is based on the currently selected points. There are two types of selection: secondary and primary. Points picked the first time are "secondary". If the User picks them again they become "primary". If a point is picked a third time it will revert back to being unconstrained.

Six Control Point Manipulation techniques are provided, with their specific Parameters.

Set Absolute

Moves the selected point(s) to the absolute position specified by X, Y and Z.

Offset Relative

Moves the selected point(s) the specified distances (X, Y and Z) in the relative axes directions.

Snap to Plane

Moves the selected point(s) to the specified orthogonal plane (X, Y or Z), located at the Position defined. Alternatively, if 3 of the points selected are primary points, then all secondary points selected can be snapped to the plane defined by these 3 points, if 3 Points is selected.

Snap to Line

Moves all the selected secondary point(s) to a line defined by 2 primary control points.

Spread 2 Pts

Moves all the selected secondary point(s) to a line defined by 2 primary control points, spreading them evenly between the 2 primary control points.

Snap to Point

Moves all the selected point(s) to the position of the single primary selected control point.

Having selected the appropriate technique and entered the relevant data, click Alter to affect the change.

To fair the control points of a surface patch click Fair. When fairing, the selected control points will not move with the exception of the rows and columns of control points directly adjacent to the boundaries, if they have primary selection, to improve tangency conditions. The maximum movement while fairing the surface can be limited by typing the appropriate value in the Max Offset field. for further information on automatic fairing see Automatic Fairing.

Finally use the Discard or Apply buttons to discard or accept respectively, any change made to the control points.