Grid and 3-D Cursor

A curve or a primitive surface is defined by control points. Control points are, for example, the end points of a straight line, the center and two end points of acircular arc, or the center of a sphere. Thus, a curve or a primitive surface is constructed by inputting the coordinates of its control points. VisualFEA assumes that all the coordinates are in 3 dimensional Cartesian space. There are two methods of inputting the coordinates of control points, namely one using the mouse and the other using the keyboard.