The OpenGL function glLineWidth requires one parameter and sets the current line width. For example, the call glLineWidth(5.0), given with the float value 5.0, establishes that lines are to be drawn with this width. Further, all lines are drawn with this width until another call to glLineWidth is made and defines a new current line width. If we do not make a call to glLineWidth, then the default line width is used, which is 1.