METHOD FOR CHANGING SHAPE OF NURBS CURVE

PURPOSE: An NURBPS(Non Uinform Rational B-Spline) curve shape change method is provided to change the local shape of the curve by changing a knot position on a connection line between control points controlling an overall shape of the NURBPS curve, largely used in a CAD or CADD, in a 3 dimensional space. CONSTITUTION: An NURBPS(Non Uinform Rational B-Spline) curve shape change method comprises a 1st step of arranging a plurality of knots on a connection line between control points by using the control points and a knot vector, a 2nd step of changing a position of an arbitrary knot for changing the shape of the curve, a 3rd step of obtaining a new knot vector by using the position of the changed knot, and a 4th step of changing the shape of the curve by using the new knot vector. The 1st step includes steps of receiving the position of the control points, a dimension of the curve and the knot vector, obtaining the connection line between the adjacent control points and its length, obtaining a division rate of the connection line, and arranging knots on the connection line by using the division rate. The 3rd step includes steps of reading an index of a currently changing knot value, obtaining a length of a front and a rear linear segment using a position of a changed knot as an end point, obtaining a position ratio of the changed knot, and obtaining a changed knot value.