向量相切到曲线

Synopsis

CTANF(obj,scalar)

Description

Returns the components of a vector tangent to a curve at a point a specified distance from the curve's starting point. As in the curve position function, CPOSF, the object may be a line, an arc, a conic, or a spline. The scalar value for the CTANF function works exactly the same as the scalar value in the CPOSF function. For information concerning the object dependent considerations of the scalar value, refer to the desired object type in the CPOSF function.

Parameters

Parameter

Description

obj

An existing object along which the position for the vector is calculated. The object may be a line, an arc, a conic or a spline.

scalar

A numerical value which represents the percentage distance along the curve where the position is calculated. The distance along the curve is specified as a percentage of the total curve length, where 0 is the beginning of the curve and 1 is the end of the curve. A scalar value of .75 therefore, represents 3/4 of the total curve length and a scalar value of .5 specifies the midpoint of the curve.

Parameter	Description
obj	An existing object along which the position for the vector is calculated. The object may be a line, an arc, a conic or a spline.
scalar	A numerical value which represents the percentage distance along the curve where the position is calculated. The distance along the curve is specified as a percentage of the total curve length, where 0 is the beginning of the curve and 1 is the end of the curve. A scalar value of .75 therefore, represents 3/4 of the total curve length and a scalar value of .5 specifies the midpoint of the curve.