PHIGURE F77 REFERENCE MANUAL - 3D ARC - CENTER,STARTING POINT,END POINT

3D ARC - CENTER,STARTING POINT,END POINT

TACPP3

CALL SEQUENCE

TACPP3 (STRID, XC, YC, ZC, XPI, YPI, ZPI, XPF, YPF, ZPF, OPNCLS)

INPUT PARAMETERS

INTEGER	STRID
REAL	XC,YC,ZC
REAL	XPI,YPI,ZPI
REAL	XPF,YPF,ZPF
INTEGER	OPNCLS

ARGUMENTS

STRID

Identifier of the arc structure.

XC,YC,ZC

Coordinates of the center of the circle.

XPI,YPI,ZPI

Coordinates of the starting point of the arc.

XPF,YPF,ZPF

Coordinates of the endpoint of the arc.

OPNCLS

Flag indicating whether the arc is opened or closed (see TACPA2).

0: The arc is open.
1: The arc is closed at both ends.
2: The arc is closed at the center of the circle.

EFFECT

This function generates a structure representing an arc defined by the geometrical center of the circle, a starting point of the arc and an endpoint of the arc. If the two given points are not the same distance from the center, the radius chosen will be equal to the distance from the center to the starting point, but the angle of the arc shall remain equal to the angle formed by the three given points. Of the two possible mathematical solutions, the arc chosen will always be the one with the smallest angle. The arc is defined by a certain number of points. The distribution of points can be controlled by first calling the TSTPAN function to set the angle between two points.

According to the value of the OPNCLS flag, the arc is represented by the PHIGS primitive polyline 3 (OPNCLS=0), or by the primitive fill area set 3 (OPNCLS=1 or 2).