SGS_ARC

Draw arc of a circle

ACTION:
Draws an arc of a circle, centre (x,y), radius r, starting at angle theta1 and finishing at angle theta2 in an anti-clockwise direction.
CALL:
SGS_ARC(x,y,r,theta1,theta2)
INPUT PARAMETERS:

x,y

R

Centre of complete circle in world coordinates.

r

R

Radius of complete circle in world coordinates.

theta1,theta2

R

Start and finish angle of the arc in radians. The angle increases anti-clockwise and 0 is at (x+r,y).

GKS EFFECT:
Starts a new polyline (equivalent of SGS_BPOLY). Adds lines to the polyline, approximating the arc. Finally, the polyline is sent to GKS. The line length is chosen to correspond to the addressability of the finest active workstation (inquiry is made of GKS to determine this).