NAME

ellipse, partial_ellipse - define an elliptical region to be filled and/or edged. 

SYNOPSIS

C Syntax:

void ellipse (fildes,x_radius,y_radius,
x_center,y_center,rotation);
int fildes;
float x_radius,y_radius,x_center,y_center,rotation;

void partial_ellipse (fildes,x_radius,y_radius,
x_center,y_center,rotation,closure);
int fildes,closure;
float x_radius,y_radius,x_center,y_center,rotation;

FORTRAN77 Syntax:

subroutine ellipse (fildes,x_radius,y_radius,x_center,y_center,rotation)
integer*4 fildes
real x_radius,y_radius,x_center,y_center,rotation

subroutine partial_ellipse (fildes,x_radius,y_radius,x_center,y_center,
rotation,close_type,closure)
integer*4 fildes,close_type
real x_radius,y_radius,x_center,y_center,rotation

Pascal Syntax:

procedure ellipse (fildes:integer; x_radius,y_radius,
x_center,y_center,rotation:real);

procedure partial_ellipse (fildes:integer;
x_radius,y_radius,x_center, y_center,rotation:real;
closure:integer);

DESCRIPTION

Input Parameters

fildes Integer file descriptor returned by gopen when an I/O path to a graphics device is opened. 

x_radius,y_radius Radii of the ellipse in the x and y directions respectively. 

x_center,y_center Coordinate of the ellipse center. 

rotation Specifies the amount the ellipse is to be rotated in radians. 

closure If TRUE (1), and the polygon vertex list is non-empty and the last subpolygon was not yet closed, a boundary is added to close that subpolygon with a boundary.  If FALSE (0), no boundary is added. 

Discussion

An ellipse of specified radii centered at ( x_center,y_center ) is filled and/or outlined according to the current interior style.  As with all output primitives, the arc is affected by the current drawing mode and write enable.  The curve is drawn with chords of length specified in curve_resolution. For partial_ellipse, the vertices of the arc are added to the polygon vertex list, as in the case of partial_polygons.

If the transform mode has been set to THREE_D, the z value used is that of the current position.  Circles are drawn by specifying x_radius and y_radius to be equal.  Non-filled ellipses are generated by setting the interior style to INT_HOLLOW and edged. 

SEE ALSO

arc(3G), curve_resolution(3G), drawing_mode(3G), fill_color(3G), interior_style(3G),
perimeter_color(3G), perimeter_type(3G),
perimeter_repeat_length(3G), polygon(3G), write_enable(3G),
Starbase Graphics Techniques.

NOTE

Doing any other Starbase call besides partial_arc, partial_ellipse, partial_polygon2d, partial_polygon3d, or dcpartial_polygon, in the middle of a list of procedure calls that add vertices to the polygon buffer and before a call to polygon, rectangle, arc, or ellipse produces unpredictable, device-dependent results. 

Hewlett-Packard Company  —  May 11, 2021