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researchv10 Dan Cross

.ds ZZ DEVELOPMENT PACKAGE
.TH JELLIPSE 3L "630 MTG"
.XE "jellipse()"
.XE "jeldisc()"
.XE "jelarc()"
.SH NAME
jellipse, jeldisc, jelarc \- draw ellipse on display
.SH SYNOPSIS
.B #include <dmd.h>
.sp
.B void jellipse (p, a, b, f)
.PP
.B void jeldisc (p, a, b, f)
.PP
\fBvoid jelarc (p, a, b, p1, p2, f)\fR
.PP
.B Point p, p1, p2;
.br
.B int a, b;
.br
.B Code f;
.SH DESCRIPTION
The
.I jellipse
function
draws 
an approximate ellipse centered at
.IR p ,
with horizontal semi-axis
.I a
and vertical semi-axis
.I b
with Code
.IR  f 
in the display bitmap.
.PP
The
.I jeldisc
function
draws an elliptical disc centered at
.IR p ,
with horizontal semi-axis
.I a
and vertical semi-axis
.I b
with Code
.IR f 
in the display bitmap.
.PP
The
.I jelarc
function
draws the corresponding elliptical arc,
centered at
.IR p ,
counterclockwise from the ellipse point closest to
.I p1
to the ellipse point closest to
.I p2
with Code
.IR f 
in the display bitmap.
.PP
All coordinates and semi-axes are in window coordinates.
.SH EXAMPLE
The following routine draws a row of eight ellipses,
a row of eight discs, and a row of eight arcs, scaled
to the shape of the window.
.PP
.RS 3
.ft CM
.nf
#include <dmd.h>

draw()
{
  Point p;
  int i, r;

  r = 50;
  p.y = 200;
  for ( p.x=100; p.x < XMAX-50; p.x+=120)
       jellipse (p, r, r-25, F_XOR);
  p.y = 600;
  for ( p.x=100; p.x < XMAX-50; p.x+=120)
       jeldisc (p, r-25, r, F_XOR);
  p.y = 900;
  for (p.x=100; p.x < XMAX-50; p.x+=120)
       jelarc (p, r, r, Pt(p.x-r, p.y),
               Pt(p.x+r, p.y), F_XOR);

  request(KBD);
  wait(KBD);
}
.fi
.RE
.ft R
.SH SEE ALSO
circle(3L), ellipse(3L), globals(3R), jcircle(3L),
structures(3R), transform(3R/3L).

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