shape (version 1.1)

getellipse: x-y coordinates of ellipse

Description

calculates x-y values for (part of) an ellipse; the ellipse can be rotated

Usage

getellipse(rx=1, ry=rx, mid=c(0,0), dr=0.01, 
  angle=0, from=-pi, to=pi)

Arguments

rx

long radius of ellipse

ry

short radius of ellipse

mid

midpoint of ellipse

dr

size of segments, in radians, to specify ellipse (decrease for smoother)

angle

rotation angle, degrees

from

starting angle for ellipse segment, radians

to

final angle for ellipse segment, radians

Value

• a 2-column matrix with x-y values of the ellipse

Details

rx and ry are the horizontal and vertical radiusses of the ellipses. Here "horizontal" and "vertical" denote the position BEFORE rotation

See Also

plotellipse, filledellipse

Examples

plot(getellipse(1,from=0,to=pi/2),type="l",col="red",lwd=2,main="getellipse")
  lines(getellipse(0.5,0.25,mid=c(0.5,0.5)),type="l",col="blue",lwd=2)
  lines(getellipse(0.5,0.25,mid=c(0.5,0.5),angle=45),type="l",
        col="green",lwd=2)
  emptyplot(main="getellipse")
  col <-femmecol(90)
  for (i in seq(0,180,by=2)) 
      lines(getellipse(0.5,0.25,mid=c(0.5,0.5),angle=i),
            type="l",col=col[(i/2)+1],lwd=2)