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draw.arc.R
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executable file
·47 lines (46 loc) · 1.96 KB
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draw.arc <- function(x=1, y=NULL, radius=1, angle1=deg1*pi/180,
angle2=deg2*pi/180, deg1=0, deg2=45, n=0.05, col=NA, lwd=NA, ...) {
if (all(is.na(col)))
col <- par("col")
if (all(is.na(lwd)))
lwd <- par("lwd")
xylim<-par("usr")
ymult <- getYmult()
devunits <- dev.size("px")
draw.arc.0 <- function(x, y, radius, angle1, angle2, n, col, lwd, ...)
{
delta.angle <- (angle2 - angle1)
if (n != as.integer(n))
n <- as.integer(1+delta.angle/n) # Divide total angle by desired segment angle to get number of segments
delta.angle <- delta.angle/n
angleS <- angle1 + seq(0, length=n) * delta.angle
angleE <- c(angleS[-1], angle2)
# Move segment starts/ends so that segments overlap enough to make wide segments
# not have an open slice in them. The slice is open by delta.angle*half.lwd.user.
# That subtends an angle of that/(radius+half.lwd.user) radians, from center.
# Move segment endpoints by half of that, so together they equal that.
if (n > 1)
{
half.lwd.user <- (lwd/2)*(xylim[2]-xylim[1])/devunits[1]
adj.angle = delta.angle*half.lwd.user/(2*(radius+half.lwd.user))
angleS[2:n] = angleS[2:n] - adj.angle
angleE[1:(n-1)] = angleE[1:(n-1)] + adj.angle
}
p1x <- x + radius * cos(angleS)
p1y <- y + radius * sin(angleS) * ymult
p2x <- x + radius * cos(angleE)
p2y <- y + radius * sin(angleE) * ymult
segments(p1x, p1y, p2x, p2y, col=col, lwd=lwd, ...)
}
xy <- xy.coords(x, y)
x <- xy$x
y <- xy$y
a1 <- pmin(angle1, angle2)
a2 <- pmax(angle1, angle2)
angle1 <- a1
angle2 <- a2
args <- data.frame(x, y, radius, angle1, angle2, n, col, lwd, stringsAsFactors=FALSE)
for (i in 1:nrow(args))
do.call("draw.arc.0", c(args[i, ], ...))
invisible(args)
}