#
# 円，円弧，扇形を描く関数群
#
#    2008-02-28  by TAKENAKA, A.

# 円を描く

circle <- function(x, y, r = 1, color = 1, color.fill = 0, lwd = 1, by = 10)
{
	center.x <- x
	center.y <- y
	x.array <- c()
	y.array <- c()

	for (i in seq(0, 360, by = by)) {
		d <- 3.14159 * i / 180
		x.array <- c(x.array, sin(d))
		y.array <- c(y.array, cos(d))
	}
	x.array <- r * x.array + center.x
	y.array <- r * y.array + center.y

 	polygon(x.array, y.array, co = color.fill)
	lines(x.array, y.array, co = color, lwd = lwd)
}


###################
#
#  円弧を描く

arc <- function(x, y, r = 1, start = 0, end = 180, color = 1, lwd = 1)
{
	center.x <- x
	center.y <- y

	x.array <- c()
	y.array <- c()

	deg.by <- (end - start) / 36
	if (start > end) {
		deg.by <- -deg.by
	}

	for (i in seq(start, end, by = deg.by)) {
		d <- 3.14159 * i / 180
		x.array <- c(x.array, sin(d))
		y.array <- c(y.array, cos(d))
	}
	x.array <- r * x.array + center.x
	y.array <- r * y.array + center.y

	lines(x.array, y.array, co = color, lwd = lwd)
}

###################
#
#  扇形を描く

fan <- function(x, y, r = 1, start = 0, end = 180, color = 1, color.fill = 0, lwd = 1)
{
	center.x <- x
	center.y <- y

	x.array <- c(center.x)
	y.array <- c(center.y)

	deg.by <- (end - start) / 36
	if (start > end) {
		deg.by <- -deg.by
	}

	for (i in seq(start, end, by = deg.by)) {
		d <- 3.14159 * i / 180
		x.array <- c(x.array, sin(d))
		y.array <- c(y.array, cos(d))
	}

	x.array <- c(x.array, center.x)
	y.array <- c(y.array, center.y)

	x.array <- r * x.array + center.x
	y.array <- r * y.array + center.y

 	polygon(x.array, y.array, co = color.fill)
	lines(x.array, y.array, co = color, lwd = lwd)
}