png(file="img%05d.png", width=300, height=300, pointsize = 16)
plot.bk <- function(s){
	d1 <<- 1
	d2 <<- 1.5
	My <<- sqrt(d2^2 - d1)
	pause <<- 1L:30L
	angL <<- 30
	ang <<- seq(0,2*pi, length=angL)
	x1 <<- cos(ang)*d2 - d1
	x2 <<- cos(ang+pi)*d2 + d1
	y <<- sin(ang)*d2
	arc <<- seq(0, 2*pi, length=angL*10)
	xarc1 <<- cos(arc)*d2 - d1
	xarc2 <<- cos(arc+pi)*d2 + d1
	yarc <<- sin(arc)*d2

	par(mar=c(0,0,0,0))
	plot(NULL, xlim=c(-2.1,2.1), ylim=c(-2.1,2.1), type="n", xaxt="n", yaxt="n", asp=1, frame.plot=F)
	lines(c(-1*d1,d1), c(0,0), lwd=2)
	points(c(-d1,d1), c(0,0), pch=20)
	text(-1,0.3,"A")
	text( 1,0.3,"B")
	if(s == 1) {return()}

	lines(c(-1*d2/2,d2/2), c(2,2), lwd=1, col=2)
	if(s == 2) {return()}

	# lines(c(-1,x1[length(x1)]), c(0,y[length(y)]), lwd=1, col=2)
	lines(xarc1[1:length(xarc1)], yarc[1:length(yarc)], col=2)
	if(s == 3) {return()}

	# lines(c( 1,x2[length(x2)]), c(0,y[length(y)]), lwd=1, col=2)
	lines(xarc2[1:length(xarc1)], yarc[1:length(yarc)], col=2)
	if(s == 4) {return()}

	points(c(0,0), c(My,-1*My), pch=20, col=2)
	if(s == 5) {return()}

}

for(i in pause){plot.bk(1)}
for(i in pause){plot.bk(2)}
lp.x <- seq(-1*d2/2,-1*d1,length=length(pause))
lp.y <- seq(2,0,length=length(pause))
for(i in pause){
	plot.bk(2)
	lines(c(lp.x[i], lp.x[i]+d2), c(lp.y[i], lp.y[i]), col=2)
}

# 左紅一圓
for(i in 1:angL){
	plot.bk(2)
	lines(c(-1*d1,x1[i]), c(0,y[i]), lwd=1, col=2)
	lines(xarc1[1:(i-1)*10], yarc[1:(i-1)*10], col=2)
}

lp.x <- seq(-1*d2/2,d1-d2,length=length(pause))
lp.y <- seq(2,0,length=length(pause))
for(i in pause){
	plot.bk(3)
	lines(c(lp.x[i], lp.x[i]+d2), c(lp.y[i], lp.y[i]), col=2)
}

for(i in 1:angL){
	plot.bk(3)
	lines(c( d1,x2[i]), c(0,y[i]), lwd=1, col=2)
	lines(xarc2[1:(i-1)*10], yarc[1:(i-1)*10], col=2)
}

for(j in pause){plot.bk(4)}
for(j in pause){plot.bk(5)}
for(j in pause){
	plot.bk(1)
	points(c(0,0), c(My,-1*My), pch=20, col=2)
}
Myy <- seq(2, -2, length=length(pause))
for(j in pause){
	plot.bk(1)
	points(c(0,0), c(My,-1*My), pch=20, col=2)
	lines(c(0,0), c(Myy[1], Myy[j]), col=2)
}

for(j in pause){
	plot.bk(1)
	points(c(0,0), c(My,-1*My), pch=20, col=2)
	lines(c(0,0), c(Myy[1], Myy[length(Myy)]), col=2)
}

for(j in pause){
	plot.bk(1)
	points(c(0,0), c(My,-1*My), pch=20, col=2)
	lines(c(0,0), c(Myy[1], Myy[length(Myy)]), col=2)
	points(0,0,pch=20, col=1)
}

for(j in rep(pause, 2)){
	plot.bk(1)
	lines(c(0,0), c(Myy[1], Myy[length(Myy)]), col=2)
	text(0.3,0.3, "M", col=1)
	points(0,0,pch=20, col=1)
	lines(c(-0.45,-0.45), c(0.1,-0.1))
	lines(c(-0.55,-0.55), c(0.1,-0.1))
	lines(c(0.45, 0.45), c(0.1,-0.1))
	lines(c(0.55, 0.55), c(0.1,-0.1))
	lines(c(0,-0.2), c(0.2,0.2))
	lines(c(-0.2,-0.2), c(0.2,0))
}

dev.off()

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