On 13/06/2019 4:32 p.m., Duncan Murdoch wrote:
On 13/06/2019 12:47 p.m., ravi via R-help wrote:
Hi,I want to plot a surface joining a circle on a plane with another circle (a
little offset w.r.t. the first one) on a parallel plane. This is a very
simplified version of my problem.
I will explain with the following code :
# First, I plot the two circlesorig1 <- 0.4;radius1=0.3;theta <- seq(0,2*pi,pi/8)x1
<- orig1+radius1*cos(theta)y1 <- orig1+radius1*sin(theta)
orig2 <- 0.7;radius2=0.2;theta <- seq(0,2*pi,pi/8)x2 <- orig2+radius2*cos(theta)y2
<- orig2+radius2*sin(theta)
plot(x1,y1,type='b',col="red",xlim=c(0,1),ylim=c(0,1),asp=1)lines(x2,y2,type="b",col="blue")
#### the z coordinates on two parallel plnesz1 <- rep(0,length(x1))z2 <-
rep(1,length(x2))
I have tried to plot my 3d figure using the packages plot3D, misc3d, rgl etc.
All these packages require z as a matrix. In my case, all of x,y and z are
vectors. How can I plot this surface? In addition, I would like to add similiar
surfaces to the same plot.
It's not true that rgl requires z as a matrix: that's one possibility,
but there are others. Here's one way to do what you want.
# First, compute the two circles
orig1 <- 0.4;radius1=0.3;theta <- seq(0,2*pi,pi/8)
x1 <- orig1+radius1*cos(theta)
y1 <- orig1+radius1*sin(theta)
orig2 <- 0.7;radius2=0.2
x2 <- orig2+radius2*cos(theta)
y2 <- orig2+radius2*sin(theta)
#### the z coordinates on two parallel plnes
z1 <- rep(0,length(x1))
z2 <- rep(1,length(x2))
library(rgl)
p1 <- cbind(x1,y1,z1)
plot3d(p1, col="red")
p2 <- cbind(x2, y2, z2)
points3d(p2, col="blue")
quads <- matrix(numeric(), 0, 3)
for (i in seq_along(x1)[-1]) {
quads <- rbind(quads, p1[i-1,], p1[i,], p2[i,], p2[i-1,])
}
quads3d(quads, col = "green")
There are more efficient ways to do this (the for loop would be slow if
you had bigger vectors), but this should give you the idea.
Here's one of the more efficient ways:
cylinder3d(rbind(c(0.4, 0.4, 0), c(0.7, 0.7, 1)),
radius = c(0.3, 0.2),
e1 = rbind(c(0,0,1), c(0,0,1)), sides=20) %>%
addNormals() %>%
shade3d(col = "green")
Duncan Murdoch
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