Hi Duncan,Thanks a lot for your help. You have really opened up a road for me
to to pursue further.
Your later solution with cylinder3d is interesting. However, in my real
application, I have several parallel planes and very irregular contours in each
of them. So the quad3d command is more useful. Are there more efficient ways
of using this without the for loops?
Other points where I would like to have help are : 1. I would like to
smoothen the surface. But I have not been able to figure out how I can use the
addNormals command along with quad3d. Are there other ways of improving the
smoothness?
2. As I said before, I can have 5 to 6 parallel planes. Sometimes, the jump
between two of them can be too high. So, I am thinking of using an
interpolation method at an intermediate plane. Do you have any recommendations?
I was thing of using a gam method where I make an additive model for y ~ s(x) +
s(z). Then predict y at height z given x. I may have to figure out how I do
this for closed curves (two or more values of y for a given x). I just wonder
if you can indicate generally the route hat I should follow.
3. How do I make the surface transparent? How do I add an alpha value to
the quad3d command?
Once again, I would like to thank you for your fantastic help.Thanking you,Ravi
On Thursday, 13 June 2019, 22:52:07 CEST, Duncan Murdoch
<murdoch.dun...@gmail.com> wrote:
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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