How to make a 3D Mesh in RGL with shade3d or wire3d using tmesh3d in R - r

Question

I have some data which I have collected.
It consists of Vertices and then Triangles which I have made using a meshing software.
I am able to use R with
trimesh(triangles, vertices)
to make a nice mesh plot.
But can't figure out how to use RGL to make an interactive plot that I can view, and I can't work out how to colour the faces of the mesh based on a different value in the data frame.
here are the vertices in a data frame. x, y, z are the coordinates of the nodes/points (nn)
'data.frame': 23796 obs. of 7 variables:
$ nn : int 0 1 2 3 4 5 6 7 8 9 ...
$ x : num 39.5 70.8 49 83.5 -16 ...
$ y : num 28.2 -2.97 -25.67 -9.1 -39.75 ...
$ z: num 160 158 109 121 188 ...
$ uni: num 3.87 6.64 5.02 4.48 1.91 ...
$ bi : num 0.749 0.784 1.045 0.935 0.733 ...
nn x y z uni bi
0 39.527 28.202 160.219 3.86942 0.74871
1 70.804 -2.966 157.578 6.64361 0.78373
2 48.982 -25.674 109.022 5.02491 1.0451
3 83.514 -9.096 120.988 4.47977 0.9348
4 -16.04 -39.749 188.467 1.90873 0.73286
5 74.526 -3.096 174.347 8.4263 0.70594
6 54.93 -56.347 151.496 7.53334 2.17128
7 56.936 -20.131 186.177 7.16118 1.44875
8 -14.627 -47.1 162.185 2.13939 0.70887
9 38.207 -59.201 147.993 5.83457 4.32971
10 50.645 -32.04 110.418 5.3741 1.14543
The triangles for the vertices are
'data.frame': 47602 obs. of 7 variables:
$ X : int 3435 3161 18424 13600 1564 21598 21283 1171 51 9331 ...
$ Y : int 19658 17204 17467 19721 10099 19018 11341 2723 15729 5851 ...
$ Z : int 2764 9466 16955 2669 10091 21205 18399 20833 15865 9106 ...
X Y Z
3435 19658 2764
3161 17204 9466
18424 17467 16955
13600 19721 2669
1564 10099 10091
21598 19018 21205
21283 11341 18399
1171 2723 20833
51 15729 15865
9331 5851 9106
310 3513 9121
5651 11928 15468
8594 2295 6852
22725 22636 11114
I need to make this into a mesh as I can in trimesh, but with RGL and I need to colour the faces of the mesh based on a scale of uni, where <0.5 is red, 0/5-1/5 is orange and >1.5 is green
It looks something like this in trimesh but how to i do it in RGL for R, WITH COLOURING BASED ON VALUE ON UNI in the first data table

Answer 1

Here is an example, starting with two dataframes.
> library(rgl)
> vertices
x y z
1 1 -1 1
2 1 -1 -1
3 1 1 -1
4 1 1 1
5 -1 -1 1
6 -1 -1 -1
7 -1 1 -1
8 -1 1 1
> triangles
T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12
1 5 5 1 1 2 2 6 6 8 8 1 1
2 1 4 2 3 6 7 5 8 4 3 6 5
3 4 8 3 4 7 3 8 7 3 7 2 6
You need matrices to deal with tmesh3d. A row of 1's must be added to the table of vertices.
verts <- rbind(t(as.matrix(vertices)),1)
trgls <- as.matrix(triangles)
tmesh <- tmesh3d(verts, trgls)
Now you can plot the mesh:
wire3d(tmesh)
About colors, you have to associate one color to each triangle:
tmesh$material <- list(color=rainbow(ncol(trgls)))
wire3d(tmesh)
> shade3d(tmesh)
UPDATE 2019-03-09
The newest version of rgl (0.100.18) allows different interpretation of the material colors.
You can assign a color to each face:
vertices <- as.matrix(vertices)
triangles <- as.matrix(triangles)
mesh1 <- tmesh3d(
vertices = t(vertices),
indices = triangles,
homogeneous = FALSE,
material = list(color = rainbow(ncol(triangles)))
)
shade3d(mesh1, meshColor = "faces")
or assign a color to each vertex:
mesh2 <- tmesh3d(
vertices = t(vertices),
indices = triangles,
homogeneous = FALSE,
material = list(color = rainbow(nrow(vertices)))
)
shade3d(mesh2, meshColor = "vertices")