Plot specified area of a surface mesh with color

Question

I have data for 3D facia surface mesh. Data are available here, where vb.xlsx contains coordinates for 7160 3D vertices and it.xlsx contains face information. The color coding.t

Answer 1

Is it the expected result?

library(rgl)
library(readxl)
# Import data
vb <- read_xlsx("vb.xlsx", sheet = 1, col_names = FALSE)
it <- read_xlsx("it.xlsx", sheet = 1, col_names = FALSE)
colorCoding <- read.table("Color coding.txt")$V1
colors <- c("darkgrey","midnightblue")[colorCoding]

vb_mat <- rbind(t(as.matrix(vb)), 1)
rownames(vb_mat) <- c("xpts", "ypts", "zpts", "")
it_mat <- t(as.matrix(it))
rownames(it_mat) <- NULL
vertices <- c(vb_mat)
indices <- c(it_mat)

mesh <- addNormals(
  tmesh3d(vertices = vertices, indices = indices, homogeneous = TRUE,
          material = list(color=colors)))
shade3d(mesh, specular = "#202020")

Answer 2

The tricky thing in colouring surfaces is deciding how to use the colours. You can colour by vertex, by edge, or by face. You want to do it by vertex.

As long as you are using rgl version 0.100.2 or newer, this is relatively easy. Specify the colours one per vertex, and use argument meshColor = "vertices" to tell rgl that's what you did. For example,

shade3d(try2, col=c("green", "pink")[col], meshColor = "vertices", specular = "#202020")

which gives

This version of rgl isn't on CRAN yet, but it's available on R-forge and Github.