DGVM3D (version 1.0.0)

triClose: fill a polygon (number of vertices) with triangles

Description

Method 'circular' (default) used the most triangles so far by going round in the circle and connecting the next three vertices. 'fix' uses vertex id 1 and creates triangles to all other points round. 'planar' always flips the triangles.

Usage

triClose(n, method = "circular", center = NA)

Arguments

n

number of vertices.

method

Method how to organize the triangles 'circular', 'planar', 'fix' and 'center'.

center

The center vertex ID for the central point (method 'center' only; default NA).

Value

A vector of indices for the polygon vertices.

Examples

# NOT RUN {
par(mfrow=c(2,2))
for (m in c("plan", "fix", "center", "")) {
  faces <- sample(12:20, 1)
  vertices <- sapply(seq(0, 2*pi*(faces-1)/faces, length.out=faces),
                     function(x){c(sin(x), cos(x))})
  tri = triClose(faces, method=m)
  if (m == "center") {
    tri[is.na(tri)] = faces + 1
    vertices = cbind(vertices, c(mean(vertices[1,]), mean(vertices[2, ])))
  }
  plot(vertices[1,1:faces], vertices[2,1:faces], type="b")
  text(x=1.05*vertices[1,], y=1.05*vertices[2,], labels=1:faces, adj=0.5)
  for (i in seq(1, length(tri), 3))
    polygon(vertices[1,tri[i:(i+2)]], vertices[2,tri[i:(i+2)]],
            col=rgb(runif(1), runif(1), runif(1)))
}

par(mfrow=c(2,2))
for (faces in c(6, 12, 13, 25)) {
  vertices <- sapply(seq(0, 2*pi*(faces-1)/faces, length.out=faces),
                     function(x){c(sin(x), cos(x))})
  tri = triClose(faces, method=m)
  plot(vertices[1,], vertices[2,], type="b")
  text(x=1.05*vertices[1,], y=1.05*vertices[2,], labels=1:faces, adj=0.5)
  for (i in seq(1, length(tri), 3))
    polygon(vertices[1,tri[i:(i+2)]], vertices[2,tri[i:(i+2)]],
            col=rgb(runif(1), runif(1), runif(1)))
}
# }