Trisurf Cube

Mix.install([
  {:plotly_ex, "~> 0.3"},
  {:kino, "~> 0.18"}
])

Section

A cube can also be built as a Tri-Surf: sample points on each of the 6 faces and let alphahull: 0 reconstruct the surface. This gives the same result as explicit i/j/k but from a parametric point-sampling approach. Each face contributes a uniform grid of points.

alias Plotly.{Figure, Mesh3d}

# Sample each face of a unit cube as a grid of points
steps = [0, 0.25, 0.5, 0.75, 1.0]

face_points =
  # bottom (z=0), top (z=1)
  (for x <- steps, y <- steps, z <- [0, 1], do: {x, y, z}) ++
  # front (y=0), back (y=1)
  (for x <- steps, z <- steps, y <- [0, 1], do: {x, y, z}) ++
  # left (x=0), right (x=1)
  (for y <- steps, z <- steps, x <- [0, 1], do: {x, y, z})

# Deduplicate
face_points = Enum.uniq(face_points)

xs = Enum.map(face_points, &elem(&1, 0))
ys = Enum.map(face_points, &elem(&1, 1))
zs = Enum.map(face_points, &elem(&1, 2))

Figure.new()
|> Figure.add_trace(
  Mesh3d.new(
    x: xs, y: ys, z: zs,
    alphahull: 0,
    intensity: zs,
    colorscale: "Portland",
    opacity: 0.7
  )
)
|> Figure.update_layout(
  title: "Trisurf Cube — Sampled Faces",
  scene: %{
    xaxis: %{title: "X"},
    yaxis: %{title: "Y"},
    zaxis: %{title: "Z"}
  }
)
|> Plotly.show()