Basic Isosurface Plot

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

Section

Isosurface.new(x:, y:, z:, value:, isomin:, isomax:) renders surfaces of constant scalar value through a 3D volume. The x/y/z arrays define a regular grid; value is the scalar at each grid point. isomin/isomax controls which isosurface level(s) are shown. Here the scalar field is f(x,y,z) = x² + y² + z² — the isosurfaces are concentric spherical shells.

alias Plotly.{Figure, Isosurface}

# 20×20×20 grid from -2 to 2
n = 20
vals = Enum.map(0..(n - 1), &(&1 / (n - 1) * 4 - 2))  # -2..2

grid = for x <- vals, y <- vals, z <- vals, do: {x, y, z}

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

# Scalar field: distance squared from origin
values = Enum.map(grid, fn {x, y, z} -> x * x + y * y + z * z end)

Figure.new()
|> Figure.add_trace(
  Isosurface.new(
    x: xs, y: ys, z: zs,
    value: values,
    isomin: 1,
    isomax: 4,
    colorscale: "RdBu",
    showscale: true,
    opacity: 0.6
  )
)
|> Figure.update_layout(
  title: "Basic Isosurface — Spherical Shells (x²+y²+z²)",
  scene: %{
    xaxis: %{title: "X"},
    yaxis: %{title: "Y"},
    zaxis: %{title: "Z"}
  }
)
|> Plotly.show()