Basic 3D Cone

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

Section

Cone.new(x:, y:, z:, u:, v:, w:) visualizes a vector field. Each (x,y,z) is a cone position; (u,v,w) is the vector direction and magnitude. sizemode: "absolute" makes cone size proportional to vector magnitude. colorscale: maps magnitude to color. anchor: "tail" positions the cone's base at the given point.

alias Plotly.{Figure, Cone}

# 3×3×3 grid with a simple rotational vector field: u=-y, v=x, w=0
positions = for x <- [-1, 0, 1], y <- [-1, 0, 1], z <- [-1, 0, 1], do: {x, y, z}

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

# Rotational field: vectors circle around the z-axis
us = Enum.map(ys, &(-&1))
vs = Enum.map(xs, & &1)
ws = List.duplicate(0, length(xs))

Figure.new()
|> Figure.add_trace(
  Cone.new(
    x: xs, y: ys, z: zs,
    u: us, v: vs, w: ws,
    colorscale: "Blues",
    sizemode: "absolute",
    sizeref: 0.5,
    anchor: "tail",
    showscale: true
  )
)
|> Figure.update_layout(
  title: "Basic 3D Cone — Rotational Field",
  scene: %{
    xaxis: %{title: "X"},
    yaxis: %{title: "Y"},
    zaxis: %{title: "Z"}
  }
)
|> Plotly.show()