Customize Hover for Surface Contours

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

Section

The contours key on a Surface trace enables projected contour lines on the axis planes and highlights the contour under the cursor on hover. Set show: true and usecolormap: true to colour them from the surface colorscale.

alias Plotly.{Figure, Surface}

z = for i <- 0..19, do: (for j <- 0..19, do: :math.sin(i / 5.0) * :math.cos(j / 5.0))

Figure.new()
|> Figure.add_trace(Surface.new(
  z: z,
  colorscale: "RdBu",
  contours: %{
    x: %{show: true, usecolormap: true, highlightcolor: "#42f462", project: %{x: true}},
    y: %{show: true, usecolormap: true, highlightcolor: "#42f462", project: %{y: true}},
    z: %{show: true, usecolormap: true, highlightcolor: "#42f462"}
  }
))
|> Figure.update_layout(
  title: "3D Hover — Surface Contours (hover to highlight)",
  scene: %{camera: %{eye: %{x: 1.5, y: 1.5, z: 1.2}}}
)
|> Plotly.show()