Hello,
I would like to make a band filled by a vertical gradient using CairoMakie.jl. The result should be similar to this example.
How can I do it in a clear way using CairoMakie.jl?
I noticed that the following code
x = range(-2, 2, 100) |> collect
y = exp.(-x.^2)
fig = Figure()
ax = Axis(fig[1, 1], xlabel="x", ylabel="y")
band!(ax, x, zeros(length(x)), y, color=range(0, 1, 100))
fig
generates this figure
But I want the gradient in the y-axis.
The documentation says
Sets the color of the mesh. Can be a
Vector{<:Colorant}for per vertex colors or a singleColorant. AMatrix{<:Colorant}can be used to color the mesh with a texture, which requires the mesh to contain texture coordinates.
But I don’t know how to use the matrix case.
The following code works
fig = Figure()
ax = Axis(fig[1, 1])
points = Point2f[(x_i, y_i) for (x_i, y_i) in zip(x, y)]
poly!(ax, points, color = y)
fig
It uses poly instead of band. However, the colormap is mapped following the edges and not the y axis. Indeed, if I use a colormap involving some transparency, I get something strange
x = range(-2, 2, 100) |> collect
y = exp.(-x.^2)
fig = Figure()
ax = Axis(fig[1, 1])
points = Point2f[(x_i, y_i) for (x_i, y_i) in zip(x, y)]
mycolor = colorant"purple"
cmap = range(RGBAf(mycolor.r, mycolor.g, mycolor.b, 0.0), RGBAf(mycolor.r, mycolor.g, mycolor.b, 1.0), 100)
poly!(ax, points, color = y, colormap = cmap)
fig
Looking at the recipe of the function density you could try something like this:
using CairoMakie
x = range(-2, 2, 100) |> collect
y = exp.(-x.^2)
f = Figure()
Axis(f[1, 1])
lines!(x, y, linewidth = 4, color = :black)
lowerv = Point2f.(x, zeros(length(x)))
upperv = Point2f.(x, y)
col = vcat(Float32[1-l[2] for l in lowerv], Float32[1-l[2] for l in upperv])
band!(lowerv, upperv, color=col, colormap = :grays)
f
1 Like
Thanks a lot!
With PNG everything already works. However, I have to put the rasterize=true as an argument of band! to correctly export it as a PDF.