Directly use `Makie` instead of `Meshes` for visualization

[maltezfaria]

Inti uses Meshes.viz for the visualization of elements and meshes, but this can be achieved directly by e.g. writing simple Makie recipes. The main advantages would be:

• Drop Meshes dependency (we only use it for plotting)
• Custom control of recipes, easier to extend to our needs
• Simpler user interface. At present, we mix viz from Meshes with pure Makie commands such as arrows for the normals, thus requiring familiarity with both packages.

[mdmaas]

I haven't used Makie's recipies yet, but this is how I directly plot meshes with Makie (and GeometryBasics) in case it helps:

fig = Figure()
ax = LScene(fig[1, 1])

tri_mesh = GeometryBasics.Mesh(vertices,faces)
mesh!(ax, tri_mesh, color=:lightblue, alpha=0.7)
wireframe!(ax, tri_mesh, color=(:black, 0.2), linewidth=2, transparency=true, alpha=0.4)

[maltezfaria]

Thanks for the info, this is certainly a good starting point for the triangular meshes in 3D.

For future reference, transitioning to full Makie essentially requires replacing the to_meshes methods in the IntiMakieExt module by an equivalent Makie.convert_argument function as described here.

[mdmaas]

Alright, well, in visualization one typically only needs trianglular meshes, because OpenGL doesn't support any other primitive types. The usual way to go would be to decompose any other element into triangles, and also "sample" high-order elements using multiple triangles. That way visualization of high-order elements could be achieved, too, which doesn't seem to be currently supported.