Spherical cap plot recipe

```julia using GLMakie import GeometryOps as GO import GeometryOps.UnitSpherical import LinearAlgebra, Rotations, GeometryBasics function Makie.convert_arguments(::Type{Makie.Mesh}, cap::UnitSpherical.SphericalCap) N = 40 rmin = 0.1 rect = GeometryBasics.Tesselation(Rect2d(0, 0, 2pi, cap.radius), (N, ceil(Int, cap.radius / rmin))) faces = GeometryBasics.decompose(Makie.GLTriangleFace, rect) points = GeometryBasics.coordinates(rect) # Remove the first N points and set the first point to (0,0) # such that the first point is the center of the cap. points = points[N:end] points[1] = Point2d(0) faces = map(faces) do f Makie.GLTriangleFace( f[1] <= N ? Makie.GLIndex(1) : f[1] - N + 1, f[2] <= N ? Makie.GLIndex(1) : f[2] - N + 1, f[3] <= N ? Makie.GLIndex(1) : f[3] - N + 1, ) end # Convert back to unit-spherical space. three_d_points = map(points) do (theta, phi) if phi == 0 offset_point = cap.point else offset_point = LinearAlgebra.normalize(cap.point + LinearAlgebra.normalize(Point3d(cos(phi), sin(phi), 0.0))) end LinearAlgebra.normalize(Point3d(cap.point + phi * Rotations.AngleAxis(theta, cap.point...) * offset_point)) end # Convert back to geographic space. # This is so that `zlevel` works right. return (GeometryBasics.normal_mesh(UnitSpherical.GeographicFromUnitSphere().(three_d_points) .|> Point2d, faces),) # return (GeometryBasics.normal_mesh(three_d_points, faces),) end Makie.convert_arguments(::Type{Makie.Poly}, cap::UnitSpherical.SphericalCap) = Makie.convert_arguments(Makie.Mesh, cap) ``` ```julia cap = UnitSpherical.SphericalCap((90, 0), 0.3) f, a, p = meshimage(-180..180, -90..90, GeoMakie.earth(); uv_transform = :rotr90, axis = (; type = GlobeAxis, camera_longlat = (90, 0))) poly!(a, cap; alpha = 0.7, zlevel = 100_000) f ``` <img width="356" height="313" alt="Image" src="https://github.com/user-attachments/assets/b2bb2095-7be6-4170-b55a-95cb6cb1af38" />