Update Proj implementation (#1007)

* Update 'Proj' implementation

* Apply suggestions from code review

Co-authored-by: Júlio Hoffimann <[email protected]>

* Fix ambiguities

* Fix tests

* Apply suggestions

* Update comments

---------

Co-authored-by: Júlio Hoffimann <[email protected]>

Author: eliascarv

src/Meshes.jl

@@ -20,6 +20,7 @@ using Distances: Haversine, SphericalAngle
 using Distances: evaluate, result_type
 using Rotations: Rotation, QuatRotation, Angle2d
 using Rotations: rotation_between
+using CoordRefSystems: Basic, Projected, Geographic
 using NearestNeighbors: KDTree, BallTree
 using NearestNeighbors: knn, inrange
 using DelaunayTriangulation: triangulate, voronoi

src/transforms/proj.jl

@@ -29,15 +29,25 @@ Proj(code::Type{<:ESRI}) = Proj{CoordRefSystems.get(code)}()
 
 parameters(::Proj{CRS}) where {CRS} = (; CRS)
 
-applycoord(::Proj{CRS}, p::Point) where {CRS} = Point(convert(CRS, coords(p)))
+# convert the CRS and preserve the manifold
+applycoord(::Proj{CRS}, p::Point{<:🌐}) where {CRS<:Basic} = Point{🌐}(convert(CRS, coords(p)))
+
+# convert the CRS and (possibly) change the manifold
+applycoord(::Proj{CRS}, p::Point{<:🌐}) where {CRS<:Projected} = _proj(CRS, p)
+applycoord(::Proj{CRS}, p::Point{<:🌐}) where {CRS<:Geographic} = _proj(CRS, p)
+applycoord(::Proj{CRS}, p::Point{<:𝔼}) where {CRS<:Basic} = _proj(CRS, p)
+applycoord(::Proj{CRS}, p::Point{<:𝔼}) where {CRS<:Projected} = _proj(CRS, p)
+applycoord(::Proj{CRS}, p::Point{<:𝔼}) where {CRS<:Geographic} = _proj(CRS, p)
 
 applycoord(::Proj, v::Vec) = v
 
 # --------------
 # SPECIAL CASES
 # --------------
 
-applycoord(t::Proj, g::Primitive) = TransformedGeometry(g, t)
+applycoord(t::Proj{<:Projected}, g::Primitive{<:🌐}) = TransformedGeometry(g, t)
+
+applycoord(t::Proj{<:Geographic}, g::Primitive{<:𝔼}) = TransformedGeometry(g, t)
 
 applycoord(t::Proj, g::RectilinearGrid) = applycoord(t, convert(SimpleMesh, g))
 
@@ -54,3 +64,9 @@ function Base.show(io::IO, ::MIME"text/plain", t::Proj{CRS}) where {CRS}
   println(io)
   print(io, "└─ CRS: $CRS")
 end
+
+# -----------------
+# HELPER FUNCTIONS
+# -----------------
+
+_proj(CRS, p) = Point(convert(CRS, coords(p)))

test/meshes.jl

@@ -726,7 +726,7 @@
     mesh = SimpleMesh(points, connec)
     trans = Proj(Cartesian)
     tmesh = Meshes.TransformedMesh(mesh, trans)
-    @test manifold(tmesh) === 𝔼{3}
+    @test manifold(tmesh) === 🌐
     @test crs(tmesh) <: Cartesian
     trans = Proj(Polar)
     tgrid = Meshes.TransformedMesh(grid, trans)

test/transforms.jl

@@ -1107,6 +1107,20 @@
     r, c = TB.apply(f, g)
     @test r ≈ Point(Polar(T(√2), T(π / 4)))
 
+    # change the manifold
+    f = Proj(Mercator)
+    g = latlon(0, 0)
+    r, c = TB.apply(f, g)
+    @test manifold(r) === 𝔼{2}
+    @test r ≈ merc(0, 0)
+
+    # preserve the manifold
+    f = Proj(Cartesian)
+    g = latlon(0, 0)
+    r, c = TB.apply(f, g)
+    @test manifold(r) === 🌐
+    @test r ≈ cart(6378137.0, 0, 0)
+
     # --------
     # SEGMENT
     # --------
@@ -1213,6 +1227,20 @@
     d = SimpleMesh(p, c)
     r, c = TB.apply(f, d)
     @test r ≈ SimpleMesh(f.(vertices(d)), topology(d))
+
+    # --------------
+    # SPECIAL CASES
+    # --------------
+
+    f = Proj(Mercator)
+    g = Box(latlon(0, 180), latlon(45, 90))
+    r, c = TB.apply(f, g)
+    @test manifold(r) === 𝔼{2}
+
+    f = Proj(LatLon)
+    g = Box(merc(0, 0), merc(1, 1))
+    r, c = TB.apply(f, g)
+    @test manifold(r) === 🌐
   end
 
   @testset "LengthUnit" begin