Add mesh support for 2D boundary curve of rectangle

src/CompScienceMeshes.jl

@@ -22,7 +22,7 @@ export euclidianbasis, point
 
 # default mesh creation
 export mesh, readmesh, writemesh, meshgeo, setminus, load_gmsh_mesh
-export meshsegment, meshcircle, meshcurve
+export meshsegment, meshcircle, meshcurve, meshrect
 export meshcuboid, meshcylinder, meshdisk, meshicosphere, meshmobius, meshrectangle, meshsphere, meshtorus
 export gmshcuboid, gmshrectangle, gmshsphere
 export tetmeshsphere, tetmeshcuboid, tetgmshcuboid, meshball

src/primitives/linemeshes/linemeshes.jl

@@ -59,6 +59,63 @@ function meshcircle(radius::T, delta::T, udim=2) where T<:Real
     return Mesh(vertices, faces)
 end
 
+"""
+    meshrect(a::T, b::T, delta::T) where T<:Real
+
+Meshes the boundary of a rectangle with side lengths `a` and `b`. 
+The rectangle is meshed in a counter-clockwise manner, starting at the origin (0, 0).
+"""
+function meshrect(a::T, b::T, delta::T) where T<:Real
+
+    udim = 2
+
+    PT = SVector{udim, T}
+    CT = SimplexGraph{2}
+
+    num_segments_a = ceil(Int, a/delta)
+    num_segments_b = ceil(Int, b/delta)
+
+    actual_delta_a = a / num_segments_a
+    actual_delta_b = b / num_segments_b
+
+    x = collect(0:num_segments_a) * actual_delta_a
+    y = collect(0:num_segments_b) * actual_delta_b
+
+    vertices = zeros(PT, 2*(num_segments_a + num_segments_b))
+
+    for i in 1 : num_segments_a
+        Δx = zeros(T, udim)
+        Δx[1] = x[i]
+        vertices[i] = PT(Δx)
+    end
+    for i in 1 : num_segments_b
+        Δy = zeros(T, udim)
+        Δy[1] = a
+        Δy[2] = y[i]
+        vertices[num_segments_a + i] = PT(Δy)
+    end
+    for i in 1 : num_segments_a
+        Δx = zeros(T, udim)
+        Δx[1] = x[end - i + 1]
+        Δx[2] = b
+        vertices[num_segments_a + num_segments_b + i] = PT(Δx)
+    end
+    for i in 1 : num_segments_b
+        Δy = zeros(T, udim)
+        Δy[1] = 0.0
+        Δy[2] = y[end - i + 1]
+        vertices[2*(num_segments_a + num_segments_b) - num_segments_b + i] = PT(Δy)
+    end
+
+    faces = Vector{CT}(undef, 2*(num_segments_a + num_segments_b))
+    for i in 1 : length(faces)-1
+        faces[i] = SimplexGraph(i, i+1)
+    end
+    faces[end] = SimplexGraph(length(faces), 1)
+
+    return Mesh(vertices, faces)
+end
+
 """
     meshcurve(curve, delta::T) where T<:Real
 

test/primitives/linemeshes/test_meshrect.jl

@@ -0,0 +1,11 @@
+using CompScienceMeshes
+using StaticArrays
+using Test
+
+@testset "Test meshrect function" begin
+    m = meshrect(1.0, 1.0, 1.0)
+
+    @test numvertices(m) == 4
+    @test m.vertices[3] == SVector(1.0, 1.0)
+    @test m.faces[1] == CompScienceMeshes.SimplexGraph(1, 2)
+end

test/runtests.jl

@@ -49,6 +49,7 @@ include("test_mapper.jl")
 include("test_convert.jl")
 
 include("primitives/linemeshes/test_curve.jl")
+include("primitives/linemeshes/test_meshrect.jl")
 include("primitives/surfacemeshes/test_cuboid.jl")
 include("primitives/surfacemeshes/test_icosphere.jl")
 include("primitives/surfacemeshes/test_rectangle.jl")