From dc706c85143c22c54cc6c03676e86dff8f2fbb6e Mon Sep 17 00:00:00 2001
From: Michael Schlottke-Lakemper <michael@sloede.com>
Date: Thu, 25 Jan 2024 17:35:42 +0100
Subject: [PATCH] First example to actualy use smesh

---
 .gitignore                               |  1 +
 examples/build_delaunay_triangulation.jl | 12 +++++++
 examples/dummy.jl                        |  3 --
 src/Smesh.jl                             | 45 ++++++++++++++++++++++++
 test/test_examples.jl                    |  4 +--
 test/test_unit.jl                        |  9 +++--
 6 files changed, 67 insertions(+), 7 deletions(-)
 create mode 100644 examples/build_delaunay_triangulation.jl
 delete mode 100644 examples/dummy.jl

diff --git a/.gitignore b/.gitignore
index 359e63b..4c7705c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,3 @@
 Manifest.toml
+LocalPreferences.toml
 run/
diff --git a/examples/build_delaunay_triangulation.jl b/examples/build_delaunay_triangulation.jl
new file mode 100644
index 0000000..bda809e
--- /dev/null
+++ b/examples/build_delaunay_triangulation.jl
@@ -0,0 +1,12 @@
+using Smesh
+
+# Create data points
+# Note: the transpose + collect is just such that we can write the matrix in human readable
+# form here
+data_points = collect([0.0 0.0
+                       1.0 0.0
+                       1.0 1.0
+                       0.0 1.0]')
+
+# Create triangulation
+ve = build_delaunay_triangulation(data_points; verbose = true)
diff --git a/examples/dummy.jl b/examples/dummy.jl
deleted file mode 100644
index 065499d..0000000
--- a/examples/dummy.jl
+++ /dev/null
@@ -1,3 +0,0 @@
-using Smesh
-
-Smesh.greet()
diff --git a/src/Smesh.jl b/src/Smesh.jl
index e9fb662..6390bff 100644
--- a/src/Smesh.jl
+++ b/src/Smesh.jl
@@ -1,5 +1,50 @@
 module Smesh
 
+using Preferences: @load_preference, @has_preference 
+
+export build_delaunay_triangulation
+
+if !@has_preference("libsmesh")
+    error("""
+          Missing preference `libsmesh` for package Smesh.jl. Please add a
+          `LocalPreferences.toml` file to your current Julia project with the following
+          content, where `path/to/libsmesh.{ext}` is the path to your local build of
+          libsmesh and `{ext}` is the appropriate extension for shared libraries on your
+          system (e.g., `so` on Linux, `dylib` on macOS, `dll` on Windows). Afterwards,
+          you need to restart Julia.
+
+          Content of `LocalPreferences.toml` (between the '```' marks):
+
+          ```
+          [Smesh]
+          libsmesh = "path/to/libsmesh.{ext}"
+          ```
+          """)
+end
+const libsmesh = @load_preference("libsmesh")
+
+
+function build_delaunay_triangulation(data_points; shuffle = false, verbose = false)
+    # Pre-allocate output array
+    npoints = size(data_points, 2)
+    ve_max = @ccall libsmesh.delaunay_triangulation_temparray_size_c(npoints::Cint)::Cint
+    ve_internal = Matrix{Cint}(undef, 3, ve_max)
+
+    # Perform triangulation
+    ntriangles = @ccall libsmesh.build_delaunay_triangulation_c(ve_internal::Ref{Cint},
+                                                                data_points::Ref{Float64},
+                                                                npoints::Cint,
+                                                                ve_max::Cint,
+                                                                shuffle::Cint,
+                                                                verbose::Cint)::Cint
+
+    # Copy to array of appropriate size and convert to Julia `Int`s for convenience
+    ve_out = convert(Matrix{Int}, ve_internal[:, 1:ntriangles])
+
+    return ve_out
+end
+
+
 """
     greet()
 
diff --git a/test/test_examples.jl b/test/test_examples.jl
index bca07d6..4ad85fe 100644
--- a/test/test_examples.jl
+++ b/test/test_examples.jl
@@ -5,8 +5,8 @@ using Smesh
 
 @testset verbose=true showtiming=true "test_examples.jl" begin
 
-@testset verbose=true showtiming=true "examples/dummy.jl" begin
-    @test_nowarn include("../examples/dummy.jl")
+@testset verbose=true showtiming=true "examples/build_delaunay_triangulation.jl" begin
+    @test_nowarn include("../examples/build_delaunay_triangulation.jl")
 end
 
 end # @testset "test_examples.jl"
diff --git a/test/test_unit.jl b/test/test_unit.jl
index 79cd771..021b37b 100644
--- a/test/test_unit.jl
+++ b/test/test_unit.jl
@@ -5,8 +5,13 @@ using Smesh
 
 @testset verbose=true showtiming=true "test_unit.jl" begin
 
-@testset verbose=true showtiming=true "greet" begin
-    @test_nowarn Smesh.greet()
+@testset verbose=true showtiming=true "build_delaunay_triangulation" begin
+    data_points = collect([0.0 0.0
+                           1.0 0.0
+                           1.0 1.0
+                           0.0 1.0]')
+
+    @test build_delaunay_triangulation(data_points) == [3 1; 1 3; 2 4]
 end
 
 end # @testset "test_unit.jl"