Save STL

src/preprocessing/geometries/io.jl

@@ -96,3 +96,41 @@ function trixi2vtk(geometry::TriangleMesh; output_directory="out", prefix="",
     return trixi2vtk(stack(geometry.vertices); output_directory, filename, prefix,
                      vertex_normals=vertex_normals, custom_quantities...)
 end
+
+function save(filename, mesh; faces=eachface(mesh))
+    save(FileIO.File{FileIO.format"STL_BINARY"}(filename), mesh; faces)
+end
+
+function save(fn::FileIO.File{FileIO.format"STL_BINARY"},
+              mesh::TriangleMesh; faces=eachface(mesh))
+    open(fn, "w") do s
+        save(s, mesh; faces)
+    end
+end
+
+function save(f::FileIO.Stream{FileIO.format"STL_BINARY"},
+              mesh::TriangleMesh; faces)
+    io = FileIO.stream(f)
+    points = mesh.face_vertices
+    normals = mesh.face_normals
+
+    # Implementation made according to https://en.wikipedia.org/wiki/STL_%28file_format%29#Binary_STL
+    for i in 1:80 # Write empty header
+        write(io, 0x00)
+    end
+
+    write(io, UInt32(length(faces))) # Write triangle count
+    for i in faces
+        n = SVector{3, Float32}(normals[i])
+        triangle = points[i]
+
+        for j in 1:3
+            write(io, n[j])
+        end
+
+        for point in triangle, p in point
+            write(io, Float32(p))
+        end
+        write(io, 0x0000) # 16 empty bits
+    end
+end