Merge pull request #4146 from ochafik/sort-stl

Experimental sort-stl feature for stable outputs (fixes #420).

src/export.cc

@@ -138,18 +138,22 @@ namespace Export {
 
 ExportMesh::ExportMesh(const PolySet& ps)
 {
+  std::map<Vertex, int> vertexMap;
   std::vector<std::array<int, 3>> triangleIndices;
   for (const auto& p : ps.polygons) {
-    auto pos1 = vertexMap.emplace(std::make_pair<std::array<double, 3>, int>({p[0].x(), p[0].y(), p[0].z()}, vertexMap.size()));
-    auto pos2 = vertexMap.emplace(std::make_pair<std::array<double, 3>, int>({p[1].x(), p[1].y(), p[1].z()}, vertexMap.size()));
-    auto pos3 = vertexMap.emplace(std::make_pair<std::array<double, 3>, int>({p[2].x(), p[2].y(), p[2].z()}, vertexMap.size()));
+    auto pos1 = vertexMap.emplace(std::make_pair<Vertex, int>({p[0].x(), p[0].y(), p[0].z()}, vertexMap.size()));
+    auto pos2 = vertexMap.emplace(std::make_pair<Vertex, int>({p[1].x(), p[1].y(), p[1].z()}, vertexMap.size()));
+    auto pos3 = vertexMap.emplace(std::make_pair<Vertex, int>({p[2].x(), p[2].y(), p[2].z()}, vertexMap.size()));
     triangleIndices.push_back({pos1.first->second, pos2.first->second, pos3.first->second});
   }
 
-  int index = 0;
-  std::map<int, int> indexTranslationMap;
+  std::vector<size_t> indexTranslationMap(vertexMap.size());
+  vertices.reserve(vertexMap.size());
+
+  size_t index = 0;
   for (const auto& e : vertexMap) {
-    indexTranslationMap.emplace(e.second, index++);
+    vertices.push_back(e.first);
+    indexTranslationMap[e.second] = index++;
   }
 
   for (const auto& i : triangleIndices) {
@@ -160,17 +164,17 @@ ExportMesh::ExportMesh(const PolySet& ps)
     });
 }
 
-bool ExportMesh::foreach_vertex(const std::function<bool(const std::array<double, 3>&)> callback) const
+bool ExportMesh::foreach_vertex(const std::function<bool(const Vertex&)> callback) const
 {
-  for (const auto& e : vertexMap) {
-    if (!callback(e.first)) {
+  for (const auto& v : vertices) {
+    if (!callback(v)) {
       return false;
     }
   }
   return true;
 }
 
-bool ExportMesh::foreach_triangle(const std::function<bool(const std::array<int, 3>&)> callback) const
+bool ExportMesh::foreach_indexed_triangle(const std::function<bool(const std::array<int, 3>&)> callback) const
 {
   for (const auto& t : triangles) {
     if (!callback(t.key)) {
@@ -180,4 +184,17 @@ bool ExportMesh::foreach_triangle(const std::function<bool(const std::array<int,
   return true;
 }
 
+bool ExportMesh::foreach_triangle(const std::function<bool(const std::array<std::array<double, 3>, 3>&)> callback) const
+{
+  for (const auto& t : triangles) {
+    auto& v0 = vertices[t.key[0]];
+    auto& v1 = vertices[t.key[1]];
+    auto& v2 = vertices[t.key[2]];
+    if (!callback({ v0, v1, v2 })) {
+      return false;
+    }
+  }
+  return true;
+}
+
 } // namespace Export

src/export.h

@@ -154,13 +154,16 @@ struct Triangle {
 class ExportMesh
 {
 public:
+  typedef std::array<double, 3> Vertex;
+
   ExportMesh(const PolySet& ps);
 
-  bool foreach_vertex(const std::function<bool(const std::array<double, 3>&)> callback) const;
-  bool foreach_triangle(const std::function<bool(const std::array<int, 3>&)> callback) const;
+  bool foreach_vertex(const std::function<bool(const Vertex&)> callback) const;
+  bool foreach_indexed_triangle(const std::function<bool(const std::array<int, 3>&)> callback) const;
+  bool foreach_triangle(const std::function<bool(const std::array<Vertex, 3>&)> callback) const;
 
 private:
-  std::map<std::array<double, 3>, int> vertexMap;
+  std::vector<Vertex> vertices;
   std::vector<Triangle> triangles;
 };
 

src/export_3mf.cc

@@ -98,7 +98,7 @@ static bool append_polyset(const PolySet& ps, PLib3MFModelMeshObject *& model)
     return false;
   }
 
-  if (!exportMesh.foreach_triangle(triangleFunc)) {
+  if (!exportMesh.foreach_indexed_triangle(triangleFunc)) {
     export_3mf_error("Can't add triangle to 3MF model.", model);
     return false;
   }
@@ -261,7 +261,7 @@ static bool append_polyset(const PolySet& ps, Lib3MF::PWrapper& wrapper, Lib3MF:
       return false;
     }
 
-    if (!exportMesh.foreach_triangle(triangleFunc)) {
+    if (!exportMesh.foreach_indexed_triangle(triangleFunc)) {
       export_3mf_error("Can't add triangle to 3MF model.");
       return false;
     }

src/export_stl.cc

@@ -42,6 +42,10 @@ std::string toString(const Vector3d& v)
   return STR(v[0] << " " << v[1] << " " << v[2]);
 }
 
+Vector3d toVector(const std::array<double, 3>& pt) {
+  return Vector3d(pt[0], pt[1], pt[2]);
+}
+
 Vector3d fromString(const std::string& vertexString)
 {
   Vector3d v;
@@ -74,8 +78,7 @@ uint64_t append_stl(const PolySet& ps, std::ostream& output, bool binary)
   PolySet triangulated(3);
   PolysetUtils::tessellate_faces(ps, triangulated);
 
-  for (const auto& p : triangulated.polygons) {
-    assert(p.size() == 3); // STL only allows triangles
+  auto processTriangle = [&](const std::array<Vector3d, 3>& p) {
     triangle_count++;
 
     if (binary) {
@@ -135,6 +138,19 @@ uint64_t append_stl(const PolySet& ps, std::ostream& output, bool binary)
         output << "  endfacet\n";
       }
     }
+  };
+
+  if (Feature::ExperimentalSortStl.is_enabled()) {
+    Export::ExportMesh exportMesh { triangulated };
+    exportMesh.foreach_triangle([&](const auto& pts) {
+        processTriangle({ toVector(pts[0]), toVector(pts[1]), toVector(pts[2]) });
+        return true;
+      });
+  } else {
+    for (const auto& p : triangulated.polygons) {
+      assert(p.size() == 3); // STL only allows triangles
+      processTriangle({ p[0], p[1], p[2] });
+    }
   }
 
   return triangle_count;

src/feature.cc

@@ -46,6 +46,7 @@ const Feature Feature::ExperimentalVxORenderersDirect("vertex-object-renderers-d
 const Feature Feature::ExperimentalVxORenderersPrealloc("vertex-object-renderers-prealloc", "Enable preallocating buffers in vertex object renderers");
 const Feature Feature::ExperimentalTextMetricsFunctions("textmetrics", "Enable the <code>textmetrics()</code> and <code>fontmetrics()</code> functions.");
 const Feature Feature::ExperimentalImportFunction("import-function", "Enable import function returning data instead of geometry.");
+const Feature Feature::ExperimentalSortStl("sort-stl", "Sort the STL output for predictible, diffable results.");
 
 Feature::Feature(const std::string& name, const std::string& description)
   : enabled(false), name(name), description(description)

src/feature.h

@@ -28,6 +28,7 @@ class Feature
   static const Feature ExperimentalVxORenderersPrealloc;
   static const Feature ExperimentalTextMetricsFunctions;
   static const Feature ExperimentalImportFunction;
+  static const Feature ExperimentalSortStl;
 
   const std::string& get_name() const;
   const std::string& get_description() const;

tests/CMakeLists.txt

@@ -1166,8 +1166,7 @@ add_cmdline_test(pdfexporttest SCRIPT ${EXPORT_PNGTEST_PY} SUFFIX png FILES ${SC
 
 add_cmdline_test(monotonepngtest OPENSCAD SUFFIX png FILES ${EXPORT3D_CGAL_TEST_FILES} ${EXPORT3D_CGALCGAL_TEST_FILES} ARGS --colorscheme=Monotone --render)
 
-# Disabled for now, needs implementation of #420 to be stable
-#add_cmdline_test(stlexport             ARGS SUFFIX stl FILES ${EXPORT_STL_TEST_FILES})
+add_cmdline_test(stlexport             OPENSCAD SUFFIX stl FILES ${EXPORT_STL_TEST_FILES} ARGS --enable=sort-stl --render)
 add_cmdline_test(3mfexport             OPENSCAD ARGS SUFFIX 3mf FILES ${EXPORT_3MF_TEST_FILES})
 
 # stlpngtest: direct STL output, preview rendering