Improved accuracy of ModelVolume matrix store / restore

into the 3MF / AMF.
Improved accuracy of ModelVolume's mesh transform back from Object's
coordinate space to its own coordinate space after reloading
from 3MF / AMF.

src/libslic3r/Format/3mf.cpp

@@ -34,10 +34,12 @@ namespace pt = boost::property_tree;
 // VERSION NUMBERS
 // 0 : .3mf, files saved by older slic3r or other applications. No version definition in them.
 // 1 : Introduction of 3mf versioning. No other change in data saved into 3mf files.
-// 2 : Meshes saved in their local system; Volumes' matrices and source data added to Metadata/Slic3r_PE_model.config file.
+// 2 : Volumes' matrices and source data added to Metadata/Slic3r_PE_model.config file, meshes transformed back to their coordinate system on loading.
 // WARNING !! -> the version number has been rolled back to 1
 //               the next change should use 3
 const unsigned int VERSION_3MF = 1;
+// Allow loading version 2 file as well.
+const unsigned int VERSION_3MF_COMPATIBLE = 2;
 const char* SLIC3RPE_3MF_VERSION = "slic3rpe:Version3mf"; // definition of the metadata name saved into .model file
 
 const std::string MODEL_FOLDER = "3D/";
@@ -1513,7 +1515,7 @@ namespace Slic3r {
         {
             m_version = (unsigned int)atoi(m_curr_characters.c_str());
 
-            if (m_check_version && (m_version > VERSION_3MF))
+            if (m_check_version && (m_version > VERSION_3MF_COMPATIBLE))
             {
                 // std::string msg = _(L("The selected 3mf file has been saved with a newer version of " + std::string(SLIC3R_APP_NAME) + " and is not compatible."));
                 // throw version_error(msg.c_str());
@@ -1699,20 +1701,19 @@ namespace Slic3r {
                 return false;
             }
 
-            Slic3r::Geometry::Transformation transform;
-            if (m_version > 1)
-            {
+            Transform3d volume_matrix_to_object = Transform3d::Identity();
+            bool        has_transform 		    = false;
             // extract the volume transformation from the volume's metadata, if present
             for (const Metadata& metadata : volume_data.metadata)
             {
                 if (metadata.key == MATRIX_KEY)
                 {
-                        transform.set_from_string(metadata.value);
+                    volume_matrix_to_object = Slic3r::Geometry::transform3d_from_string(metadata.value);
+                    has_transform 			= ! volume_matrix_to_object.isApprox(Transform3d::Identity(), 1e-10);
                     break;
                 }
             }
-            }
-            Transform3d inv_matrix = transform.get_matrix().inverse();
+            Transform3d inv_matrix = volume_matrix_to_object.inverse();
 
             // splits volume out of imported geometry
 			TriangleMesh triangle_mesh;
@@ -1733,10 +1734,10 @@ namespace Slic3r {
                 {
                     unsigned int tri_id = geometry.triangles[src_start_id + ii + v] * 3;
                     Vec3f vertex(geometry.vertices[tri_id + 0], geometry.vertices[tri_id + 1], geometry.vertices[tri_id + 2]);
-                    if (m_version > 1)
+                    facet.vertex[v] = has_transform ?
                         // revert the vertices to the original mesh reference system
-                        vertex = (inv_matrix * vertex.cast<double>()).cast<float>();
-                    ::memcpy(facet.vertex[v].data(), (const void*)vertex.data(), 3 * sizeof(float));
+                        (inv_matrix * vertex.cast<double>()).cast<float>() :
+                        vertex;
                 }
             }
 
@@ -1745,8 +1746,8 @@ namespace Slic3r {
 
 			ModelVolume* volume = object.add_volume(std::move(triangle_mesh));
             // apply the volume matrix taken from the metadata, if present
-            if (m_version > 1)
-                volume->set_transformation(transform);
+            if (has_transform)
+                volume->set_transformation(Slic3r::Geometry::Transformation(volume_matrix_to_object));
             volume->calculate_convex_hull();
 
             // apply the remaining volume's metadata
@@ -2471,6 +2472,9 @@ namespace Slic3r {
     bool _3MF_Exporter::_add_model_config_file_to_archive(mz_zip_archive& archive, const Model& model, const IdToObjectDataMap &objects_data)
     {
         std::stringstream stream;
+        // Store mesh transformation in full precision, as the volumes are stored transformed and they need to be transformed back
+        // when loaded as accurately as possible.
+		stream << std::setprecision(std::numeric_limits<double>::max_digits10);
         stream << "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n";
         stream << "<" << CONFIG_TAG << ">\n";
 

src/libslic3r/Format/AMF.cpp

@@ -41,10 +41,11 @@ namespace pt = boost::property_tree;
 //     Added x and y components of rotation
 //     Added x, y and z components of scale
 //     Added x, y and z components of mirror
-// 3 : Meshes saved in their local system; Added volumes' matrices and source data
+// 3 : Added volumes' matrices and source data, meshes transformed back to their coordinate system on loading.
 // WARNING !! -> the version number has been rolled back to 2
 //               the next change should use 4
 const unsigned int VERSION_AMF = 2;
+const unsigned int VERSION_AMF_COMPATIBLE = 3;
 const char* SLIC3RPE_AMF_VERSION = "slic3rpe_amf_version";
 
 const char* SLIC3R_CONFIG_TYPE = "slic3rpe_config";
@@ -230,6 +231,8 @@ struct AMFParserContext
     ModelVolume             *m_volume;
     // Faces collected for the current m_volume.
     std::vector<int>         m_volume_facets;
+    // Transformation matrix of a volume mesh from its coordinate system to Object's coordinate system.
+    Transform3d 			 m_volume_transform;
     // Current material allocated for an amf/metadata subtree.
     ModelMaterial           *m_material;
     // Current instance allocated for an amf/constellation/instance subtree.
@@ -321,6 +324,7 @@ void AMFParserContext::startElement(const char *name, const char **atts)
 			else if (strcmp(name, "volume") == 0) {
 				assert(! m_volume);
                 m_volume = m_object->add_volume(TriangleMesh());
+                m_volume_transform = Transform3d::Identity();
                 node_type_new = NODE_TYPE_VOLUME;
 			}
         } else if (m_path[2] == NODE_TYPE_INSTANCE) {
@@ -580,27 +584,25 @@ void AMFParserContext::endElement(const char * /* name */)
         stl.stats.original_num_facets = stl.stats.number_of_facets;
         stl_allocate(&stl);
 
-        Slic3r::Geometry::Transformation transform;
-        if (m_version > 2)
-            transform = m_volume->get_transformation();
-
-        Transform3d inv_matrix = transform.get_matrix().inverse();
-
+        bool has_transform = ! m_volume_transform.isApprox(Transform3d::Identity(), 1e-10);
+        Transform3d inv_matrix = m_volume_transform.inverse();
         for (size_t i = 0; i < m_volume_facets.size();) {
             stl_facet &facet = stl.facet_start[i/3];
             for (unsigned int v = 0; v < 3; ++v)
             {
                 unsigned int tri_id = m_volume_facets[i++] * 3;
                 Vec3f vertex(m_object_vertices[tri_id + 0], m_object_vertices[tri_id + 1], m_object_vertices[tri_id + 2]);
-                if (m_version > 2)
+                facet.vertex[v] = has_transform ?
                     // revert the vertices to the original mesh reference system
-                    vertex = (inv_matrix * vertex.cast<double>()).cast<float>();
-                ::memcpy((void*)facet.vertex[v].data(), (const void*)vertex.data(), 3 * sizeof(float));
+                    (inv_matrix * vertex.cast<double>()).cast<float>() :
+                    vertex;
             }
         }        
         stl_get_size(&stl);
         mesh.repair();
 		m_volume->set_mesh(std::move(mesh));
+		if (has_transform)
+			m_volume->set_transformation(m_volume_transform);
         if (m_volume->source.input_file.empty() && (m_volume->type() == ModelVolumeType::MODEL_PART))
         {
             m_volume->source.object_idx = (int)m_model.objects.size() - 1;
@@ -720,9 +722,7 @@ void AMFParserContext::endElement(const char * /* name */)
                     m_volume->set_type(ModelVolume::type_from_string(m_value[1]));
                 }
                 else if (strcmp(opt_key, "matrix") == 0) {
-                    Geometry::Transformation transform;
-                    transform.set_from_string(m_value[1]);
-                    m_volume->set_transformation(transform);
+                    m_volume_transform = Slic3r::Geometry::transform3d_from_string(m_value[1]);
                 }
                 else if (strcmp(opt_key, "source_file") == 0) {
                     m_volume->source.input_file = m_value[1];
@@ -912,7 +912,7 @@ bool extract_model_from_archive(mz_zip_archive& archive, const mz_zip_archive_fi
 
     ctx.endDocument();
 
-    if (check_version && (ctx.m_version > VERSION_AMF))
+    if (check_version && (ctx.m_version > VERSION_AMF_COMPATIBLE))
     {
         // std::string msg = _(L("The selected amf file has been saved with a newer version of " + std::string(SLIC3R_APP_NAME) + " and is not compatible."));
         // throw std::runtime_error(msg.c_str());
@@ -1148,6 +1148,7 @@ bool store_amf(const char *path, Model *model, const DynamicPrintConfig *config)
             stream << "        <metadata type=\"slic3r.volume_type\">" << ModelVolume::type_to_string(volume->type()) << "</metadata>\n";
             stream << "        <metadata type=\"slic3r.matrix\">";
             const Transform3d& matrix = volume->get_matrix();
+			stream << std::setprecision(std::numeric_limits<double>::max_digits10);
             for (int r = 0; r < 4; ++r)
             {
                 for (int c = 0; c < 4; ++c)
@@ -1167,6 +1168,7 @@ bool store_amf(const char *path, Model *model, const DynamicPrintConfig *config)
                 stream << "        <metadata type=\"slic3r.source_offset_y\">" << volume->source.mesh_offset(1) << "</metadata>\n";
                 stream << "        <metadata type=\"slic3r.source_offset_z\">" << volume->source.mesh_offset(2) << "</metadata>\n";
             }
+			stream << std::setprecision(std::numeric_limits<float>::max_digits10);
             const indexed_triangle_set &its = volume->mesh().its;
             for (size_t i = 0; i < its.indices.size(); ++i) {
                 stream << "        <triangle>\n";

src/libslic3r/Geometry.cpp

@@ -1187,14 +1187,12 @@ MedialAxis::validate_edge(const VD::edge_type* edge)
     return true;
 }
 
-const Line&
-MedialAxis::retrieve_segment(const VD::cell_type* cell) const
+const Line& MedialAxis::retrieve_segment(const VD::cell_type* cell) const
 {
     return this->lines[cell->source_index()];
 }
 
-const Point&
-MedialAxis::retrieve_endpoint(const VD::cell_type* cell) const
+const Point& MedialAxis::retrieve_endpoint(const VD::cell_type* cell) const
 {
     const Line& line = this->retrieve_segment(cell);
     if (cell->source_category() == SOURCE_CATEGORY_SEGMENT_START_POINT) {
@@ -1208,11 +1206,8 @@ void assemble_transform(Transform3d& transform, const Vec3d& translation, const
 {
     transform = Transform3d::Identity();
     transform.translate(translation);
-    transform.rotate(Eigen::AngleAxisd(rotation(2), Vec3d::UnitZ()));
-    transform.rotate(Eigen::AngleAxisd(rotation(1), Vec3d::UnitY()));
-    transform.rotate(Eigen::AngleAxisd(rotation(0), Vec3d::UnitX()));
-    transform.scale(scale);
-    transform.scale(mirror);
+    transform.rotate(Eigen::AngleAxisd(rotation(2), Vec3d::UnitZ()) * Eigen::AngleAxisd(rotation(1), Vec3d::UnitY()) * Eigen::AngleAxisd(rotation(0), Vec3d::UnitX()));
+    transform.scale(scale.cwiseProduct(mirror));
 }
 
 Transform3d assemble_transform(const Vec3d& translation, const Vec3d& rotation, const Vec3d& scale, const Vec3d& mirror)
@@ -1420,32 +1415,6 @@ void Transformation::set_from_transform(const Transform3d& transform)
 //        std::cout << "something went wrong in extracting data from matrix" << std::endl;
 }
 
-void Transformation::set_from_string(const std::string& transform_str)
-{
-    Transform3d transform = Transform3d::Identity();
-
-    if (!transform_str.empty())
-    {
-        std::vector<std::string> mat_elements_str;
-        boost::split(mat_elements_str, transform_str, boost::is_any_of(" "), boost::token_compress_on);
-
-        unsigned int size = (unsigned int)mat_elements_str.size();
-        if (size == 16)
-        {
-            unsigned int i = 0;
-            for (unsigned int r = 0; r < 4; ++r)
-            {
-                for (unsigned int c = 0; c < 4; ++c)
-                {
-                    transform(r, c) = ::atof(mat_elements_str[i++].c_str());
-                }
-            }
-        }
-    }
-
-    set_from_transform(transform);
-}
-
 void Transformation::reset()
 {
     m_offset = Vec3d::Zero();
@@ -1536,6 +1505,33 @@ Transformation Transformation::volume_to_bed_transformation(const Transformation
     return out;
 }
 
+// For parsing a transformation matrix from 3MF / AMF.
+Transform3d transform3d_from_string(const std::string& transform_str)
+{
+    Transform3d transform = Transform3d::Identity();
+
+    if (!transform_str.empty())
+    {
+        std::vector<std::string> mat_elements_str;
+        boost::split(mat_elements_str, transform_str, boost::is_any_of(" "), boost::token_compress_on);
+
+        unsigned int size = (unsigned int)mat_elements_str.size();
+        if (size == 16)
+        {
+            unsigned int i = 0;
+            for (unsigned int r = 0; r < 4; ++r)
+            {
+                for (unsigned int c = 0; c < 4; ++c)
+                {
+                    transform(r, c) = ::atof(mat_elements_str[i++].c_str());
+                }
+            }
+        }
+    }
+
+    return transform;
+}
+
 Eigen::Quaterniond rotation_xyz_diff(const Vec3d &rot_xyz_from, const Vec3d &rot_xyz_to)
 {
     return

src/libslic3r/Geometry.hpp

@@ -360,7 +360,6 @@ public:
     void set_mirror(Axis axis, double mirror);
 
     void set_from_transform(const Transform3d& transform);
-    void set_from_string(const std::string& transform_str);
 
     void reset();
 
@@ -385,6 +384,9 @@ private:
 	}
 };
 
+// For parsing a transformation matrix from 3MF / AMF.
+extern Transform3d transform3d_from_string(const std::string& transform_str);
+
 // Rotation when going from the first coordinate system with rotation rot_xyz_from applied
 // to a coordinate system with rot_xyz_to applied.
 extern Eigen::Quaterniond rotation_xyz_diff(const Vec3d &rot_xyz_from, const Vec3d &rot_xyz_to);

src/libslic3r/Model.hpp

@@ -466,6 +466,7 @@ public:
 
     const Geometry::Transformation& get_transformation() const { return m_transformation; }
     void set_transformation(const Geometry::Transformation& transformation) { m_transformation = transformation; }
+    void set_transformation(const Transform3d &trafo) { m_transformation.set_from_transform(trafo); }
 
     const Vec3d& get_offset() const { return m_transformation.get_offset(); }
     double get_offset(Axis axis) const { return m_transformation.get_offset(axis); }