Mirror CAD persistence (K1+K2+G1) from snaporca-cad onto mainline OrcaSlicer

Dual-fork mandate: port the parametric-recipe 3MF persistence from
snaporca-cad commits ed19eac+147e1c4 so a saved project reopens with the
editable CAD feature tree, not just the baked mesh.

Shared kernel/format/GUI (identical to snaporca-cad):
- CadDocument serialize_recipe/deserialize_recipe (cereal BinaryArchive,
  versioned) + CadFeature split save/load + imported_solid<->BRep string.
- Model::cad_recipe carried through 3MF zip entry Metadata/SnapOrca_cad.bin
  (writer + binary-verbatim reader branch).
- DesignPanel on_commit() stamps the recipe; on_tab_shown() rehydrates a
  loaded project via load_recipe() (deserialize -> feed_bodies + refresh_tree).

Mainline-only adapters (no snaporca-cad counterpart — Catch2 v3 vs v2):
- tests/libslic3r/test_caddocument.cpp: <catch2/catch_all.hpp> +
  `using Catch::Approx;` (v3 scopes Approx under Catch::).
- tests/libslic3r/CMakeLists.txt: register test_caddocument.cpp (the
  original CAD port had left it out of the test build).

Verified on behemoth (snaporca-deps toolchain): libslic3r_tests clean;
[CadDocument] 17/18 (only the pre-existing tangent-to-circle SIGABRT fails,
identical to snaporca-tkz); K1 serialize round-trip + version-reject pass
(13 assertions); new [3mf] "CAD recipe blob survives a 3mf save/load cycle"
passes byte-for-byte; orca-slicer GUI links clean (186/186, DesignPanel.cpp
compiled). Interactive :10 click-through pending (no Design-tab automation).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BVzKmX6Y1aEteit1HTXG4Q

src/libslic3r/CadDocument.cpp

@@ -42,6 +42,10 @@
 #include <cmath>
 #include <stdexcept>
 #include <algorithm>
+#include <sstream>
+
+#include <cereal/archives/binary.hpp>
+#include <BRepTools.hxx>
 
 namespace Slic3r {
 
@@ -1537,4 +1541,52 @@ bool CadDocument::preview(const CadFeature& candidate, TriangleMesh& out_mesh, s
     return preview(candidate, out_mesh, ignore, err);
 }
 
+std::string brep_to_string(const TopoDS_Shape& s)
+{
+    if (s.IsNull()) return {};
+    std::ostringstream oss;
+    BRepTools::Write(s, oss);
+    return oss.str();
+}
+
+TopoDS_Shape brep_from_string(const std::string& d)
+{
+    if (d.empty()) return {};
+    std::istringstream iss(d);
+    TopoDS_Shape s;
+    BRep_Builder b;
+    BRepTools::Read(s, iss, b);
+    return s;
+}
+
+std::string CadDocument::serialize_recipe() const
+{
+    std::ostringstream oss;
+    {
+        cereal::BinaryOutputArchive ar(oss);
+        uint32_t v = SNAPORCA_CAD_RECIPE_VERSION;
+        ar(v);
+        ar(features);
+    }
+    return oss.str();
+}
+
+bool CadDocument::deserialize_recipe(const std::string& blob)
+{
+    try {
+        std::istringstream iss(blob);
+        cereal::BinaryInputArchive ar(iss);
+        uint32_t v;
+        ar(v);
+        if (v > SNAPORCA_CAD_RECIPE_VERSION)
+            return false;
+        ar(features);
+        return recompute();
+    } catch (const Standard_Failure&) {
+        return false;
+    } catch (...) {
+        return false;
+    }
+}
+
 } // namespace Slic3r

src/libslic3r/CadDocument.hpp

@@ -8,6 +8,9 @@
 
 #include <TopoDS_Shape.hxx>
 #include <TopoDS_Wire.hxx>
+#include <cereal/cereal.hpp>
+#include <cereal/types/vector.hpp>
+#include <cereal/types/string.hpp>
 #include <string>
 #include <vector>
 #include <utility>
@@ -20,6 +23,11 @@ enum class BooleanMode    { New, Add, Cut, Intersect };
 
 enum class ExtrudeEnd { Blind, Symmetric, TwoSided, ThroughAll, UpToFace, UpToVertex };
 
+// Serialize a TopoDS_Shape to/from a BRep string (declared before CadFeature so its
+// inline cereal save()/load() can resolve these non-dependent calls).
+std::string brep_to_string(const TopoDS_Shape& s);
+TopoDS_Shape brep_from_string(const std::string& d);
+
 struct CadFeature {
     CadFeatureType type{CadFeatureType::Sketch};
     std::string    name;
@@ -181,8 +189,56 @@ struct CadFeature {
     bool   cut_flip{false};       // flip the normal => swaps which side is "upper"
     bool   cut_keep_upper{true};  // keep the +normal half
     bool   cut_keep_lower{false}; // keep the -normal half (both => split into two bodies)
+
+    template<class Archive>
+    void save(Archive& ar) const {
+        std::string brep = (type == CadFeatureType::Import) ? brep_to_string(imported_solid) : std::string();
+        ar(type, name, enabled, shape, plane, width, height, radius,
+           profile, entities, constraints, entity_constraints, imported_regions,
+           import_offset, import_scale_x, import_scale_y, import_on_face, import_face_body,
+           sketch_ref, distance, symmetric, mode, extrude_end, distance2, taper_deg, flip,
+           up_to_face, extrude_src_face, up_to_point, target_body,
+           dressup_size, face_group, dressup_edge,
+           hole_diameter, hole_depth, hole_through, hole_x, hole_y,
+           thread_radius, thread_pitch, thread_height, thread_depth, thread_internal, thread_x, thread_y,
+           shell_thickness, shell_face,
+           draft_face, draft_angle,
+           revolve_angle, revolve_axis,
+           sweep_path_ref, loft_profile_refs, loft_ruled,
+           pattern_circular, pattern_count, pattern_spacing, pattern_dir, pattern_angle,
+           plane_base, plane_offset, plane_angle_tilt, plane_axis,
+           bool_tool_body, bool_keep_tool, bool_tolerance, bool_target_face, bool_tool_face,
+           cut_offset, cut_flip, cut_keep_upper, cut_keep_lower,
+           brep);
+    }
+    template<class Archive>
+    void load(Archive& ar) {
+        std::string brep;
+        ar(type, name, enabled, shape, plane, width, height, radius,
+           profile, entities, constraints, entity_constraints, imported_regions,
+           import_offset, import_scale_x, import_scale_y, import_on_face, import_face_body,
+           sketch_ref, distance, symmetric, mode, extrude_end, distance2, taper_deg, flip,
+           up_to_face, extrude_src_face, up_to_point, target_body,
+           dressup_size, face_group, dressup_edge,
+           hole_diameter, hole_depth, hole_through, hole_x, hole_y,
+           thread_radius, thread_pitch, thread_height, thread_depth, thread_internal, thread_x, thread_y,
+           shell_thickness, shell_face,
+           draft_face, draft_angle,
+           revolve_angle, revolve_axis,
+           sweep_path_ref, loft_profile_refs, loft_ruled,
+           pattern_circular, pattern_count, pattern_spacing, pattern_dir, pattern_angle,
+           plane_base, plane_offset, plane_angle_tilt, plane_axis,
+           bool_tool_body, bool_keep_tool, bool_tolerance, bool_target_face, bool_tool_face,
+           cut_offset, cut_flip, cut_keep_upper, cut_keep_lower,
+           brep);
+        imported_solid = brep_from_string(brep);
+    }
 };
 
+// Serialize a TopoDS_Shape to/from a BRep string for cereal persistence.
+std::string brep_to_string(const TopoDS_Shape& s);
+TopoDS_Shape brep_from_string(const std::string& d);
+
 // One independent solid in a multi-body document.
 struct CadBody {
     TopoDS_Shape shape;
@@ -279,6 +335,10 @@ public:
     void clear();
     bool recompute();   // replay features -> body + display_mesh; false on error
 
+    static constexpr uint32_t SNAPORCA_CAD_RECIPE_VERSION = 1;
+    std::string serialize_recipe() const;
+    bool deserialize_recipe(const std::string& blob);
+
     // Undo/redo of the feature recipe (Onshape-style Ctrl+Z). The caller marks a
     // user-action boundary by calling checkpoint() BEFORE the mutation(s) for that
     // action (add/delete/move/replace, or a direct features edit). undo()/redo() then

src/libslic3r/Format/3mf.cpp

@@ -73,6 +73,7 @@ const std::string THUMBNAIL_FILE = "Metadata/thumbnail.png";
 const std::string PRINT_CONFIG_FILE = "Metadata/Slic3r_PE.config";
 const std::string MODEL_CONFIG_FILE = "Metadata/Slic3r_PE_model.config";
 const std::string LAYER_HEIGHTS_PROFILE_FILE = "Metadata/Slic3r_PE_layer_heights_profile.txt";
+const std::string CAD_RECIPE_FILE = "Metadata/SnapOrca_cad.bin";
 const std::string LAYER_CONFIG_RANGES_FILE = "Metadata/Prusa_Slicer_layer_config_ranges.xml";
 const std::string SLA_SUPPORT_POINTS_FILE = "Metadata/Slic3r_PE_sla_support_points.txt";
 const std::string SLA_DRAIN_HOLES_FILE = "Metadata/Slic3r_PE_sla_drain_holes.txt";
@@ -805,6 +806,17 @@ ModelVolumeType type_from_string(const std::string &s)
                         return false;
                     }
                 }
+                if (boost::algorithm::iequals(name, CAD_RECIPE_FILE)) {
+                    if (stat.m_uncomp_size > 0) {
+                        std::string buffer((size_t)stat.m_uncomp_size, 0);
+                        if (mz_zip_reader_extract_file_to_mem(&archive, stat.m_filename,
+                                (void*)buffer.data(), (size_t)stat.m_uncomp_size, 0) != 0) {
+                            model.cad_recipe = std::move(buffer);
+                        } else {
+                            add_error("Error while reading CAD recipe data");
+                        }
+                    }
+                }
             }
         }
 
@@ -2317,6 +2329,7 @@ ModelVolumeType type_from_string(const std::string &s)
         bool _add_mesh_to_object_stream(mz_zip_writer_staged_context &context, ModelObject& object, VolumeToOffsetsMap& volumes_offsets);
         bool _add_build_to_model_stream(std::stringstream& stream, const BuildItemsList& build_items);
         bool _add_layer_height_profile_file_to_archive(mz_zip_archive& archive, Model& model);
+        bool _add_cad_recipe_file_to_archive(mz_zip_archive& archive, Model& model);
         bool _add_layer_config_ranges_file_to_archive(mz_zip_archive& archive, Model& model);
         bool _add_sla_support_points_file_to_archive(mz_zip_archive& archive, Model& model);
         bool _add_sla_drain_holes_file_to_archive(mz_zip_archive& archive, Model& model);
@@ -2387,6 +2400,13 @@ ModelVolumeType type_from_string(const std::string &s)
             return false;
         }
 
+        // Adds CAD recipe file ("Metadata/SnapOrca_cad.bin").
+        if (!_add_cad_recipe_file_to_archive(archive, model)) {
+            close_zip_writer(&archive);
+            boost::filesystem::remove(filename);
+            return false;
+        }
+
         // Adds layer config ranges file ("Metadata/Slic3r_PE_layer_config_ranges.txt").
         // All layer height profiles of all ModelObjects are stored here, indexed by 1 based index of the ModelObject in Model.
         // The index differes from the index of an object ID of an object instance of a 3MF file!
@@ -2919,6 +2939,19 @@ ModelVolumeType type_from_string(const std::string &s)
         return true;
     }
 
+    bool _3MF_Exporter::_add_cad_recipe_file_to_archive(mz_zip_archive& archive, Model& model)
+    {
+        if (model.cad_recipe.empty())
+            return true;
+        if (!mz_zip_writer_add_mem(&archive, CAD_RECIPE_FILE.c_str(),
+                (const void*)model.cad_recipe.data(), model.cad_recipe.length(),
+                MZ_DEFAULT_COMPRESSION)) {
+            add_error("Unable to add CAD recipe file to archive");
+            return false;
+        }
+        return true;
+    }
+
     bool _3MF_Exporter::_add_layer_config_ranges_file_to_archive(mz_zip_archive& archive, Model& model)
     {
         std::string out = "";

src/libslic3r/Model.cpp

@@ -105,6 +105,8 @@ Model& Model::assign_copy(const Model &rhs)
     this->md_name = rhs.md_name;
     this->md_value = rhs.md_value;
 
+    this->cad_recipe = rhs.cad_recipe;
+
     return *this;
 }
 
@@ -148,6 +150,7 @@ Model& Model::assign_copy(Model &&rhs)
     rhs.model_info.reset();
     this->profile_info = rhs.profile_info;
     rhs.profile_info.reset();
+    this->cad_recipe = std::move(rhs.cad_recipe);
     return *this;
 }
 

src/libslic3r/Model.hpp

@@ -1547,6 +1547,10 @@ public:
     std::vector<std::string> md_name;
     std::vector<std::string> md_value;
 
+    // SnapOrca: opaque parametric CAD recipe (CadDocument::serialize_recipe()),
+    // round-tripped through the 3MF as Metadata/SnapOrca_cad.bin. Empty for non-CAD projects.
+    std::string cad_recipe;
+
     void SetDesigner(std::string designer, std::string designer_user_id) {
         if (design_info == nullptr) {
             design_info = std::make_shared<ModelDesignInfo>();

src/slic3r/GUI/DesignPanel.cpp

@@ -2652,6 +2652,29 @@ int DesignPanel::tree_icon_for(CadFeatureType t)
 void DesignPanel::on_tab_shown()
 {
     if (m_viewport) m_viewport->refresh_bed();
+
+    // Rehydrate the parametric model from a freshly loaded project (the 3MF carried the
+    // recipe in Metadata/SnapOrca_cad.bin). Only when nothing is in progress here, so we
+    // never clobber an active design when the user just toggles back to the Design tab.
+    if (m_doc.features.empty()) {
+        if (Plater* plater = wxGetApp().plater()) {
+            const std::string& blob = plater->model().cad_recipe;
+            if (!blob.empty()) load_recipe(blob);
+        }
+    }
+}
+
+void DesignPanel::load_recipe(const std::string& blob)
+{
+    if (blob.empty()) return;
+    if (!m_doc.deserialize_recipe(blob)) {
+        m_status->SetLabel(_L("Could not restore the CAD model from this project"));
+        return;
+    }
+    m_feature_counter = int(m_doc.features.size());
+    feed_bodies();    // push the restored bodies into the viewport
+    refresh_tree();   // rebuild the feature tree from the restored recipe
+    set_status_ok();
 }
 
 void DesignPanel::refresh_tree()
@@ -4526,6 +4549,13 @@ void DesignPanel::on_commit()
         obj_list->load_mesh_object(m_disp_pick_mesh, "Design Body");
     }
 
+    // Persist the editable parametric recipe alongside the committed meshes so the
+    // saved 3MF reopens with the full feature tree, not just the baked solid. An empty
+    // doc clears it, keeping non-CAD projects clean.
+    if (Plater* plater = wxGetApp().plater())
+        plater->model().cad_recipe =
+            m_doc.features.empty() ? std::string() : m_doc.serialize_recipe();
+
     if (wxGetApp().mainframe != nullptr)
         wxGetApp().mainframe->select_tab(size_t(MainFrame::tp3DEditor));
 }

src/slic3r/GUI/DesignPanel.hpp

@@ -86,6 +86,9 @@ private:
     // a modal dialog editing the feature's placement transform in place.
     void on_transform_imported(int feat_idx);
     void on_commit();
+    // Rehydrate the parametric model from a project's saved recipe (3MF
+    // Metadata/SnapOrca_cad.bin): deserialize -> recompute -> refresh viewport + tree.
+    void load_recipe(const std::string& blob);
     void refresh_tree();
     void set_status_ok();