Fix of "Variable layer height feature breaks after rotating part #2073"

There was an approximate bounding box used at the GUI, while a snug
bounding box was used at the back end, causing invalidation
of the variable layer height editing profile on rotated objects.

A snug bounding box around the first instance is now cached.

src/libslic3r/Model.cpp

@@ -593,6 +593,8 @@ ModelObject& ModelObject::assign_copy(const ModelObject &rhs)
     this->origin_translation          = rhs.origin_translation;
     m_bounding_box                    = rhs.m_bounding_box;
     m_bounding_box_valid              = rhs.m_bounding_box_valid;
+    m_raw_bounding_box                = rhs.m_raw_bounding_box;
+    m_raw_bounding_box_valid          = rhs.m_raw_bounding_box_valid;
     m_raw_mesh_bounding_box           = rhs.m_raw_mesh_bounding_box;
     m_raw_mesh_bounding_box_valid     = rhs.m_raw_mesh_bounding_box_valid;
 
@@ -627,6 +629,8 @@ ModelObject& ModelObject::assign_copy(ModelObject &&rhs)
     this->origin_translation          = std::move(rhs.origin_translation);
     m_bounding_box                    = std::move(rhs.m_bounding_box);
     m_bounding_box_valid              = std::move(rhs.m_bounding_box_valid);
+    m_raw_bounding_box                = rhs.m_raw_bounding_box;
+    m_raw_bounding_box_valid          = rhs.m_raw_bounding_box_valid;
     m_raw_mesh_bounding_box           = rhs.m_raw_mesh_bounding_box;
     m_raw_mesh_bounding_box_valid     = rhs.m_raw_mesh_bounding_box_valid;
 
@@ -859,7 +863,7 @@ TriangleMesh ModelObject::full_raw_mesh() const
     return mesh;
 }
 
-BoundingBoxf3 ModelObject::raw_mesh_bounding_box() const
+const BoundingBoxf3& ModelObject::raw_mesh_bounding_box() const
 {
     if (! m_raw_mesh_bounding_box_valid) {
         m_raw_mesh_bounding_box_valid = true;
@@ -880,33 +884,36 @@ BoundingBoxf3 ModelObject::full_raw_mesh_bounding_box() const
 }
 
 // A transformed snug bounding box around the non-modifier object volumes, without the translation applied.
-// This bounding box is only used for the actual slicing.
-BoundingBoxf3 ModelObject::raw_bounding_box() const
+// This bounding box is only used for the actual slicing and for layer editing UI to calculate the layers.
+const BoundingBoxf3& ModelObject::raw_bounding_box() const
 {
-    BoundingBoxf3 bb;
-#if ENABLE_GENERIC_SUBPARTS_PLACEMENT
-    if (this->instances.empty())
-        throw std::invalid_argument("Can't call raw_bounding_box() with no instances");
+    if (! m_raw_bounding_box_valid) {
+        m_raw_bounding_box_valid = true;
+        m_raw_bounding_box.reset();
+    #if ENABLE_GENERIC_SUBPARTS_PLACEMENT
+        if (this->instances.empty())
+            throw std::invalid_argument("Can't call raw_bounding_box() with no instances");
 
-    const Transform3d& inst_matrix = this->instances.front()->get_transformation().get_matrix(true);
-#endif // ENABLE_GENERIC_SUBPARTS_PLACEMENT
-    for (const ModelVolume *v : this->volumes)
-        if (v->is_model_part()) {
-#if !ENABLE_GENERIC_SUBPARTS_PLACEMENT
-            if (this->instances.empty())
-                throw std::invalid_argument("Can't call raw_bounding_box() with no instances");
-#endif // !ENABLE_GENERIC_SUBPARTS_PLACEMENT
+        const Transform3d& inst_matrix = this->instances.front()->get_transformation().get_matrix(true);
+    #endif // ENABLE_GENERIC_SUBPARTS_PLACEMENT
+        for (const ModelVolume *v : this->volumes)
+            if (v->is_model_part()) {
+    #if !ENABLE_GENERIC_SUBPARTS_PLACEMENT
+                if (this->instances.empty())
+                    throw std::invalid_argument("Can't call raw_bounding_box() with no instances");
+    #endif // !ENABLE_GENERIC_SUBPARTS_PLACEMENT
 
-#if ENABLE_GENERIC_SUBPARTS_PLACEMENT
-            bb.merge(v->mesh.transformed_bounding_box(inst_matrix * v->get_matrix()));
-#else
-            // unmaintaned
-            assert(false);
-            // vol_mesh.transform(v->get_matrix());
-            // bb.merge(this->instances.front()->transform_mesh_bounding_box(vol_mesh, true));
-#endif // ENABLE_GENERIC_SUBPARTS_PLACEMENT
-        }
-    return bb;
+    #if ENABLE_GENERIC_SUBPARTS_PLACEMENT
+				m_raw_bounding_box.merge(v->mesh.transformed_bounding_box(inst_matrix * v->get_matrix()));
+    #else
+                // unmaintaned
+                assert(false);
+                // vol_mesh.transform(v->get_matrix());
+                // m_raw_bounding_box_valid.merge(this->instances.front()->transform_mesh_bounding_box(vol_mesh, true));
+    #endif // ENABLE_GENERIC_SUBPARTS_PLACEMENT
+            }
+    }
+	return m_raw_bounding_box;
 }
 
 // This returns an accurate snug bounding box of the transformed object instance, without the translation applied.

src/libslic3r/Model.hpp

@@ -212,7 +212,7 @@ public:
     // This bounding box is approximate and not snug.
     // This bounding box is being cached.
     const BoundingBoxf3& bounding_box() const;
-    void invalidate_bounding_box() { m_bounding_box_valid = false; m_raw_mesh_bounding_box_valid = false; }
+    void invalidate_bounding_box() { m_bounding_box_valid = false; m_raw_bounding_box_valid = false; m_raw_mesh_bounding_box_valid = false; }
 
     // A mesh containing all transformed instances of this object.
     TriangleMesh mesh() const;
@@ -223,11 +223,11 @@ public:
     TriangleMesh full_raw_mesh() const;
     // A transformed snug bounding box around the non-modifier object volumes, without the translation applied.
     // This bounding box is only used for the actual slicing.
-    BoundingBoxf3 raw_bounding_box() const;
+    const BoundingBoxf3& raw_bounding_box() const;
     // A snug bounding box around the transformed non-modifier object volumes.
     BoundingBoxf3 instance_bounding_box(size_t instance_idx, bool dont_translate = false) const;
 	// A snug bounding box of non-transformed (non-rotated, non-scaled, non-translated) sum of non-modifier object volumes.
-	BoundingBoxf3 raw_mesh_bounding_box() const;
+	const BoundingBoxf3& raw_mesh_bounding_box() const;
 	// A snug bounding box of non-transformed (non-rotated, non-scaled, non-translated) sum of all object volumes.
     BoundingBoxf3 full_raw_mesh_bounding_box() const;
 
@@ -285,7 +285,7 @@ protected:
 
 private:
     ModelObject(Model *model) : m_model(model), origin_translation(Vec3d::Zero()), 
-        m_bounding_box_valid(false), m_raw_mesh_bounding_box_valid(false) {}
+        m_bounding_box_valid(false), m_raw_bounding_box_valid(false), m_raw_mesh_bounding_box_valid(false) {}
     ~ModelObject();
 
     /* To be able to return an object from own copy / clone methods. Hopefully the compiler will do the "Copy elision" */
@@ -304,6 +304,8 @@ private:
     // Bounding box, cached.
     mutable BoundingBoxf3 m_bounding_box;
     mutable bool          m_bounding_box_valid;
+    mutable BoundingBoxf3 m_raw_bounding_box;
+    mutable bool          m_raw_bounding_box_valid;
     mutable BoundingBoxf3 m_raw_mesh_bounding_box;
     mutable bool          m_raw_mesh_bounding_box_valid;    
 };

src/libslic3r/Print.hpp

@@ -132,7 +132,7 @@ public:
     // The slicing parameters are dependent on various configuration values
     // (layer height, first layer height, raft settings, print nozzle diameter etc).
     const SlicingParameters&    slicing_parameters() const { return m_slicing_params; }
-    static SlicingParameters    slicing_parameters(const DynamicPrintConfig &full_config, const ModelObject &model_object);
+    static SlicingParameters    slicing_parameters(const DynamicPrintConfig &full_config, const ModelObject &model_object, float object_max_z);
 
     // returns 0-based indices of extruders used to print the object (without brim, support and other helper extrusions)
     std::vector<unsigned int>   object_extruders() const;

src/libslic3r/PrintObject.cpp

@@ -1370,7 +1370,7 @@ void PrintObject::update_slicing_parameters()
             this->print()->config(), m_config, unscale<double>(this->size(2)), this->object_extruders());
 }
 
-SlicingParameters PrintObject::slicing_parameters(const DynamicPrintConfig &full_config, const ModelObject &model_object)
+SlicingParameters PrintObject::slicing_parameters(const DynamicPrintConfig &full_config, const ModelObject &model_object, float object_max_z)
 {
     PrintConfig         print_config;
     PrintObjectConfig   object_config;
@@ -1390,7 +1390,9 @@ SlicingParameters PrintObject::slicing_parameters(const DynamicPrintConfig &full
                 object_extruders);
     sort_remove_duplicates(object_extruders);
 
-    return SlicingParameters::create_from_config(print_config, object_config, model_object.bounding_box().max.z(), object_extruders);
+    if (object_max_z <= 0.f)
+        object_max_z = model_object.raw_bounding_box().size().z();
+	return SlicingParameters::create_from_config(print_config, object_config, object_max_z, object_extruders);
 }
 
 // returns 0-based indices of extruders used to print the object (without brim, support and other helper extrusions)

src/slic3r/GUI/GLCanvas3D.cpp

@@ -255,16 +255,21 @@ void GLCanvas3D::LayersEditing::set_config(const DynamicPrintConfig* config)
 void GLCanvas3D::LayersEditing::select_object(const Model &model, int object_id)
 {
     const ModelObject *model_object_new = (object_id >= 0) ? model.objects[object_id] : nullptr;
-    if (model_object_new == nullptr || this->last_object_id != object_id || m_model_object != model_object_new || m_model_object->id() != model_object_new->id()) {
+    // Maximum height of an object changes when the object gets rotated or scaled.
+    // Changing maximum height of an object will invalidate the layer heigth editing profile.
+    // m_model_object->raw_bounding_box() is cached, therefore it is cheap even if this method is called frequently.
+    float new_max_z = (m_model_object == nullptr) ? 0.f : m_model_object->raw_bounding_box().size().z();
+	if (m_model_object != model_object_new || this->last_object_id != object_id || m_object_max_z != new_max_z ||
+        (model_object_new != nullptr && m_model_object->id() != model_object_new->id())) {
         m_layer_height_profile.clear();
         m_layer_height_profile_modified = false;
         delete m_slicing_parameters;
-        m_slicing_parameters = nullptr;
+        m_slicing_parameters   = nullptr;
         m_layers_texture.valid = false;
+        this->last_object_id   = object_id;
+        m_model_object         = model_object_new;
+        m_object_max_z         = new_max_z;
     }
-    this->last_object_id = object_id;
-    m_model_object       = model_object_new;
-    m_object_max_z       = (m_model_object == nullptr) ? 0.f : m_model_object->bounding_box().max.z();
 }
 
 bool GLCanvas3D::LayersEditing::is_allowed() const
@@ -623,7 +628,7 @@ void GLCanvas3D::LayersEditing::update_slicing_parameters()
 {
 	if (m_slicing_parameters == nullptr) {
 		m_slicing_parameters = new SlicingParameters();
-    	*m_slicing_parameters = PrintObject::slicing_parameters(*m_config, *m_model_object);
+    	*m_slicing_parameters = PrintObject::slicing_parameters(*m_config, *m_model_object, m_object_max_z);
     }
 }