Follow-up to 3349644964

Reworked handling of approximate / snug bounding boxes
at Model / ModelObject / PrintObject
Further optimized, so that the bounding boxes are not recalculated
unnecesarilly.

src/libslic3r/Geometry.cpp

@@ -918,4 +918,30 @@ double rotation_diff_z(const Transform3d &trafo_from, const Transform3d &trafo_t
     return atan2(vx.y(), vx.x());
 }
 
+bool trafos_differ_in_rotation_by_z_and_mirroring_by_xy_only(const Transform3d &t1, const Transform3d &t2)
+{
+    if (std::abs(t1.translation().z() - t2.translation().z()) > EPSILON)
+        // One of the object is higher than the other above the build plate (or below the build plate).
+        return false;
+    Matrix3d m1 = t1.matrix().block<3, 3>(0, 0);
+    Matrix3d m2 = t2.matrix().block<3, 3>(0, 0);
+    Matrix3d m = m2.inverse() * m1;
+    Vec3d    z = m.block<3, 1>(0, 2);
+    if (std::abs(z.x()) > EPSILON || std::abs(z.y()) > EPSILON || std::abs(z.z() - 1.) > EPSILON)
+        // Z direction or length changed.
+        return false;
+    // Z still points in the same direction and it has the same length.
+    Vec3d    x = m.block<3, 1>(0, 0);
+    Vec3d    y = m.block<3, 1>(0, 1);
+    if (std::abs(x.z()) > EPSILON || std::abs(y.z()) > EPSILON)
+        return false;
+    double   lx2 = x.squaredNorm();
+    double   ly2 = y.squaredNorm();
+    if (lx2 - 1. > EPSILON * EPSILON || ly2 - 1. > EPSILON * EPSILON)
+        return false;
+    // Verify whether the vectors x, y are still perpendicular.
+    double   d   = x.dot(y);
+    return std::abs(d * d) < EPSILON * lx2 * ly2;
+}
+
 }} // namespace Slic3r::Geometry

src/libslic3r/Geometry.hpp

@@ -584,6 +584,13 @@ inline bool is_rotation_ninety_degrees(const Vec3d &rotation)
     return is_rotation_ninety_degrees(rotation.x()) && is_rotation_ninety_degrees(rotation.y()) && is_rotation_ninety_degrees(rotation.z());
 }
 
+// Returns true if one transformation may be converted into another transformation by
+// rotation around Z and by mirroring in X / Y only. Two objects sharing such transformation
+// may share support structures and they share Z height.
+bool trafos_differ_in_rotation_by_z_and_mirroring_by_xy_only(const Transform3d &t1, const Transform3d &t2);
+inline bool trafos_differ_in_rotation_by_z_and_mirroring_by_xy_only(const Transformation &t1, const Transformation &t2)
+    { return trafos_differ_in_rotation_by_z_and_mirroring_by_xy_only(t1.get_matrix(), t2.get_matrix()); }
+
 template <class Tout = double, class Tin>
 std::pair<Tout, Tout> dir_to_spheric(const Vec<3, Tin> &n, Tout norm = 1.)
 {

src/libslic3r/Model.cpp

@@ -643,15 +643,7 @@ ModelObject& ModelObject::assign_copy(const ModelObject &rhs)
     this->printable                   = rhs.printable;
     this->origin_translation          = rhs.origin_translation;
     this->cut_id.copy(rhs.cut_id);
-    m_bounding_box_approx             = rhs.m_bounding_box_approx;
-    m_bounding_box_approx_valid       = rhs.m_bounding_box_approx_valid;
-    m_bounding_box_exact              = rhs.m_bounding_box_exact;
-    m_bounding_box_exact_valid        = rhs.m_bounding_box_exact_valid;
-    m_min_max_z_valid                 = rhs.m_min_max_z_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;
+    this->copy_transformation_caches(rhs);
 
     this->clear_volumes();
     this->volumes.reserve(rhs.volumes.size());
@@ -687,15 +679,7 @@ ModelObject& ModelObject::assign_copy(ModelObject &&rhs)
     this->layer_height_profile        = std::move(rhs.layer_height_profile);
     this->printable                   = std::move(rhs.printable);
     this->origin_translation          = std::move(rhs.origin_translation);
-    m_bounding_box_approx             = std::move(rhs.m_bounding_box_approx);
-    m_bounding_box_approx_valid       = std::move(rhs.m_bounding_box_approx_valid);
-    m_bounding_box_exact              = std::move(rhs.m_bounding_box_exact);
-    m_bounding_box_exact_valid        = std::move(rhs.m_bounding_box_exact_valid);
-    m_min_max_z_valid                 = rhs.m_min_max_z_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;
+    this->copy_transformation_caches(rhs);
 
     this->clear_volumes();
 	this->volumes = std::move(rhs.volumes);

src/libslic3r/Model.hpp

@@ -606,6 +606,19 @@ private:
     mutable BoundingBoxf3 m_raw_mesh_bounding_box;
     mutable bool          m_raw_mesh_bounding_box_valid { false };
 
+    // Only use this method if now the source and dest ModelObjects are equal, for example they were synchronized by Print::apply().
+    void copy_transformation_caches(const ModelObject &src) {
+        m_bounding_box_approx             = src.m_bounding_box_approx;
+        m_bounding_box_approx_valid       = src.m_bounding_box_approx_valid;
+        m_bounding_box_exact              = src.m_bounding_box_exact;
+        m_bounding_box_exact_valid        = src.m_bounding_box_exact_valid;
+        m_min_max_z_valid                 = src.m_min_max_z_valid;
+        m_raw_bounding_box                = src.m_raw_bounding_box;
+        m_raw_bounding_box_valid          = src.m_raw_bounding_box_valid;
+        m_raw_mesh_bounding_box           = src.m_raw_mesh_bounding_box;
+        m_raw_mesh_bounding_box_valid     = src.m_raw_mesh_bounding_box_valid;
+    }
+
     // Called by Print::apply() to set the model pointer after making a copy.
     friend class Print;
     friend class SLAPrint;

src/libslic3r/PrintApply.cpp

@@ -1250,7 +1250,6 @@ Print::ApplyStatus Print::apply(const Model &model, DynamicPrintConfig new_full_
 	        						           l->get_transformation().get_matrix().isApprox(r->get_transformation().get_matrix()); })) {
 	        	// If some of the instances changed, the bounding box of the updated ModelObject is likely no more valid.
 	        	// This is safe as the ModelObject's bounding box is only accessed from this function, which is called from the main thread only.
-	 			model_object.invalidate_bounding_box();
 	        	// Synchronize the content of instances.
 	        	auto new_instance = model_object_new.instances.begin();
 				for (auto old_instance = model_object.instances.begin(); old_instance != model_object.instances.end(); ++ old_instance, ++ new_instance) {
@@ -1259,6 +1258,8 @@ Print::ApplyStatus Print::apply(const Model &model, DynamicPrintConfig new_full_
                     (*old_instance)->printable 		    = (*new_instance)->printable;
   				}
 	        }
+            // Source / dest object share the same bounding boxes, just copy them.
+            model_object.copy_transformation_caches(model_object_new);
         }
     }