When loading an AMF file having multiple objects that look like multiple parts of a single object, prompt user and ask how to consider it. #2970

Conflicts:

	lib/Slic3r/Model.pm

lib/Slic3r/Format/AMF/Parser.pm

@@ -143,6 +143,7 @@ sub end_document {
         }
         
         foreach my $instance (@{ $self->{_instances}{$object_id} }) {
+            next if !defined($instance->{deltax}) || !defined($instance->{deltay});
             $self->{_model}->objects->[$new_object_id]->add_instance(
                 rotation => $instance->{rz} || 0,
                 offset   => Slic3r::Pointf->new($instance->{deltax} || 0, $instance->{deltay} || 0),

lib/Slic3r/GUI/Plater.pm

@@ -523,6 +523,16 @@ sub load_file {
     Slic3r::GUI::show_error($self, $@) if $@;
     
     if (defined $model) {
+        if ($model->looks_like_multipart_object) {
+            my $dialog = Wx::MessageDialog->new($self,
+                "This file contains several objects positioned at multiple heights. "
+                . "Instead of considering them as multiple objects, should I consider\n"
+                . "this file as a single object having multiple parts?\n",
+                'Multi-part object detected', wxICON_WARNING | wxYES | wxNO);
+            if ($dialog->ShowModal() == wxID_YES) {
+                $model->convert_multipart_object;
+            }
+        }
         $self->load_model_objects(@{$model->objects});
         $self->statusbar->SetStatusText("Loaded " . basename($input_file));
     }

lib/Slic3r/Model.pm

@@ -1,6 +1,6 @@
 package Slic3r::Model;
 
-use List::Util qw(first max);
+use List::Util qw(first max any);
 use Slic3r::Geometry qw(X Y Z move_points);
 
 sub read_from_file {
@@ -72,6 +72,33 @@ sub print_info {
     $_->print_info for @{$self->objects};
 }
 
+sub looks_like_multipart_object {
+    my ($self) = @_;
+    
+    return 0 if $self->objects_count == 1;
+    return 0 if any { $_->volumes_count > 1 } @{$self->objects};
+    return 0 if any { @{$_->config->get_keys} > 1 } @{$self->objects};
+    
+    my %heights = map { $_ => 1 } map $_->mesh->bounding_box->z_min, map @{$_->volumes}, @{$self->objects};
+    return scalar(keys %heights) > 1;
+}
+
+sub convert_multipart_object {
+    my ($self) = @_;
+    
+    my @objects = @{$self->objects};
+    my $object = $self->add_object(
+        input_file          => $objects[0]->input_file,
+    );
+    foreach my $v (map @{$_->volumes}, @objects) {
+        my $volume = $object->add_volume($v);
+        $volume->set_name($v->object->name);
+    }
+    $object->add_instance($_) for map @{$_->instances}, @objects;
+    
+    $self->delete_object($_) for reverse 0..($self->objects_count-2);
+}
+
 package Slic3r::Model::Material;
 
 sub apply {

xs/src/libslic3r/Model.cpp

@@ -324,7 +324,7 @@ ModelMaterial::apply(const t_model_material_attributes &attributes)
 
 
 ModelObject::ModelObject(Model *model)
-    : model(model)
+    : model(model), _bounding_box_valid(false)
 {}
 
 ModelObject::ModelObject(Model *model, const ModelObject &other, bool copy_volumes)