From d98fd64534570e406cabef8895fc98c34687d18f Mon Sep 17 00:00:00 2001
From: enricoturri1966 <enricoturri@seznam.cz>
Date: Thu, 2 Feb 2023 12:40:28 +0100
Subject: [PATCH] Method Transformation::reset_rotation() modified to use SVD
 decomposition of transformation matrix and object manipulator reset button
 set to use it

---
 src/libslic3r/Geometry.cpp                |  7 +++++++
 src/libslic3r/Geometry.hpp                |  2 +-
 src/slic3r/GUI/GUI_ObjectManipulation.cpp | 22 ++++++++++++++++------
 3 files changed, 24 insertions(+), 7 deletions(-)

diff --git a/src/libslic3r/Geometry.cpp b/src/libslic3r/Geometry.cpp
index c815719b7a..f3b8926d92 100644
--- a/src/libslic3r/Geometry.cpp
+++ b/src/libslic3r/Geometry.cpp
@@ -720,6 +720,13 @@ void Transformation::reset()
 }
 
 #if ENABLE_WORLD_COORDINATE
+void Transformation::reset_rotation()
+{
+    const Geometry::TransformationSVD svd(*this);
+    const Transform3d mirror = is_left_handed() ? Geometry::scale_transform({ -1.0, 1.0, 1.0 }) : Transform3d::Identity();
+    m_matrix = get_offset_matrix() * mirror * Transform3d(svd.v * svd.s * svd.v.transpose());
+}
+
 void Transformation::reset_scaling_factor()
 {
     const Geometry::TransformationSVD svd(*this);
diff --git a/src/libslic3r/Geometry.hpp b/src/libslic3r/Geometry.hpp
index 531f7cac80..f7b08b9b29 100644
--- a/src/libslic3r/Geometry.hpp
+++ b/src/libslic3r/Geometry.hpp
@@ -492,7 +492,7 @@ public:
     void reset();
 #if ENABLE_WORLD_COORDINATE
     void reset_offset() { set_offset(Vec3d::Zero()); }
-    void reset_rotation() { set_rotation(Vec3d::Zero()); }
+    void reset_rotation();
     void reset_scaling_factor();
     void reset_mirror() { set_mirror(Vec3d::Ones()); }
     void reset_skew();
diff --git a/src/slic3r/GUI/GUI_ObjectManipulation.cpp b/src/slic3r/GUI/GUI_ObjectManipulation.cpp
index a80b47d2dd..1d6212ce58 100644
--- a/src/slic3r/GUI/GUI_ObjectManipulation.cpp
+++ b/src/slic3r/GUI/GUI_ObjectManipulation.cpp
@@ -448,14 +448,21 @@ ObjectManipulation::ObjectManipulation(wxWindow* parent) :
         Selection& selection = canvas->get_selection();
 
 #if ENABLE_WORLD_COORDINATE
-        if (selection.is_single_volume_or_modifier())
+        if (selection.is_single_volume_or_modifier()) {
+            GLVolume* vol = const_cast<GLVolume*>(selection.get_first_volume());
+            Geometry::Transformation trafo = vol->get_volume_transformation();
+            trafo.reset_rotation();
+            vol->set_volume_transformation(trafo);
+        }
 #else
         if (selection.is_single_volume() || selection.is_single_modifier())
-#endif // ENABLE_WORLD_COORDINATE
             const_cast<GLVolume*>(selection.get_first_volume())->set_volume_rotation(Vec3d::Zero());
+#endif // ENABLE_WORLD_COORDINATE
         else if (selection.is_single_full_instance()) {
+            Geometry::Transformation trafo = selection.get_first_volume()->get_instance_transformation();
+            trafo.reset_rotation();
             for (unsigned int idx : selection.get_volume_idxs()) {
-                const_cast<GLVolume*>(selection.get_volume(idx))->set_instance_rotation(Vec3d::Zero());
+                const_cast<GLVolume*>(selection.get_volume(idx))->set_instance_transformation(trafo);
             }
         }
         else
@@ -484,14 +491,17 @@ ObjectManipulation::ObjectManipulation(wxWindow* parent) :
         GLCanvas3D* canvas = wxGetApp().plater()->canvas3D();
         Selection& selection = canvas->get_selection();
         if (selection.is_single_volume_or_modifier()) {
-            Geometry::Transformation trafo = selection.get_first_volume()->get_volume_transformation();
+            GLVolume* vol = const_cast<GLVolume*>(selection.get_first_volume());
+            Geometry::Transformation trafo = vol->get_volume_transformation();
             trafo.reset_scaling_factor();
-            const_cast<GLVolume*>(selection.get_first_volume())->set_volume_transformation(trafo);
+            vol->set_volume_transformation(trafo);
         }
         else if (selection.is_single_full_instance()) {
             Geometry::Transformation trafo = selection.get_first_volume()->get_instance_transformation();
             trafo.reset_scaling_factor();
-            const_cast<GLVolume*>(selection.get_first_volume())->set_instance_transformation(trafo);
+            for (unsigned int idx : selection.get_volume_idxs()) {
+                const_cast<GLVolume*>(selection.get_volume(idx))->set_instance_transformation(trafo);
+            }
         }
         else
             return;