From cc9cf7f39e2fed77b6b5f76c8225afee873e11ab Mon Sep 17 00:00:00 2001
From: Enrico Turri <enricoturri@seznam.cz>
Date: Wed, 23 Jan 2019 11:08:18 +0100
Subject: [PATCH] Fixed unselected instance synchronization when rotating using
 rotate gizmo

---
 src/libslic3r/Geometry.cpp    | 17 ++++++-----------
 src/slic3r/GUI/GLCanvas3D.cpp |  4 ++--
 2 files changed, 8 insertions(+), 13 deletions(-)

diff --git a/src/libslic3r/Geometry.cpp b/src/libslic3r/Geometry.cpp
index c84169676..db64f97a7 100644
--- a/src/libslic3r/Geometry.cpp
+++ b/src/libslic3r/Geometry.cpp
@@ -1189,17 +1189,12 @@ Vec3d extract_euler_angles(const Eigen::Matrix<double, 3, 3, Eigen::DontAlign>&
     Vec3d angles2 = Vec3d::Zero();
     if (is_approx(std::abs(rotation_matrix(2, 0)), 1.0))
     {
-        angles1(2) = 0.0;
-        if (rotation_matrix(2, 0) > 0.0) // == +1.0
-        {
-            angles1(1) = -0.5 * (double)PI;
-            angles1(0) = -angles1(2) + ::atan2(-rotation_matrix(0, 1), -rotation_matrix(0, 2));
-        }
-        else // == -1.0
-        {
-            angles1(1) = 0.5 * (double)PI;
-            angles1(0) = angles1(2) + ::atan2(rotation_matrix(0, 1), rotation_matrix(0, 2));
-        }
+        // the handling of singular cases deviates from the cited paper
+        // the following code works better when rotating an object with the gizmo after having
+        // changed its orientation using the place on bed gizmo
+        angles1(0) = 0.0;
+        angles1(1) = 0.5 * (double)PI;
+        angles1(2) = angles1(0) + ::atan2(rotation_matrix(0, 1), rotation_matrix(0, 2));
         angles2 = angles1;
     }
     else
diff --git a/src/slic3r/GUI/GLCanvas3D.cpp b/src/slic3r/GUI/GLCanvas3D.cpp
index 42899b96b..47da5574a 100644
--- a/src/slic3r/GUI/GLCanvas3D.cpp
+++ b/src/slic3r/GUI/GLCanvas3D.cpp
@@ -2408,7 +2408,7 @@ void GLCanvas3D::Selection::_update_type()
 void GLCanvas3D::Selection::_set_caches()
 {
     m_cache.volumes_data.clear();
-    for (unsigned int i : m_list)
+    for (unsigned int i = 0; i < (unsigned int)m_volumes->size(); ++i)
     {
         const GLVolume* v = (*m_volumes)[i];
         m_cache.volumes_data.emplace(i, VolumeCache(v->get_volume_transformation(), v->get_instance_transformation()));
@@ -2699,7 +2699,7 @@ void GLCanvas3D::Selection::_synchronize_unselected_instances(bool including_z)
             if ((v->object_idx() != object_idx) || (v->instance_idx() == instance_idx))
                 continue;
 
-            v->set_instance_rotation(Vec3d(rotation(0), rotation(1), including_z ? rotation(2) : v->get_instance_rotation()(2)));
+            v->set_instance_rotation(Vec3d(rotation(0), rotation(1), including_z ? rotation(2) : m_cache.volumes_data[j].get_instance_rotation()(2) + rotation(2)));
             v->set_instance_scaling_factor(scaling_factor);
             v->set_instance_mirror(mirror);