From 4846b504a2977dc31fe8db3855356cc2cc621466 Mon Sep 17 00:00:00 2001
From: enricoturri1966 <enricoturri@seznam.cz>
Date: Thu, 19 May 2022 12:19:18 +0200
Subject: [PATCH] Tech ENABLE_TRANSFORMATIONS_BY_MATRICES - Improved detection
 and removal of skew in matrices

Fixed conflicts during rebase with master
---
 src/slic3r/GUI/GUI_ObjectManipulation.cpp | 30 ++++----------
 src/slic3r/GUI/Selection.cpp              | 50 +++++++++++++++--------
 2 files changed, 43 insertions(+), 37 deletions(-)

diff --git a/src/slic3r/GUI/GUI_ObjectManipulation.cpp b/src/slic3r/GUI/GUI_ObjectManipulation.cpp
index ff8fe940c..c6ca3f746 100644
--- a/src/slic3r/GUI/GUI_ObjectManipulation.cpp
+++ b/src/slic3r/GUI/GUI_ObjectManipulation.cpp
@@ -944,18 +944,12 @@ void ObjectManipulation::update_reset_buttons_visibility()
             const Geometry::Transformation& trafo = volume->get_instance_transformation();
             rotation = trafo.get_rotation_matrix();
             scale = trafo.get_scaling_factor_matrix();
-            if (trafo.has_skew())
-                // the instance transform contains skew
-                skew = trafo;
-            else {
-                // the world transform contains skew
-                const Selection::IndicesList& idxs = selection.get_volume_idxs();
-                for (unsigned int id : idxs) {
-                    const Geometry::Transformation world_trafo(selection.get_volume(id)->world_matrix());
-                    if (world_trafo.has_skew()) {
-                        skew = world_trafo;
-                        break;
-                    }
+            const Selection::IndicesList& idxs = selection.get_volume_idxs();
+            for (unsigned int id : idxs) {
+                const Geometry::Transformation world_trafo(selection.get_volume(id)->world_matrix());                
+                if (world_trafo.has_skew()) {
+                    skew = world_trafo;
+                    break;
                 }
             }
 #else
@@ -971,15 +965,9 @@ void ObjectManipulation::update_reset_buttons_visibility()
             const Geometry::Transformation& trafo = volume->get_volume_transformation();
             rotation = trafo.get_rotation_matrix();
             scale = trafo.get_scaling_factor_matrix();
-            if (trafo.has_skew())
-                // the volume transform contains skew
-                skew = trafo;
-            else {
-                // the world transform contains skew
-                const Geometry::Transformation world_trafo(volume->world_matrix());
-                if (world_trafo.has_skew())
-                    skew = world_trafo;
-            }
+            const Geometry::Transformation world_trafo(volume->world_matrix());
+            if (world_trafo.has_skew())
+                skew = world_trafo;
 #else
             rotation = volume->get_volume_rotation();
             scale = volume->get_volume_scaling_factor();
diff --git a/src/slic3r/GUI/Selection.cpp b/src/slic3r/GUI/Selection.cpp
index be6abeee3..02edd9c31 100644
--- a/src/slic3r/GUI/Selection.cpp
+++ b/src/slic3r/GUI/Selection.cpp
@@ -1495,23 +1495,41 @@ void Selection::reset_skew()
     for (unsigned int i : m_list) {
         GLVolume& v = *(*m_volumes)[i];
         const VolumeCache& volume_data = m_cache.volumes_data[i];
-        const Geometry::Transformation& inst_trafo = volume_data.get_instance_transform();
-        const Geometry::Transformation& vol_trafo = volume_data.get_volume_transform();
-        const Geometry::Transformation world_trafo = inst_trafo * vol_trafo;
-        if (!inst_trafo.has_skew() && !vol_trafo.has_skew() && world_trafo.has_skew()) {
-            Geometry::Transformation mod_world_trafo = Geometry::Transformation(world_trafo.get_matrix_no_offset());
-            mod_world_trafo.reset_skew();
-            v.set_volume_transformation(vol_trafo.get_offset_matrix() * inst_trafo.get_matrix_no_offset().inverse() * mod_world_trafo.get_matrix());
+        Geometry::Transformation inst_trafo = volume_data.get_instance_transform();
+        Geometry::Transformation vol_trafo = volume_data.get_volume_transform();
+        Geometry::Transformation world_trafo = inst_trafo * vol_trafo;
+        if (world_trafo.has_skew()) {
+            if (!inst_trafo.has_skew() && !vol_trafo.has_skew()) {
+                // <W> = [I][V]
+                world_trafo.reset_offset();
+                world_trafo.reset_skew();
+                v.set_volume_transformation(vol_trafo.get_offset_matrix() * inst_trafo.get_matrix_no_offset().inverse() * world_trafo.get_matrix());
+            }
+            else {
+                // <W> = <I><V>
+                // <W> = <I>[V]
+                // <W> = [I]<V>
+                if (inst_trafo.has_skew()) {
+                    inst_trafo.reset_skew();
+                    v.set_instance_transformation(inst_trafo);
+                }
+                if (vol_trafo.has_skew()) {
+                    vol_trafo.reset_skew();
+                    v.set_volume_transformation(vol_trafo);
+                }
+            }
         }
-        else if (m_mode == Instance && inst_trafo.has_skew()) {
-            Geometry::Transformation trafo = inst_trafo;
-            trafo.reset_skew();
-            v.set_instance_transformation(trafo);
-        }
-        else if (m_mode == Volume && vol_trafo.has_skew()) {
-            Geometry::Transformation trafo = vol_trafo;
-            trafo.reset_skew();
-            v.set_volume_transformation(trafo);
+        else {
+            // [W] = [I][V]
+            // [W] = <I><V>
+            if (inst_trafo.has_skew()) {
+                inst_trafo.reset_skew();
+                v.set_instance_transformation(inst_trafo);
+            }
+            if (vol_trafo.has_skew()) {
+                vol_trafo.reset_skew();
+                v.set_volume_transformation(vol_trafo);
+            }
         }
     }