diff --git a/src/libslic3r/Point.hpp b/src/libslic3r/Point.hpp
index e5ce68420..ceb235244 100644
--- a/src/libslic3r/Point.hpp
+++ b/src/libslic3r/Point.hpp
@@ -27,6 +27,7 @@ using Vec2crd = Eigen::Matrix<coord_t,  2, 1, Eigen::DontAlign>;
 using Vec3crd = Eigen::Matrix<coord_t,  3, 1, Eigen::DontAlign>;
 using Vec2i   = Eigen::Matrix<int,      2, 1, Eigen::DontAlign>;
 using Vec3i   = Eigen::Matrix<int,      3, 1, Eigen::DontAlign>;
+using Vec4i   = Eigen::Matrix<int,      4, 1, Eigen::DontAlign>;
 using Vec2i32 = Eigen::Matrix<int32_t,  2, 1, Eigen::DontAlign>;
 using Vec2i64 = Eigen::Matrix<int64_t,  2, 1, Eigen::DontAlign>;
 using Vec3i32 = Eigen::Matrix<int32_t,  3, 1, Eigen::DontAlign>;
@@ -50,12 +51,15 @@ using Matrix2f       = Eigen::Matrix<float,  2, 2, Eigen::DontAlign>;
 using Matrix2d       = Eigen::Matrix<double, 2, 2, Eigen::DontAlign>;
 using Matrix3f       = Eigen::Matrix<float,  3, 3, Eigen::DontAlign>;
 using Matrix3d       = Eigen::Matrix<double, 3, 3, Eigen::DontAlign>;
+using Matrix4f       = Eigen::Matrix<float,  4, 4, Eigen::DontAlign>;
+using Matrix4d       = Eigen::Matrix<double, 4, 4, Eigen::DontAlign>;
 
 using Transform2f    = Eigen::Transform<float,  2, Eigen::Affine, Eigen::DontAlign>;
 using Transform2d    = Eigen::Transform<double, 2, Eigen::Affine, Eigen::DontAlign>;
 using Transform3f    = Eigen::Transform<float,  3, Eigen::Affine, Eigen::DontAlign>;
 using Transform3d    = Eigen::Transform<double, 3, Eigen::Affine, Eigen::DontAlign>;
 
+
 inline bool operator<(const Vec2d &lhs, const Vec2d &rhs) { return lhs(0) < rhs(0) || (lhs(0) == rhs(0) && lhs(1) < rhs(1)); }
 
 template<int Options>
diff --git a/src/slic3r/GUI/GLCanvas3D.cpp b/src/slic3r/GUI/GLCanvas3D.cpp
index eaa4c7f0d..880e69bbd 100644
--- a/src/slic3r/GUI/GLCanvas3D.cpp
+++ b/src/slic3r/GUI/GLCanvas3D.cpp
@@ -1,6 +1,8 @@
 #include "libslic3r/libslic3r.h"
 #include "GLCanvas3D.hpp"
 
+#include <igl/unproject.h>
+
 #include "libslic3r/ClipperUtils.hpp"
 #include "libslic3r/PrintConfig.hpp"
 #include "libslic3r/GCode/ThumbnailData.hpp"
@@ -5391,9 +5393,9 @@ Vec3d GLCanvas3D::_mouse_to_3d(const Point& mouse_pos, float* z)
         return Vec3d(DBL_MAX, DBL_MAX, DBL_MAX);
 
     const Camera& camera = wxGetApp().plater()->get_camera();
-    const std::array<int, 4>& viewport = camera.get_viewport();
-    const Transform3d& modelview_matrix = camera.get_view_matrix();
-    const Transform3d& projection_matrix = camera.get_projection_matrix();
+    Matrix4d modelview = camera.get_view_matrix().matrix();
+    Matrix4d projection= camera.get_projection_matrix().matrix();
+    Vec4i viewport(camera.get_viewport().data());
 
     GLint y = viewport[3] - (GLint)mouse_pos(1);
     GLfloat mouse_z;
@@ -5402,9 +5404,9 @@ Vec3d GLCanvas3D::_mouse_to_3d(const Point& mouse_pos, float* z)
     else
         mouse_z = *z;
 
-    GLdouble out_x, out_y, out_z;
-    ::gluUnProject((GLdouble)mouse_pos(0), (GLdouble)y, (GLdouble)mouse_z, (GLdouble*)modelview_matrix.data(), (GLdouble*)projection_matrix.data(), (GLint*)viewport.data(), &out_x, &out_y, &out_z);
-    return Vec3d((double)out_x, (double)out_y, (double)out_z);
+    Vec3d out;
+    igl::unproject(Vec3d(mouse_pos(0), y, mouse_z), modelview, projection, viewport, out);
+    return out;
 }
 
 Vec3d GLCanvas3D::_mouse_to_bed_3d(const Point& mouse_pos)
diff --git a/src/slic3r/GUI/GLSelectionRectangle.cpp b/src/slic3r/GUI/GLSelectionRectangle.cpp
index d7f3f7a3a..13467499a 100644
--- a/src/slic3r/GUI/GLSelectionRectangle.cpp
+++ b/src/slic3r/GUI/GLSelectionRectangle.cpp
@@ -4,6 +4,7 @@
 #include "GLCanvas3D.hpp"
 #include "GUI_App.hpp"
 #include "Plater.hpp"
+#include <igl/project.h>
 
 #include <GL/glew.h>
 
@@ -38,23 +39,26 @@ namespace GUI {
         m_state = Off;
 
         const Camera& camera = wxGetApp().plater()->get_camera();
-        const std::array<int, 4>& viewport = camera.get_viewport();
-        const Transform3d& modelview_matrix = camera.get_view_matrix();
-        const Transform3d& projection_matrix = camera.get_projection_matrix();
+        Matrix4d modelview = camera.get_view_matrix().matrix();
+        Matrix4d projection= camera.get_projection_matrix().matrix();
+        Vec4i viewport(camera.get_viewport().data());
+
+        // Convert our std::vector to Eigen dynamic matrix.
+        Eigen::Matrix<double, Eigen::Dynamic, 3, Eigen::DontAlign> pts(points.size(), 3);
+        for (size_t i=0; i<points.size(); ++i)
+            pts.block<1, 3>(i, 0) = points[i];
+
+        // Get the projections.
+        Eigen::Matrix<double, Eigen::Dynamic, 3, Eigen::DontAlign> projections;
+        igl::project(pts, modelview, projection, viewport, projections);
 
         // bounding box created from the rectangle corners - will take care of order of the corners
         BoundingBox rectangle(Points{ Point(m_start_corner.cast<coord_t>()), Point(m_end_corner.cast<coord_t>()) });
 
         // Iterate over all points and determine whether they're in the rectangle.
-        for (unsigned int i = 0; i<points.size(); ++i) {
-            const Vec3d& point = points[i];
-            GLdouble out_x, out_y, out_z;
-            ::gluProject((GLdouble)point(0), (GLdouble)point(1), (GLdouble)point(2), (GLdouble*)modelview_matrix.data(), (GLdouble*)projection_matrix.data(), (GLint*)viewport.data(), &out_x, &out_y, &out_z);
-            out_y = canvas.get_canvas_size().get_height() - out_y;
-
-            if (rectangle.contains(Point(out_x, out_y)))
+        for (int i = 0; i<projections.rows(); ++i)
+            if (rectangle.contains(Point(projections(i, 0), canvas.get_canvas_size().get_height() - projections(i, 1))))
                 out.push_back(i);
-        }
 
         return out;
     }
diff --git a/src/slic3r/GUI/Gizmos/GLGizmoRotate.cpp b/src/slic3r/GUI/Gizmos/GLGizmoRotate.cpp
index eceeb5e87..eb026a8e8 100644
--- a/src/slic3r/GUI/Gizmos/GLGizmoRotate.cpp
+++ b/src/slic3r/GUI/Gizmos/GLGizmoRotate.cpp
@@ -30,7 +30,6 @@ GLGizmoRotate::GLGizmoRotate(GLCanvas3D& parent, GLGizmoRotate::Axis axis)
     : GLGizmoBase(parent, "", -1)
     , m_axis(axis)
     , m_angle(0.0)
-    , m_quadric(nullptr)
     , m_center(0.0, 0.0, 0.0)
     , m_radius(0.0f)
     , m_snap_coarse_in_radius(0.0f)
@@ -44,7 +43,6 @@ GLGizmoRotate::GLGizmoRotate(const GLGizmoRotate& other)
     : GLGizmoBase(other.m_parent, other.m_icon_filename, other.m_sprite_id)
     , m_axis(other.m_axis)
     , m_angle(other.m_angle)
-    , m_quadric(nullptr)
     , m_center(other.m_center)
     , m_radius(other.m_radius)
     , m_snap_coarse_in_radius(other.m_snap_coarse_in_radius)
@@ -52,9 +50,6 @@ GLGizmoRotate::GLGizmoRotate(const GLGizmoRotate& other)
     , m_snap_fine_in_radius(other.m_snap_fine_in_radius)
     , m_snap_fine_out_radius(other.m_snap_fine_out_radius)
 {
-    m_quadric = ::gluNewQuadric();
-    if (m_quadric != nullptr)
-        ::gluQuadricDrawStyle(m_quadric, GLU_FILL);
 }
 
 
@@ -329,9 +324,6 @@ void GLGizmoRotate::render_grabber(const BoundingBoxf3& box) const
 
 void GLGizmoRotate::render_grabber_extension(const BoundingBoxf3& box, bool picking) const
 {
-    if (m_quadric == nullptr)
-        return;
-
     float mean_size = (float)((box.size()(0) + box.size()(1) + box.size()(2)) / 3.0);
     double size = m_dragging ? (double)m_grabbers[0].get_dragging_half_size(mean_size) : (double)m_grabbers[0].get_half_size(mean_size);
 
diff --git a/src/slic3r/GUI/MeshUtils.cpp b/src/slic3r/GUI/MeshUtils.cpp
index c65d2b5a9..073bb6f78 100644
--- a/src/slic3r/GUI/MeshUtils.cpp
+++ b/src/slic3r/GUI/MeshUtils.cpp
@@ -9,6 +9,8 @@
 
 #include <GL/glew.h>
 
+#include <igl/unproject.h>
+
 
 namespace Slic3r {
 namespace GUI {
@@ -122,14 +124,16 @@ Vec3f MeshRaycaster::get_triangle_normal(size_t facet_idx) const
 void MeshRaycaster::line_from_mouse_pos(const Vec2d& mouse_pos, const Transform3d& trafo, const Camera& camera,
                                         Vec3d& point, Vec3d& direction) const
 {
-    const std::array<int, 4>& viewport = camera.get_viewport();
-    const Transform3d& model_mat = camera.get_view_matrix();
-    const Transform3d& proj_mat = camera.get_projection_matrix();
+    Matrix4d modelview = camera.get_view_matrix().matrix();
+    Matrix4d projection= camera.get_projection_matrix().matrix();
+    Vec4i viewport(camera.get_viewport().data());
 
     Vec3d pt1;
     Vec3d pt2;
-    ::gluUnProject(mouse_pos(0), viewport[3] - mouse_pos(1), 0., model_mat.data(), proj_mat.data(), viewport.data(), &pt1(0), &pt1(1), &pt1(2));
-    ::gluUnProject(mouse_pos(0), viewport[3] - mouse_pos(1), 1., model_mat.data(), proj_mat.data(), viewport.data(), &pt2(0), &pt2(1), &pt2(2));
+    igl::unproject(Vec3d(mouse_pos(0), viewport[3] - mouse_pos(1), 0.),
+                   modelview, projection, viewport, pt1);
+    igl::unproject(Vec3d(mouse_pos(0), viewport[3] - mouse_pos(1), 1.),
+                   modelview, projection, viewport, pt2);
 
     Transform3d inv = trafo.inverse();
     pt1 = inv * pt1;