Six degrees of freedom camera - 1st installment

src/libslic3r/Technologies.hpp

@@ -74,5 +74,7 @@
 // Enable configurable paths export (fullpath or not) to 3mf and amf
 #define ENABLE_CONFIGURABLE_PATHS_EXPORT_TO_3MF_AND_AMF (1 && ENABLE_2_2_0_BETA1)
 
+// Enable 6 degrees of freedom camera
+#define ENABLE_6DOF_CAMERA (1 && ENABLE_2_2_0_BETA1)
 
 #endif // _technologies_h_

src/slic3r/GUI/3DBed.cpp

@@ -262,7 +262,11 @@ Point Bed3D::point_projection(const Point& point) const
     return m_polygon.point_projection(point);
 }
 
+#if ENABLE_6DOF_CAMERA
+void Bed3D::render(GLCanvas3D& canvas, bool bottom, float scale_factor, bool show_axes) const
+#else
 void Bed3D::render(GLCanvas3D& canvas, float theta, float scale_factor, bool show_axes) const
+#endif // ENABLE_6DOF_CAMERA
 {
     m_scale_factor = scale_factor;
 
@@ -273,6 +277,15 @@ void Bed3D::render(GLCanvas3D& canvas, float theta, float scale_factor, bool sho
 
     switch (m_type)
     {
+#if ENABLE_6DOF_CAMERA
+    case MK2: { render_prusa(canvas, "mk2", bottom); break; }
+    case MK3: { render_prusa(canvas, "mk3", bottom); break; }
+    case SL1: { render_prusa(canvas, "sl1", bottom); break; }
+    case MINI: { render_prusa(canvas, "mini", bottom); break; }
+    case ENDER3: { render_prusa(canvas, "ender3", bottom); break; }
+    default:
+    case Custom: { render_custom(canvas, bottom); break; }
+#else
     case MK2: { render_prusa(canvas, "mk2", theta > 90.0f); break; }
     case MK3: { render_prusa(canvas, "mk3", theta > 90.0f); break; }
     case SL1: { render_prusa(canvas, "sl1", theta > 90.0f); break; }
@@ -280,6 +293,7 @@ void Bed3D::render(GLCanvas3D& canvas, float theta, float scale_factor, bool sho
     case ENDER3: { render_prusa(canvas, "ender3", theta > 90.0f); break; }
     default:
     case Custom: { render_custom(canvas, theta > 90.0f); break; }
+#endif // ENABLE_6DOF_CAMERA
     }
 
     glsafe(::glDisable(GL_DEPTH_TEST));

src/slic3r/GUI/3DBed.hpp

@@ -110,7 +110,11 @@ public:
     bool contains(const Point& point) const;
     Point point_projection(const Point& point) const;
 
+#if ENABLE_6DOF_CAMERA
+    void render(GLCanvas3D& canvas, bool bottom, float scale_factor, bool show_axes) const;
+#else
     void render(GLCanvas3D& canvas, float theta, float scale_factor, bool show_axes) const;
+#endif // ENABLE_6DOF_CAMERA
 
 private:
     void calc_bounding_boxes() const;

src/slic3r/GUI/Camera.cpp

@@ -34,18 +34,27 @@ double Camera::FrustrumZMargin = 10.0;
 double Camera::MaxFovDeg = 60.0;
 
 Camera::Camera()
+#if ENABLE_6DOF_CAMERA
+    : requires_zoom_to_bed(false)
+#else
     : phi(45.0f)
     , requires_zoom_to_bed(false)
     , inverted_phi(false)
+#endif // ENABLE_6DOF_CAMERA
     , m_type(Perspective)
     , m_target(Vec3d::Zero())
+#if !ENABLE_6DOF_CAMERA
     , m_theta(45.0f)
+#endif // !ENABLE_6DOF_CAMERA
     , m_zoom(1.0)
     , m_distance(DefaultDistance)
     , m_gui_scale(1.0)
     , m_view_matrix(Transform3d::Identity())
     , m_projection_matrix(Transform3d::Identity())
 {
+#if ENABLE_6DOF_CAMERA
+    set_default_orientation();
+#endif // ENABLE_6DOF_CAMERA
 }
 
 std::string Camera::get_type_as_string() const
@@ -91,6 +100,9 @@ void Camera::select_next_type()
 
 void Camera::set_target(const Vec3d& target)
 {
+#if ENABLE_6DOF_CAMERA
+    translate_world(target - m_target);
+#else
     BoundingBoxf3 test_box = m_scene_box;
     test_box.translate(-m_scene_box.center());
     // We may let this factor be customizable
@@ -101,8 +113,10 @@ void Camera::set_target(const Vec3d& target)
     m_target(0) = clamp(test_box.min(0), test_box.max(0), target(0));
     m_target(1) = clamp(test_box.min(1), test_box.max(1), target(1));
     m_target(2) = clamp(test_box.min(2), test_box.max(2), target(2));
+#endif // ENABLE_6DOF_CAMERA
 }
 
+#if !ENABLE_6DOF_CAMERA
 void Camera::set_theta(float theta, bool apply_limit)
 {
     if (apply_limit)
@@ -114,6 +128,7 @@ void Camera::set_theta(float theta, bool apply_limit)
             m_theta += 360.0f;
     }
 }
+#endif // !ENABLE_6DOF_CAMERA
 
 void Camera::update_zoom(double delta_zoom)
 {
@@ -130,7 +145,25 @@ void Camera::set_zoom(double zoom)
     // Don't allow to zoom too close to the scene.
     m_zoom = std::min(zoom, 100.0);
 }
-
+#if ENABLE_6DOF_CAMERA
+void Camera::select_view(const std::string& direction)
+{
+    if (direction == "iso")
+        set_default_orientation();
+    else if (direction == "left")
+        m_view_matrix = look_at(m_target - m_distance * Vec3d::UnitX(), m_target, Vec3d::UnitZ());
+    else if (direction == "right")
+        m_view_matrix = look_at(m_target + m_distance * Vec3d::UnitX(), m_target, Vec3d::UnitZ());
+    else if (direction == "top")
+        m_view_matrix = look_at(m_target + m_distance * Vec3d::UnitZ(), m_target, Vec3d::UnitY());
+    else if (direction == "bottom")
+        m_view_matrix = look_at(m_target - m_distance * Vec3d::UnitZ(), m_target, -Vec3d::UnitY());
+    else if (direction == "front")
+        m_view_matrix = look_at(m_target - m_distance * Vec3d::UnitY(), m_target, Vec3d::UnitZ());
+    else if (direction == "rear")
+        m_view_matrix = look_at(m_target + m_distance * Vec3d::UnitY(), m_target, Vec3d::UnitZ());
+}
+#else
 bool Camera::select_view(const std::string& direction)
 {
     const float* dir_vec = nullptr;
@@ -159,6 +192,7 @@ bool Camera::select_view(const std::string& direction)
     else
         return false;
 }
+#endif // ENABLE_6DOF_CAMERA
 
 double Camera::get_fov() const
 {
@@ -180,20 +214,26 @@ void Camera::apply_viewport(int x, int y, unsigned int w, unsigned int h) const
 
 void Camera::apply_view_matrix() const
 {
+#if !ENABLE_6DOF_CAMERA
     double theta_rad = Geometry::deg2rad(-(double)m_theta);
     double phi_rad = Geometry::deg2rad((double)phi);
     double sin_theta = ::sin(theta_rad);
     Vec3d camera_pos = m_target + m_distance * Vec3d(sin_theta * ::sin(phi_rad), sin_theta * ::cos(phi_rad), ::cos(theta_rad));
+#endif // !ENABLE_6DOF_CAMERA
 
     glsafe(::glMatrixMode(GL_MODELVIEW));
     glsafe(::glLoadIdentity());
 
+#if ENABLE_6DOF_CAMERA
+    glsafe(::glMultMatrixd(m_view_matrix.data()));
+#else
     glsafe(::glRotatef(-m_theta, 1.0f, 0.0f, 0.0f)); // pitch
     glsafe(::glRotatef(phi, 0.0f, 0.0f, 1.0f));      // yaw
 
     glsafe(::glTranslated(-camera_pos(0), -camera_pos(1), -camera_pos(2))); 
 
     glsafe(::glGetDoublev(GL_MODELVIEW_MATRIX, m_view_matrix.data()));
+#endif // ENABLE_6DOF_CAMERA
 }
 
 void Camera::apply_projection(const BoundingBoxf3& box, double near_z, double far_z) const
@@ -300,7 +340,11 @@ void Camera::zoom_to_box(const BoundingBoxf3& box, int canvas_w, int canvas_h)
     {
         m_zoom = zoom;
         // center view around box center
+#if ENABLE_6DOF_CAMERA
+        set_target(box.center());
+#else
         m_target = box.center();
+#endif // ENABLE_6DOF_CAMERA
     }
 }
 
@@ -313,7 +357,11 @@ void Camera::zoom_to_volumes(const GLVolumePtrs& volumes, int canvas_w, int canv
     {
         m_zoom = zoom;
         // center view around the calculated center
+#if ENABLE_6DOF_CAMERA
+        set_target(center);
+#else
         m_target = center;
+#endif // ENABLE_6DOF_CAMERA
     }
 }
 #endif // ENABLE_THUMBNAIL_GENERATOR
@@ -360,6 +408,43 @@ void Camera::debug_render() const
 }
 #endif // ENABLE_CAMERA_STATISTICS
 
+#if ENABLE_6DOF_CAMERA
+void Camera::translate_world(const Vec3d& displacement)
+{
+    Vec3d new_target = validate_target(m_target + displacement);
+    Vec3d new_displacement = new_target - m_target;
+    if (!new_displacement.isApprox(Vec3d::Zero()))
+    {
+        m_target += new_displacement;
+        m_view_matrix.translate(-new_displacement);
+    }
+}
+
+void Camera::rotate_on_sphere(double delta_azimut_rad, double delta_zenit_rad, bool apply_limit)
+{
+    Vec3d target = m_target;
+    translate_world(-target);
+    m_view_matrix.rotate(Eigen::AngleAxisd(delta_zenit_rad, get_dir_right()));
+    m_view_matrix.rotate(Eigen::AngleAxisd(delta_azimut_rad, Vec3d::UnitZ()));
+    translate_world(target);
+}
+
+void Camera::rotate_local_around_target(const Vec3d& rotation_rad)
+{
+    Vec3d target = m_target;
+    translate_world(-target);
+    m_view_matrix.rotate(Eigen::AngleAxisd(rotation_rad(0), get_dir_right()));
+    m_view_matrix.rotate(Eigen::AngleAxisd(rotation_rad(1), get_dir_up()));
+    m_view_matrix.rotate(Eigen::AngleAxisd(rotation_rad(2), get_dir_forward()));
+    translate_world(target);
+}
+
+bool Camera::is_looking_downward() const
+{
+    return get_dir_forward().dot(Vec3d::UnitZ()) < 0.0;
+}
+#endif // ENABLE_6DOF_CAMERA
+
 std::pair<double, double> Camera::calc_tight_frustrum_zs_around(const BoundingBoxf3& box) const
 {
     std::pair<double, double> ret;
@@ -540,6 +625,63 @@ void Camera::set_distance(double distance) const
     apply_view_matrix();
 }
 
+#if ENABLE_6DOF_CAMERA
+Transform3d Camera::look_at(const Vec3d& position, const Vec3d& target, const Vec3d& up) const
+{
+    Vec3d unit_z = (position - target).normalized();
+    Vec3d unit_x = up.cross(unit_z).normalized();
+    Vec3d unit_y = unit_z.cross(unit_x).normalized();
+
+    Transform3d matrix;
+
+    matrix(0, 0) = unit_x(0);
+    matrix(0, 1) = unit_x(1);
+    matrix(0, 2) = unit_x(2);
+    matrix(0, 3) = -unit_x.dot(position);
+
+    matrix(1, 0) = unit_y(0);
+    matrix(1, 1) = unit_y(1);
+    matrix(1, 2) = unit_y(2);
+    matrix(1, 3) = -unit_y.dot(position);
+
+    matrix(2, 0) = unit_z(0);
+    matrix(2, 1) = unit_z(1);
+    matrix(2, 2) = unit_z(2);
+    matrix(2, 3) = -unit_z.dot(position);
+
+    matrix(3, 0) = 0.0;
+    matrix(3, 1) = 0.0;
+    matrix(3, 2) = 0.0;
+    matrix(3, 3) = 1.0;
+
+    return matrix;
+}
+
+void Camera::set_default_orientation()
+{
+    double theta_rad = Geometry::deg2rad(-45.0);
+    double phi_rad = Geometry::deg2rad(45.0);
+    double sin_theta = ::sin(theta_rad);
+    Vec3d camera_pos = m_target + m_distance * Vec3d(sin_theta * ::sin(phi_rad), sin_theta * ::cos(phi_rad), ::cos(theta_rad));
+    m_view_matrix = Transform3d::Identity();
+    m_view_matrix.rotate(Eigen::AngleAxisd(theta_rad, Vec3d::UnitX())).rotate(Eigen::AngleAxisd(phi_rad, Vec3d::UnitZ())).translate(-camera_pos);
+}
+
+Vec3d Camera::validate_target(const Vec3d& target) const
+{
+    BoundingBoxf3 test_box = m_scene_box;
+    test_box.translate(-m_scene_box.center());
+    // We may let this factor be customizable
+    static const double ScaleFactor = 1.5;
+    test_box.scale(ScaleFactor);
+    test_box.translate(m_scene_box.center());
+
+    return Vec3d(std::clamp(target(0), test_box.min(0), test_box.max(0)),
+        std::clamp(target(1), test_box.min(1), test_box.max(1)),
+        std::clamp(target(2), test_box.min(2), test_box.max(2)));
+}
+#endif // ENABLE_6DOF_CAMERA
+
 } // GUI
 } // Slic3r
 

src/slic3r/GUI/Camera.hpp

@@ -30,21 +30,29 @@ struct Camera
         Num_types
     };
 
+#if !ENABLE_6DOF_CAMERA
     float phi;
-    bool requires_zoom_to_bed;
     bool inverted_phi;
+#endif // !ENABLE_6DOF_CAMERA
+    bool requires_zoom_to_bed;
 
 private:
     EType m_type;
     Vec3d m_target;
+#if !ENABLE_6DOF_CAMERA
     float m_theta;
+#endif // !ENABLE_6DOF_CAMERA
     double m_zoom;
     // Distance between camera position and camera target measured along the camera Z axis
     mutable double m_distance;
     mutable double m_gui_scale;
 
     mutable std::array<int, 4> m_viewport;
+#if ENABLE_6DOF_CAMERA
+    Transform3d m_view_matrix;
+#else
     mutable Transform3d m_view_matrix;
+#endif // ENABLE_6DOF_CAMERA
     mutable Transform3d m_projection_matrix;
     mutable std::pair<double, double> m_frustrum_zs;
 
@@ -66,8 +74,10 @@ public:
     double get_distance() const { return m_distance; }
     double get_gui_scale() const { return m_gui_scale; }
 
+#if !ENABLE_6DOF_CAMERA
     float get_theta() const { return m_theta; }
     void set_theta(float theta, bool apply_limit);
+#endif // !ENABLE_6DOF_CAMERA
 
     double get_zoom() const { return m_zoom; }
     void update_zoom(double delta_zoom);
@@ -76,7 +86,11 @@ public:
     const BoundingBoxf3& get_scene_box() const { return m_scene_box; }
     void set_scene_box(const BoundingBoxf3& box) { m_scene_box = box; }
 
+#if ENABLE_6DOF_CAMERA
+    void select_view(const std::string& direction);
+#else
     bool select_view(const std::string& direction);
+#endif // ENABLE_6DOF_CAMERA
 
     const std::array<int, 4>& get_viewport() const { return m_viewport; }
     const Transform3d& get_view_matrix() const { return m_view_matrix; }
@@ -110,6 +124,21 @@ public:
     void debug_render() const;
 #endif // ENABLE_CAMERA_STATISTICS
 
+#if ENABLE_6DOF_CAMERA
+    // translate the camera in world space
+    void translate_world(const Vec3d& displacement);
+
+    // rotate the camera on a sphere having center == m_target and radius == m_distance
+    // using the given variations of spherical coordinates
+    void rotate_on_sphere(double delta_azimut_rad, double delta_zenit_rad, bool apply_limit);
+
+    // rotate the camera around three axes parallel to the camera local axes and passing through m_target
+    void rotate_local_around_target(const Vec3d& rotation_rad);
+
+    // returns true if the camera z axis (forward) is pointing in the negative direction of the world z axis
+    bool is_looking_downward() const;
+#endif // ENABLE_6DOF_CAMERA
+
 private:
     // returns tight values for nearZ and farZ plane around the given bounding box
     // the camera MUST be outside of the bounding box in eye coordinate of the given box
@@ -121,6 +150,12 @@ private:
     double calc_zoom_to_bounding_box_factor(const BoundingBoxf3& box, int canvas_w, int canvas_h) const;
 #endif // ENABLE_THUMBNAIL_GENERATOR
     void set_distance(double distance) const;
+
+#if ENABLE_6DOF_CAMERA
+    Transform3d look_at(const Vec3d& position, const Vec3d& target, const Vec3d& up) const;
+    void set_default_orientation();
+    Vec3d validate_target(const Vec3d& target) const;
+#endif // ENABLE_6DOF_CAMERA
 };
 
 } // GUI

src/slic3r/GUI/GLCanvas3D.cpp

@@ -1792,8 +1792,14 @@ void GLCanvas3D::zoom_to_selection()
 
 void GLCanvas3D::select_view(const std::string& direction)
 {
+#if ENABLE_6DOF_CAMERA
+    m_camera.select_view(direction);
+    if (m_canvas != nullptr)
+        m_canvas->Refresh();
+#else
     if (m_camera.select_view(direction) && (m_canvas != nullptr))
         m_canvas->Refresh();
+#endif // ENABLE_6DOF_CAMERA
 }
 
 void GLCanvas3D::update_volumes_colors_by_extruder()
@@ -1850,10 +1856,12 @@ void GLCanvas3D::render()
     GLfloat position_top[4] = { -0.5f, -0.5f, 1.0f, 0.0f };
     glsafe(::glLightfv(GL_LIGHT0, GL_POSITION, position_top));
 
+#if !ENABLE_6DOF_CAMERA
     float theta = m_camera.get_theta();
     if (theta > 180.f)
         // absolute value of the rotation
         theta = 360.f - theta;
+#endif // !ENABLE_6DOF_CAMERA
 
     wxGetApp().imgui()->new_frame();
 
@@ -1878,7 +1886,11 @@ void GLCanvas3D::render()
     _render_objects();
     _render_sla_slices();
     _render_selection();
+#if ENABLE_6DOF_CAMERA
+    _render_bed(!m_camera.is_looking_downward(), true);
+#else
     _render_bed(theta, true);
+#endif // ENABLE_6DOF_CAMERA
 
 #if ENABLE_RENDER_SELECTION_CENTER
     _render_selection_center();
@@ -3213,7 +3225,11 @@ void GLCanvas3D::on_mouse(wxMouseEvent& evt)
             // we do not want to translate objects if the user just clicked on an object while pressing shift to remove it from the selection and then drag
             if (m_selection.contains_volume(get_first_hover_volume_idx()))
             {
+#if ENABLE_6DOF_CAMERA
+                if (std::abs(m_camera.get_dir_forward()(2)) < EPSILON)
+#else
                 if (m_camera.get_theta() == 90.0f)
+#endif // ENABLE_6DOF_CAMERA
                 {
                     // side view -> move selected volumes orthogonally to camera view direction
                     Linef3 ray = mouse_ray(pos);
@@ -3273,9 +3289,15 @@ void GLCanvas3D::on_mouse(wxMouseEvent& evt)
             if (m_hover_volume_idxs.empty() && m_mouse.is_start_position_3D_defined())
             {
                 const Vec3d& orig = m_mouse.drag.start_position_3D;
+#if ENABLE_6DOF_CAMERA
+                m_camera.rotate_on_sphere(Geometry::deg2rad((pos(0) - orig(0))* (double)TRACKBALLSIZE),
+                    Geometry::deg2rad((pos(1) - orig(1))* (double)TRACKBALLSIZE),
+                    wxGetApp().preset_bundle->printers.get_edited_preset().printer_technology() != ptSLA);
+#else
                 float sign = m_camera.inverted_phi ? -1.0f : 1.0f;
                 m_camera.phi += sign * ((float)pos(0) - (float)orig(0)) * TRACKBALLSIZE;
                 m_camera.set_theta(m_camera.get_theta() - ((float)pos(1) - (float)orig(1)) * TRACKBALLSIZE, wxGetApp().preset_bundle->printers.get_edited_preset().printer_technology() != ptSLA);
+#endif // ENABLE_6DOF_CAMERA
                 m_dirty = true;
             }
             m_mouse.drag.start_position_3D = Vec3d((double)pos(0), (double)pos(1), 0.0);
@@ -3325,9 +3347,11 @@ void GLCanvas3D::on_mouse(wxMouseEvent& evt)
             if (!evt.ShiftDown() && m_picking_enabled)
                 deselect_all();
         }
+#if !ENABLE_6DOF_CAMERA
         else if (evt.LeftUp() && m_mouse.dragging)
             // Flips X mouse deltas if bed is upside down
             m_camera.inverted_phi = (m_camera.get_dir_up()(2) < 0.0);
+#endif // !ENABLE_6DOF_CAMERA
         else if (evt.RightUp())
         {
             m_mouse.position = pos.cast<double>();
@@ -3932,6 +3956,9 @@ void GLCanvas3D::_render_thumbnail_internal(ThumbnailData& thumbnail_data, bool
 
     Camera camera;
     camera.set_type(Camera::Ortho);
+#if ENABLE_6DOF_CAMERA
+    camera.set_scene_box(scene_bounding_box());
+#endif // ENABLE_6DOF_CAMERA
     camera.zoom_to_volumes(visible_volumes, thumbnail_data.width, thumbnail_data.height);
     camera.apply_viewport(0, 0, thumbnail_data.width, thumbnail_data.height);
     camera.apply_view_matrix();
@@ -3982,7 +4009,11 @@ void GLCanvas3D::_render_thumbnail_internal(ThumbnailData& thumbnail_data, bool
     glsafe(::glDisable(GL_DEPTH_TEST));
 
     if (show_bed)
+#if ENABLE_6DOF_CAMERA
+        _render_bed(!camera.is_looking_downward(), false);
+#else
         _render_bed(camera.get_theta(), false);
+#endif // ENABLE_6DOF_CAMERA
 
     if (transparent_background)
         glsafe(::glClearColor(1.0f, 1.0f, 1.0f, 1.0f));

src/slic3r/GUI/Mouse3DController.cpp

@@ -168,12 +168,17 @@ bool Mouse3DController::State::apply(Camera& camera)
 
     if (has_rotation())
     {
+#if ENABLE_6DOF_CAMERA
+        Vec3d rotation = (m_rotation_params.scale * m_rotation.queue.front()).cast<double>();
+        camera.rotate_local_around_target(Vec3d(Geometry::deg2rad(rotation(0)), Geometry::deg2rad(-rotation(2)), Geometry::deg2rad(-rotation(1))));
+#else
         const Vec3f& rotation = m_rotation.queue.front();
         float theta = m_rotation_params.scale * rotation(0);
         float phi = m_rotation_params.scale * rotation(2);
         float sign = camera.inverted_phi ? -1.0f : 1.0f;
         camera.phi += sign * phi;
         camera.set_theta(camera.get_theta() + theta, wxGetApp().preset_bundle->printers.get_edited_preset().printer_technology() != ptSLA);
+#endif // ENABLE_6DOF_CAMERA
         m_rotation.queue.pop();
         ret = true;
     }
@@ -877,9 +882,15 @@ bool Mouse3DController::handle_packet_translation(const DataPacket& packet)
 bool Mouse3DController::handle_packet_rotation(const DataPacket& packet, unsigned int first_byte)
 {
     double deadzone = (double)m_state.get_rotation_deadzone();
+#if ENABLE_6DOF_CAMERA
+    Vec3f rotation((float)convert_input(packet[first_byte + 0], packet[first_byte + 1], deadzone),
+        (float)convert_input(packet[first_byte + 2], packet[first_byte + 3], deadzone),
+        (float)convert_input(packet[first_byte + 4], packet[first_byte + 5], deadzone));
+#else
     Vec3f rotation(-(float)convert_input(packet[first_byte + 0], packet[first_byte + 1], deadzone),
         (float)convert_input(packet[first_byte + 2], packet[first_byte + 3], deadzone),
         -(float)convert_input(packet[first_byte + 4], packet[first_byte + 5], deadzone));
+#endif // ENABLE_6DOF_CAMERA
 
     if (!rotation.isApprox(Vec3f::Zero()))
     {

src/slic3r/GUI/Selection.cpp

@@ -2004,7 +2004,11 @@ void Selection::render_sidebar_layers_hints(const std::string& sidebar_field) co
     const float max_y = box.max(1) + Margin;
 
     // view dependend order of rendering to keep correct transparency
+#if ENABLE_6DOF_CAMERA
+    bool camera_on_top = wxGetApp().plater()->get_camera().is_looking_downward();
+#else
     bool camera_on_top = wxGetApp().plater()->get_camera().get_theta() <= 90.0f;
+#endif // ENABLE_6DOF_CAMERA
     float z1 = camera_on_top ? min_z : max_z;
     float z2 = camera_on_top ? max_z : min_z;