Emboss text along base line(object cut)

- need alignment of text(center, left, right)
- (NOTE) edit text change its position
+ add polygon point

src/libslic3r/Emboss.cpp

@@ -1321,15 +1321,31 @@ std::vector<ExPolygons> Emboss::text2vshapes(FontFileWithCache &font_with_cache,
     return result;
 }
 
+#include <boost/range/adaptor/reversed.hpp>
 unsigned Emboss::get_count_lines(const std::wstring& ws)
 {
     if (ws.empty())
         return 0;
+    unsigned prev_count = 0;
+    for (wchar_t wc : ws)
+        if (wc == '\n')
+            ++prev_count;
+        else
+            break;
+    
+    unsigned post_count = 0;
+    for (wchar_t wc : boost::adaptors::reverse(ws))
+        if (wc == '\n')
+            ++post_count;
+        else
+            break;
+
     unsigned count = 1;
     for (wchar_t wc : ws)
         if (wc == '\n')
             ++count;
-    return count;
+
+    return count - prev_count - post_count;
 }
 
 unsigned Emboss::get_count_lines(const std::string &text)
@@ -1730,6 +1746,178 @@ std::optional<Vec2d> Emboss::OrthoProject::unproject(const Vec3d &p, double *dep
     return Vec2d(pp.x(), pp.y());
 }
 
+// sample slice
+namespace {
+
+// using coor2 = int64_t;
+using Coord2 = double;
+using P2     = Eigen::Matrix<Coord2, 2, 1, Eigen::DontAlign>;
+
+bool point_in_distance(const Coord2 &distance_sq, PolygonPoint &polygon_point, const size_t &i, const Slic3r::Polygon &polygon, bool is_first, bool is_reverse = false)
+{
+    size_t s  = polygon.size();
+    size_t ii = (i + polygon_point.index) % s;
+
+    // second point of line
+    const Point &p = polygon[ii];
+    Point p_d = p - polygon_point.point;
+
+    P2 p_d2 = p_d.cast<Coord2>();
+    Coord2 p_distance_sq = p_d2.squaredNorm();
+    if (p_distance_sq < distance_sq)
+        return false;
+
+    // found line
+    if (is_first) {
+        // on same line
+        // center also lay on line
+        // new point is distance moved from point by direction
+        polygon_point.point += p_d * sqrt(distance_sq / p_distance_sq);
+        return true;
+    }
+
+    // line cross circle
+
+    // start point of line
+    size_t ii2          = (is_reverse) ? (ii + 1) % s : (ii + s - 1) % s;
+    polygon_point.index = (is_reverse) ? ii : ii2;
+    const Point &p2 = polygon[ii2];
+
+    Point line_dir  = p2 - p;
+    P2    line_dir2 = line_dir.cast<Coord2>();
+
+    Coord2 a = line_dir2.dot(line_dir2);
+    Coord2 b = 2 * p_d2.dot(line_dir2);
+    Coord2 c = p_d2.dot(p_d2) - distance_sq;
+
+    double discriminant = b * b - 4 * a * c;
+    if (discriminant < 0) {
+        assert(false);
+        // no intersection
+        polygon_point.point = p;
+        return true;
+    }
+
+    // ray didn't totally miss sphere,
+    // so there is a solution to
+    // the equation.
+    discriminant = sqrt(discriminant);
+
+    // either solution may be on or off the ray so need to test both
+    // t1 is always the smaller value, because BOTH discriminant and
+    // a are nonnegative.
+    double t1 = (-b - discriminant) / (2 * a);
+    double t2 = (-b + discriminant) / (2 * a);
+
+    double t = std::min(t1, t2);
+    if (t < 0. || t > 1.) {
+        // Bad intersection
+        assert(false);
+        polygon_point.point = p;
+        return true;
+    }
+
+    polygon_point.point = p + (t * line_dir2).cast<Point::coord_type>();
+    return true;
+}
+
+void point_in_distance(int32_t distance, PolygonPoint &p, const Slic3r::Polygon &polygon)
+{
+    Coord2 distance_sq = static_cast<Coord2>(distance) * distance;
+    bool is_first = true;
+    for (size_t i = 1; i < polygon.size(); ++i) {
+        if (point_in_distance(distance_sq, p, i, polygon, is_first))
+            return;
+        is_first = false;
+    }
+    // There is not point on polygon with this distance
+}
+
+void point_in_reverse_distance(int32_t distance, PolygonPoint &p, const Slic3r::Polygon &polygon)
+{
+    Coord2 distance_sq = static_cast<Coord2>(distance) * distance;
+    bool is_first = true;
+    bool is_reverse = true;
+    for (size_t i = polygon.size(); i > 0; --i) {
+        if (point_in_distance(distance_sq, p, i, polygon, is_first, is_reverse))
+            return;
+        is_first = false;
+    }
+    // There is not point on polygon with this distance
+}
+} // namespace
+
+// calculate rotation, need copy of polygon point
+double Emboss::calculate_angle(int32_t distance, PolygonPoint polygon_point, const Polygon &polygon)
+{
+    PolygonPoint polygon_point2 = polygon_point; // copy
+    point_in_distance(distance, polygon_point, polygon);
+    point_in_reverse_distance(distance, polygon_point2, polygon);
+
+    Point surface_dir = polygon_point2.point - polygon_point.point;
+    Point norm(-surface_dir.y(), surface_dir.x());
+    Vec2d norm_d = norm.cast<double>();
+    //norm_d.normalize();
+    return std::atan2(norm_d.y(), norm_d.x());
+}
+
+std::vector<double> Emboss::calculate_angles(int32_t distance, const PolygonPoints& polygon_points, const Polygon &polygon)
+{
+    std::vector<double> result;
+    result.reserve(polygon_points.size());
+    for(const PolygonPoint& pp: polygon_points)
+        result.emplace_back(calculate_angle(distance, pp, polygon));
+    return result;
+}
+
+PolygonPoints Emboss::sample_slice(const TextLine &slice, const BoundingBoxes &bbs, int32_t center_x, double scale)
+{
+    // find BB in center of line
+    size_t first_right_index = 0;
+    for (const BoundingBox &bb : bbs)
+        if (bb.min.x() > center_x) {
+            break;
+        } else {
+            ++first_right_index;
+        }
+
+    PolygonPoints samples(bbs.size());
+    int32_t shapes_x_cursor = center_x;
+
+    PolygonPoint cursor = slice.start; //copy
+
+    auto create_sample = [&] //polygon_cursor, &polygon_line_index, &line_bbs, &shapes_x_cursor, &shape_scale, &em_2_polygon, &line, &offsets]
+    (const BoundingBox &bb, bool is_reverse) {
+        if (!bb.defined)
+            return cursor;
+        Point   letter_center  = bb.center();
+        int32_t shape_distance = shapes_x_cursor - letter_center.x();
+        shapes_x_cursor        = letter_center.x();
+        double  distance_mm    = shape_distance * scale;
+        int32_t distance_polygon = static_cast<int32_t>(std::round(scale_(distance_mm)));
+        if (is_reverse)
+            point_in_distance(distance_polygon, cursor, slice.polygon);
+        else
+            point_in_reverse_distance(distance_polygon, cursor, slice.polygon);
+        return cursor;
+    };
+
+    // calc transformation for letters on the Right side from center
+    bool is_reverse = true;
+    for (size_t index = first_right_index; index < bbs.size(); ++index)
+        samples[index] = create_sample(bbs[index], is_reverse);
+
+    // calc transformation for letters on the Left side from center
+    shapes_x_cursor = center_x;
+    cursor = slice.start; // copy    
+    is_reverse = false;
+    for (size_t index_plus_one = first_right_index; index_plus_one > 0; --index_plus_one) {
+        size_t index = index_plus_one - 1;
+        samples[index] = create_sample(bbs[index], is_reverse);
+    }
+    return samples;
+}
+
 #ifdef REMOVE_SPIKES
 #include <Geometry.hpp>
 void priv::remove_spikes(Polygon &polygon, const SpikeDesc &spike_desc)

src/libslic3r/Emboss.hpp

@@ -8,6 +8,7 @@
 #include <admesh/stl.h> // indexed_triangle_set
 #include "Polygon.hpp"
 #include "ExPolygon.hpp"
+#include "BoundingBox.hpp"
 #include "TextConfiguration.hpp"
 
 namespace Slic3r {
@@ -403,7 +404,44 @@ namespace Emboss
         Vec3d project(const Vec3d &point) const override;
         std::optional<Vec2d> unproject(const Vec3d &p, double * depth = nullptr) const override;     
     };
-} // namespace Emboss
 
+    /// <summary>
+    /// Define polygon for draw letters
+    /// </summary>
+    struct TextLine
+    {
+        // slice of object
+        Polygon polygon;
+
+        // point laying on polygon closest to zero
+        PolygonPoint start;
+
+        // offset of text line in volume mm
+        float y;
+    };
+    using TextLines = std::vector<TextLine>;
+
+    /// <summary>
+    /// Sample slice polygon by bounding boxes centers
+    /// slice start point has shape_center_x coor
+    /// </summary>
+    /// <param name="slice">Polygon and start point</param>
+    /// <param name="bbs">Bounding boxes of letter on one line</param>
+    /// <param name="center_x">Center x coor of bbs line</param>
+    /// <param name="scale">Scale for bbs</param>
+    /// <returns>Sampled polygon by bounding boxes</returns>
+    PolygonPoints sample_slice(const TextLine &slice, const BoundingBoxes &bbs, int32_t center_x, double scale);
+
+    /// <summary>
+    /// Calculate angle for polygon point
+    /// </summary>
+    /// <param name="distance">Distance for found normal in point</param>
+    /// <param name="polygon_point">Select point on polygon</param>
+    /// <param name="polygon">Polygon know neighbor of point</param>
+    /// <returns>angle(atan2) of normal in polygon point</returns>
+    double calculate_angle(int32_t distance, PolygonPoint polygon_point, const Polygon &polygon);
+    std::vector<double> calculate_angles(int32_t distance, const PolygonPoints& polygon_points, const Polygon &polygon);
+
+} // namespace Emboss
 } // namespace Slic3r
 #endif // slic3r_Emboss_hpp_

src/libslic3r/Polygon.hpp

@@ -266,6 +266,21 @@ bool polygons_match(const Polygon &l, const Polygon &r);
 Polygon make_circle(double radius, double error);
 Polygon make_circle_num_segments(double radius, size_t num_segments);
 
+/// <summary>
+/// Define point laying on polygon
+/// keep index of polygon line and point coordinate
+/// </summary>
+struct PolygonPoint
+{
+    // index of line inside of polygon
+    // 0 .. from point polygon[0] to polygon[1]
+    size_t index;
+
+    // Point, which lay on line defined by index
+    Point point;
+};
+using PolygonPoints = std::vector<PolygonPoint>;
+
 } // Slic3r
 
 // start Boost

src/slic3r/GUI/Gizmos/GLGizmoEmboss.cpp

@@ -403,6 +403,8 @@ bool GLGizmoEmboss::on_mouse_for_rotation(const wxMouseEvent &mouse_event)
                 angle_opt = angle;
             m_style_manager.get_font_prop().angle = angle_opt;
         }
+
+        volume_transformation_changing();
     }
     return used;
 }
@@ -421,14 +423,8 @@ bool GLGizmoEmboss::on_mouse_for_translate(const wxMouseEvent &mouse_event)
     bool is_dragging = m_surface_drag.has_value();
 
     // End with surface dragging?
-    if (was_dragging && !is_dragging) {
+    if (was_dragging && !is_dragging) 
-        // Update surface by new position
+        volume_transformation_changed();
-        if (m_volume->text_configuration->style.prop.use_surface)
-            process();
-
-        // Show correct value of height & depth inside of inputs
-        calculate_scale();
-    }
     
     // Start with dragging
     else if (!was_dragging && is_dragging) {
@@ -452,6 +448,8 @@ bool GLGizmoEmboss::on_mouse_for_translate(const wxMouseEvent &mouse_event)
 
             m_style_manager.get_style().prop.angle = calc_up(gl_volume->world_matrix(), priv::up_limit);
         }
+
+        volume_transformation_changing();
     }
     return res;
 }
@@ -552,6 +550,36 @@ bool GLGizmoEmboss::on_mouse(const wxMouseEvent &mouse_event)
     return false;
 }
 
+void GLGizmoEmboss::volume_transformation_changing()
+{
+    if (m_volume == nullptr || !m_volume->text_configuration.has_value()) {
+        assert(false);
+        return;
+    }
+    const FontProp &prop = m_volume->text_configuration->style.prop;
+    if (prop.per_glyph)
+        init_text_lines();
+}
+
+void GLGizmoEmboss::volume_transformation_changed()
+{
+    if (m_volume == nullptr || !m_volume->text_configuration.has_value()) {
+        assert(false);
+        return;
+    }
+
+    const FontProp &prop = m_volume->text_configuration->style.prop;
+    if (prop.per_glyph)
+        init_text_lines();
+
+    // Update surface by new position
+    if (prop.use_surface || prop.per_glyph)
+        process();
+
+    // Show correct value of height & depth inside of inputs
+    calculate_scale();
+}
+
 bool GLGizmoEmboss::on_init()
 {
     m_rotate_gizmo.init();
@@ -848,9 +876,7 @@ void GLGizmoEmboss::on_stop_dragging()
 
     m_rotate_start_angle.reset();
 
-    // recalculate for surface cut
+    volume_transformation_changed();
-    const FontProp &font_prop = m_style_manager.get_style().prop;
-    if (font_prop.use_surface) process();
 }
 void GLGizmoEmboss::on_dragging(const UpdateData &data) { m_rotate_gizmo.dragging(data); }
 
@@ -1263,7 +1289,11 @@ bool GLGizmoEmboss::process()
     if (!m_style_manager.is_active_font()) return false;
     
     DataUpdate data{priv::create_emboss_data_base(m_text, m_style_manager, m_job_cancel), m_volume->id()};
-
+    if (data.text_configuration.style.prop.per_glyph){
+        if (!m_text_lines.is_init())
+            init_text_lines();
+        data.text_lines = m_text_lines.get_lines(); // copy
+    }
     std::unique_ptr<Job> job = nullptr;
 
     // check cutting from source mesh

src/slic3r/GUI/Gizmos/GLGizmoEmboss.hpp

@@ -82,6 +82,9 @@ protected:
     std::string get_gizmo_leaving_text() const override { return _u8L("Leave emboss gizmo"); }
     std::string get_action_snapshot_name() const override { return _u8L("Embossing actions"); }
 private:
+    void volume_transformation_changing();
+    void volume_transformation_changed();
+
     static EmbossStyles create_default_styles();
     // localized default text
     bool init_create(ModelVolumeType volume_type);

src/slic3r/GUI/Jobs/EmbossJob.cpp

@@ -1,6 +1,7 @@
 #include "EmbossJob.hpp"
 
 #include <stdexcept>
+#include <type_traits>
 
 #include <libslic3r/Model.hpp>
 #include <libslic3r/Format/OBJ.hpp> // load_obj for default mesh
@@ -247,8 +248,8 @@ void UpdateJob::process(Ctl &ctl)
         throw priv::JobException("Created text volume is empty. Change text or font.");
 
     // center triangle mesh
-    Vec3d shift = m_result.bounding_box().center();
+    //Vec3d shift = m_result.bounding_box().center();
-    m_result.translate(-shift.cast<float>());    
+    //m_result.translate(-shift.cast<float>());    
 }
 
 void UpdateJob::finalize(bool canceled, std::exception_ptr &eptr)
@@ -286,6 +287,8 @@ SurfaceVolumeData::ModelSources create_volume_sources(const ModelVolume *text_vo
     return create_sources(volumes, text_volume->id().id);
 }
 
+
+
 } // namespace Slic3r::GUI::Emboss
 
 /////////////////
@@ -360,6 +363,8 @@ bool priv::check(const DataBase &input, bool check_fontfile, bool use_surface)
     res &= !input.volume_name.empty();
     assert(input.text_configuration.style.prop.use_surface == use_surface);
     res &= input.text_configuration.style.prop.use_surface == use_surface;
+    assert(input.text_configuration.style.prop.per_glyph == !input.text_lines.empty());
+    res &= input.text_configuration.style.prop.per_glyph == !input.text_lines.empty();
     return res; 
 }
 bool priv::check(const DataCreateVolume &input, bool is_main_thread) {
@@ -425,10 +430,16 @@ ExPolygons priv::create_shape(DataBase &input, Fnc was_canceled) {
     return text2shapes(font, text, prop, was_canceled);
 }
 
-template<typename Fnc>
+#define STORE_SAMPLING
-TriangleMesh priv::try_create_mesh(DataBase &input, Fnc was_canceled)
+#ifdef STORE_SAMPLING
+#include "libslic3r/SVG.hpp"
+#endif // STORE_SAMPLING
+namespace {
+template<typename Fnc> TriangleMesh create_mesh_per_glyph(DataBase &input, Fnc was_canceled)
 {
-    if (!input.text_lines.empty()){
+    // method use square of coord stored into int64_t
+    static_assert(std::is_same<Point::coord_type, int32_t>());
+
     FontFileWithCache       &font = input.font_file;
     const TextConfiguration &tc   = input.text_configuration;
     assert(get_count_lines(tc.text) == input.text_lines.size());
@@ -441,10 +452,13 @@ TriangleMesh priv::try_create_mesh(DataBase &input, Fnc was_canceled)
     if (shapes.empty())
         return {};
 
+    const FontFile &ff          = *font.font_file;
+    double          shape_scale = get_shape_scale(prop, ff);
+
     BoundingBox extents; // whole text to find center
     // separate lines of text to vector
     std::vector<BoundingBoxes> bbs(count_lines);
-        size_t line_index = 0;
+    size_t                     text_line_index = 0;
     // s_i .. shape index
     for (size_t s_i = 0; s_i < shapes.size(); ++s_i) {
         const ExPolygons &shape = shapes[s_i];
@@ -453,61 +467,98 @@ TriangleMesh priv::try_create_mesh(DataBase &input, Fnc was_canceled)
             bb = get_extents(shape);
             extents.merge(bb);
         }
-            BoundingBoxes &line_bbs = bbs[line_index];
+        BoundingBoxes &line_bbs = bbs[text_line_index];
         line_bbs.push_back(bb);
         if (ws[s_i] == '\n')
-                ++line_index;
+            ++text_line_index;
     }
 
+    double projec_scale = shape_scale / SHAPE_SCALE;
+    double depth        = prop.emboss / projec_scale;
+    auto   projectZ = std::make_unique<ProjectZ>(depth);
+    auto   scale_tr = Eigen::Scaling(projec_scale); 
+    
+    // half of font em size for direction of letter emboss
+    double  em_2_mm      = prop.size_in_mm / 2.;
+    int32_t em_2_polygon = static_cast<int32_t>(std::round(scale_(em_2_mm)));
+
     Point  center     = extents.center();
     size_t s_i_offset = 0; // shape index offset(for next lines)
-        for (line_index = 0; line_index < input.text_lines.size(); ++line_index) {
+    indexed_triangle_set result;
-            const BoundingBoxes &line_bbs = bbs[line_index];
+    for (text_line_index = 0; text_line_index < input.text_lines.size(); ++text_line_index) {
-            // find BB in center of line
+        const BoundingBoxes &line_bbs = bbs[text_line_index];
-            size_t first_right_index = 0;
+        const TextLine      &line     = input.text_lines[text_line_index];
-            for (const BoundingBox &bb : line_bbs)
+        // IMPROVE: do not precalculate samples do it inline - store result its
-                if (bb.min.x() > center.x()) {
+        PolygonPoints        samples  = sample_slice(line, line_bbs, center.x(), shape_scale);
-                    break;
+        std::vector<double>  angles   = calculate_angles(em_2_polygon, samples, line.polygon);
-                } else {
-                    ++first_right_index;
-                }
 
-            // calc transformation for letters on the Right side from center            
+        for (size_t i = 0; i < line_bbs.size(); ++i) {
-            for (size_t index = first_right_index; index != line_bbs.size(); ++index) {
+            const BoundingBox &line_bb = line_bbs[i];
-                const BoundingBox &bb = line_bbs[index];
+            if (!line_bb.defined)
-                Point letter_center = bb.center();
+                continue;
 
+            Vec2d to_zero_vec = line_bb.center().cast<double>() * shape_scale; // [in mm]
+            auto  to_zero     = Eigen::Translation<double, 3>(-to_zero_vec.x(), 0., 0.);
 
-                const ExPolygons &letter_shape = shapes[s_i_offset + index];
+            const double &angle = angles[i];
-            }
+            auto rotate = Eigen::AngleAxisd(angle + M_PI_2, Vec3d::UnitY());
 
-            // calc transformation for letters on the Left side from center            
+            const PolygonPoint &sample = samples[i];
-            for (size_t index = first_right_index; index < line_bbs.size(); --index) {
+            Vec2d offset_vec = unscale(sample.point); // [in mm]
+            auto offset_tr = Eigen::Translation<double, 3>(offset_vec.x(), 0., -offset_vec.y());
 
-            }
+            //Transform3d tr = offset_tr * rotate * to_zero * scale_tr;
+            Transform3d tr = offset_tr * rotate * to_zero * scale_tr;
+            //Transform3d tr = Transform3d::Identity() * scale_tr;
+            const ExPolygons &letter_shape = shapes[s_i_offset + i];
             
-            size_t s_i = s_i_offset; // shape index
-
-            s_i_offset += line_bbs.size();
-        }
-        
-        // create per letter transformation
-        const FontFile &ff = *input.font_file.font_file;
-        // NOTE: SHAPE_SCALE is applied in ProjectZ
-        double scale = get_shape_scale(prop, ff) / SHAPE_SCALE;
-        double depth = prop.emboss / scale;    
             auto projectZ = std::make_unique<ProjectZ>(depth);
-        auto scale_tr = Eigen::Scaling(scale);
+            ProjectTransform project(std::move(projectZ), tr);
+            indexed_triangle_set glyph_its = polygons2model(letter_shape, project);
+            its_merge(result, std::move(glyph_its));
+        }
+        s_i_offset += line_bbs.size();
 
-        for (wchar_t wc: ws){
+#ifdef STORE_SAMPLING
+        { // Debug store polygon
+            //std::string stl_filepath = "C:/data/temp/line" + std::to_string(text_line_index) + "_model.stl";
+            //bool suc = its_write_stl_ascii(stl_filepath.c_str(), "label", result);
 
+            BoundingBox bbox      = get_extents(line.polygon);
+            std::string file_path = "C:/data/temp/line" + std::to_string(text_line_index) + "_letter_position.svg";
+            SVG         svg(file_path, bbox);
+            svg.draw(line.polygon);
+            int32_t radius = bbox.size().x() / 300; 
+            for (size_t i = 0; i < samples.size(); i++) {
+                const PolygonPoint &pp = samples[i];
+                const Point& p = pp.point;
+                svg.draw(p, "green", radius);
+                std::string label = std::string(" ")+tc.text[i];
+                svg.draw_text(p, label.c_str(), "black");
+
+                double a = angles[i];
+                double length = 3.0 * radius;
+                Point  n(length * std::cos(a), length * std::sin(a));
+                svg.draw(Slic3r::Line(p - n, p + n), "Lime");
+            }
+        }
+#endif // STORE_SAMPLING
     }
 
     // ProjectTransform project(std::move(projectZ), )
     // if (was_canceled()) return {};
-        //return TriangleMesh(polygons2model(shapes, project));
+    return TriangleMesh(result);
-        //indexed_triangle_set result;
+}
+} // namespace
 
+
+template<typename Fnc>
+TriangleMesh priv::try_create_mesh(DataBase &input, Fnc was_canceled)
+{
+    if (!input.text_lines.empty()) {
+        TriangleMesh tm = create_mesh_per_glyph(input, was_canceled);
+        if (!tm.empty())
+            return tm;
     }
 
     ExPolygons shapes = priv::create_shape(input, was_canceled);

src/slic3r/GUI/Jobs/EmbossJob.hpp

@@ -35,7 +35,7 @@ struct DataBase
 
     // Define per letter projection on one text line
     // [optional] It is not used when empty
-    TextLines text_lines;
+    Slic3r::Emboss::TextLines text_lines;
 };
 
 /// <summary>
@@ -220,7 +220,6 @@ SurfaceVolumeData::ModelSources create_sources(const ModelVolumePtrs &volumes, s
 /// <returns>Source data for cut surface from</returns>
 SurfaceVolumeData::ModelSources create_volume_sources(const ModelVolume *text_volume);
 
-
 /// <summary>
 /// Update text volume to use surface from object
 /// </summary>
@@ -235,7 +234,6 @@ public:
     void process(Ctl &ctl) override;
     void finalize(bool canceled, std::exception_ptr &eptr) override;
 };
-
 } // namespace Slic3r::GUI
 
 #endif // slic3r_EmbossJob_hpp_

src/slic3r/GUI/TextLines.cpp

@@ -20,10 +20,10 @@
 #include "slic3r/GUI/3DScene.hpp"
 
 using namespace Slic3r;
+using namespace Slic3r::Emboss;
 using namespace Slic3r::GUI;
 
 namespace {
-
 const Slic3r::Polygon *largest(const Slic3r::Polygons &polygons)
 {
     if (polygons.empty())
@@ -45,8 +45,8 @@ const Slic3r::Polygon *largest(const Slic3r::Polygons &polygons)
     return result;
 }
 
-indexed_triangle_set create_its(const Slic3r::Polygon &polygon, float width_half) {
+indexed_triangle_set its_create_belt(const Slic3r::Polygon &polygon, float width_half) {
-    // Improve: Create torus instead of flat path (with model overlaps)
+    // Improve: Create torus instead of flat belt path (with model overlaps)
     assert(!polygon.empty());
     if (polygon.empty())
         return {};
@@ -86,65 +86,89 @@ indexed_triangle_set create_its(const Slic3r::Polygon &polygon, float width_half
         model.indices.emplace_back(b2, t2, b1);
         prev_i = i;
     }
-
     return model;
 }
 
-/* GLModel create_model(const Slic3r::Polygon &polygon, float width_half = 0.5f, ColorRGBA color = ColorRGBA(0.f, 1.f, .2f, 0.5f))
+indexed_triangle_set its_create_torus(const Slic3r::Polygon &polygon, float radius, size_t steps = 20)
 {
-    // Improve: Create torus instead of flat path (with model overlaps)
     assert(!polygon.empty());
     if (polygon.empty())
         return {};
 
-    // add a small positive offset to avoid z-fighting
+    size_t count = polygon.size();
-    float                  offset               = static_cast<float>(scale_(0.015f));
+    if (count < 3)
-    Polygons               polygons_expanded    = expand(polygon, offset);
-    const Slic3r::Polygon *polygon_expanded_ptr = largest(polygons_expanded);
-    assert(polygon_expanded_ptr != nullptr);
-    if (polygon_expanded_ptr == nullptr || polygon_expanded_ptr->empty())
         return {};
-    const Slic3r::Polygon &polygon_expanded = *polygon_expanded_ptr;
 
-    // inspired by 3DScene.cpp void GLVolume::SinkingContours::update()
+    // convert and scale to float
-    GLModel::Geometry init_data;
+    std::vector<Vec2f> points_d;
-    init_data.format = {GLModel::Geometry::EPrimitiveType::Triangles, GUI::GLModel::Geometry::EVertexLayout::P3};
+    points_d.reserve(count);
-    init_data.color  = color;
+    for (const Point &point : polygon.points)
+        points_d.push_back(unscale(point).cast<float>());
 
-    size_t count = polygon_expanded.size();
+    // pre calculate normalized line directions
-    init_data.reserve_vertices(2 * count);
+    auto calc_line_norm = [](const Vec2f &f, const Vec2f &s) -> Vec2f { return  (s - f).normalized(); };    
-    init_data.reserve_indices(2 * count);
+    std::vector<Vec2f> line_norm(points_d.size());
+    for (size_t i = 0; i < count - 1; ++i)
+        line_norm[i] = calc_line_norm(points_d[i], points_d[i + 1]);
+    line_norm.back() = calc_line_norm(points_d.back(), points_d.front());
 
-    for (const Point &point : polygon_expanded.points) {
+    // calculate normals for each point
-        Vec2f point_d = unscale(point).cast<float>();
+    auto calc_norm = [](const Vec2f &prev, const Vec2f &next) -> Vec2f {
-        Vec3f vertex(point_d.x(), point_d.y(), width_half);
+        Vec2f dir = prev + next;
-        init_data.add_vertex(vertex);
+        return Vec2f(-dir.x(), dir.y());
-        vertex.z() *= -1;
+    };
-        init_data.add_vertex(vertex);
+    std::vector<Vec2f> points_norm(points_d.size());
+    points_norm.front() = calc_norm(line_norm.back(), line_norm[1]);
+    for (size_t i = 1; i < points_d.size() - 1; ++i)
+        points_norm[i] = calc_norm(line_norm[i - 1], line_norm[i + 1]);        
+    points_norm.back() = calc_norm(line_norm[points_d.size() - 2], line_norm.front());
+    
+    // precalculate sinus and cosinus
+    double angle_step = 2 * M_PI / steps;
+    std::vector<std::pair<double, float>> sin_cos;
+    sin_cos.reserve(steps);
+    for (size_t s = 0; s < steps; ++s) {
+        double angle = s * angle_step;
+        sin_cos.emplace_back(
+            radius * std::sin(angle), 
+            static_cast<float>(radius * std::cos(angle))
+        );
+    }
+    
+    // create torus model along polygon path
+    indexed_triangle_set model;
+    model.vertices.reserve(steps * count);
+    model.indices.reserve(2 * steps * count);
+    for (size_t i = 0; i < count; ++i) {
+        const Vec2f point_d = points_d[i];
+        const Vec2f norm = points_norm[i];
+        for (const auto &[s, c] : sin_cos) {
+            Vec2f xy = s * norm + point_d;
+            model.vertices.emplace_back(xy.x(), xy.y(), c);
+        }
     }
 
     unsigned int prev_i = count - 1;
     for (unsigned int i = 0; i < count; ++i) {        
+        // TODO: solve <180, =180 and >180 angle
+        // to not create self intersection
+
         // t .. top
         // b .. bottom
-        unsigned int t1 = prev_i * 2;
+        unsigned int prev_t = (prev_i+1) * steps - 1;
-        unsigned int b1 = t1 + 1;
+        unsigned int t = (i+1) * steps - 1;
-        unsigned int t2 = i * 2;
+        for (size_t s = 0; s < steps; ++s) {
-        unsigned int b2 = t2 + 1;
+            unsigned int prev_b = prev_i * steps + s;
-        init_data.add_triangle(t1, b1, t2);
+            unsigned int b = i * steps + s;
-        init_data.add_triangle(b2, t2, b1);
+            model.indices.emplace_back(prev_t, prev_b, t);
+            model.indices.emplace_back(b, t, prev_b);
+            prev_t = prev_b;
+            t = b;
+        }
         prev_i = i;
     }
-
+    return model;
-    
+}
-    // line .. y offset from volume(define line for sliced polygon) 
-
-
-    GLModel gl_model;
-    gl_model.init_from(std::move(init_data));
-    return gl_model;
-}*/
-
 
 // select closest contour for each line
 TextLines select_closest_contour(const std::vector<Polygons> &line_contours) {
@@ -181,41 +205,53 @@ TextLines select_closest_contour(const std::vector<Polygons> &line_contours) {
             expolygons[index.expolygons_index].holes[index.hole_index()];
 
         Point hit_point_int = hit_point.cast<Point::coord_type>();
-        TextLine tl{polygon, index.point_index, hit_point_int};
+        TextLine tl{polygon, PolygonPoint{index.point_index, hit_point_int}};
         result.emplace_back(tl);
     }
     return result;
 }
 
-GLModel create_model(const TextLines &lines, const std::vector<float> &line_centers)
+inline Eigen::AngleAxis<double> get_rotation() { return Eigen::AngleAxis(-M_PI_2, Vec3d::UnitX()); }
+
+indexed_triangle_set create_its(const TextLines &lines) 
 { 
-    double model_half_width = 0.5; // [in volume mm]
+    const float model_half_width = 0.75; // [in volume mm]
-    ColorRGBA color(.7f, .7f, .7f, .7f); // Gray
-
     indexed_triangle_set its;
-    auto rot = Eigen::AngleAxis(M_PI_2, Vec3d::UnitX());
-
-    assert(lines.size() == line_centers.size());
     // create model from polygons
-    for (size_t i = 0; i < lines.size(); ++i) {
+    for (const TextLine &line : lines) {
-        const Slic3r::Polygon &polygon = lines[i].polygon;
+        const Slic3r::Polygon &polygon = line.polygon;
         if (polygon.empty()) continue;
-        double line_center = line_centers[i];
+        indexed_triangle_set line_its = its_create_belt(polygon, model_half_width); 
-        indexed_triangle_set line_its = create_its(polygon, model_half_width);
+        //indexed_triangle_set line_its = its_create_torus(polygon, model_half_width);
-        auto transl = Eigen::Translation3d(0., -line_center, 0.);
+        auto transl = Eigen::Translation3d(0., -line.y, 0.);
-        Transform3d tr = transl * rot;
+        Transform3d tr = transl * get_rotation();
         its_transform(line_its, tr);
         its_merge(its, line_its);
     }
+    return its;
+}
 
-    GLModel gl_model;
+GLModel::Geometry create_geometry(const TextLines &lines)
-    gl_model.init_from(its);
+{
-    gl_model.set_color(color);
+    indexed_triangle_set its = create_its(lines);
-    return gl_model;
+
+    GLModel::Geometry geometry;
+    geometry.format = {GLModel::Geometry::EPrimitiveType::Triangles, GUI::GLModel::Geometry::EVertexLayout::P3};
+    ColorRGBA color(.7f, .7f, .7f, .7f); // Transparent Gray
+    geometry.color = color;
+
+    geometry.reserve_vertices(its.vertices.size());
+    for (Vec3f vertex : its.vertices)
+        geometry.add_vertex(vertex);
+
+    geometry.reserve_indices(its.indices.size() * 3);
+    for (Vec3i t : its.indices)
+        geometry.add_triangle(t[0], t[1], t[2]);
+    return geometry;    
 }
 } // namespace
 
-void TextLinesModel::init(const Selection &selection, double line_height)
+void TextLinesModel::init(const Selection &selection, double line_height, double line_offset)
 {
     const GLVolume *gl_volume_ptr = selection.get_first_volume();
     if (gl_volume_ptr == nullptr)
@@ -240,16 +276,15 @@ void TextLinesModel::init(const Selection &selection, double line_height)
     if (count_lines == 0)
         return;
     
-    double first_line_center = -((count_lines / 2) * line_height) - ((count_lines % 2 == 0)? line_height/2. : 0.);
+    double first_line_center = line_offset + (count_lines / 2) * line_height - ((count_lines % 2 == 0) ? line_height / 2. : 0.);
     std::vector<float> line_centers(count_lines);
     for (size_t i = 0; i < count_lines; ++i)
-        line_centers[i] = static_cast<float>(first_line_center + i * line_height);
+        line_centers[i] = static_cast<float>(first_line_center - i * line_height);
 
     const Transform3d &mv_trafo = gl_volume.get_volume_transformation().get_matrix();
 
     // contour transformation
-    auto rot = Eigen::AngleAxis(M_PI_2, Vec3d::UnitX());
+    Transform3d c_trafo = mv_trafo * get_rotation();
-    Transform3d c_trafo = mv_trafo * rot;
     Transform3d c_trafo_inv = c_trafo.inverse();
 
     std::vector<Polygons> line_contours(count_lines);
@@ -275,7 +310,19 @@ void TextLinesModel::init(const Selection &selection, double line_height)
     }
 
     m_lines = select_closest_contour(line_contours);
-    m_model = create_model(m_lines, line_centers);
+    assert(m_lines.size() == count_lines);
+    assert(line_centers.size() == count_lines);
+    for (size_t i = 0; i < count_lines; ++i)
+        m_lines[i].y = line_centers[i];
+
+    m_model.reset();
+    //*
+    m_model.init_from(create_geometry(m_lines));
+    /*/
+    ColorRGBA color(.7f, .7f, .7f, .7f); // Transparent Gray
+    m_model.set_color(color);
+    m_model.init_from(create_its(m_lines));
+    //*/
 }
 
 void TextLinesModel::render(const Transform3d &text_world)

src/slic3r/GUI/TextLines.hpp

@@ -7,40 +7,26 @@
 #include <libslic3r/Emboss.hpp>
 #include "slic3r/GUI/GLModel.hpp"
 
-
 namespace Slic3r::GUI {
-
 class Selection;
-
-/// <summary>
-/// Define polygon for draw letters
-/// </summary>
-struct TextLine
-{
-    // slice of object
-    Polygon polygon;
-
-    // index to point in polygon which starts line, which is closest to zero
-    size_t start_index;
-
-    // Point on line closest to zero
-    Point start_point;
-};
-using TextLines = std::vector<TextLine>;
-
 class TextLinesModel
 {
 public:
-    // line_height in mm
+    /// <summary>
-    void init(const Selection &selection, double line_height);
+    /// Initialize model and lines
+    /// </summary>
+    /// <param name="selection">Must be selected text volume</param>
+    /// <param name="line_height">Height of text line with spacing [in mm]</param>
+    /// <param name="line_offset">Offset of base line from center [in mm]</param>
+    void init(const Selection &selection, double line_height, double line_offset = 0.);
     void render(const Transform3d &text_world);
 
     bool is_init() const { return m_model.is_initialized(); }
     void reset() { m_model.reset(); }
-    const TextLines &get_lines() const { return m_lines; }
+    const Slic3r::Emboss::TextLines &get_lines() const { return m_lines; }
     static double calc_line_height(const Slic3r::Emboss::FontFile& ff, const FontProp& fp);
 private:
-    TextLines m_lines;
+    Slic3r::Emboss::TextLines m_lines;
 
     // Keep model for visualization text lines
     GLModel m_model;