Convert text to mesh

src/libslic3r/Emboss.cpp

@@ -6,6 +6,87 @@
 
 using namespace Slic3r;
 
+// do not expose out of this file stbtt_ data types
+class Privat
+{
+public:
+    Privat() = delete;
+
+    static std::optional<stbtt_fontinfo> load_font_info(const Emboss::Font &font);
+
+    struct Glyph
+    {
+        Polygons polygons;
+        int      advance_width, left_side_bearing;
+    };
+    static std::optional<Glyph> get_glyph(stbtt_fontinfo &font_info, int unicode_letter, float flatness = 2.f);
+};
+
+std::optional<stbtt_fontinfo> Privat::load_font_info(const Emboss::Font &font)
+{
+    int font_offset = stbtt_GetFontOffsetForIndex(font.buffer.data(), font.index);
+    if (font_offset < 0) {
+        std::cerr << "Font index("<<font.index<<") doesn't exist.";
+        return {};        
+    }
+    stbtt_fontinfo font_info;
+    if (stbtt_InitFont(&font_info, font.buffer.data(), font_offset) == 0) {
+        std::cerr << "Can't initialize font.";
+        return {};
+    }
+    return font_info;
+}
+
+std::optional<Privat::Glyph> Privat::get_glyph(stbtt_fontinfo &font_info, int unicode_letter, float flatness)
+{
+    int glyph_index = stbtt_FindGlyphIndex(&font_info, unicode_letter);
+    if (glyph_index == 0) { 
+        std::cerr << "Character codepoint(" << unicode_letter 
+            << " = '" << (char) unicode_letter << "') is not defined in the font.";
+        return {};
+    }
+
+    Privat::Glyph glyph;
+    stbtt_GetGlyphHMetrics(&font_info, glyph_index, &glyph.advance_width, &glyph.left_side_bearing);
+
+    stbtt_vertex *vertices;
+    int num_verts = stbtt_GetGlyphShape(&font_info, glyph_index, &vertices);
+    if (num_verts <= 0) return glyph; // no shape
+
+    int *         contour_lengths = NULL;
+    int           num_countour    = 0;
+    stbtt__point *points          = stbtt_FlattenCurves(vertices, num_verts,
+                                               flatness,
+                                               &contour_lengths,
+                                               &num_countour,
+                                               font_info.userdata);
+
+    glyph.polygons.reserve(num_countour);
+    size_t pi = 0; // point index
+    for (size_t ci = 0; ci < num_countour; ++ci) {
+        int    length = contour_lengths[ci];
+        if (length <= 0) continue;
+        Points pts;
+        pts.reserve(length);
+        for (size_t i = 0; i < length; i++) {
+            const stbtt__point &point = points[pi];
+            pi++;
+            pts.emplace_back(point.x, point.y);
+        }
+        if (pts.front() == pts.back()) { 
+            pts.pop_back(); 
+        } else {
+            int j = 42;
+        }
+
+        glyph.polygons.emplace_back(pts);
+    }
+
+    // inner ccw
+    // outer cw
+    return glyph;
+}
+
 std::optional<Emboss::Font> Emboss::load_font(const char *file_path)
 {
     FILE *file = fopen(file_path, "rb");
@@ -43,69 +124,361 @@ std::optional<Emboss::Font> Emboss::load_font(const char *file_path)
     // select default font on index 0
     res.index = 0;
     res.count = index;
-    // first fonst has offset zero
-    font_offset = 0;
 
-    stbtt_fontinfo font_info;
-    if (stbtt_InitFont(&font_info, res.buffer.data(), font_offset) == 0) {
-        std::cerr << "Can't initialize font.";
-        return {};    
-    }
+    auto font_info = Privat::load_font_info(res);
+    if (!font_info.has_value()) return {};
 
     // load information about line gap
-    stbtt_GetFontVMetrics(&(font_info), &res.ascent, &res.descent, &res.linegap);
+    stbtt_GetFontVMetrics(&(*font_info), &res.ascent, &res.descent, &res.linegap);
     return res;
 }
 
 Polygons Emboss::letter2polygons(const Font &font, char letter)
 {
-    int font_offset = stbtt_GetFontOffsetForIndex(font.buffer.data(), font.index);
-    stbtt_fontinfo font_info;
-    if (stbtt_InitFont(&font_info, font.buffer.data(), font_offset) == 0)
-        return Polygons();
+    auto font_info_opt = Privat::load_font_info(font);
+    if (!font_info_opt.has_value()) return Polygons();
+    stbtt_fontinfo *font_info = &(*font_info_opt);
 
-    int glyph_index = stbtt_FindGlyphIndex(&(font_info), letter);
-    int advanceWidth, leftSideBearing;
-    stbtt_GetGlyphHMetrics(&(font_info), glyph_index, &advanceWidth,
-                           &leftSideBearing);
+    auto glyph_opt = Privat::get_glyph(*font_info_opt, (int) letter, font.flatness);
+    if (!glyph_opt.has_value()) return Polygons();
 
-    stbtt_vertex *vertices;
-    int num_verts = stbtt_GetGlyphShape(&(font_info), glyph_index, &vertices);
-    if (num_verts < 0) return {}; // no shape
+    return glyph_opt->polygons;
+}
 
-    int *         contour_lengths = NULL;
-    int           num_countour    = 0;
-    stbtt__point *points = stbtt_FlattenCurves(vertices, num_verts, font.flatness,
-                                               &contour_lengths,
-                                               &num_countour,
-                                               (font_info).userdata);
+Polygons Emboss::text2polygons(const Font &font, const std::string &text)
+{
+    auto font_info_opt = Privat::load_font_info(font);
+    if (!font_info_opt.has_value()) return Polygons();
+    stbtt_fontinfo *font_info = &(*font_info_opt);
 
+    Point    cursor(0, 0);
     Polygons result;
-    result.reserve(num_countour);
-    size_t pi = 0; // point index
-    for (size_t ci = 0; ci < num_countour; ++ci) {
-        int    length = contour_lengths[ci];
-        Points pts;
-        pts.reserve(length);
-        for (size_t i = 0; i < length; i++) {
-            const stbtt__point &point = points[pi];
-            pi++;
-            pts.emplace_back(point.x, point.y);
-        }
-        result.emplace_back(pts);
+    for (const char &letter : text) {
+        if (letter == '\0') break;
+
+        auto glyph_opt = Privat::get_glyph(*font_info_opt, (int) letter, font.flatness);
+        if (!glyph_opt.has_value()) continue;
+
+        // move glyph to cursor position
+        Polygons polygons = glyph_opt->polygons; // copy
+        for (Polygon &polygon : polygons) 
+            for (Point &p : polygon.points) p += cursor;
+        
+        cursor.x() += glyph_opt->advance_width;
+
+        polygons_append(result, polygons);
     }
-
-    BoundingBox bb;
-    for (auto &r : result) bb.merge(r.points);
-
-    // inner ccw
-    // outer cw
     return result;
 }
 
-indexed_triangle_set Emboss::create_model(const std::string &text,
-                                          const Font &       font,
-                                          float              z_size)
+std::vector<Vec3i> its_create_neighbors_index_2(const indexed_triangle_set &its)
 {
-    return indexed_triangle_set();
+    std::vector<Vec3i> out(its.indices.size(), Vec3i(-1, -1, -1));
+
+    // Create a mapping from triangle edge into face.
+    struct EdgeToFace
+    {
+        // Index of the 1st vertex of the triangle edge. vertex_low <= vertex_high.
+        int vertex_low;
+        // Index of the 2nd vertex of the triangle edge.
+        int vertex_high;
+        // Index of a triangular face.
+        int face;
+        // Index of edge in the face, starting with 1. Negative indices if the
+        // edge was stored reverse in (vertex_low, vertex_high).
+        int  face_edge;
+        bool operator==(const EdgeToFace &other) const
+        {
+            return vertex_low == other.vertex_low &&
+                   vertex_high == other.vertex_high;
+        }
+        bool operator<(const EdgeToFace &other) const
+        {
+            return vertex_low < other.vertex_low ||
+                   (vertex_low == other.vertex_low &&
+                    vertex_high < other.vertex_high);
+        }
+    };
+    std::vector<EdgeToFace> edges_map;
+    edges_map.assign(its.indices.size() * 3, EdgeToFace());
+    for (uint32_t facet_idx = 0; facet_idx < its.indices.size(); ++facet_idx)
+        for (int i = 0; i < 3; ++i) {
+            EdgeToFace &e2f = edges_map[facet_idx * 3 + i];
+            e2f.vertex_low  = its.indices[facet_idx][i];
+            e2f.vertex_high = its.indices[facet_idx][(i + 1) % 3];
+            e2f.face        = facet_idx;
+            // 1 based indexing, to be always strictly positive.
+            e2f.face_edge = i + 1;
+            if (e2f.vertex_low > e2f.vertex_high) {
+                // Sort the vertices
+                std::swap(e2f.vertex_low, e2f.vertex_high);
+                // and make the face_edge negative to indicate a flipped edge.
+                e2f.face_edge = -e2f.face_edge;
+            }
+        }
+    std::sort(edges_map.begin(), edges_map.end());
+
+    // Assign a unique common edge id to touching triangle edges.
+    int num_edges = 0;
+    for (size_t i = 0; i < edges_map.size(); ++i) {
+        EdgeToFace &edge_i = edges_map[i];
+        if (edge_i.face == -1)
+            // This edge has been connected to some neighbor already.
+            continue;
+        // Unconnected edge. Find its neighbor with the correct orientation.
+        size_t j;
+        bool   found = false;
+        for (j = i + 1; j < edges_map.size() && edge_i == edges_map[j]; ++j)
+            if (edge_i.face_edge * edges_map[j].face_edge < 0 &&
+                edges_map[j].face != -1) {
+                // Faces touching with opposite oriented edges and none of the
+                // edges is connected yet.
+                found = true;
+                break;
+            }
+        if (!found) {
+            // FIXME Vojtech: Trying to find an edge with equal orientation.
+            // This smells.
+            // admesh can assign the same edge ID to more than two facets (which is
+            // still topologically correct), so we have to search for a
+            // duplicate of this edge too in case it was already seen in this
+            // orientation
+            for (j = i + 1; j < edges_map.size() && edge_i == edges_map[j];
+                 ++j)
+                if (edges_map[j].face != -1) {
+                    // Faces touching with equally oriented edges and none of
+                    // the edges is connected yet.
+                    found = true;
+                    break;
+                }
+        }
+        // Assign an edge index to the 1st face.
+        //        out[edge_i.face](std::abs(edge_i.face_edge) - 1) = num_edges;
+        if (found) {
+            EdgeToFace &edge_j                               = edges_map[j];
+            out[edge_i.face](std::abs(edge_i.face_edge) - 1) = edge_j.face;
+            out[edge_j.face](std::abs(edge_j.face_edge) - 1) = edge_i.face;
+            // Mark the edge as connected.
+            edge_j.face = -1;
+        }
+        ++num_edges;
+    }
+    return out;
+}
+
+void its_remove_edge_triangles(indexed_triangle_set &its)
+{
+    ////                       start, count
+    //std::vector<std::pair<uint32_t, uint32_t>> neighbors_vertices(its.vertices.size(), {0,0});
+    //// calc counts
+    //for (const auto &i : its.indices) {
+    //    for (size_t j = 0; j < 3; j++) 
+    //        ++neighbors_vertices[i[j]].second;
+    //}
+    //uint32_t triangle_start = 0;
+    //for (auto &neighbor : neighbors_vertices) {
+    //    neighbor.first = triangle_start;
+    //    triangle_start += neighbor.second; 
+    //    neighbor.second = 0;
+    //}
+    //std::vector<uint32_t> neighbors_data(its.indices.size()*3);
+    //for (const auto &i : its.indices) {
+    //    uint32_t index = &i - &its.indices.front();
+    //    for (size_t j = 0; j < 3; j++) {
+    //        auto & neighbor = neighbors_vertices[i[j]];
+    //        size_t index_data = neighbor.second + neighbor.first;
+    //        neighbors_data[index_data] = index;
+    //        ++neighbor.second;
+    //    }
+    //}
+    
+    auto neighbors = its_create_neighbors_index_2(its);
+    std::set<uint32_t> remove;
+    std::queue<uint32_t> insert;
+    int no_value = -1;
+    for (const auto &neighbor : neighbors) {
+        uint32_t index = &neighbor - &neighbors.front();
+        auto     it    = remove.find(index);
+        if (it != remove.end()) continue; // already removed
+
+        if (neighbor[0] != no_value && 
+            neighbor[1] != no_value &&
+            neighbor[2] != no_value)
+            continue;
+
+        insert.push(index);
+        while (!insert.empty()) {
+            uint32_t i = insert.front();
+            insert.pop();
+            if (remove.find(i) != remove.end()) continue;
+            remove.insert(i);
+            for (size_t j = 0; j < 3; j++) {
+                if (neighbor[j] == no_value) continue;
+                uint32_t i2 = static_cast<uint32_t>(neighbor[j]);
+                insert.push(i2);
+            }            
+        }        
+    }
+    std::vector<uint32_t> rem(remove.begin(), remove.end());
+    std::sort(rem.begin(), rem.end());
+    uint32_t offset = 0;
+    for (uint32_t i : rem) { 
+        its.indices.erase(its.indices.begin() + i - offset);
+        ++offset;
+    }
+}
+
+indexed_triangle_set Emboss::polygons2model(const Polygons &shape2d,
+                                            const IProject &projection)
+{
+    indexed_triangle_set result;
+    size_t count_point = count_points(shape2d);
+    result.vertices.reserve(2 * count_point);
+
+    std::vector<Vec3f> &front_points = result.vertices;
+    std::vector<Vec3f>  back_points;
+    back_points.reserve(count_point);
+
+    for (const Polygon &polygon : shape2d) {
+        for (const Point &p : polygon.points) {
+            auto p2 = projection.project(p);
+            front_points.emplace_back(p2.first);
+            back_points.emplace_back(p2.second);
+        }
+    }
+    // insert back points, front are already in
+    result.vertices.insert(result.vertices.end(),
+                           std::make_move_iterator(back_points.begin()),
+                           std::make_move_iterator(back_points.end()));
+
+    // CW order of triangle indices
+    std::vector<Vec3i> shape_triangles = triangulate(shape2d);
+    result.indices.reserve(shape_triangles.size() * 2 + count_point * 2);
+    // top triangles - change to CCW
+    for (const Vec3i &t : shape_triangles)
+        result.indices.emplace_back(t.x(), t.z(), t.y());
+    // bottom triangles - use CW
+    for (const Vec3i &t : shape_triangles)
+        result.indices.emplace_back(t.x() + count_point, t.y() + count_point,
+                                    t.z() + count_point);
+
+    // quads around - zig zag by triangles
+    size_t polygon_offset = 0;
+    for (const Polygon &polygon : shape2d) {
+        uint32_t polygon_points = polygon.points.size();
+        for (uint32_t p = 0; p < polygon_points; p++) { 
+            uint32_t i = polygon_offset + p;
+            // previous index
+            uint32_t ip = (p == 0) ? (polygon_offset + polygon_points - 1) : (i - 1);
+            // bottom indices
+            uint32_t i2  = i + count_point;
+            uint32_t ip2 = ip + count_point;
+
+            result.indices.emplace_back(i, i2, ip);
+            result.indices.emplace_back(ip2, ip, i2);
+        }
+        polygon_offset += polygon_points;
+    }
+
+    // remove bad triangulated faces
+    its_remove_edge_triangles(result);
+    return result;
+}
+
+#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
+#include <CGAL/Constrained_Delaunay_triangulation_2.h>
+#include <CGAL/Triangulation_vertex_base_with_info_2.h>
+std::vector<Vec3i> Emboss::triangulate(
+    const Points& points,
+    const std::set<std::pair<uint32_t, uint32_t>> &edges)
+{
+    // IMPROVE use int point insted of float !!!
+
+    // use cgal triangulation
+    using K    = CGAL::Exact_predicates_inexact_constructions_kernel;
+    using Itag = CGAL::Exact_predicates_tag;
+    using CDT  = CGAL::Constrained_Delaunay_triangulation_2<K, CGAL::Default, Itag>;
+    using Point = CDT::Point;
+
+    // construct a constrained triangulation
+    CDT                               cdt;
+    std::map<CDT::Vertex_handle, int> map;             // for indices
+    std::vector<CDT::Vertex_handle>   vertices_handle; // for constriants
+    vertices_handle.reserve(points.size());
+    for (const auto& p: points) {
+        Point  cdt_p(p.x(), p.y());
+        auto   handl = cdt.insert(cdt_p);
+        vertices_handle.push_back(handl);
+        size_t i = &p - &points.front();
+        map[handl] = i;
+    }
+
+    // triangle can not contain forbiden edge
+    for (const std::pair<uint32_t, uint32_t> &edge : edges) {
+        const CDT::Vertex_handle& vh1 = vertices_handle[edge.first];
+        const CDT::Vertex_handle& vh2 = vertices_handle[edge.second];
+        cdt.insert_constraint(vh1, vh2);
+    }
+
+    auto               faces = cdt.finite_face_handles();
+    std::vector<Vec3i> indices;
+    indices.reserve(faces.size());
+    for (CDT::Face_handle face : faces) {
+        auto v0 = face->vertex(0);
+        auto v1 = face->vertex(1);
+        auto v2 = face->vertex(2);
+        uint32_t i0 = map[v0];
+        uint32_t i1 = map[v1];
+        uint32_t i2 = map[v2];
+
+        // check forbiden triangle edge - opposit order
+        if (edges.find(std::make_pair(i0, i1)) != edges.end()) continue;
+        if (edges.find(std::make_pair(i1, i2)) != edges.end()) continue;
+        if (edges.find(std::make_pair(i2, i0)) != edges.end()) continue;
+
+        indices.emplace_back(map[v0], map[v1], map[v2]);
+    }
+    return indices;
+}
+
+std::vector<Vec3i> Emboss::triangulate(const Polygon &polygon)
+{
+    const Points &                          pts = polygon.points;
+    std::set<std::pair<uint32_t, uint32_t>> edges;
+    for (uint32_t i = 1; i < pts.size(); ++i) edges.insert({i - 1, i});
+    edges.insert({(uint32_t)pts.size() - 1, uint32_t(0)});
+    return triangulate(pts, edges);
+}
+
+std::vector<Vec3i> Emboss::triangulate(const Polygons &polygons)
+{
+    size_t count = count_points(polygons);
+    Points points;
+    points.reserve(count);
+    for (const Polygon &polygon : polygons)
+        points.insert(points.end(), polygon.points.begin(),
+                      polygon.points.end());
+
+    std::set<std::pair<uint32_t, uint32_t>> edges;
+    uint32_t offset = 0;
+    for (const Polygon& polygon : polygons) {
+        const Points &pts = polygon.points;
+        for (uint32_t i = 1; i < pts.size(); ++i) {
+            uint32_t i2 = i + offset;
+            edges.insert({i2 - 1, i2}); 
+        }
+        uint32_t size = static_cast<uint32_t>(pts.size());
+        // add connection from first to last point
+        edges.insert({offset + size - 1, offset});
+        offset += size;
+    }
+    return triangulate(points, edges);
+}
+
+std::pair<Vec3f, Vec3f> Emboss::ProjectZ::project(const Point &p) const
+{
+    Vec3f front(p.x(),p.y(),0.f);
+    Vec3f back = front; // copy
+    back.z() = m_depth;
+    return std::make_pair(front, back);
 }

src/libslic3r/Emboss.hpp

@@ -2,7 +2,9 @@
 #define slic3r_Emboss_hpp_
 
 #include <vector>
+#include <set>
 #include <optional>
+#include <memory>
 #include <admesh/stl.h> // indexed_triangle_set
 #include "Polygon.hpp"
 
@@ -38,6 +40,8 @@ public:
 
         // change size of font
         float scale = 1.;
+
+        // enum class Align: center/left/right
     };
 
     /// <summary>
@@ -53,20 +57,80 @@ public:
     /// <param name="font">Define fonts</param>
     /// <param name="letter">Character to convert</param>
     /// <returns>inner polygon ccw(outer cw)</returns>
-    static Polygons letter2polygons(const Font &font, char letter);    
+    static Polygons letter2polygons(const Font &font, char letter);
 
+    /// <summary>
+    /// Convert text into polygons
+    /// </summary>
+    /// <param name="font">Define fonts</param>
+    /// <param name="letter">Character to convert</param>
+    /// <returns>inner polygon ccw(outer cw)</returns>
     static Polygons text2polygons(const Font &font, const std::string &text);
 
+    /// <summary>
+    /// Project 2d point into space
+    /// Could be plane, sphere, cylindric, ...
+    /// </summary>
+    class IProject
+    {
+    public:
+        virtual ~IProject() = default;
+        /// <summary>
+        /// convert 2d point to 3d point
+        /// </summary>
+        /// <param name="p">2d coordinate</param>
+        /// <returns>
+        /// first - front spatial point
+        /// second - back spatial point
+        /// </returns>
+        virtual std::pair<Vec3f, Vec3f> project(const Point &p) const = 0;
+    };
+
     /// <summary>
     /// Create triangle model for text
     /// </summary>
-    /// <param name="text"></param>
-    /// <param name="font"></param>
-    /// <param name="z_size"></param>
-    /// <returns></returns>
-    static indexed_triangle_set create_model(const std::string &text,
-                                             const Font &       font,
-                                             float              z_size);
+    /// <param name="shape2d">text or image</param>
+    /// <param name="projection">Define transformation from 2d to 3d(orientation, position, scale, ...)</param>
+    /// <returns>Projected shape into space</returns>
+    static indexed_triangle_set polygons2model(const Polygons &shape2d, const IProject& projection);
+
+    /// <summary>
+    /// Connect points by triangulation to create filled surface by triangle indices
+    /// </summary>
+    /// <param name="points">Points to connect</param>
+    /// <param name="edges">Constraint for edges, pair is from point(first) to point(second)</param>
+    /// <returns>Triangles</returns>
+    static std::vector<Vec3i> triangulate(const Points &points, const std::set<std::pair<uint32_t, uint32_t>> &edges);
+    static std::vector<Vec3i> triangulate(const Polygon &polygon);
+    static std::vector<Vec3i> triangulate(const Polygons &polygons);
+
+    class ProjectZ : public IProject
+    {
+    public:
+        ProjectZ(float depth) : m_depth(depth) {}
+        // Inherited via IProject
+        virtual std::pair<Vec3f, Vec3f> project(const Point &p) const override;
+        float m_depth;
+    };
+
+    class ProjectScale : public IProject
+    {
+        std::unique_ptr<IProject> core;
+    public:
+        ProjectScale(std::unique_ptr<IProject> core, float scale)
+            : m_scale(scale)
+            , core(std::move(core))
+        {}
+
+        // Inherited via IProject
+        virtual std::pair<Vec3f, Vec3f> project(const Point &p) const override
+        {
+            auto res = core->project(p);
+            return std::make_pair(res.first * m_scale, res.second * m_scale);
+        }
+
+        float                           m_scale;
+    };
 };
 
 } // namespace Slic3r

src/libslic3r/Polygon.hpp

@@ -154,13 +154,17 @@ inline Points to_points(const Polygon &poly)
     return poly.points;
 }
 
+inline size_t count_points(const Polygons &polys) {
+    size_t n_points = 0;
+    for (size_t i = 0; i < polys.size(); ++i)
+        n_points += polys[i].points.size();
+    return n_points;
+}
+
 inline Points to_points(const Polygons &polys) 
 {
-    size_t n_points = 0;
-    for (size_t i = 0; i < polys.size(); ++ i)
-        n_points += polys[i].points.size();
     Points points;
-    points.reserve(n_points);
+    points.reserve(count_points(polys));
     for (const Polygon &poly : polys)
         append(points, poly.points);
     return points;
@@ -180,11 +184,8 @@ inline Lines to_lines(const Polygon &poly)
 
 inline Lines to_lines(const Polygons &polys) 
 {
-    size_t n_lines = 0;
-    for (size_t i = 0; i < polys.size(); ++ i)
-        n_lines += polys[i].points.size();
     Lines lines;
-    lines.reserve(n_lines);
+    lines.reserve(count_points(polys));
     for (size_t i = 0; i < polys.size(); ++ i) {
         const Polygon &poly = polys[i];
         for (Points::const_iterator it = poly.points.begin(); it != poly.points.end()-1; ++it)

src/slic3r/GUI/Gizmos/GLGizmoEmboss.cpp

@@ -7,7 +7,7 @@
 #include "slic3r/GUI/Plater.hpp"
 
 #include "libslic3r/Model.hpp"
-#include "libslic3r/QuadricEdgeCollapse.hpp"
+#include "libslic3r/Emboss.hpp"
 
 namespace Slic3r::GUI {
 
@@ -19,15 +19,10 @@ GLGizmoEmboss::GLGizmoEmboss(GLCanvas3D &       parent,
                 Slic3r::resources_dir() + "/fonts/NotoSans-Regular.ttf"},
                {"Arial", "C:/windows/fonts/arialbd.ttf"}})
     , m_selected(1)
-    , m_text_size(255)
-    , m_text(new char[255])
+    , m_text(_u8L("Embossed text"))
 {
     // TODO: suggest to use https://fontawesome.com/
-    int index = 0;
-    for (char &c : _u8L("Embossed text")) { 
-        m_text[index++] = c;
-    }
-    m_text[index] = '\0';
+    m_text.reserve(255);
 }
 
 GLGizmoEmboss::~GLGizmoEmboss() {}
@@ -66,16 +61,47 @@ void GLGizmoEmboss::on_render_input_window(float x, float y, float bottom_limit)
     }
     ImGui::SameLine();
     ImGui::Button("Add");
+    static float scale = 0.01f;
+    ImGui::InputFloat("Scale", &scale);
+    static float emboss = 100.f;
+    ImGui::InputFloat("Emboss", &emboss);
+
+    if(ImGui::Button("Preview")){ 
+        
+        auto project = std::make_unique<Emboss::ProjectScale>(
+            std::make_unique<Emboss::ProjectZ>(emboss)
+            ,scale);
+
+        auto font_path  = m_fonts[m_selected].file_path.c_str();
+        auto font_opt = Emboss::load_font(font_path);
+        if (font_opt.has_value()) {
+            Polygons polygons = Emboss::text2polygons(*font_opt, m_text);
+            indexed_triangle_set its = Emboss::polygons2model(polygons, *project);
+            // add object
+            TriangleMesh tm(its);
+            tm.repair();
+
+            tm.WriteOBJFile("text_preview.obj");
+
+            const Selection &selection  = m_parent.get_selection();
+            int              object_idx = selection.get_object_idx();
+            ModelObject *obj = wxGetApp().plater()->model().objects[object_idx];
+            ModelVolume *v = obj->volumes.front();
+            v->set_mesh(tm);
+            v->set_new_unique_id();
+            obj->invalidate_bounding_box();
+            m_parent.reload_scene(true);
+        }        
+    }
 
-    size_t text_size = 255;
-    //sizeof(*m_text.get());
     ImVec2 input_size(-FLT_MIN, ImGui::GetTextLineHeight() * 6);
     ImGuiInputTextFlags flags =
         ImGuiInputTextFlags_::ImGuiInputTextFlags_AllowTabInput 
         | ImGuiInputTextFlags_::ImGuiInputTextFlags_AutoSelectAll
         //|ImGuiInputTextFlags_::ImGuiInputTextFlags_CtrlEnterForNewLine
         ;
-    if (ImGui::InputTextMultiline("##Text", m_text.get(), text_size, input_size, flags)) {
+    if (ImGui::InputTextMultiline("##Text", (char *) m_text.c_str(),
+        m_text.capacity() + 1, input_size, flags)) {
         
     }
 

src/slic3r/GUI/Gizmos/GLGizmoEmboss.hpp

@@ -30,26 +30,6 @@ protected:
 private:
     void close();
 
-    struct MyFont;
-    MyFont createFont(const char * fileName);
-
-    struct Configuration
-    {
-        bool use_count = false;
-        // minimal triangle count
-        float    decimate_ratio = 50.f; // in percent
-        uint32_t wanted_count   = 0; // initialize by percents
-
-        // maximal quadric error
-        float max_error = 1.;
-
-        void fix_count_by_ratio(size_t triangle_count)
-        {
-            wanted_count = static_cast<uint32_t>(
-                std::round(triangle_count * (100.f-decimate_ratio) / 100.f));
-        }
-    } m_configuration;
-
     // This configs holds GUI layout size given by translated texts.
     // etc. When language changes, GUI is recreated and this class constructed again,
     // so the change takes effect. (info by GLGizmoFdmSupports.hpp)
@@ -72,9 +52,7 @@ private:
     std::vector<MyFont> m_fonts;    
     size_t              m_selected;// index to m_fonts
 
-
-    size_t m_text_size; // allocated size by m_text
-    std::unique_ptr<char[]> m_text;
+    std::string m_text;
 };
 
 } // namespace GUI

tests/libslic3r/test_meshboolean.cpp

@@ -62,9 +62,13 @@ Polygons ttf2polygons(const char * font_name, char letter, float flatness = 1.f)
 void store_to_svg(Polygons polygons,std::string file_name = "letter.svg")
 {
     double scale = 1e6;
-    for (auto &p : polygons) p.scale(scale);
-    SVG svg("letter.svg", BoundingBox(polygons.front().points));
-    svg.draw(polygons);
+    BoundingBox bb;
+    for (auto& p : polygons) {
+        p.scale(scale);
+        bb.merge(p.points);
+    }
+    SVG svg(file_name, bb);
+    svg.draw(polygons);    
 }
 
 struct Plane