The offset is applied after the elephant food compensation. The value of the brim offset is now also measured from the object after the elephant foot compensation. Thus, the brim offset set to zero means that the brim will touch the object even if elephant foot compensation is enabled.

src/libslic3r/Brim.cpp

@@ -45,16 +45,38 @@ static float max_brim_width(const ConstPrintObjectPtrsAdaptor &objects)
                                  }));
 }
 
-static ConstPrintObjectPtrs get_top_level_objects_with_brim(const Print &print)
+// Returns ExPolygons of the bottom layer of the print object after elephant foot compensation.
+static ExPolygons get_print_object_bottom_layer_expolygons(const PrintObject &print_object)
 {
+    ExPolygons ex_polygons;
+    for (LayerRegion *region : print_object.layers().front()->regions())
+        Slic3r::append(ex_polygons, offset_ex(offset_ex(region->slices.surfaces, float(SCALED_EPSILON)), -float(SCALED_EPSILON)));
+    return ex_polygons;
+}
+
+// Returns ExPolygons of bottom layer for every print object in Print after elephant foot compensation.
+static std::vector<ExPolygons> get_print_bottom_layers_expolygons(const Print &print)
+{
+    std::vector<ExPolygons> bottom_layers_expolygons;
+    bottom_layers_expolygons.reserve(print.objects().size());
+    for (const PrintObject *object : print.objects())
+        bottom_layers_expolygons.emplace_back(get_print_object_bottom_layer_expolygons(*object));
+
+    return bottom_layers_expolygons;
+}
+
+static ConstPrintObjectPtrs get_top_level_objects_with_brim(const Print &print, const std::vector<ExPolygons> &bottom_layers_expolygons)
+{
+    assert(print.objects().size() == bottom_layers_expolygons.size());
     Polygons             islands;
     ConstPrintObjectPtrs island_to_object;
-    for (const PrintObject *object : print.objects()) {
+    for(size_t print_object_idx = 0; print_object_idx < print.objects().size(); ++print_object_idx) {
         Polygons islands_object;
-        islands_object.reserve(object->layers().front()->lslices.size());
+        islands_object.reserve(bottom_layers_expolygons[print_object_idx].size());
-        for (const ExPolygon &ex_poly : object->layers().front()->lslices)
+        for (const ExPolygon &ex_poly : bottom_layers_expolygons[print_object_idx])
             islands_object.emplace_back(ex_poly.contour);
 
+        const PrintObject *object = print.objects()[print_object_idx];
         islands.reserve(islands.size() + object->instances().size() * islands_object.size());
         for (const PrintInstance &instance : object->instances())
             for (Polygon &poly : islands_object) {
@@ -110,7 +132,7 @@ static Polygons top_level_outer_brim_islands(const ConstPrintObjectPtrs &top_lev
         //FIXME how about the brim type?
         auto     brim_offset = float(scale_(object->config().brim_offset.value));
         Polygons islands_object;
-        for (const ExPolygon &ex_poly : object->layers().front()->lslices) {
+        for (const ExPolygon &ex_poly : get_print_object_bottom_layer_expolygons(*object)) {
             Polygons contour_offset = offset(ex_poly.contour, brim_offset);
             for (Polygon &poly : contour_offset)
                 poly.douglas_peucker(SCALED_RESOLUTION);
@@ -124,8 +146,12 @@ static Polygons top_level_outer_brim_islands(const ConstPrintObjectPtrs &top_lev
     return islands;
 }
 
-static ExPolygons top_level_outer_brim_area(const Print &print, const ConstPrintObjectPtrs &top_level_objects_with_brim, const float no_brim_offset)
+static ExPolygons top_level_outer_brim_area(const Print                   &print,
+                                            const ConstPrintObjectPtrs    &top_level_objects_with_brim,
+                                            const std::vector<ExPolygons> &bottom_layers_expolygons,
+                                            const float                    no_brim_offset)
 {
+    assert(print.objects().size() == bottom_layers_expolygons.size());
     std::unordered_set<size_t> top_level_objects_idx;
     top_level_objects_idx.reserve(top_level_objects_with_brim.size());
     for (const PrintObject *object : top_level_objects_with_brim)
@@ -133,15 +159,16 @@ static ExPolygons top_level_outer_brim_area(const Print &print, const ConstPrint
 
     ExPolygons brim_area;
     ExPolygons no_brim_area;
-    for (const PrintObject *object : print.objects()) {
+    for(size_t print_object_idx = 0; print_object_idx < print.objects().size(); ++print_object_idx) {
-        const BrimType brim_type         = object->config().brim_type.value;
+        const PrintObject *object            = print.objects()[print_object_idx];
-        const float    brim_offset       = scale_(object->config().brim_offset.value);
+        const BrimType     brim_type         = object->config().brim_type.value;
-        const float    brim_width        = scale_(object->config().brim_width.value);
+        const float        brim_offset       = scale_(object->config().brim_offset.value);
-        const bool     is_top_outer_brim = top_level_objects_idx.find(object->id().id) != top_level_objects_idx.end();
+        const float        brim_width        = scale_(object->config().brim_width.value);
+        const bool         is_top_outer_brim = top_level_objects_idx.find(object->id().id) != top_level_objects_idx.end();
 
         ExPolygons brim_area_object;
         ExPolygons no_brim_area_object;
-        for (const ExPolygon &ex_poly : object->layers().front()->lslices) {
+        for (const ExPolygon &ex_poly : bottom_layers_expolygons[print_object_idx]) {
             if ((brim_type == BrimType::btOuterOnly || brim_type == BrimType::btOuterAndInner) && is_top_outer_brim)
                 append(brim_area_object, diff_ex(offset(ex_poly.contour, brim_width + brim_offset), offset(ex_poly.contour, brim_offset)));
 
@@ -166,8 +193,12 @@ static ExPolygons top_level_outer_brim_area(const Print &print, const ConstPrint
     return diff_ex(brim_area, no_brim_area);
 }
 
-static ExPolygons inner_brim_area(const Print &print, const ConstPrintObjectPtrs &top_level_objects_with_brim, const float no_brim_offset)
+static ExPolygons inner_brim_area(const Print                   &print,
+                                  const ConstPrintObjectPtrs    &top_level_objects_with_brim,
+                                  const std::vector<ExPolygons> &bottom_layers_expolygons,
+                                  const float                    no_brim_offset)
 {
+    assert(print.objects().size() == bottom_layers_expolygons.size());
     std::unordered_set<size_t> top_level_objects_idx;
     top_level_objects_idx.reserve(top_level_objects_with_brim.size());
     for (const PrintObject *object : top_level_objects_with_brim)
@@ -176,16 +207,17 @@ static ExPolygons inner_brim_area(const Print &print, const ConstPrintObjectPtrs
     ExPolygons brim_area;
     ExPolygons no_brim_area;
     Polygons   holes;
-    for (const PrintObject *object : print.objects()) {
+    for(size_t print_object_idx = 0; print_object_idx < print.objects().size(); ++print_object_idx) {
-        const BrimType brim_type      = object->config().brim_type.value;
+        const PrintObject *object         = print.objects()[print_object_idx];
-        const float    brim_offset    = scale_(object->config().brim_offset.value);
+        const BrimType     brim_type      = object->config().brim_type.value;
-        const float    brim_width     = scale_(object->config().brim_width.value);
+        const float        brim_offset    = scale_(object->config().brim_offset.value);
-        const bool     top_outer_brim = top_level_objects_idx.find(object->id().id) != top_level_objects_idx.end();
+        const float        brim_width     = scale_(object->config().brim_width.value);
+        const bool         top_outer_brim = top_level_objects_idx.find(object->id().id) != top_level_objects_idx.end();
 
         ExPolygons brim_area_object;
         ExPolygons no_brim_area_object;
         Polygons   holes_object;
-        for (const ExPolygon &ex_poly : object->layers().front()->lslices) {
+        for (const ExPolygon &ex_poly : bottom_layers_expolygons[print_object_idx]) {
             if (brim_type == BrimType::btOuterOnly || brim_type == BrimType::btOuterAndInner) {
                 if (top_outer_brim)
                     no_brim_area_object.emplace_back(ex_poly);
@@ -204,7 +236,7 @@ static ExPolygons inner_brim_area(const Print &print, const ConstPrintObjectPtrs
 
             append(holes_object, ex_poly.holes);
         }
-        append(no_brim_area_object, offset_ex(object->layers().front()->lslices, brim_offset));
+        append(no_brim_area_object, offset_ex(bottom_layers_expolygons[print_object_idx], brim_offset));
 
         for (const PrintInstance &instance : object->instances()) {
             append_and_translate(brim_area, brim_area_object, instance);
@@ -236,7 +268,7 @@ static void optimize_polylines_by_reversing(Polylines *polylines)
 static Polylines connect_brim_lines(Polylines &&polylines, const Polygons &brim_area, float max_connection_length)
 {
     if (polylines.empty())
-        return Polylines();
+        return {};
 
     BoundingBox bbox = get_extents(polylines);
     bbox.merge(get_extents(brim_area));
@@ -305,16 +337,20 @@ static Polylines connect_brim_lines(Polylines &&polylines, const Polygons &brim_
             }
         }
         if (end < polylines.size())
-            polylines.erase(polylines.begin() + end, polylines.end());
+            polylines.erase(polylines.begin() + int(end), polylines.end());
     }
 
     return std::move(polylines);
 }
 
-static void make_inner_brim(const Print &print, const ConstPrintObjectPtrs &top_level_objects_with_brim, ExtrusionEntityCollection &brim)
+static void make_inner_brim(const Print                   &print,
+                            const ConstPrintObjectPtrs    &top_level_objects_with_brim,
+                            const std::vector<ExPolygons> &bottom_layers_expolygons,
+                            ExtrusionEntityCollection     &brim)
 {
+    assert(print.objects().size() == bottom_layers_expolygons.size());
     Flow       flow = print.brim_flow();
-    ExPolygons islands_ex = inner_brim_area(print, top_level_objects_with_brim, float(flow.scaled_spacing()));
+    ExPolygons islands_ex = inner_brim_area(print, top_level_objects_with_brim, bottom_layers_expolygons, float(flow.scaled_spacing()));
     Polygons   loops;
     islands_ex      = offset_ex(islands_ex, -0.5f * float(flow.scaled_spacing()), jtSquare);
     for (size_t i = 0; !islands_ex.empty(); ++i) {
@@ -334,11 +370,12 @@ static void make_inner_brim(const Print &print, const ConstPrintObjectPtrs &top_
 // Collect islands_area to be merged into the final 1st layer convex hull.
 ExtrusionEntityCollection make_brim(const Print &print, PrintTryCancel try_cancel, Polygons &islands_area)
 {
-    Flow                 flow                         = print.brim_flow();
+    Flow                    flow                        = print.brim_flow();
-    ConstPrintObjectPtrs top_level_objects_with_brim  = get_top_level_objects_with_brim(print);
+    std::vector<ExPolygons> bottom_layers_expolygons    = get_print_bottom_layers_expolygons(print);
-    Polygons             islands                      = top_level_outer_brim_islands(top_level_objects_with_brim);
+    ConstPrintObjectPtrs    top_level_objects_with_brim = get_top_level_objects_with_brim(print, bottom_layers_expolygons);
-    ExPolygons           islands_area_ex              = top_level_outer_brim_area(print, top_level_objects_with_brim, float(flow.scaled_spacing()));
+    Polygons                islands                     = top_level_outer_brim_islands(top_level_objects_with_brim);
-    islands_area                                      = to_polygons(islands_area_ex);
+    ExPolygons              islands_area_ex             = top_level_outer_brim_area(print, top_level_objects_with_brim, bottom_layers_expolygons, float(flow.scaled_spacing()));
+    islands_area                                        = to_polygons(islands_area_ex);
 
     Polygons        loops;
     size_t          num_loops = size_t(floor(max_brim_width(print.objects()) / flow.spacing()));
@@ -536,7 +573,7 @@ ExtrusionEntityCollection make_brim(const Print &print, PrintTryCancel try_cance
         extrusion_entities_append_loops_and_paths(brim.entities, std::move(all_loops), erSkirt, float(flow.mm3_per_mm()), float(flow.width()), float(print.skirt_first_layer_height()));
     }
 
-    make_inner_brim(print, top_level_objects_with_brim, brim);
+    make_inner_brim(print, top_level_objects_with_brim, bottom_layers_expolygons, brim);
     return brim;
 }
 

src/libslic3r/PrintConfig.cpp

@@ -491,10 +491,11 @@ void PrintConfigDef::init_fff_params()
     def = this->add("brim_offset", coFloat);
     def->label = L("Brim offset");
     def->category = L("Skirt and brim");
-    def->tooltip = L("The offset of the brim from the printed object.");
+    def->tooltip = L("The offset of the brim from the printed object. The offset is applied after the elephant foot compensation.");
     def->sidetext = L("mm");
+    def->min = 0;
     def->mode = comSimple;
-    def->set_default_value(new ConfigOptionFloat(0));
+    def->set_default_value(new ConfigOptionFloat(0.1f));
 
     def = this->add("clip_multipart_objects", coBool);
     def->label = L("Clip multi-part objects");