option for Slic3r/issues/1364 : use a lower safety offset when slicing the geometry.

xs/src/libslic3r/PrintConfig.cpp

@@ -26,14 +26,22 @@ PrintConfigDef::PrintConfigDef()
     // Maximum extruder temperature, bumped to 1500 to support printing of glass.
     const int max_temp = 1500;
 
-	def = this->add("avoid_crossing_perimeters", coBool);
+    def = this->add("avoid_crossing_perimeters", coBool);
     def->label = L("Avoid crossing perimeters");
-	def->tooltip = L("Optimize travel moves in order to minimize the crossing of perimeters. "
+    def->tooltip = L("Optimize travel moves in order to minimize the crossing of perimeters. "
-                   "This is mostly useful with Bowden extruders which suffer from oozing. "
+        "This is mostly useful with Bowden extruders which suffer from oozing. "
-                   "This feature slows down both the print and the G-code generation.");
+        "This feature slows down both the print and the G-code generation.");
     def->cli = "avoid-crossing-perimeters!";
     def->default_value = new ConfigOptionBool(false);
 
+    def = this->add("remove_small_gaps", coBool);
+    def->label = L("Remove small gaps");
+    def->tooltip = L("Remove the small gaps in the 3D model when slicing. Disable it if you "
+        "are very confident on your model, or you want to print an item with a geometry "
+        "designed for vase mode.");
+    def->cli = "remove-small-gaps!";
+    def->default_value = new ConfigOptionBool(true);
+
     def = this->add("bed_shape", coPoints);
 	def->label = L("Bed shape");
     def->default_value = new ConfigOptionPoints { Pointf(0,0), Pointf(200,0), Pointf(200,200), Pointf(0,200) };

xs/src/libslic3r/PrintConfig.hpp

@@ -341,6 +341,7 @@ class PrintObjectConfig : public StaticPrintConfig
     STATIC_PRINT_CONFIG_CACHE(PrintObjectConfig)
 public:
     ConfigOptionBool                clip_multipart_objects;
+    ConfigOptionBool                remove_small_gaps;
     ConfigOptionBool                dont_support_bridges;
     ConfigOptionFloat               elefant_foot_compensation;
     ConfigOptionFloatOrPercent      extrusion_width;
@@ -388,6 +389,7 @@ protected:
     void initialize(StaticCacheBase &cache, const char *base_ptr)
     {
         OPT_PTR(clip_multipart_objects);
+        OPT_PTR(remove_small_gaps);
         OPT_PTR(dont_support_bridges);
         OPT_PTR(elefant_foot_compensation);
         OPT_PTR(extrusion_width);

xs/src/libslic3r/PrintObject.cpp

@@ -1856,6 +1856,7 @@ std::vector<ExPolygons> PrintObject::_slice_volumes(const std::vector<float> &z,
             mesh.translate(- float(unscale(this->_copies_shift.x)), - float(unscale(this->_copies_shift.y)), -float(this->model_object()->bounding_box().min.z));
             // perform actual slicing
             TriangleMeshSlicer mslicer(&mesh);
+            mslicer.safety_offset = (this->config.remove_small_gaps ? scale_(0.0499) : SCALED_EPSILON);
             mslicer.slice(z, &layers);
         }
     }

xs/src/libslic3r/TriangleMesh.cpp

@@ -1792,7 +1792,7 @@ void TriangleMeshSlicer::make_expolygons(const Polygons &loops, ExPolygons* slic
     //}
 
     // perform a safety offset to merge very close facets (TODO: find test case for this)
-    double safety_offset = scale_(0.0499);
+    //double safety_offset = scale_(0.0499); // now a config value
 //FIXME see https://github.com/prusa3d/Slic3r/issues/520
 //    double safety_offset = scale_(0.0001);
 

xs/src/libslic3r/TriangleMesh.hpp

@@ -168,6 +168,7 @@ public:
         const float min_z, const float max_z, IntersectionLine *line_out) const;
     void cut(float z, TriangleMesh* upper, TriangleMesh* lower) const;
     
+    double safety_offset = scale_(0.0499);
 private:
     const TriangleMesh      *mesh;
     // Map from a facet to an edge index.

xs/src/slic3r/GUI/Preset.cpp

@@ -308,6 +308,7 @@ const std::vector<std::string>& Preset::print_options()
         "only_one_perimeter_top", "single_extruder_multi_material_priming", "compatible_printers", "compatible_printers_condition", "inherits", 
         "infill_dense", "infill_dense_algo", "no_perimeter_unsupported", "min_perimeter_unsupported", "noperi_bridge_only",
         "support_material_solid_first_layer", "perimeter_loop", "perimeter_loop_seam", "seam_travel"
+        , "remove_small_gaps"
     };
     return s_opts;
 }

xs/src/slic3r/GUI/Tab.cpp

@@ -819,7 +819,8 @@ void TabPrint::build()
         optgroup->append_line(line);
 
         optgroup = page->new_optgroup(_(L("Advanced")));
-        line = { _(L("Seam options")), "" };
+        optgroup->append_single_option_line("remove_small_gaps");
+        line = { _(L("Avoid unsupported perimeters")), "" };
         line.append_option(optgroup->get_option("seam_position"));
         line.append_option(optgroup->get_option("seam_travel"));
         optgroup->append_line(line);