reforged support z distance:

 - choice between "from filament, from plane, soluble
 - different settings for top & bottom.

14 files changed, 169 insertions, 78 deletions

diff --git a/src/libslic3r/Fill/FillRectilinear2.cpp b/src/libslic3r/Fill/FillRectilinear2.cpp
index df4f9f42b..23a404098 100644
--- a/src/libslic3r/Fill/FillRectilinear2.cpp
+++ b/src/libslic3r/Fill/FillRectilinear2.cpp
@@ -288,9 +288,9 @@ public:
         // for the infill pattern, don't cut the corners.
         // default miterLimt = 3
         //double mitterLimit = 10.;
-        assert(aoffset1 < 0);
-        assert(aoffset2 < 0);
-        assert(aoffset2 < aoffset1);
+        //assert(aoffset1 < 0);
+        //assert(aoffset2 < 0);
+        //assert(aoffset2 < aoffset1);
         bool sticks_removed = remove_sticks(polygons_src);
 //        if (sticks_removed) printf("Sticks removed!\n");
         polygons_outer = offset(polygons_src, aoffset1,
@@ -881,7 +881,7 @@ bool FillRectilinear2::fill_surface_by_lines(const Surface *surface, const FillP
     std::pair<float, Point> rotate_vector = this->_infill_direction(surface);
     rotate_vector.first += angleBase;
 
-    assert(params.density > 0.0001f && params.density <= 1.f);
+    assert(params.density > 0.0001f);
     coord_t line_spacing = _line_spacing_for_density(params.density);
 
     // On the polygons of poly_with_offset, the infill lines will be connected.
diff --git a/src/libslic3r/PerimeterGenerator.cpp b/src/libslic3r/PerimeterGenerator.cpp
index 13652f86a..5302a3b5a 100644
--- a/src/libslic3r/PerimeterGenerator.cpp
+++ b/src/libslic3r/PerimeterGenerator.cpp
@@ -192,7 +192,6 @@ void PerimeterGenerator::process()
                         if (true) {
                             //only consider the part that can be bridged (really, by the bridge algorithm)
                             //first, separate into islands (ie, each ExPlolygon)
-                            int numploy = 0;
                             //only consider the bottom layer that intersect unsupported, to be sure it's only on our island.
                             ExPolygonCollection lower_island(diff_ex(last, unsupported, true));
                             BridgeDetector detector(unsupported,
@@ -570,7 +569,7 @@ ExtrusionEntityCollection PerimeterGenerator::_traverse_loops(
         // detect overhanging/bridging perimeters
         ExtrusionPaths paths;
         if (this->config->overhangs && this->layer_id > 0
-            && !(this->object_config->support_material && this->object_config->support_material_contact_distance.value == 0)) {
+            && !(this->object_config->support_material && this->object_config->support_material_contact_distance_type.value == zdNone)) {
             // get non-overhang paths by intersecting this loop with the grown lower slices
             extrusion_paths_append(
                 paths,
@@ -839,7 +838,7 @@ PerimeterGenerator::_extrude_and_cut_loop(const PerimeterGeneratorLoop &loop, co
 
         // detect overhanging/bridging perimeters
         if (this->config->overhangs && this->layer_id > 0
-            && !(this->object_config->support_material && this->object_config->support_material_contact_distance.value == 0)) {
+            && !(this->object_config->support_material && this->object_config->support_material_contact_distance_type.value == zdNone)) {
             ExtrusionPaths paths;
             // get non-overhang paths by intersecting this loop with the grown lower slices
             extrusion_paths_append(
diff --git a/src/libslic3r/Print.cpp b/src/libslic3r/Print.cpp
index a4034981b..f89c316da 100644
--- a/src/libslic3r/Print.cpp
+++ b/src/libslic3r/Print.cpp
@@ -1258,7 +1258,9 @@ std::string Print::validate() const
                 return L("The Wipe Tower is only supported for multiple objects if they have equal layer heigths");
             if (slicing_params.raft_layers() != slicing_params0.raft_layers())
                 return L("The Wipe Tower is only supported for multiple objects if they are printed over an equal number of raft layers");
-            if (object->config().support_material_contact_distance != m_objects.front()->config().support_material_contact_distance)
+            if (object->config().support_material_contact_distance_type != m_objects.front()->config().support_material_contact_distance_type
+				|| object->config().support_material_contact_distance_top != m_objects.front()->config().support_material_contact_distance_top
+				|| object->config().support_material_contact_distance_bottom != m_objects.front()->config().support_material_contact_distance_bottom)
                 return L("The Wipe Tower is only supported for multiple objects if they are printed with the same support_material_contact_distance");
             if (! equal_layering(slicing_params, slicing_params0))
                 return L("The Wipe Tower is only supported for multiple objects if they are sliced equally.");
diff --git a/src/libslic3r/PrintConfig.cpp b/src/libslic3r/PrintConfig.cpp
index 32d4ee101..490f10203 100644
--- a/src/libslic3r/PrintConfig.cpp
+++ b/src/libslic3r/PrintConfig.cpp
@@ -2189,16 +2189,51 @@ void PrintConfigDef::init_fff_params()
     def->mode = comAdvanced;
     def->default_value = new ConfigOptionBool(false);
 
-    def = this->add("support_material_contact_distance", coFloat);
+    def = this->add("support_material_contact_distance_type", coEnum);
+    def->label = L("Type");
+    def->category = L("Support material");
+    def->tooltip = L("How to compute the vertical z-distance.\n"
+        "From filament: it use the nearest bit of the filament. When a bridge is extruded, it goes below the current plane.\n"
+        "From plane: it use the plane-z. Same than 'from filament' if no 'bridge' is extruded.\n"
+        "None: No z-offset. Useful for Soluble supports.\n");
+    def->cli = "support-material-contact-type=s";
+    def->enum_keys_map = &ConfigOptionEnum<SupportZDistanceType>::get_enum_values();
+    def->enum_values.push_back("filament");
+    def->enum_values.push_back("plane");
+    def->enum_values.push_back("none");
+    def->enum_labels.push_back("From filament");
+    def->enum_labels.push_back("From plane");
+    def->enum_labels.push_back("None");
+    def->mode = comAdvanced;
+    def->default_value = new ConfigOptionEnum<SupportZDistanceType>(zdFilament);
+
+    def = this->add("support_material_contact_distance_top", coFloat);
     def->gui_type = "f_enum_open";
-    def->label = L("Contact Z distance");
+    def->label = L("Top");
+    def->category = L("Support material");
+    def->tooltip = L("The vertical distance between support material interface and the object"
+        "(when the object is printed on top of the support). "
+        "Setting this to 0 will also prevent Slic3r from using bridge flow and speed "
+        "for the first object layer.");
+    def->sidetext = L("mm");
+    def->cli = "support-material-contact-distance-top=f";
+    //    def->min = 0;
+    def->enum_values.push_back("0");
+    def->enum_values.push_back("0.2");
+    def->enum_labels.push_back((boost::format("0 (%1%)") % L("soluble")).str());
+    def->enum_labels.push_back((boost::format("0.2 (%1%)") % L("detachable")).str());
+    def->mode = comAdvanced;
+    def->default_value = new ConfigOptionFloat(0.2);
+
+    def = this->add("support_material_contact_distance_bottom", coFloat);
+    def->gui_type = "f_enum_open";
+    def->label = L("Bottom");
     def->category = L("Support material");
-    def->tooltip = L("The vertical distance between object and support material interface. "
-                   "Setting this to 0 will also prevent Slic3r from using bridge flow and speed "
-                   "for the first object layer.");
+    def->tooltip = L("The vertical distance between object and support material interface"
+        "(when the support is printed on top of the object).");
     def->sidetext = L("mm");
-    def->cli = "support-material-contact-distance=f";
-//    def->min = 0;
+    def->cli = "support-material-contact-distance-bottom=f";
+    //    def->min = 0;
     def->enum_values.push_back("0");
     def->enum_values.push_back("0.2");
     def->enum_labels.push_back((boost::format("0 (%1%)") % L("soluble")).str());
diff --git a/src/libslic3r/PrintConfig.hpp b/src/libslic3r/PrintConfig.hpp
index 607ca2596..c2fc9350d 100644
--- a/src/libslic3r/PrintConfig.hpp
+++ b/src/libslic3r/PrintConfig.hpp
@@ -61,6 +61,10 @@ enum DenseInfillAlgo {
     dfaAutomatic, dfaAutoNotFull, dfaEnlarged,
 };
 
+enum SupportZDistanceType {
+    zdFilament, zdPlane, zdNone,
+};
+
 enum SLADisplayOrientation {
     sladoLandscape,
     sladoPortrait
@@ -174,6 +178,15 @@ template<> inline const t_config_enum_values& ConfigOptionEnum<DenseInfillAlgo>:
     return keys_map;
 }
 
+template<> inline const t_config_enum_values& ConfigOptionEnum<SupportZDistanceType>::get_enum_values() {
+    static const t_config_enum_values keys_map = {
+        { "filament", zdFilament },
+        { "plane", zdPlane },
+        { "none", zdNone }
+    };
+    return keys_map;
+} 
+
 template<> inline const t_config_enum_values& ConfigOptionEnum<SLADisplayOrientation>::get_enum_values() {
     static const t_config_enum_values keys_map = {
         { "landscape", sladoLandscape},
@@ -396,7 +409,9 @@ public:
     // Direction of the support pattern (in XY plane).
     ConfigOptionFloat               support_material_angle;
     ConfigOptionBool                support_material_buildplate_only;
-    ConfigOptionFloat               support_material_contact_distance;
+    ConfigOptionEnum<SupportZDistanceType>  support_material_contact_distance_type;
+    ConfigOptionFloat               support_material_contact_distance_top;
+    ConfigOptionFloat               support_material_contact_distance_bottom;
     ConfigOptionInt                 support_material_enforce_layers;
     ConfigOptionInt                 support_material_extruder;
     ConfigOptionFloatOrPercent      support_material_extrusion_width;
@@ -442,7 +457,9 @@ protected:
         OPT_PTR(support_material_auto);
         OPT_PTR(support_material_angle);
         OPT_PTR(support_material_buildplate_only);
-        OPT_PTR(support_material_contact_distance);
+        OPT_PTR(support_material_contact_distance_type);
+        OPT_PTR(support_material_contact_distance_top);
+        OPT_PTR(support_material_contact_distance_bottom);
         OPT_PTR(support_material_enforce_layers);
         OPT_PTR(support_material_interface_contact_loops);
         OPT_PTR(support_material_extruder);
diff --git a/src/libslic3r/PrintObject.cpp b/src/libslic3r/PrintObject.cpp
index aeee8750c..8bf7475eb 100644
--- a/src/libslic3r/PrintObject.cpp
+++ b/src/libslic3r/PrintObject.cpp
@@ -481,7 +481,9 @@ bool PrintObject::invalidate_state_by_config_options(const std::vector<t_config_
         else if (
                opt_key == "clip_multipart_objects"
             || opt_key == "elefant_foot_compensation"
-            || opt_key == "support_material_contact_distance" 
+            || opt_key == "support_material_contact_distance_type" 
+            || opt_key == "support_material_contact_distance_top" 
+            || opt_key == "support_material_contact_distance_bottom" 
             || opt_key == "xy_size_compensation"
             || opt_key == "external_infill_margin"
             || opt_key == "bridged_infill_margin"
@@ -912,12 +914,12 @@ void PrintObject::detect_surfaces_type()
             [this, idx_region, interface_shells, &surfaces_new](const tbb::blocked_range<size_t>& range) {
                 // If we have raft layers, consider bottom layer as a bridge just like any other bottom surface lying on the void.
                 SurfaceType surface_type_bottom_1st =
-                    (m_config.raft_layers.value > 0 && m_config.support_material_contact_distance.value > 0) ?
+                    (m_config.raft_layers.value > 0 && m_config.support_material_contact_distance_type.value != zdNone) ?
                     stBottomBridge : stBottom;
                 // If we have soluble support material, don't bridge. The overhang will be squished against a soluble layer separating
                 // the support from the print.
                 SurfaceType surface_type_bottom_other =
-                    (m_config.support_material.value && m_config.support_material_contact_distance.value == 0) ?
+                    (m_config.support_material.value && m_config.support_material_contact_distance_type.value == zdNone) ?
                     stBottom : stBottomBridge;
                 for (size_t idx_layer = range.begin(); idx_layer < range.end(); ++ idx_layer) {
                     m_print->throw_if_canceled();
diff --git a/src/libslic3r/Slicing.cpp b/src/libslic3r/Slicing.cpp
index 14467893e..f0647736a 100644
--- a/src/libslic3r/Slicing.cpp
+++ b/src/libslic3r/Slicing.cpp
@@ -57,7 +57,7 @@ SlicingParameters SlicingParameters::create_from_config(
     // In that case all the nozzles have to be of the same diameter.
     coordf_t support_material_extruder_dmr           = print_config.nozzle_diameter.get_at(object_config.support_material_extruder.value - 1);
     coordf_t support_material_interface_extruder_dmr = print_config.nozzle_diameter.get_at(object_config.support_material_interface_extruder.value - 1);
-    bool     soluble_interface                       = object_config.support_material_contact_distance.value == 0.;
+    bool     soluble_interface                       = object_config.support_material_contact_distance_type.value == zdNone;
 
     SlicingParameters params;
     params.layer_height = object_config.layer_height.value;
@@ -95,9 +95,9 @@ SlicingParameters SlicingParameters::create_from_config(
     params.max_layer_height = std::max(params.max_layer_height, params.layer_height);
 
     if (! soluble_interface) {
-        params.gap_raft_object    = object_config.support_material_contact_distance.value;
-        params.gap_object_support = object_config.support_material_contact_distance.value;
-        params.gap_support_object = object_config.support_material_contact_distance.value;
+        params.gap_raft_object    = object_config.support_material_contact_distance_top.value;
+        params.gap_object_support = object_config.support_material_contact_distance_bottom.value;
+        params.gap_support_object = object_config.support_material_contact_distance_top.value;
     }
 
     if (params.base_raft_layers > 0) {
diff --git a/src/libslic3r/SupportMaterial.cpp b/src/libslic3r/SupportMaterial.cpp
index 60fb0f71a..f208a2ed4 100644
--- a/src/libslic3r/SupportMaterial.cpp
+++ b/src/libslic3r/SupportMaterial.cpp
@@ -284,8 +284,8 @@ void PrintObjectSupportMaterial::generate(PrintObject &object)
 
 //    this->trim_support_layers_by_object(object, top_contacts, m_slicing_params.soluble_interface ? 0. : m_support_layer_height_min, 0., m_gap_xy);
     this->trim_support_layers_by_object(object, top_contacts, 
-        m_slicing_params.soluble_interface ? 0. : m_object_config->support_material_contact_distance.value, 
-        m_slicing_params.soluble_interface ? 0. : m_object_config->support_material_contact_distance.value, m_gap_xy);
+        m_slicing_params.soluble_interface ? 0. : m_object_config->support_material_contact_distance_top.value, 
+        m_slicing_params.soluble_interface ? 0. : m_object_config->support_material_contact_distance_bottom.value, m_gap_xy);
 
 #ifdef SLIC3R_DEBUG
     for (const MyLayer *layer : top_contacts)
@@ -1207,7 +1207,7 @@ PrintObjectSupportMaterial::MyLayersPtr PrintObjectSupportMaterial::top_contact_
                         new_layer.height   = object.layers()[layer_id - 1]->height;
                         new_layer.bottom_z = (layer_id == 1) ? m_slicing_params.object_print_z_min : object.layers()[layer_id - 2]->print_z;
                     } else {
-                        new_layer.print_z  = layer.print_z - layer.height - m_object_config->support_material_contact_distance;
+                        new_layer.print_z  = layer.print_z - layer.height - m_object_config->support_material_contact_distance_top;
                         new_layer.bottom_z = new_layer.print_z;
                         new_layer.height   = 0.;
                         // Ignore this contact area if it's too low.
@@ -1230,11 +1230,14 @@ PrintObjectSupportMaterial::MyLayersPtr PrintObjectSupportMaterial::top_contact_
                         // Contact layer will be printed with a normal flow, but
                         // it will support layers printed with a bridging flow.
                         if (SupportMaterialInternal::has_bridging_extrusions(layer)) {
-                            coordf_t bridging_height = 0.;
-                            for (const LayerRegion *region : layer.regions())
-                                bridging_height += region->region()->bridging_height_avg(*m_print_config);
-                            bridging_height /= coordf_t(layer.regions().size());
-                            coordf_t bridging_print_z = layer.print_z - bridging_height - m_object_config->support_material_contact_distance;
+                            coordf_t bridging_height = layer.height;
+                            if (m_object_config->support_material_contact_distance_type == zdFilament) {
+                                bridging_height = 0.;
+                                for (const LayerRegion *region : layer.regions())
+                                    bridging_height += region->region()->bridging_height_avg(*m_print_config);
+                                bridging_height /= coordf_t(layer.regions().size());
+                            }
+                            coordf_t bridging_print_z = layer.print_z - bridging_height - m_object_config->support_material_contact_distance_top;
                             if (bridging_print_z >= m_slicing_params.first_print_layer_height - EPSILON) {
                                 // Not below the first layer height means this layer is printable.
                                 if (new_layer.print_z < m_slicing_params.first_print_layer_height + EPSILON) {
@@ -1491,7 +1494,7 @@ PrintObjectSupportMaterial::MyLayersPtr PrintObjectSupportMaterial::bottom_conta
                             // top shapes so this can be done here
                             //FIXME calculate layer height based on the actual thickness of the layer:
                             // If the layer is extruded with no bridging flow, support just the normal extrusions.
-                            layer_new.height  = m_slicing_params.soluble_interface ? 
+                            layer_new.height = m_slicing_params.soluble_interface ?
                                 // Align the interface layer with the object's layer height.
                                 object.layers()[layer_id + 1]->height :
                                 // Place a bridge flow interface layer over the top surface.
@@ -1499,8 +1502,9 @@ PrintObjectSupportMaterial::MyLayersPtr PrintObjectSupportMaterial::bottom_conta
                                 // According to Jindrich the bottom surfaces work well.
                                 //FIXME test the bridging flow instead?
                                 m_support_material_interface_flow.nozzle_diameter;
+                            layer_new.height_block = ((m_object_config->support_material_contact_distance_type == zdPlane) ? object.layers()[layer_id + 1]->height : layer_new.height);
                             layer_new.print_z = m_slicing_params.soluble_interface ? object.layers()[layer_id + 1]->print_z :
-                                layer.print_z + layer_new.height + m_object_config->support_material_contact_distance.value;
+                                (layer.print_z + layer_new.height_block + m_object_config->support_material_contact_distance_bottom.value);
                             layer_new.bottom_z = layer.print_z;
                             layer_new.idx_object_layer_below = layer_id;
                             layer_new.bridging = ! m_slicing_params.soluble_interface;
@@ -1534,6 +1538,7 @@ PrintObjectSupportMaterial::MyLayersPtr PrintObjectSupportMaterial::bottom_conta
                                     }
                                 }
                             }
+
                 #ifdef SLIC3R_DEBUG
                             Slic3r::SVG::export_expolygons(
                                 debug_out_path("support-bottom-contacts-%d-%lf.svg", iRun, layer_new.print_z),
@@ -1637,8 +1642,8 @@ PrintObjectSupportMaterial::MyLayersPtr PrintObjectSupportMaterial::bottom_conta
         std::reverse(bottom_contacts.begin(), bottom_contacts.end());
 //        trim_support_layers_by_object(object, bottom_contacts, 0., 0., m_gap_xy);
         trim_support_layers_by_object(object, bottom_contacts, 
-            m_slicing_params.soluble_interface ? 0. : m_object_config->support_material_contact_distance.value, 
-            m_slicing_params.soluble_interface ? 0. : m_object_config->support_material_contact_distance.value, m_gap_xy);
+            m_slicing_params.soluble_interface ? 0. : m_object_config->support_material_contact_distance_top.value, 
+            m_slicing_params.soluble_interface ? 0. : m_object_config->support_material_contact_distance_bottom.value, m_gap_xy);
 
     } // ! top_contacts.empty()
 
@@ -1801,9 +1806,10 @@ PrintObjectSupportMaterial::MyLayersPtr PrintObjectSupportMaterial::raft_and_int
             assert(extr2->print_z >= m_slicing_params.first_print_layer_height + m_support_layer_height_min - EPSILON);
             if (intermediate_layers.empty() || intermediate_layers.back()->print_z < m_slicing_params.first_print_layer_height) {
                 MyLayer &layer_new = layer_allocate(layer_storage, sltIntermediate);
-                layer_new.bottom_z = 0.;
-                layer_new.print_z  = m_slicing_params.first_print_layer_height;
-                layer_new.height   = m_slicing_params.first_print_layer_height;
+                layer_new.bottom_z      = 0.;
+                layer_new.print_z       = m_slicing_params.first_print_layer_height;
+                layer_new.height        = m_slicing_params.first_print_layer_height;
+                layer_new.height_block  = layer_new.height;
                 intermediate_layers.push_back(&layer_new);
             }
             continue;
@@ -1823,9 +1829,10 @@ PrintObjectSupportMaterial::MyLayersPtr PrintObjectSupportMaterial::raft_and_int
             assert(extr2z >= m_slicing_params.first_print_layer_height + EPSILON);
             // Generate a new intermediate layer.
             MyLayer &layer_new = layer_allocate(layer_storage, sltIntermediate);
-            layer_new.bottom_z = 0.;
-            layer_new.print_z  = extr1z = m_slicing_params.first_print_layer_height;
-            layer_new.height   = extr1z;
+            layer_new.bottom_z      = 0.;
+            layer_new.print_z       = extr1z = m_slicing_params.first_print_layer_height;
+            layer_new.height        = extr1z;
+            layer_new.height_block  = layer_new.height;
             intermediate_layers.push_back(&layer_new);
             // Continue printing the other layers up to extr2z.
         }
@@ -1842,18 +1849,20 @@ PrintObjectSupportMaterial::MyLayersPtr PrintObjectSupportMaterial::raft_and_int
                 ++ idx_layer_object;
             if (idx_layer_object == 0 && extr1z == m_slicing_params.raft_interface_top_z) {
                 // Insert one base support layer below the object.
-                MyLayer &layer_new = layer_allocate(layer_storage, sltIntermediate);
-                layer_new.print_z  = m_slicing_params.object_print_z_min;
-                layer_new.bottom_z = m_slicing_params.raft_interface_top_z;
-                layer_new.height   = layer_new.print_z - layer_new.bottom_z;
+                MyLayer &layer_new      = layer_allocate(layer_storage, sltIntermediate);
+                layer_new.print_z       = m_slicing_params.object_print_z_min;
+                layer_new.bottom_z      = m_slicing_params.raft_interface_top_z;
+                layer_new.height        = layer_new.print_z - layer_new.bottom_z;
+                layer_new.height_block  = layer_new.height;
                 intermediate_layers.push_back(&layer_new);
             }
             // Emit all intermediate support layers synchronized with object layers up to extr2z.
             for (; idx_layer_object < object.layers().size() && object.layers()[idx_layer_object]->print_z < extr2z + EPSILON; ++ idx_layer_object) {
-                MyLayer &layer_new = layer_allocate(layer_storage, sltIntermediate);
-                layer_new.print_z  = object.layers()[idx_layer_object]->print_z;
-                layer_new.height   = object.layers()[idx_layer_object]->height;
-                layer_new.bottom_z = (idx_layer_object > 0) ? object.layers()[idx_layer_object - 1]->print_z : (layer_new.print_z - layer_new.height);
+                MyLayer &layer_new      = layer_allocate(layer_storage, sltIntermediate);
+                layer_new.print_z       = object.layers()[idx_layer_object]->print_z;
+                layer_new.height        = object.layers()[idx_layer_object]->height;
+                layer_new.height_block  = layer_new.height;
+                layer_new.bottom_z      = (idx_layer_object > 0) ? object.layers()[idx_layer_object - 1]->print_z : (layer_new.print_z - layer_new.height);
                 assert(intermediate_layers.empty() || intermediate_layers.back()->print_z < layer_new.print_z + EPSILON);
                 intermediate_layers.push_back(&layer_new);
             }
@@ -1868,10 +1877,11 @@ PrintObjectSupportMaterial::MyLayersPtr PrintObjectSupportMaterial::raft_and_int
                 // between the 1st intermediate layer print_z and extr1->print_z is not too small.
                 assert(extr1->bottom_z + m_support_layer_height_min < extr1->print_z + EPSILON);
                 // Generate the first intermediate layer.
-                MyLayer &layer_new = layer_allocate(layer_storage, sltIntermediate);
-                layer_new.bottom_z = extr1->bottom_z;
-                layer_new.print_z  = extr1z = extr1->print_z;
-                layer_new.height   = extr1->height;
+                MyLayer &layer_new      = layer_allocate(layer_storage, sltIntermediate);
+                layer_new.bottom_z      = extr1->bottom_z;
+                layer_new.print_z       = extr1z = extr1->print_z;
+                layer_new.height        = extr1->height;
+                layer_new.height_block  = layer_new.height;
                 intermediate_layers.push_back(&layer_new);
                 dist = extr2z - extr1z;
                 n_layers_extra = size_t(ceil(dist / m_slicing_params.max_suport_layer_height));
@@ -1898,12 +1908,14 @@ PrintObjectSupportMaterial::MyLayersPtr PrintObjectSupportMaterial::raft_and_int
                     layer_new.bottom_z = (i == 0) ? extr1z : intermediate_layers.back()->print_z;
                     layer_new.print_z = extr2z_large_steps;
                     layer_new.height = layer_new.print_z - layer_new.bottom_z;
+                    layer_new.height_block = layer_new.height;
                 }
                 else {
                     // Intermediate layer, not the last added.
                     layer_new.height = step;
                     layer_new.bottom_z = extr1z + i * step;
                     layer_new.print_z = layer_new.bottom_z + step;
+                    layer_new.height_block = layer_new.height;
                 }
                 assert(intermediate_layers.empty() || intermediate_layers.back()->print_z <= layer_new.print_z);
                 intermediate_layers.push_back(&layer_new);
@@ -2059,8 +2071,8 @@ void PrintObjectSupportMaterial::generate_base_layers(
 
 //    trim_support_layers_by_object(object, intermediate_layers, 0., 0., m_gap_xy);
     this->trim_support_layers_by_object(object, intermediate_layers, 
-        m_slicing_params.soluble_interface ? 0. : m_object_config->support_material_contact_distance.value, 
-        m_slicing_params.soluble_interface ? 0. : m_object_config->support_material_contact_distance.value, m_gap_xy);
+        m_slicing_params.soluble_interface ? 0. : m_object_config->support_material_contact_distance_top.value, 
+        m_slicing_params.soluble_interface ? 0. : m_object_config->support_material_contact_distance_bottom.value, m_gap_xy);
 }
 
 void PrintObjectSupportMaterial::trim_support_layers_by_object(
@@ -2094,7 +2106,7 @@ void PrintObjectSupportMaterial::trim_support_layers_by_object(
                 // BOOST_LOG_TRIVIAL(trace) << "Support generator - trim_support_layers_by_object - trimmming non-empty layer " << idx_layer << " of " << nonempty_layers.size();
                 assert(! support_layer.polygons.empty() && support_layer.print_z >= m_slicing_params.raft_contact_top_z + EPSILON);
                 // Find the overlapping object layers including the extra above / below gap.
-                coordf_t z_threshold = support_layer.print_z - support_layer.height - gap_extra_below + EPSILON;
+                coordf_t z_threshold = support_layer.print_z - support_layer.height_block - gap_extra_below + EPSILON;
                 idx_object_layer_overlapping = idx_higher_or_equal(
                     object.layers(), idx_object_layer_overlapping, 
                     [z_threshold](const Layer *layer){ return layer->print_z >= z_threshold; });
@@ -2107,13 +2119,15 @@ void PrintObjectSupportMaterial::trim_support_layers_by_object(
                         break;
                     polygons_append(polygons_trimming, offset(object_layer.slices.expolygons, gap_xy_scaled, SUPPORT_SURFACES_OFFSET_PARAMETERS));
                 }
-                if (! m_slicing_params.soluble_interface) {
+                if (!m_slicing_params.soluble_interface) {
                     // Collect all bottom surfaces, which will be extruded with a bridging flow.
                     for (; i < object.layers().size(); ++ i) {
                         const Layer &object_layer = *object.layers()[i];
                         bool some_region_overlaps = false;
                         for (LayerRegion *region : object_layer.regions()) {
-                            coordf_t bridging_height = region->region()->bridging_height_avg(*this->m_print_config);
+                            coordf_t bridging_height = m_object_config->support_material_contact_distance_type == zdFilament
+                                ? region->region()->bridging_height_avg(*this->m_print_config)
+                                : object_layer.height;
                             if (object_layer.print_z - bridging_height > support_layer.print_z + gap_extra_above - EPSILON)
                                 break;
                             some_region_overlaps = true;
@@ -3101,7 +3115,7 @@ void PrintObjectSupportMaterial::generate_toolpaths(
         size_t idx_layer_top_contact      = size_t(-1);
         size_t idx_layer_intermediate     = size_t(-1);
         size_t idx_layer_inteface         = size_t(-1);
-        std::unique_ptr<Fill> filler_interface = std::unique_ptr<Fill>(Fill::new_from_type(m_slicing_params.soluble_interface ? ipConcentricGapFill : ipRectilinear));
+        std::unique_ptr<Fill> filler_interface = std::unique_ptr<Fill>(Fill::new_from_type(m_slicing_params.soluble_interface ? ipRectilinear : ipRectilinear));
         std::unique_ptr<Fill> filler_support = std::unique_ptr<Fill>(Fill::new_from_type(infill_pattern));
         std::unique_ptr<Fill> filler_solid = std::unique_ptr<Fill>(Fill::new_from_type(ipRectiWithPerimeter));
         filler_interface->set_bounding_box(bbox_object);
@@ -3180,7 +3194,7 @@ void PrintObjectSupportMaterial::generate_toolpaths(
                     layer_ex.layer->bridging);
                 Fill *filler = filler_interface.get();
                 float density = interface_density;
-                //if first alyer and solid first layer : draw concentric with 100% density
+                //if first layer and solid first layer : draw concentric with 100% density
                 if (support_layer.id() == 0 && this->m_object_config->support_material_solid_first_layer.value) {
                     filler = filler_solid.get();
                     density = 1.f;
diff --git a/src/libslic3r/SupportMaterial.hpp b/src/libslic3r/SupportMaterial.hpp
index 2e1a05946..743fccc40 100644
--- a/src/libslic3r/SupportMaterial.hpp
+++ b/src/libslic3r/SupportMaterial.hpp
@@ -52,11 +52,12 @@ public:
 	class MyLayer
 	{
 	public:
-		MyLayer() :
-			layer_type(sltUnknown),
-			print_z(0.),
-			bottom_z(0.),
-			height(0.),
+        MyLayer() :
+            layer_type(sltUnknown),
+            print_z(0.),
+            bottom_z(0.),
+            height(0.),
+            height_block(0.),
 			idx_object_layer_above(size_t(-1)),
 			idx_object_layer_below(size_t(-1)),
 			bridging(false),
@@ -77,6 +78,7 @@ public:
 			print_z 				= 0.;
 			bottom_z 				= 0.;
 			height 					= 0.;
+            height_block            = 0.;
 			idx_object_layer_above  = size_t(-1);
 			idx_object_layer_below  = size_t(-1);
 			bridging 				= false;
@@ -119,9 +121,11 @@ public:
 		coordf_t print_z;
 		// Bottom Z of this layer. For soluble layers, bottom_z + height = print_z,
 		// otherwise bottom_z + gap + height = print_z.
-		coordf_t bottom_z;
-		// Layer height in unscaled coordinates.
-    	coordf_t height;
+        coordf_t bottom_z;
+        // Layer height in unscaled coordinates.
+        coordf_t height;
+        // Layer height for collision in unscaled coordinates.
+        coordf_t height_block;
     	// Index of a PrintObject layer_id supported by this layer. This will be set for top contact layers.
     	// If this is not a contact layer, it will be set to size_t(-1).
     	size_t 	 idx_object_layer_above;
diff --git a/src/slic3r/GUI/Field.cpp b/src/slic3r/GUI/Field.cpp
index 501d1f1bc..8b84ef1df 100644
--- a/src/slic3r/GUI/Field.cpp
+++ b/src/slic3r/GUI/Field.cpp
@@ -718,6 +718,8 @@ boost::any& Choice::get_value()
             m_value = static_cast<PrintHostType>(ret_enum);
         else if (m_opt_id.compare("infill_dense_algo") == 0)
             m_value = static_cast<DenseInfillAlgo>(ret_enum);
+        else if (m_opt_id.compare("support_material_contact_distance_type") == 0)
+            m_value = static_cast<SupportZDistanceType>(ret_enum);
 		else if (m_opt_id.compare("display_orientation") == 0)
 			m_value = static_cast<SLADisplayOrientation>(ret_enum);
 	}
diff --git a/src/slic3r/GUI/GUI.cpp b/src/slic3r/GUI/GUI.cpp
index 58fb0dc5e..186fcb110 100644
--- a/src/slic3r/GUI/GUI.cpp
+++ b/src/slic3r/GUI/GUI.cpp
@@ -198,6 +198,8 @@ void change_opt_value(DynamicPrintConfig& config, const t_config_option_key& opt
                 config.set_key_value(opt_key, new ConfigOptionEnum<PrintHostType>(boost::any_cast<PrintHostType>(value)));
             else if (opt_key.compare("infill_dense_algo") == 0)
                 config.set_key_value(opt_key, new ConfigOptionEnum<DenseInfillAlgo>(boost::any_cast<DenseInfillAlgo>(value)));
+            else if (opt_key.compare("support_material_contact_distance_type") == 0)
+                config.set_key_value(opt_key, new ConfigOptionEnum<SupportZDistanceType>(boost::any_cast<SupportZDistanceType>(value)));
 			else if (opt_key.compare("display_orientation") == 0)
 				config.set_key_value(opt_key, new ConfigOptionEnum<SLADisplayOrientation>(boost::any_cast<SLADisplayOrientation>(value)));
 			}
diff --git a/src/slic3r/GUI/OptionsGroup.cpp b/src/slic3r/GUI/OptionsGroup.cpp
index c5a85e3a6..52edb4493 100644
--- a/src/slic3r/GUI/OptionsGroup.cpp
+++ b/src/slic3r/GUI/OptionsGroup.cpp
@@ -557,6 +557,9 @@ boost::any ConfigOptionsGroup::get_config_value(const DynamicPrintConfig& config
         else if (opt_key.compare("infill_dense_algo") == 0){
             ret = static_cast<int>(config.option<ConfigOptionEnum<DenseInfillAlgo>>(opt_key)->value);
         }
+        else if (opt_key.compare("support_material_contact_distance_type") == 0){
+            ret = static_cast<int>(config.option<ConfigOptionEnum<SupportZDistanceType>>(opt_key)->value);
+        }
         else if (opt_key.compare("display_orientation") == 0) {
             ret  = static_cast<int>(config.option<ConfigOptionEnum<SLADisplayOrientation>>(opt_key)->value);
         }
diff --git a/src/slic3r/GUI/Preset.cpp b/src/slic3r/GUI/Preset.cpp
index 84fae86b3..645ec6f41 100644
--- a/src/slic3r/GUI/Preset.cpp
+++ b/src/slic3r/GUI/Preset.cpp
@@ -186,7 +186,7 @@ void Preset::set_num_extruders(DynamicPrintConfig &config, unsigned int num_extr
 			continue;
         auto *opt = config.option(key, false);
         assert(opt != nullptr);
-        assert(opt->is_vector());
+        //assert(opt->is_vector());
         if (opt != nullptr && opt->is_vector())
             static_cast<ConfigOptionVectorBase*>(opt)->resize(num_extruders, defaults.option(key));
     }
@@ -332,8 +332,11 @@ const std::vector<std::string>& Preset::print_options()
         "support_material", "support_material_auto", "support_material_threshold", "support_material_enforce_layers", 
         "raft_layers", "support_material_pattern", "support_material_with_sheath", "support_material_spacing", 
         "support_material_synchronize_layers", "support_material_angle", "support_material_interface_layers", 
-        "support_material_interface_spacing", "support_material_interface_contact_loops", "support_material_contact_distance", 
-        "support_material_buildplate_only", "dont_support_bridges", "notes", "complete_objects", "extruder_clearance_radius", 
+        "support_material_interface_spacing", "support_material_interface_contact_loops"
+		, "support_material_contact_distance_type"
+		, "support_material_contact_distance_top"
+		, "support_material_contact_distance_bottom" 
+        , "support_material_buildplate_only", "dont_support_bridges", "notes", "complete_objects", "extruder_clearance_radius", 
         "extruder_clearance_height", "gcode_comments", "output_filename_format", "post_process", "perimeter_extruder", 
         "infill_extruder", "solid_infill_extruder", "support_material_extruder", "support_material_interface_extruder", 
         "ooze_prevention", "standby_temperature_delta", "interface_shells", "extrusion_width", "first_layer_extrusion_width", 
diff --git a/src/slic3r/GUI/Tab.cpp b/src/slic3r/GUI/Tab.cpp
index fa67a9b61..76e8e8143 100644
--- a/src/slic3r/GUI/Tab.cpp
+++ b/src/slic3r/GUI/Tab.cpp
@@ -1007,7 +1007,11 @@ void TabPrint::build()
 //		# optgroup->append_single_option_line(get_option_("raft_contact_distance");
 
 		optgroup = page->new_optgroup(_(L("Options for support material and raft")));
-		optgroup->append_single_option_line("support_material_contact_distance");
+        line = { _(L("Z-offset")), "" };
+        line.append_option(optgroup->get_option("support_material_contact_distance_type"));
+        line.append_option(optgroup->get_option("support_material_contact_distance_top"));
+        line.append_option(optgroup->get_option("support_material_contact_distance_bottom"));
+        optgroup->append_line(line);
 		optgroup->append_single_option_line("support_material_pattern");
 		optgroup->append_single_option_line("support_material_with_sheath");
 		optgroup->append_single_option_line("support_material_spacing");
@@ -1221,7 +1225,7 @@ void TabPrint::update()
 	}
 
 	if (m_config->opt_bool("wipe_tower") && m_config->opt_bool("support_material") &&
-		m_config->opt_float("support_material_contact_distance") > 0. &&
+        ((ConfigOptionEnumGeneric*)m_config->option("support_material_contact_distance_type"))->value != zdNone &&
 		(m_config->opt_int("support_material_extruder") != 0 || m_config->opt_int("support_material_interface_extruder") != 0)) {
 		wxString msg_text = _(L("The Wipe Tower currently supports the non-soluble supports only\n"
 			"if they are printed with the current extruder without triggering a tool change.\n"
@@ -1239,7 +1243,7 @@ void TabPrint::update()
 	}
 
 	if (m_config->opt_bool("wipe_tower") && m_config->opt_bool("support_material") &&
-		m_config->opt_float("support_material_contact_distance") == 0 &&
+        ((ConfigOptionEnumGeneric*)m_config->option("support_material_contact_distance_type"))->value == zdNone &&
 		!m_config->opt_bool("support_material_synchronize_layers")) {
 		wxString msg_text = _(L("For the Wipe Tower to work with the soluble supports, the support layers\n"
 			"need to be synchronized with the object layers.\n"
@@ -1390,13 +1394,17 @@ void TabPrint::update()
 	bool have_support_material = m_config->opt_bool("support_material") || have_raft;
 	bool have_support_material_auto = have_support_material && m_config->opt_bool("support_material_auto");
 	bool have_support_interface = m_config->opt_int("support_material_interface_layers") > 0;
-	bool have_support_soluble = have_support_material && m_config->opt_float("support_material_contact_distance") == 0;
+    bool have_support_soluble = have_support_material && ((ConfigOptionEnumGeneric*)m_config->option("support_material_contact_distance_type"))->value == zdNone;
 	for (auto el : {"support_material_pattern", "support_material_with_sheath",
 					"support_material_spacing", "support_material_angle", "support_material_interface_layers",
-					"dont_support_bridges", "support_material_extrusion_width", "support_material_contact_distance",
+					"dont_support_bridges", "support_material_extrusion_width", 
+					"support_material_contact_distance_type", 
 					"support_material_xy_spacing" })
 		get_field(el)->toggle(have_support_material);
-	get_field("support_material_threshold")->toggle(have_support_material_auto);
+    get_field("support_material_threshold")->toggle(have_support_material_auto);
+    for (auto el : { "support_material_contact_distance_top",
+        "support_material_contact_distance_bottom"})
+        get_field(el)->toggle(have_support_material && !have_support_soluble);
 
 	for (auto el : {"support_material_interface_spacing", "support_material_interface_extruder",
 					"support_material_interface_speed", "support_material_interface_contact_loops" })