Add "bridge type" setting.

A bit like the prusa "no thick bridges" but more powerful.

7 files changed, 55 insertions, 33 deletions

diff --git a/resources/ui_layout/print.ui b/resources/ui_layout/print.ui
index ed6cfa481..6ed8eaabc 100644
--- a/resources/ui_layout/print.ui
+++ b/resources/ui_layout/print.ui
@@ -376,8 +376,8 @@ group:sidetext_width$2:Flow
 		setting:fill_top_flow_ratio
 		setting:first_layer_flow_ratio
 	end_line
+	setting:bridge_type
 	setting:external_perimeter_cut_corners
-
 page:Multiple extruders:funnel
 group:Extruders
 	setting:perimeter_extruder
diff --git a/src/libslic3r/Fill/Fill.cpp b/src/libslic3r/Fill/Fill.cpp
index c601a4342..0aa41de77 100644
--- a/src/libslic3r/Fill/Fill.cpp
+++ b/src/libslic3r/Fill/Fill.cpp
@@ -28,6 +28,7 @@ struct SurfaceFillParams : FillParams
     float           angle = 0.f;
     // Non-negative for a bridge.
     float           bridge_angle = 0.f;
+    BridgeType      bridge_type = BridgeType::btFromNozzle;
 
     // Various print settings?
 
@@ -43,6 +44,7 @@ struct SurfaceFillParams : FillParams
         if (this->bridge_angle > rhs.bridge_angle) return true; 
         if (this->bridge_angle < rhs.bridge_angle) return false;
 
+        RETURN_COMPARE_NON_EQUAL(bridge_type);
         RETURN_COMPARE_NON_EQUAL(extruder);
         RETURN_COMPARE_NON_EQUAL_TYPED(unsigned, pattern);
         RETURN_COMPARE_NON_EQUAL(spacing);
@@ -69,6 +71,7 @@ struct SurfaceFillParams : FillParams
                 this->spacing               == rhs.spacing          &&
 //                this->overlap               == rhs.overlap          &&
                 this->angle                 == rhs.angle            &&
+                this->bridge_type           == rhs.bridge_type      &&
                 this->density               == rhs.density          &&
                 this->monotonic             == rhs.monotonic        &&
                 this->connection            == rhs.connection       &&
@@ -127,8 +130,10 @@ std::vector<SurfaceFill> group_fills(const Layer &layer)
                     if (surface.has_pos_bottom())
                         params.connection = region_config.infill_connection_bottom.value;
                     //FIXME for non-thick bridges, shall we allow a bottom surface pattern?
-                    if (is_bridge)
+                    if (is_bridge) {
                         params.connection = InfillConnection::icConnected;
+                        params.bridge_type = region_config.bridge_type.value;
+                    }
                     if (surface.has_pos_external() && !is_bridge)
                         params.pattern = surface.has_pos_top() ? region_config.top_fill_pattern.value : region_config.bottom_fill_pattern.value;
                     else if (!is_bridge)
@@ -193,7 +198,15 @@ std::vector<SurfaceFill> group_fills(const Layer &layer)
                 //    layerm.flow(extrusion_role, (surface.thickness == -1) ? layer.height : surface.thickness);
                 if (is_bridge) {
                     float nozzle_diameter = layer.object()->print()->config().nozzle_diameter.get_at(layerm.region().extruder(extrusion_role, *layer.object()) - 1);
-                    params.flow = Flow::bridging_flow(nozzle_diameter * std::sqrt(region_config.bridge_flow_ratio.get_abs_value(1)), nozzle_diameter);
+                    if (region_config.bridge_type == BridgeType::btFromFlow) {
+                        Flow reference_flow = layerm.flow(FlowRole::frSolidInfill);
+                        double diameter = sqrt(4 * reference_flow.mm3_per_mm() / PI);
+                        params.flow = Flow::bridging_flow(float(diameter), nozzle_diameter);
+                    } else if (region_config.bridge_type == BridgeType::btFromHeight) {
+                        params.flow = Flow::bridging_flow(float(layerm.layer()->height), nozzle_diameter);
+                    } else /*if (region_config.bridge_type == BridgeType::btFromNozzle)*/ {
+                        params.flow = Flow::bridging_flow(nozzle_diameter * std::sqrt(region_config.bridge_flow_ratio.get_abs_value(1)), nozzle_diameter);
+                    }
                 } else
                     params.flow = layerm.region().flow(
                         *layer.object(),
diff --git a/src/libslic3r/LayerRegion.cpp b/src/libslic3r/LayerRegion.cpp
index 59e54387c..ab561944b 100644
--- a/src/libslic3r/LayerRegion.cpp
+++ b/src/libslic3r/LayerRegion.cpp
@@ -31,11 +31,17 @@ Flow LayerRegion::bridging_flow(FlowRole role) const
     const PrintRegion       &region         = this->region();
     const PrintRegionConfig &region_config  = region.config();
     const PrintObject       &print_object   = *this->layer()->object();
-    if (true /*print_object.config().thick_bridges*/) {
-        // The old Slic3r way (different from all other slicers): Use rounded extrusions.
+    // Here this->extruder(role) - 1 may underflow to MAX_INT, but then the get_at() will follback to zero'th element, so everything is all right.
+    auto nozzle_diameter = float(print_object.print()->config().nozzle_diameter.get_at(region.extruder(role, *this->layer()->object()) - 1));
+    if (region_config.bridge_type == BridgeType::btFromFlow) {
+        Flow reference_flow = flow(role);
+        double diameter = sqrt(4 * reference_flow.mm3_per_mm() / PI);
+        return Flow::bridging_flow(float(diameter), nozzle_diameter);
+    } else if (region_config.bridge_type == BridgeType::btFromHeight) {
+        return Flow::bridging_flow(float(m_layer->height), nozzle_diameter);
+    } else /*if (region_config.bridge_type == BridgeType::btFromNozzle)*/ {
+        // The good Slic3r way: Use rounded extrusions.
         // Get the configured nozzle_diameter for the extruder associated to the flow role requested.
-        // Here this->extruder(role) - 1 may underflow to MAX_INT, but then the get_at() will follback to zero'th element, so everything is all right.
-        auto nozzle_diameter = float(print_object.print()->config().nozzle_diameter.get_at(region.extruder(role, *this->layer()->object()) - 1));
         // Applies default bridge spacing.
         return Flow::bridging_flow(float(sqrt(region_config.bridge_flow_ratio.get_abs_value(1.))) * nozzle_diameter, nozzle_diameter);
     }
diff --git a/src/libslic3r/Preset.cpp b/src/libslic3r/Preset.cpp
index 7db1c37dc..4fb97b926 100644
--- a/src/libslic3r/Preset.cpp
+++ b/src/libslic3r/Preset.cpp
@@ -620,7 +620,9 @@ static std::vector<std::string> s_Preset_print_options {
         "top_infill_extrusion_width",
         "support_material_extrusion_width",
         // overlap, ratios
-        "infill_overlap", "bridge_flow_ratio",
+        "infill_overlap",
+        "bridge_flow_ratio",
+        "bridge_type",
         "solid_infill_overlap",
         "infill_anchor",
         "infill_anchor_max",
diff --git a/src/libslic3r/PrintConfig.cpp b/src/libslic3r/PrintConfig.cpp
index 499d5f4fe..56e1651b8 100644
--- a/src/libslic3r/PrintConfig.cpp
+++ b/src/libslic3r/PrintConfig.cpp
@@ -689,13 +689,13 @@ void PrintConfigDef::init_fff_params()
     def = this->add("bridge_type", coEnum);
     def->label = L("Bridge flow baseline");
     def->category = OptionCategory::width;
-    def->tooltip = L("A brideg is an extrusion with nothing under it to flatten it, and so it can't have a 'rectangle' shape but a circle one."
-        "\nThe default way to compute a bridge flow is to use the nozzle diameter as the diameter of the extrusion cross-section. It shouldn't be higher than that to prevent sagging."
-        "\nA second way to compute a bridge flow is to use the current layer height, so it shouldn't protrude below it. Note that may create too thin extrusions and so a bad bridge quality."
-        "\nA Third way to compute a bridge flow is to continue to use the current flow. It's what PrusaSlicer call 'not thick bridge'. If there is no current flow, it will use the perimeter one."
-        " To use if you have some difficulties with the big flow changes from periemter flow to bridge flow and vice-versa."
-        "\nThis setting allow you to choose the base for the bridge flow compute, the result will be multiplied by the bridge flow to have the final result."
-        " The preview will display the expected shape of the bridge extrusion (cylinder), don't expect a magical thick and solid air to flatten the extrusion magically.");
+    def->tooltip = L("This setting allow you to choose the base for the bridge flow compute, the result will be multiplied by the bridge flow to have the final result."
+        "\nA bridge is an extrusion with nothing under it to flatten it, and so it can't have a 'rectangle' shape but a circle one."
+        "\n * The default way to compute a bridge flow is to use the nozzle diameter as the diameter of the extrusion cross-section. It shouldn't be higher than that to prevent sagging."
+        "\n * A second way to compute a bridge flow is to use the current layer height, so it shouldn't protrude below it. Note that may create too thin extrusions and so a bad bridge quality."
+        "\n * A Third way to compute a bridge flow is to continue to use the current section (mm3 per mm). If there is no current flow, it will use the solid infill one."
+        " To use if you have some difficulties with the big flow changes from perimeter and infill flow to bridge flow and vice-versa, the bridge flow ratio let you compensate for the change in speed."
+        " \nThe preview will display the expected shape of the bridge extrusion (cylinder), don't expect a magical thick and solid air to flatten the extrusion magically.");
     def->sidetext = L("%");
     def->enum_keys_map = &ConfigOptionEnum<BridgeType>::get_enum_values();
     def->enum_values.push_back("nozzle");
@@ -703,7 +703,7 @@ void PrintConfigDef::init_fff_params()
     def->enum_values.push_back("flow");
     def->enum_labels.push_back(L("Nozzle diameter"));
     def->enum_labels.push_back(L("Layer height"));
-    def->enum_labels.push_back(L("Keep current flow"));
+    def->enum_labels.push_back(L("Keep current section"));
     def->min = -1;
     def->max = 100;
     def->mode = comAdvanced;
diff --git a/src/libslic3r/PrintConfig.hpp b/src/libslic3r/PrintConfig.hpp
index ea088ae7a..e5f411544 100644
--- a/src/libslic3r/PrintConfig.hpp
+++ b/src/libslic3r/PrintConfig.hpp
@@ -653,7 +653,6 @@ protected: \
 PRINT_CONFIG_CLASS_DEFINE(
     PrintObjectConfig,
 
-    ((ConfigOptionEnum<BridgeType>,     bridge_type))
     ((ConfigOptionBool,                 brim_inside_holes))
     ((ConfigOptionFloat,                brim_width))
     ((ConfigOptionFloat,                brim_width_interior))
@@ -741,6 +740,7 @@ PRINT_CONFIG_CLASS_DEFINE(
     PrintRegionConfig,
 
     ((ConfigOptionFloat,                bridge_angle))
+    ((ConfigOptionEnum<BridgeType>,     bridge_type))
     ((ConfigOptionInt,                  bottom_solid_layers))
     ((ConfigOptionFloat,                bottom_solid_min_thickness))
     ((ConfigOptionPercent,              bridge_flow_ratio))
diff --git a/src/libslic3r/SupportMaterial.cpp b/src/libslic3r/SupportMaterial.cpp
index d1bfa9a4a..87d99e278 100644
--- a/src/libslic3r/SupportMaterial.cpp
+++ b/src/libslic3r/SupportMaterial.cpp
@@ -4393,24 +4393,25 @@ void PrintObjectSupportMaterial::generate_toolpaths(
     });
 
 #ifndef NDEBUG
-    struct Test {
-        static bool verify_nonempty(const ExtrusionEntityCollection *collection) {
-            for (const ExtrusionEntity *ee : collection->entities()) {
-                if (const ExtrusionPath *path = dynamic_cast<const ExtrusionPath*>(ee))
-                    assert(! path->empty());
-                else if (const ExtrusionMultiPath *multipath = dynamic_cast<const ExtrusionMultiPath*>(ee))
-                    assert(! multipath->empty());
-                else if (const ExtrusionEntityCollection *eecol = dynamic_cast<const ExtrusionEntityCollection*>(ee)) {
-                    assert(! eecol->empty());
-                    return verify_nonempty(eecol);
-                } else
-                    assert(false);
-            }
-            return true;
+    class verify_nonempty : public ExtrusionVisitorRecursiveConst {
+    public:
+        virtual void use(const ExtrusionPath& path) override { assert(!path.empty()); }
+        virtual void use(const ExtrusionPath3D& path3D) override { assert(!path3D.empty()); }
+        virtual void use(const ExtrusionMultiPath& truc) override {
+            ExtrusionVisitorRecursiveConst::use(truc); assert(!truc.empty());
+        }
+        virtual void use(const ExtrusionMultiPath3D& truc) override {
+            ExtrusionVisitorRecursiveConst::use(truc); assert(!truc.empty());
+        }
+        virtual void use(const ExtrusionLoop& truc) override {
+            ExtrusionVisitorRecursiveConst::use(truc); assert(!truc.paths.empty());
+        }
+        virtual void use(const ExtrusionEntityCollection& truc) override {
+            ExtrusionVisitorRecursiveConst::use(truc); assert(!truc.empty());
         }
     };
-    for (const SupportLayer *support_layer : support_layers)
-    assert(Test::verify_nonempty(&support_layer->support_fills));
+    for (const SupportLayer* support_layer : support_layers)
+        support_layer->support_fills.visit(verify_nonempty{});
 #endif // NDEBUG
 }