NEW: enable lightning infill pattern for model and tree support

Change-Id: I6e2cbfdd30f8d222f88301ed0c8cc89e21cfdc24
(cherry picked from commit ddfee7c069cfc42685be509d48b8c609e1dc0cfc)

src/libslic3r/Fill/FillLightning.hpp

@@ -3,6 +3,13 @@
 
 #include "FillBase.hpp"
 
+/*
+* A few modifications based on dba1179(2022.06.10) from Prusa, mainly in Generator.hpp and .cpp: 
+* 1. delete the second parameter(a throw back function) of Generator(), since I didnt find corresponding throw back function in BBS code
+* 2. those codes that call the functions above
+* 3. add codes of generating lightning in TreeSupport.cpp
+*/
+
 namespace Slic3r {
 
 class PrintObject;
@@ -24,8 +31,13 @@ public:
     Generator   *generator { nullptr };
 protected:
     Fill* clone() const override { return new Filler(*this); }
-    // Perform the fill.
-    Polylines fill_surface(const Surface *surface, const FillParams &params) override;
+
+    void _fill_surface_single(const FillParams              &params,
+                              unsigned int                   thickness_layers,
+                              const std::pair<float, Point> &direction,
+                              ExPolygon                      expolygon,
+                              Polylines &polylines_out) override;
+
     // Let the G-code export reoder the infill lines.
 	bool no_sort() const override { return false; }
 };