3 files changed, 12 insertions, 7 deletions
diff --git a/svg-flatten/include/gerbolyze.hpp b/svg-flatten/include/gerbolyze.hpp
index dc06c89..aea8748 100644
--- a/svg-flatten/include/gerbolyze.hpp
+++ b/svg-flatten/include/gerbolyze.hpp
@@ -214,7 +214,7 @@ namespace gerbolyze {
 
     class SimpleGerberOutput : public StreamPolygonSink {
     public:
-        SimpleGerberOutput(std::ostream &out, bool only_polys=false, int digits_int=4, int digits_frac=6, double scale=1.0, d2p offset={0,0});
+        SimpleGerberOutput(std::ostream &out, bool only_polys=false, int digits_int=4, int digits_frac=6, double scale=1.0, d2p offset={0,0}, bool flip_polarity=false);
         virtual ~SimpleGerberOutput() {}
         virtual SimpleGerberOutput &operator<<(const Polygon &poly);
         virtual SimpleGerberOutput &operator<<(GerberPolarityToken pol);
@@ -229,6 +229,7 @@ namespace gerbolyze {
         long long int m_gerber_scale;
         d2p m_offset;
         double m_scale;
+        bool m_flip_pol;
     };
 
     class SimpleSVGOutput : public StreamPolygonSink {
diff --git a/svg-flatten/src/main.cpp b/svg-flatten/src/main.cpp
index 0abe3d1..722b356 100644
--- a/svg-flatten/src/main.cpp
+++ b/svg-flatten/src/main.cpp
@@ -39,6 +39,9 @@ int main(int argc, char **argv) {
             {"svg_dark_color", {"--dark-color"},
                 "SVG color to use for \"dark\" areas (default: black)",
                 1},
+            {"flip_gerber_polarity", {"-f", "--flip-gerber-polarity"},
+                "Flip polarity of all output gerber primitives for --format gerber.",
+                0},
             {"min_feature_size", {"-d", "--trace-space"},
                 "Minimum feature size of elements in vectorized graphics (trace/space) in mm. Default: 0.1mm.",
                 1},
@@ -189,7 +192,7 @@ int main(int argc, char **argv) {
     } else if (fmt == "gbr" || fmt == "grb" || fmt == "gerber") {
         double scale = args["scale"].as<double>(1.0);
         cerr << "loading @scale=" << scale << endl;
-        sink = new SimpleGerberOutput(*out_f, only_polys, 4, precision, scale);
+        sink = new SimpleGerberOutput(*out_f, only_polys, 4, precision, scale, {0,0}, args["flip_gerber_polarity"]);
 
     } else if (fmt == "s-exp" || fmt == "sexp" || fmt == "kicad") {
         if (!args["sexp_mod_name"]) {
diff --git a/svg-flatten/src/out_gerber.cpp b/svg-flatten/src/out_gerber.cpp
index f16a06b..9513c0b 100644
--- a/svg-flatten/src/out_gerber.cpp
+++ b/svg-flatten/src/out_gerber.cpp
@@ -27,12 +27,13 @@
 using namespace gerbolyze;
 using namespace std;
 
-SimpleGerberOutput::SimpleGerberOutput(ostream &out, bool only_polys, int digits_int, int digits_frac, double scale, d2p offset)
+SimpleGerberOutput::SimpleGerberOutput(ostream &out, bool only_polys, int digits_int, int digits_frac, double scale, d2p offset, bool flip_polarity)
     : StreamPolygonSink(out, only_polys),
     m_digits_int(digits_int),
     m_digits_frac(digits_frac),
     m_offset(offset),
-    m_scale(scale)
+    m_scale(scale),
+    m_flip_pol(flip_polarity)
 {
     assert(1 <= digits_int && digits_int <= 9);
     assert(0 <= digits_frac && digits_frac <= 9);
@@ -58,12 +59,12 @@ void SimpleGerberOutput::header_impl(d2p origin, d2p size) {
 }
 
 SimpleGerberOutput& SimpleGerberOutput::operator<<(GerberPolarityToken pol) {
-    if (pol == GRB_POL_DARK) {
+    assert(pol == GRB_POL_DARK || pol == GRB_POL_CLEAR);
+
+    if ((pol == GRB_POL_DARK) != m_flip_pol) {
         m_out << "%LPD*%" << endl;
     } else if (pol == GRB_POL_CLEAR) {
         m_out << "%LPC*%" << endl;
-    } else {
-        assert(false);
     }
 
     return *this;