WIP

6 files changed, 92 insertions, 42 deletions

diff --git a/svg-flatten/include/geom2d.hpp b/svg-flatten/include/geom2d.hpp
index 4fafd80..47cf3be 100644
--- a/svg-flatten/include/geom2d.hpp
+++ b/svg-flatten/include/geom2d.hpp
@@ -104,11 +104,26 @@ namespace gerbolyze {
             };
 
             double doc2phys_dist(double dist_doc) {
-                return dist_doc * sqrt(xx*xx + xy * xy);
+                return dist_doc * sqrt(xx*xx + xy*xy);
             }
 
             double phys2doc_dist(double dist_doc) {
-                return dist_doc / sqrt(xx*xx + xy * xy);
+                return dist_doc / sqrt(xx*xx + xy*xy);
+            }
+
+            double doc2phys_skew(double dist_doc) {
+                /* https://math.stackexchange.com/a/3521141 */
+                /* xx yx x0
+                 * xy yy y0 */
+                s_x = sqrt();
+            }
+
+            double doc2phys_min(double dist_doc) {
+                return dist_doc * fmin(sqrt(xx*xx + xy*xy), sqrt(yy*yy + yx*yx));
+            }
+
+            double doc2phys_max(double dist_doc) {
+                return dist_doc * fmax(sqrt(xx*xx + xy*xy), sqrt(yy*yy + yx*yx));
             }
 
             d2p doc2phys(const d2p p) {
@@ -141,13 +156,31 @@ namespace gerbolyze {
             }
 
             /* Transform given clipper paths */
-            void transform_paths(ClipperLib::Paths &paths) {
+            void doc2phys_clipper(ClipperLib::Paths &paths) {
+                for (auto &p : paths) {
+                    doc2phys_clipper(p);
+                }
+            }
+
+            void doc2phys_clipper(ClipperLib::Path &path) {
+                std::transform(path.begin(), path.end(), path.begin(),
+                        [this](ClipperLib::IntPoint p) -> ClipperLib::IntPoint {
+                            d2p out(this->doc2phys(d2p{p.X / clipper_scale, p.Y / clipper_scale}));
+                            return {
+                                (ClipperLib::cInt)round(out[0] * clipper_scale),
+                                (ClipperLib::cInt)round(out[1] * clipper_scale)
+                            };
+                        });
+            }
+
+            /* Transform given clipper paths */
+            void phys2doc_clipper(ClipperLib::Paths &paths) {
                 for (auto &p : paths) {
-                    transform_clipper_path(p);
+                    phys2doc_clipper(p);
                 }
             }
 
-            void transform_clipper_path(ClipperLib::Path &path) {
+            void phys2doc_clipper(ClipperLib::Path &path) {
                 std::transform(path.begin(), path.end(), path.begin(),
                         [this](ClipperLib::IntPoint p) -> ClipperLib::IntPoint {
                             d2p out(this->doc2phys(d2p{p.X / clipper_scale, p.Y / clipper_scale}));
diff --git a/svg-flatten/include/gerbolyze.hpp b/svg-flatten/include/gerbolyze.hpp
index 8bd948a..f90b9bf 100644
--- a/svg-flatten/include/gerbolyze.hpp
+++ b/svg-flatten/include/gerbolyze.hpp
@@ -208,7 +208,8 @@ namespace gerbolyze {
     class RenderSettings {
     public:
         double m_minimum_feature_size_mm = 0.1;
-        double curve_tolerance_mm;
+        double geometric_tolerance_mm = 0.1;
+        double stroke_width_cutoff = 0.01;
         double drill_test_polsby_popper_tolerance = 0.01;
         double aperture_circle_test_tolerance = 0.01;
         double aperture_rect_test_tolerance = 0.01;
diff --git a/svg-flatten/src/main.cpp b/svg-flatten/src/main.cpp
index 1fe3454..6ba32a9 100644
--- a/svg-flatten/src/main.cpp
+++ b/svg-flatten/src/main.cpp
@@ -82,8 +82,11 @@ int main(int argc, char **argv) {
             {"min_feature_size", {"-d", "--trace-space"},
                 "Minimum feature size of elements in vectorized graphics (trace/space) in mm. Default: 0.1mm.",
                 1},
-            {"curve_tolerance", {"-c", "--curve-tolerance"},
-                "Tolerance for curve flattening in mm. Default: 0.1mm.",
+            {"geometric_tolerance", {"-t", "--tolerance"},
+                "Tolerance in mm for geometric approximation such as curve flattening. Default: 0.1mm.",
+                1},
+            {"stroke_width_cutoff", {"--min-stroke-width"},
+                "Don't render strokes thinner than the given width in mm. Default: 0.01mm.",
                 1},
             {"drill_test_polsby_popper_tolerance", {"--drill-test-tolerance"},
                 "Tolerance for identifying circles as drills in outline mode",
@@ -313,7 +316,8 @@ int main(int argc, char **argv) {
     delete vec;
 
     double min_feature_size = args["min_feature_size"].as<double>(0.1); /* mm */
-    double curve_tolerance = args["curve_tolerance"].as<double>(0.1); /* mm */
+    double geometric_tolerance = args["geometric_tolerance"].as<double>(0.1); /* mm */
+    double stroke_width_cutoff = args["stroke_width_cutoff"].as<double>(0.01); /* mm */
     double drill_test_polsby_popper_tolerance = args["drill_test_polsby_popper_tolerance"].as<double>(0.1);
     double aperture_rect_test_tolerance = args["aperture_rect_test_tolerance"].as<double>(0.1);
     double aperture_circle_test_tolerance = args["aperture_circle_test_tolerance"].as<double>(0.1);
@@ -450,7 +454,8 @@ int main(int argc, char **argv) {
 
     RenderSettings rset {
         min_feature_size,
-        curve_tolerance,
+        geometric_tolerance,
+        stroke_width_cutoff,
         drill_test_polsby_popper_tolerance,
         aperture_circle_test_tolerance,
         aperture_rect_test_tolerance,
diff --git a/svg-flatten/src/svg_doc.cpp b/svg-flatten/src/svg_doc.cpp
index 323a12b..df6e67a 100644
--- a/svg-flatten/src/svg_doc.cpp
+++ b/svg-flatten/src/svg_doc.cpp
@@ -159,7 +159,7 @@ void gerbolyze::SVGDocument::export_svg_group(RenderContext &ctx, const pugi::xm
 
     } else {
         clip_path = *lookup;
-        ctx.mat().transform_paths(clip_path);
+        ctx.mat().doc2phys_clipper(clip_path);
     }
 
     /* Clip against parent's clip path (both are now in document coordinates) */
@@ -225,6 +225,13 @@ void gerbolyze::SVGDocument::export_svg_group(RenderContext &ctx, const pugi::xm
 
 /* Export an SVG path element to gerber. Apply patterns and clip on the fly. */
 void gerbolyze::SVGDocument::export_svg_path(RenderContext &ctx, const pugi::xml_node &node) {
+    /* Important note on the document transform:
+     *
+     * We have to make sure that we dash & stroke (outline) the path *before* transforming into physical units because
+     * the transform may not be uniform, i.e. scale may depend on direction. As an example, imagine you stroke a 10 by
+     * 10mm square with an 1mm stroke, but there is a transform that scales by 1 in y-direction, and 2 in x-direction.
+     * In the output, the stroke is going to be 2mm wide on the left and right, and 1mm wide on the top/bottom.
+     */
     enum gerber_color fill_color = gerber_fill_color(node, ctx.settings());
     enum gerber_color stroke_color = gerber_stroke_color(node, ctx.settings());
     //cerr << "path: resolved colors, stroke=" << stroke_color << ", fill=" << fill_color << endl;
@@ -242,19 +249,22 @@ void gerbolyze::SVGDocument::export_svg_path(RenderContext &ctx, const pugi::xml
         return;
     }
 
-    /* Load path from SVG path data and transform into document units. */
-    stroke_width = ctx.mat().doc2phys_dist(stroke_width);
-
+    /* Load path from SVG path data */
     Paths stroke_open, stroke_closed;
     PolyTree ptree_fill;
     PolyTree ptree;
-    load_svg_path(ctx.mat(), node, stroke_open, stroke_closed, ptree_fill, ctx.settings().curve_tolerance_mm);
+    double geometric_tolerance_px = ctx.mat().doc2phys_min(ctx.settings().geometric_tolerance_mm);
+    load_svg_path(node, stroke_open, stroke_closed, ptree_fill, geometric_tolerance_px);
 
     Paths fill_paths;
     PolyTreeToPaths(ptree_fill, fill_paths);
+    /* Since we do not need to stroke them, transform the fill paths to physical units now. For polsby-popper to work
+     * properly, they need to be transformed already. However, we leave the stroke paths un-transformed since they can
+     * only be transformed after outlining. */ 
+    ctx.mat().doc2phys_clipper(fill_paths);
 
     bool has_fill = fill_color;
-    bool has_stroke = stroke_color && stroke_width > 0.0;
+    bool has_stroke = stroke_color && ctx.mat().doc2phys_min(stroke_width) > ctx.settings().stroke_width_cutoff;
 
     cerr << "processing svg path" << endl;
     cerr << "  * " << fill_paths.size() << " fill paths" << endl;
@@ -288,7 +298,6 @@ void gerbolyze::SVGDocument::export_svg_path(RenderContext &ctx, const pugi::xml
                 centroid[0] /= clipper_scale;
                 centroid[1] /= clipper_scale;
                 double diameter = sqrt(4*fabs(area)/M_PI) / clipper_scale;
-                diameter = ctx.mat().doc2phys_dist(diameter); /* FIXME is this correct w.r.t. PolygonScaler? */
                 diameter = round(diameter * 1000.0) / 1000.0; /* Round to micrometer precsion; FIXME: make configurable */
                 ctx.sink() << ApertureToken(diameter) << FlashToken(centroid);
             }
@@ -375,6 +384,7 @@ void gerbolyze::SVGDocument::export_svg_path(RenderContext &ctx, const pugi::xml
             auto open_copy(stroke_open);
             stroke_open.clear();
 
+            /* FIXME do we handle really really long dashes correctly? */
             for (auto &poly : stroke_closed) {
                 poly.push_back(poly[0]);
                 dash_path(poly, stroke_open, dasharray, stroke_dashoffset);
@@ -387,7 +397,10 @@ void gerbolyze::SVGDocument::export_svg_path(RenderContext &ctx, const pugi::xml
             }
         }
 
-        if (stroke_color != GRB_PATTERN_FILL) {
+        if (stroke_color != GRB_PATTERN_FILL
+                && ctx.sink().can_do_apertures()
+                /* check if we have an uniform transform */
+                && ctx.mat().doc2phys_skew(stroke_width) < ctx.settings().geometric_tolerance_mm) {
             // cerr << "Analyzing direct conversion of stroke" << endl;
             // cerr << "  stroke_closed.size() = " << stroke_closed.size() << endl;
             // cerr << "  stroke_open.size() = " << stroke_open.size() << endl;
@@ -403,11 +416,15 @@ void gerbolyze::SVGDocument::export_svg_path(RenderContext &ctx, const pugi::xml
             Paths dilated_clip;
             ClosedPathsFromPolyTree(clip_ptree, dilated_clip);
 
+            Paths stroke_open_phys(stroke_open), stroke_closed_phys(stroke_closed);
+            ctx.mat().doc2phys_clipper(stroke_open_phys);
+            ctx.mat().doc2phys_clipper(stroke_closed_phys);
+
             Clipper stroke_clip;
             stroke_clip.StrictlySimple(true);
             stroke_clip.AddPaths(dilated_clip, ptClip, /* closed */ true);
-            stroke_clip.AddPaths(stroke_closed, ptSubject, /* closed */ true);
-            stroke_clip.AddPaths(stroke_open, ptSubject, /* closed */ false);
+            stroke_clip.AddPaths(stroke_closed_phys, ptSubject, /* closed */ true);
+            stroke_clip.AddPaths(stroke_open_phys, ptSubject, /* closed */ false);
             stroke_clip.Execute(ctDifference, ptree, pftNonZero, pftNonZero);
             cerr << "  > " << ptree.ChildCount() << " clipped stroke ptree top-level children" << endl;
             
@@ -433,7 +450,7 @@ void gerbolyze::SVGDocument::export_svg_path(RenderContext &ctx, const pugi::xml
             // cerr << "  ends_can_be_mapped = " << ends_can_be_mapped << endl;
             // cerr << "  joins_can_be_mapped = " << joins_can_be_mapped << endl;
             /* Accept loss of precision in outline mode. */
-            if (ctx.sink().can_do_apertures() && (ctx.settings().outline_mode || gerber_lossless )) {
+            if (ctx.settings().outline_mode || gerber_lossless) {
                 // cerr << "  -> converting directly" << endl;
                 ctx.sink() << ApertureToken(stroke_width);
                 for (auto &path : stroke_closed) {
@@ -452,7 +469,7 @@ void gerbolyze::SVGDocument::export_svg_path(RenderContext &ctx, const pugi::xml
         }
 
         ClipperOffset offx;
-        offx.ArcTolerance = 0.01 * clipper_scale; /* 10µm; TODO: Make this configurable */
+        offx.ArcTolerance = ctx.mat().phys2doc_min(ctx.settings().geometric_tolerance_mm) * clipper_scale;
         offx.MiterLimit = stroke_miterlimit;
 
         //cerr << "offsetting " << stroke_closed.size() << " closed and " << stroke_open.size() << " open paths" << endl;
@@ -468,9 +485,13 @@ void gerbolyze::SVGDocument::export_svg_path(RenderContext &ctx, const pugi::xml
         if (!ctx.clip().empty()) {
             Paths outline_paths;
             PolyTreeToPaths(ptree, outline_paths);
+
+            Paths clip(ctx.clip());
+            ctx.mat().phys2doc_clipper(clip);
+
             Clipper stroke_clip;
             stroke_clip.StrictlySimple(true);
-            stroke_clip.AddPaths(ctx.clip(), ptClip, /* closed */ true);
+            stroke_clip.AddPaths(clip, ptClip, /* closed */ true);
             stroke_clip.AddPaths(outline_paths, ptSubject, /* closed */ true);
             /* fill rules are nonzero since both subject and clip have already been normalized by clipper. */ 
             stroke_clip.Execute(ctIntersection, ptree, pftNonZero, pftNonZero);
@@ -486,6 +507,8 @@ void gerbolyze::SVGDocument::export_svg_path(RenderContext &ctx, const pugi::xml
             } else {
                 Paths clip;
                 PolyTreeToPaths(ptree, clip);
+                ctx.mat().phys2doc_clipper(clip);
+
                 RenderContext local_ctx(ctx, xform2d(), clip, true);
                 pattern->tile(local_ctx);
             }
@@ -493,6 +516,7 @@ void gerbolyze::SVGDocument::export_svg_path(RenderContext &ctx, const pugi::xml
         } else {
             Paths s_polys;
             dehole_polytree(ptree, s_polys);
+            ctx.mat().doc2phys_clipper(s_polys);
             /* color has alredy been pushed above. */
             ctx.sink() << ApertureToken() << s_polys;
         }
@@ -566,7 +590,7 @@ void gerbolyze::SVGDocument::load_clips(const RenderSettings &rset) {
             xform2d child_xf(local_xf);
             child_xf.transform(xform2d(child.attribute("transform").value()));
 
-            load_svg_path(child_xf, child, _stroke_open, _stroke_closed, ptree_fill, rset.curve_tolerance_mm);
+            load_svg_path(child_xf, child, _stroke_open, _stroke_closed, ptree_fill, rset.geometric_tolerance_mm);
 
             Paths paths;
             PolyTreeToPaths(ptree_fill, paths);
diff --git a/svg-flatten/src/svg_path.cpp b/svg-flatten/src/svg_path.cpp
index 71c7bd2..e2ed370 100644
--- a/svg-flatten/src/svg_path.cpp
+++ b/svg-flatten/src/svg_path.cpp
@@ -28,7 +28,7 @@
 
 using namespace std;
 
-static pair<bool, bool> flatten_path(gerbolyze::xform2d &mat, ClipperLib::Paths &stroke_open, ClipperLib::Paths &stroke_closed, ClipperLib::Clipper &c_fill, const pugi::char_t *path_data, double distance_tolerance_mm) {
+static pair<bool, bool> flatten_path(ClipperLib::Paths &stroke_open, ClipperLib::Paths &stroke_closed, ClipperLib::Clipper &c_fill, const pugi::char_t *path_data, double distance_tolerance_px) {
     istringstream in(path_data);
 
     string cmd;
@@ -63,14 +63,6 @@ static pair<bool, bool> flatten_path(gerbolyze::xform2d &mat, ClipperLib::Paths
             in >> a[0] >> a[1];
             assert (!in.fail()); /* guaranteed by usvg */
 
-            /* We need to transform all points ourselves here, and cannot use the transform feature of cairo_to_clipper:
-             * Our transform may contain offsets, and clipper only passes its data into cairo's transform functions
-             * after scaling up to its internal fixed-point ints, but it does not scale the transform accordingly. This
-             * means a scale/rotation we set before calling clipper works out fine, but translations get lost as they
-             * get scaled by something like 1e-6.
-             */
-            a = mat.doc2phys(a);
-
             in_poly.emplace_back(ClipperLib::IntPoint{
                     (ClipperLib::cInt)round(a[0]*clipper_scale),
                     (ClipperLib::cInt)round(a[1]*clipper_scale)
@@ -80,7 +72,6 @@ static pair<bool, bool> flatten_path(gerbolyze::xform2d &mat, ClipperLib::Paths
             in >> a[0] >> a[1];
             assert (!in.fail()); /* guaranteed by usvg */
 
-            a = mat.doc2phys(a);
             in_poly.emplace_back(ClipperLib::IntPoint{
                     (ClipperLib::cInt)round(a[0]*clipper_scale),
                     (ClipperLib::cInt)round(a[1]*clipper_scale)
@@ -93,11 +84,7 @@ static pair<bool, bool> flatten_path(gerbolyze::xform2d &mat, ClipperLib::Paths
             in >> d[0] >> d[1]; /* end point */
             assert (!in.fail()); /* guaranteed by usvg */
 
-            b = mat.doc2phys(b);
-            c = mat.doc2phys(c);
-            d = mat.doc2phys(d);
-
-            gerbolyze::curve4_div c4div(distance_tolerance_mm);
+            gerbolyze::curve4_div c4div(distance_tolerance_px);
             c4div.run(a[0], a[1], b[0], b[1], c[0], c[1], d[0], d[1]);
 
             for (auto &pt : c4div.points()) {
@@ -122,7 +109,7 @@ static pair<bool, bool> flatten_path(gerbolyze::xform2d &mat, ClipperLib::Paths
     return {has_closed, num_subpaths > 1};
 }
 
-void gerbolyze::load_svg_path(xform2d &mat, const pugi::xml_node &node, ClipperLib::Paths &stroke_open, ClipperLib::Paths &stroke_closed, ClipperLib::PolyTree &ptree_fill, double curve_tolerance) {
+void gerbolyze::load_svg_path(const pugi::xml_node &node, ClipperLib::Paths &stroke_open, ClipperLib::Paths &stroke_closed, ClipperLib::PolyTree &ptree_fill, double geometric_tolerance_px) {
     auto *path_data = node.attribute("d").value();
     auto fill_rule = clipper_fill_rule(node);
 
@@ -131,7 +118,7 @@ void gerbolyze::load_svg_path(xform2d &mat, const pugi::xml_node &node, ClipperL
      * open/closed properties for stroke offsetting. */
     ClipperLib::Clipper c_fill;
     c_fill.StrictlySimple(true);
-    auto res = flatten_path(mat, stroke_open, stroke_closed, c_fill, path_data, curve_tolerance);
+    auto res = flatten_path(stroke_open, stroke_closed, c_fill, path_data, geometric_tolerance_px);
     bool has_closed = res.first, has_multiple = res.second;
 
     if (!has_closed && !has_multiple) {
diff --git a/svg-flatten/src/svg_path.h b/svg-flatten/src/svg_path.h
index c0b2d88..4e62a1b 100644
--- a/svg-flatten/src/svg_path.h
+++ b/svg-flatten/src/svg_path.h
@@ -23,7 +23,7 @@
 #include "geom2d.hpp"
 
 namespace gerbolyze {
-void load_svg_path(xform2d &mat, const pugi::xml_node &node, ClipperLib::Paths &stroke_open, ClipperLib::Paths &stroke_closed, ClipperLib::PolyTree &ptree_fill, double curve_tolerance);
+void load_svg_path(const pugi::xml_node &node, ClipperLib::Paths &stroke_open, ClipperLib::Paths &stroke_closed, ClipperLib::PolyTree &ptree_fill, double geometric_tolerance_px);
 void parse_dasharray(const pugi::xml_node &node, std::vector<double> &out);
 void dash_path(const ClipperLib::Path &in, ClipperLib::Paths &out, const std::vector<double> dasharray, double dash_offset=0.0);
 }