From 7c6ecf8a06302c4896fa1477a3f9e98b5c91587f Mon Sep 17 00:00:00 2001
From: EiNSTeiN- <einstein@g3nius.org>
Date: Sun, 2 Jul 2023 14:21:33 -0400
Subject: [PATCH] Fix artifacts created when manipulating extrusion loops and
 other gcode generation issues

---
 src/libslic3r/GCode.cpp    |  8 ++++++--
 src/libslic3r/Polyline.cpp | 14 +++++++++++---
 2 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/src/libslic3r/GCode.cpp b/src/libslic3r/GCode.cpp
index d5919f552..5b4b0a651 100644
--- a/src/libslic3r/GCode.cpp
+++ b/src/libslic3r/GCode.cpp
@@ -2787,10 +2787,11 @@ std::string GCode::extrude_loop(ExtrusionLoop loop, const std::string_view descr
         // Shift by no more than a nozzle diameter.
         //FIXME Hiding the seams will not work nicely for very densely discretized contours!
         Point  pt = ((nd * nd >= l2) ? p2 : (p1 + v * (nd / sqrt(l2)))).cast<coord_t>();
+        pt.nonplanar_z = paths.front().polyline.points.front().nonplanar_z;
         // Rotate pt inside around the seam point.
         pt.rotate(angle_inside / 3., paths.front().polyline.points.front());
         // generate the travel move
-        gcode += m_writer.travel_to_xy(this->point_to_gcode(pt), "move inwards before travel");
+        gcode += m_writer.travel_to_xyz(this->point3_to_gcode(pt), "move inwards before travel");
     }
 
     return gcode;
@@ -3279,7 +3280,10 @@ std::string GCode::travel_to(const Point &point, ExtrusionRole role, std::string
 
         // Move Z up if necessary
         if (needs_zmove) {
-            gcode += m_writer.travel_to_z(this->layer()->print_z, "Move up for non planar extrusion");
+            float move_z = unscale<double>(travel.points[0].nonplanar_z);
+            if(travel.points[0].nonplanar_z == -1)
+                move_z = this->layer()->print_z;
+            gcode += m_writer.travel_to_z(move_z, "Move up for non planar extrusion");
         }
 
         gcode += m_writer.set_travel_acceleration((unsigned int)(m_config.travel_acceleration.value + 0.5));
diff --git a/src/libslic3r/Polyline.cpp b/src/libslic3r/Polyline.cpp
index ec7732ccf..05ecc444a 100644
--- a/src/libslic3r/Polyline.cpp
+++ b/src/libslic3r/Polyline.cpp
@@ -51,7 +51,9 @@ void Polyline::clip_end(double distance)
         Vec2d  v    = this->last_point().cast<double>() - last_point;
         double lsqr = v.squaredNorm();
         if (lsqr > distance * distance) {
-            this->points.emplace_back((last_point + v * (distance / sqrt(lsqr))).cast<coord_t>());
+            Point p((last_point + v * (distance / sqrt(lsqr))).cast<coord_t>());
+            p.nonplanar_z = this->last_point().nonplanar_z;
+            this->points.emplace_back(p);
             return;
         }
         distance -= sqrt(lsqr);
@@ -102,7 +104,9 @@ Points Polyline::equally_spaced_points(double distance) const
             continue;
         }
         double take = segment_length - (len - distance);  // how much we take of this segment
-        points.emplace_back((p1 + v * (take / v.norm())).cast<coord_t>());
+        Point p((p1 + v * (take / v.norm())).cast<coord_t>());
+        p.nonplanar_z = (*it).nonplanar_z;
+        points.emplace_back(p);
         -- it;
         len = - take;
     }
@@ -247,6 +251,7 @@ std::pair<int, Point> foot_pt(const Points &polyline, const Point &pt)
         if (double d2 = line_alg::distance_to_squared(Line(prev, *it), pt, &foot_pt); d2 < d2_min) {
             d2_min      = d2;
             foot_pt_min = foot_pt;
+            foot_pt_min.nonplanar_z = (*it).nonplanar_z;
             it_proj     = it;
         }
         prev = *it;
@@ -272,6 +277,7 @@ void ThickPolyline::clip_end(double distance)
         assert(this->width.size() == (this->points.size() - 1) * 2);
         while (distance > 0) {
             Vec2d last_point = this->last_point().cast<double>();
+            coord_t last_z = this->last_point().nonplanar_z;
             this->points.pop_back();
             if (this->points.empty()) {
                 assert(this->width.empty());
@@ -285,7 +291,9 @@ void ThickPolyline::clip_end(double distance)
             double   vec_length_sqr = vec.squaredNorm();
             if (vec_length_sqr > distance * distance) {
                 double t = (distance / std::sqrt(vec_length_sqr));
-                this->points.emplace_back((last_point + vec * t).cast<coord_t>());
+                Point p((last_point + vec * t).cast<coord_t>());
+                p.nonplanar_z = last_z;
+                this->points.emplace_back(p);
                 this->width.emplace_back(last_width + width_diff * t);
                 assert(this->width.size() == (this->points.size() - 1) * 2);
                 return;