add scarf seam

src/libslic3r/ExtrusionEntity.cpp

@@ -9,6 +9,9 @@
 #include <limits>
 #include <sstream>
 
+//w37
+#include "libslic3r/Utils.hpp"
+
 namespace Slic3r {
     
 void ExtrusionPath::intersect_expolygons(const ExPolygons &collection, ExtrusionEntityCollection* retval) const
@@ -334,4 +337,48 @@ double ExtrusionLoop::min_mm3_per_mm() const
     return min_mm3_per_mm;
 }
 
+//w37
+bool ExtrusionLoop::check_seam_point_angle(double angle_threshold, double min_arm_length) const
+{
+    // go through all the points in the loop and check if the angle between two segments(AB and BC) is less than the threshold
+    size_t idx_prev = 0;
+    size_t idx_curr = 0;
+    size_t idx_next = 0;
+
+    float distance_to_prev = 0;
+    float distance_to_next = 0;
+
+    const auto    _polygon = polygon();
+    const Points &points   = _polygon.points;
+
+    std::vector<float> lengths{};
+    for (size_t point_idx = 0; point_idx < points.size() - 1; ++point_idx) {
+        lengths.push_back((unscale(points[point_idx]) - unscale(points[point_idx + 1])).norm());
+    }
+    lengths.push_back(std::max((unscale(points[0]) - unscale(points[points.size() - 1])).norm(), 0.1));
+
+    // push idx_prev far enough back as initialization
+    while (distance_to_prev < min_arm_length) {
+        idx_prev = Slic3r::prev_idx_modulo(idx_prev, points.size());
+        distance_to_prev += lengths[idx_prev];
+    }
+
+    // push idx_next forward as far as needed
+    while (distance_to_next < min_arm_length) {
+        distance_to_next += lengths[idx_next];
+        idx_next = Slic3r::next_idx_modulo(idx_next, points.size());
+    }
+
+    // Calculate angle between idx_prev, idx_curr, idx_next.
+    const Point &p0 = points[idx_prev];
+    const Point &p1 = points[idx_curr];
+    const Point &p2 = points[idx_next];
+    const auto   a  = angle(p0 - p1, p2 - p1);
+    if (a > 0 ? a < angle_threshold : a > -angle_threshold) {
+        return false;
+    }
+
+    return true;
+}
+
 }