From 77d007c4843c7736cf3d1b295cbc4f060ba8ca23 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Luk=C3=A1=C5=A1=20Hejl?= <hejl.lukas@gmail.com>
Date: Tue, 23 Feb 2021 20:56:36 +0100
Subject: [PATCH] Fixed calculation of a distance from begin of a contour in
 the avoid crossing perimeters.

The total length of a contour was incorrectly computed, which could cause the longest detour was selected instead of the shortest one in some cases.
---
 src/libslic3r/GCode/AvoidCrossingPerimeters.cpp | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/libslic3r/GCode/AvoidCrossingPerimeters.cpp b/src/libslic3r/GCode/AvoidCrossingPerimeters.cpp
index 8801f5b3b..e00284fe1 100644
--- a/src/libslic3r/GCode/AvoidCrossingPerimeters.cpp
+++ b/src/libslic3r/GCode/AvoidCrossingPerimeters.cpp
@@ -283,8 +283,10 @@ static size_t avoid_perimeters_inner(const AvoidCrossingPerimeters::Boundary &bo
         AllIntersectionsVisitor visitor(edge_grid, intersections, Line(start, end));
         edge_grid.visit_cells_intersecting_line(start, end, visitor);
         Vec2d dir = (end - start).cast<double>();
-        for (Intersection &intersection : intersections)
-            intersection.distance = boundary.boundaries_params[intersection.border_idx][intersection.line_idx];
+        for (Intersection &intersection : intersections) {
+            float dist_from_line_begin = (intersection.point - boundary.boundaries[intersection.border_idx][intersection.line_idx]).cast<float>().norm();
+            intersection.distance = boundary.boundaries_params[intersection.border_idx][intersection.line_idx] + dist_from_line_begin;
+        }
         std::sort(intersections.begin(), intersections.end(), [dir](const auto &l, const auto &r) { return (r.point - l.point).template cast<double>().dot(dir) > 0.; });
     }
 
@@ -568,7 +570,7 @@ static void precompute_polygon_distances(const Polygon &polygon, std::vector<flo
     polygon_distances_out.assign(polygon.size() + 1, 0.f);
     for (size_t point_idx = 1; point_idx < polygon.size(); ++point_idx)
         polygon_distances_out[point_idx] = polygon_distances_out[point_idx - 1] + (polygon[point_idx].cast<float>() - polygon[point_idx - 1].cast<float>()).norm();
-    polygon_distances_out.back() = polygon_distances_out[polygon.size() - 1] + (polygon.last_point().cast<float>() - polygon.first_point().cast<float>()).norm();
+    polygon_distances_out.back() = polygon_distances_out[polygon.size() - 1] + (polygon.points.back().cast<float>() - polygon.points.front().cast<float>()).norm();
 }
 
 static void precompute_expolygon_distances(const ExPolygon &ex_polygon, std::vector<std::vector<float>> &expolygon_distances_out)