BoundingBox support for Lines,

BoundingBox constructor will no more throw for empty vector of points.

GMP allowed for Vojtech's fork of boost::polygon Voronoi implementation.

Added libslic3r tests for boost::polygon Voronoi. All Voronoi issues
ever reported on the Internet are captured by the tests. Two issues
reported (the two test cases) are real issues which may influence
PrusaSlicer negatively, namely

https://github.com/boostorg/polygon/issues/43

src/libslic3r/BoundingBox.cpp

@@ -11,17 +11,6 @@ template BoundingBoxBase<Vec2d>::BoundingBoxBase(const std::vector<Vec2d> &point
 
 template BoundingBox3Base<Vec3d>::BoundingBox3Base(const std::vector<Vec3d> &points);
 
-BoundingBox::BoundingBox(const Lines &lines)
-{
-    Points points;
-    points.reserve(lines.size());
-    for (const Line &line : lines) {
-        points.emplace_back(line.a);
-        points.emplace_back(line.b);
-    }
-    *this = BoundingBox(points);
-}
-
 void BoundingBox::polygon(Polygon* polygon) const
 {
     polygon->points.clear();

src/libslic3r/BoundingBox.hpp

@@ -20,9 +20,10 @@ public:
         min(pmin), max(pmax), defined(pmin(0) < pmax(0) && pmin(1) < pmax(1)) {}
     BoundingBoxBase(const std::vector<PointClass>& points) : min(PointClass::Zero()), max(PointClass::Zero())
     {
-        if (points.empty())
-            throw std::invalid_argument("Empty point set supplied to BoundingBoxBase constructor");
-
+        if (points.empty()) {
+            this->defined = false;
+            // throw std::invalid_argument("Empty point set supplied to BoundingBoxBase constructor");
+        } else {
             typename std::vector<PointClass>::const_iterator it = points.begin();
             this->min = *it;
             this->max = *it;
@@ -32,6 +33,7 @@ public:
             }
             this->defined = (this->min(0) < this->max(0)) && (this->min(1) < this->max(1));
         }
+    }
     void reset() { this->defined = false; this->min = PointClass::Zero(); this->max = PointClass::Zero(); }
     void merge(const PointClass &point);
     void merge(const std::vector<PointClass> &points);
@@ -143,7 +145,6 @@ public:
     BoundingBox() : BoundingBoxBase<Point>() {}
     BoundingBox(const Point &pmin, const Point &pmax) : BoundingBoxBase<Point>(pmin, pmax) {}
     BoundingBox(const Points &points) : BoundingBoxBase<Point>(points) {}
-    BoundingBox(const Lines &lines);
 
     friend BoundingBox get_extents_rotated(const Points &points, double angle);
 };

src/libslic3r/Geometry.hpp

@@ -10,6 +10,7 @@
 // Serialization through the Cereal library
 #include <cereal/access.hpp>
 
+#define BOOST_VORONOI_USE_GMP 1
 #include "boost/polygon/voronoi.hpp"
 
 namespace ClipperLib {

src/libslic3r/Line.cpp

@@ -125,4 +125,14 @@ Vec3d Linef3::intersect_plane(double z) const
     return Vec3d(this->a(0) + v(0) * t, this->a(1) + v(1) * t, z);
 }
 
+BoundingBox get_extents(const Lines &lines)
+{
+    BoundingBox bbox;
+    for (const Line &line : lines) {
+        bbox.merge(line.a);
+        bbox.merge(line.b);
+    }
+    return bbox;
+}
+
 }

src/libslic3r/Line.hpp

@@ -103,6 +103,8 @@ public:
     Vec3d b;
 };
 
+extern BoundingBox get_extents(const Lines &lines);
+
 } // namespace Slic3r
 
 // start Boost

src/libslic3r/MotionPlanner.cpp

@@ -6,6 +6,7 @@
 #include <limits> // for numeric_limits
 #include <assert.h>
 
+#define BOOST_VORONOI_USE_GMP 1
 #include "boost/polygon/voronoi.hpp"
 using boost::polygon::voronoi_builder;
 using boost::polygon::voronoi_diagram;

tests/libslic3r/CMakeLists.txt

@@ -16,6 +16,7 @@ add_executable(${_TEST_NAME}_tests
 	test_meshboolean.cpp
 	test_marchingsquares.cpp
 	test_timeutils.cpp
+	test_voronoi.cpp
 	)
 
 if (TARGET OpenVDB::openvdb)