From fac2340989564cb03ad6688317e7e49ef156b43c Mon Sep 17 00:00:00 2001
From: Marius Kintel <marius@kintel.net>
Date: Thu, 27 Nov 2014 20:40:37 -0500
Subject: [PATCH] More correct handling of empty geometry. Should fix a few
 crash bugs

---
 src/GeometryEvaluator.cc | 20 +++++++++++++-------
 src/clipper-utils.cc     | 13 ++++---------
 2 files changed, 17 insertions(+), 16 deletions(-)

diff --git a/src/GeometryEvaluator.cc b/src/GeometryEvaluator.cc
index 0f50141c..71b52a81 100644
--- a/src/GeometryEvaluator.cc
+++ b/src/GeometryEvaluator.cc
@@ -90,7 +90,7 @@ GeometryEvaluator::ResultObject GeometryEvaluator::applyToChildren(const Abstrac
 	}
     if (dim == 2) {
         Polygon2d *p2d = applyToChildren2D(node, op);
-        assert(!p2d || !p2d->isEmpty());
+        assert(p2d);
         return ResultObject(p2d);
     }
     else if (dim == 3) return applyToChildren3D(node, op);
@@ -129,10 +129,16 @@ GeometryEvaluator::ResultObject GeometryEvaluator::applyToChildren3D(const Abstr
 }
 
 
+
+/*!
+	Apply 2D hull.
+
+	May return an empty geometry but will not return NULL.
+*/
 Polygon2d *GeometryEvaluator::applyHull2D(const AbstractNode &node)
 {
 	std::vector<const Polygon2d *> children = collectChildren2D(node);
-	Polygon2d *geometry = NULL;
+	Polygon2d *geometry = new Polygon2d();
 
 	typedef CGAL::Point_2<CGAL::Cartesian<double> > CGALPoint2;
 	// Collect point cloud
@@ -154,7 +160,6 @@ Polygon2d *GeometryEvaluator::applyHull2D(const AbstractNode &node)
 		BOOST_FOREACH(const CGALPoint2 &p, result) {
 			outline.vertices.push_back(Vector2d(p[0], p[1]));
 		}
-		geometry = new Polygon2d();
 		geometry->addOutline(outline);
 	}
 	return geometry;
@@ -275,12 +280,12 @@ Geometry::ChildList GeometryEvaluator::collectChildren3D(const AbstractNode &nod
 		smartCacheInsert(*chnode, chgeom);
 		
 		if (chgeom) {
-			if (chgeom->isEmpty() || chgeom->getDimension() == 3) {
-				children.push_back(item);
-			}
-			else {
+			if (chgeom->getDimension() == 2) {
 				PRINT("WARNING: Ignoring 2D child object for 3D operation");
 			}
+			else if (chgeom->isEmpty() || chgeom->getDimension() == 3) {
+				children.push_back(item);
+			}
 		}
 	}
 	return children;
@@ -447,6 +452,7 @@ Response GeometryEvaluator::visit(State &state, const LeafNode &node)
 		shared_ptr<const Geometry> geom;
 		if (!isSmartCached(node)) {
 			const Geometry *geometry = node.createGeometry();
+            assert(geometry);
 			if (const Polygon2d *polygon = dynamic_cast<const Polygon2d*>(geometry)) {
 				if (!polygon->isSanitized()) {
 					Polygon2d *p = ClipperUtils::sanitize(*polygon);
diff --git a/src/clipper-utils.cc b/src/clipper-utils.cc
index 8754f578..7b1c1463 100644
--- a/src/clipper-utils.cc
+++ b/src/clipper-utils.cc
@@ -84,9 +84,7 @@ namespace ClipperUtils {
 	/*!
 		Apply the clipper operator to the given paths.
 
-		Returns a Polygon2d, or NULL if the result is empty.
-
-		NB! Will not return an empty Polygon2d.
+     May return an empty Polygon2d, but will not return NULL.
 	 */
 	Polygon2d *apply(const std::vector<ClipperLib::Paths> &pathsvector,
 									 ClipperLib::ClipType clipType)
@@ -106,7 +104,7 @@ namespace ClipperUtils {
                     clipper.Clear();
                 }
 			}
-			return (result.Total() == 0) ? NULL : ClipperUtils::toPolygon2d(result);
+			return ClipperUtils::toPolygon2d(result);
 		}
 
 		bool first = true;
@@ -116,7 +114,6 @@ namespace ClipperUtils {
 		}
 		ClipperLib::PolyTree sumresult;
 		clipper.Execute(clipType, sumresult, ClipperLib::pftNonZero, ClipperLib::pftNonZero);
-		if (sumresult.Total() == 0) return NULL;
 		// The returned result will have outlines ordered according to whether 
 		// they're positive or negative: Positive outlines counter-clockwise and 
 		// negative outlines clockwise.
@@ -126,9 +123,7 @@ namespace ClipperUtils {
   /*!
 		Apply the clipper operator to the given polygons.
 		
-		Returns a Polygon2d, or NULL if the result is empty.
-
-		NB! Will not return an empty Polygon2d.
+		May return an empty Polygon2d, but will not return NULL.
 	 */
 	Polygon2d *apply(const std::vector<const Polygon2d*> &polygons, 
 									 ClipperLib::ClipType clipType)
@@ -140,7 +135,7 @@ namespace ClipperUtils {
 			pathsvector.push_back(polypaths);
 		}
 		Polygon2d *res = apply(pathsvector, clipType);
-		assert(!res || !res->isEmpty());
+        assert(res);
 		return res;
 	}