From: Walter Doekes <walter+github@wjd.nu>
Date: Sun, 17 Jul 2022 20:16:36 +0000 (+0200)
Subject: Do not crash in Winding_Clip when using -D_GLIBCXX_ASSERTIONS
X-Git-Url: https://git.rm.cloudns.org/?a=commitdiff_plain;h=bf7521b8672fe7554ade075542ba4e8ffe6f7305;p=xonotic%2Fnetradiant.git

Do not crash in Winding_Clip when using -D_GLIBCXX_ASSERTIONS

When setting -D_GLIBCXX_ASSERTIONS, invalid vector accesses are found,
like empty_vector.back(). In this case, the result was not used so the
bug wasn't found without the assertion.

This changeset fixes so dragging a brush to 0 size does not crash/abort
netradiant.

Closes #156.
---

diff --git a/radiant/winding.cpp b/radiant/winding.cpp
index 9651af2c..8865db52 100644
--- a/radiant/winding.cpp
+++ b/radiant/winding.cpp
@@ -194,6 +194,10 @@ const double DEBUG_EPSILON_SQUARED = DEBUG_EPSILON * DEBUG_EPSILON;
 /// If \p winding is completely in back of the plane, \p clipped will be empty.
 /// If \p winding intersects the plane, the edge of \p clipped which lies on \p clipPlane will store the value of \p adjacent.
 void Winding_Clip( const FixedWinding& winding, const Plane3& plane, const Plane3& clipPlane, std::size_t adjacent, FixedWinding& clipped ){
+	// if there are no points, we're done
+	if ( winding.size() == 0 ) {
+		return;
+	}
 	PlaneClassification classification = Winding_ClassifyDistance( plane3_distance_to_point( clipPlane, winding.back().vertex ), ON_EPSILON );
 	PlaneClassification nextClassification;
 	// for each edge