From a34da81ac5d4207b2b977d83f432e7ea498f0f29 Mon Sep 17 00:00:00 2001
From: Richard Brice <37087370+RickBrice@users.noreply.github.com>
Date: Wed, 10 Apr 2024 14:09:46 -0700
Subject: [PATCH] Fixes tilt slope for cant

---
 src/ifcgeom/mapping/IfcCurveSegment.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/ifcgeom/mapping/IfcCurveSegment.cpp b/src/ifcgeom/mapping/IfcCurveSegment.cpp
index 7949cbd7b2..c4b2e769cf 100644
--- a/src/ifcgeom/mapping/IfcCurveSegment.cpp
+++ b/src/ifcgeom/mapping/IfcCurveSegment.cpp
@@ -272,7 +272,7 @@ class cant_adjuster : public GEOMETRY_ADJUSTER {
        // compute h is greater than PI/2 and the tangent of that angle is negative.
        // For this reason, use fabs(h) so tilt is between 0 and PI
        double cant = parent_curve_point.col(3)(1);
-       auto tilt = atan2(fabs(h), cant);
+       auto tilt = -atan2(fabs(h), cant);
 
        // Create a transformation matrix
        Eigen::Matrix4d m = Eigen::Matrix4d::Identity();