compile problem related to sdf.hpp

[mohradza]

When trying to compile Btraj, I am getting the following compiler error:

In file included from /home/ohrad/catkin_ws/src/Btraj/third_party/sdf_tools/include/sdf_tools/collision_map.hpp:14:0,
from /home/ohrad/catkin_ws/src/Btraj/include/a_star.h:9,
from /home/ohrad/catkin_ws/src/Btraj/src/a_star.cpp:1:
/home/ohrad/catkin_ws/src/Btraj/third_party/sdf_tools/include/sdf_tools/sdf.hpp: In member function ‘double sdf_tools::SignedDistanceField::EstimateDistanceInternal(double, double, double, int64_t, int64_t, int64_t) const’:
/home/ohrad/catkin_ws/src/Btraj/third_party/sdf_tools/include/sdf_tools/sdf.hpp:435:89: error: operands to ?: have different types ‘const ScalarMultipleReturnType {aka const Eigen::CwiseUnaryOp<Eigen::internal::scalar_multiple_op, const Eigen::Matrix<double, 3, 1> >}’ and ‘const Vector3d {aka const Eigen::Matrix<double, 3, 1>}’
const Eigen::Vector3d direction_to_boundary = (nominal_sdf_distance >= 0.0) ? -gradient : gradient;
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
/home/ohrad/catkin_ws/src/Btraj/third_party/sdf_tools/include/sdf_tools/sdf.hpp:435:89: note: and each type can be converted to the other

I see that there is a TODO note related to gradient and I am wondering if that is related.

Removing the negative sign in front of gradient fixes this compile error, but this does not seem like the proper fix.