Fix torque for multiple collisions

Signed-off-by: Louise Poubel <[email protected]>

src/systems/buoyancy/Buoyancy.cc

@@ -239,7 +239,7 @@ std::pair<math::Vector3d, math::Vector3d> BuoyancyPrivate::ResolveForces(
  // Offset between the link origin and the force application point
  auto offset = _linkInWorld.Pos() - pointInWorld.Pos();
 
- torque += force.Cross(offset);
+ torque += b.force.Cross(offset);
  }
 
  return {force, torque};