First step for something doing static friction stuff.
Add an id field to identify BVHMotionTransforms.
Provide a factory for ids.
Use that to identify velocity data.
Track the lowermost id in the visitors.
Modified Files:
simgear/scene/bvh/BVHLineSegmentVisitor.cxx
simgear/scene/bvh/BVHLineSegmentVisitor.hxx
simgear/scene/bvh/BVHMotionTransform.cxx
simgear/scene/bvh/BVHMotionTransform.hxx
simgear/scene/bvh/BVHNearestPointVisitor.hxx
simgear/scene/bvh/BVHNode.cxx simgear/scene/bvh/BVHNode.hxx
simgear/scene/util/SGSceneUserData.cxx
simgear/scene/util/SGSceneUserData.hxx