unsafe static void AddContact(ref NonconvexReductionChild child, int contactIndexInChild, NonconvexContactManifold *targetManifold)
{
ref var contact = ref Unsafe.Add(ref child.Manifold.Contact0, contactIndexInChild);
unsafe void AddContact(NonconvexContactManifold *manifold, ref NonconvexReductionChild sourceChild,
ref Vector3 offset, float depth, ref Vector3 normal, int featureId)
{
ref var target = ref NonconvexContactManifold.Allocate(manifold);
