7.5 OEHasDepictionHydrogens

bool OEHasDepictionHydrogens(const OEAtomBase *atm)

This function determines whether the specified heavy atom has a "depiction" hydrogen. Depiction hydrogens are hydrogens that need to be explicitly drawn in a 2D depiction to faithfully represent tetrahedral stereochemistry. A depiction hydrogen is currently defined as the single hydrogen attached to a non-hydrogen atom that has tetrahedral chirality specified and either has only two non-hydrogen neighbors, or has three non-hydrogen neighbors that are connected via cyclic ``ring'' bonds. See the implementation of OEHasDepictionHydrogens below. For example, the fusion atoms of decalin have depiction hydrogens.

bool OEHasDepictionHydrogens(const OEAtomBase *atm)
{
  if (atm->GetAtomicNum() == 1)
    return false;
  if (atm->GetTotalHCount() != 1)
    return false;

  unsigned int degree = atm->GetHvyDegree();
  if (atm->HasStereoSpecified())
  {
    if (degree == 2)
      return true;
    if (degree == 3 && RingBondCount(atm) == 3)
      return true;
  }

  if (degree == 1)
  {
    OEBondBase *bptr = OEGetSoleDoubleBond(atm);
    if (bptr && bptr->HasStereoSpecified(OEBondStereo::CisTrans))
      return true;
  }
  return false;
}

				Ogham 2D Chemical Structure Layout and Rendering

				Ogham 2D Chemical Structure Layout and Rendering