  In this paper, we make progress on understanding the collapsing behavior of
Calabi-Yau metrics on a degenerating family of polarized Calabi-Yau manifolds.
In the case of a family of smooth Calabi-Yau hypersurfaces in projective space
degenerating into the transversal union of two smooth Fano hypersurfaces in a
generic way, we obtain a complete result in all dimensions establishing
explicit and precise relationships between the metric collapsing and complex
structure degenerations. This result is new even in complex dimension two. This
is achieved via gluing and singular perturbation techniques, and a key
geometric ingredient involving the construction of certain (not necessarily
smooth) K\"ahler metrics with torus symmetry. We also discuss possible
extensions of this result to more general settings.
