The Darboux--Dressing Transformations are applied to the Lax pair associated
to the system of nonlinear equations describing the resonant interaction of
three waves in 1+1 dimensions. We display explicit solutions featuring
localized waves whose profile vanishes at the spacial boundary plus and minus
infinity, and which are not pure soliton solutions. These solutions depend on
an arbitrary function and allow to deal with collisions of waves with various
profiles.Comment: 15 pages, 9 figures, standard LaTeX2e, submitted for publication to
Physica