Thanks, Denis. What I'm trying to build now (this is actually a static lib) is already a part of SUBDIRS type .pro file. I thought about making the lib's top .pro file with SUBDIRS template, and putting a separate .pro file in all nested directories with OBJECTS_DIR overridden for each directory, so that object files do not conflict. I will keep this solution in mind.
To my point view, the best solution would be making qmake create the same directory structure under specified OBJECTS_DIR. I mean, let say we have
@OBJECTS_DIR = .obj
SOURCES = Type1/.cpp
Type2/.cpp@
and it will be just great, if qmake creates .obj, .obj/Type1, .obj/Type2 directories and puts .o files according to their location. Is this possible?