Index only items with specific file type in one folder?

I need to prepare documents with LaTeX and some other formats and I have a ‘TeX’ folder resides in my home folder, in which I create more subfolders to organize them into serval projects.
I use DT3 to save notes, assignments and references related to them. Now I hope to index the LaTeX source and generated pdf file in so I can better reference to them.
However, TeX will create lots of temp files like .aux',.log’, etc., but I only want ‘.tex’ and ‘.pdf’ get indexed in. Directly save TeX source into DT3 and compile them in the database wont work since these temp files will become orphan.
So how can I get only these file types in and (hopefully) retain there directory structure so I can save some classification work?

You can’t exclude files when indexing.