Me and Phofe have been working on some additions to Wind Viewer, the source is available at https://github.com/pho/WindViewer. Support for TGOB (the same as ACTR), TRES, and MULT editing has been added, as well as RARC Packing. We haven't implemented adding new objects or Yaz0 compression yet, but they are planned. I've recently been working on my own little build which has the ability to move rooms (actors, model, collision, and all) so I can create a cool ROM hack, but it's horribly coded so far and I still have some things to work out.
In my attempts to get my stuff working, I've figured out some new things about some of the file chunks. Not sure if it's all new, but it's not on spinout182.
Some changes to that on spinout:
MULT
Format:
xxxxxxxx zzzzzzzz aaaa rr cc
Where:
x = Translation on X-axis (single-precision float)
z = Translation on Z-axis (single-precision float)
a = Rotation on X-axis
r = Room number, matches number in filenames
b = Unknown
TRES
Format:
xxxxxxxxxxxxxxxx FF yyyy zzzzzzzz aaaaaaaa bbbbbbbb cccc rrrr dd
Where:
x = The word 'takara' in ASCII, followed by a number that differs from entry to entry (there are other words used here; needs investigation)
F = Padding
y = Chest type (common wooden, Big Key, ect)
z = Location on X-axis
a = Location on y-axis
b = Location on z-axis
c = Unknown
r = Rotation
d = Chest contents (IE Rupees or the Hookshot)
Regarding .dzb files, byte 0x33 of the Type_t struct often contains the room number. When I tried replacing a used room of a dungeon with an unused room, the entire room would unload unless I changed that byte in all the structs (not sure which one was the important one, but it seemed to do the job).
Hopefully some of this information was new, I have pretty high hopes for Wind Waker hacking. One thing I'm interested in that I haven't seen is the locations of loading zones. Sure SCLS is an exit listing, but I haven't come across any coordinates. That would be really cool and allow for some new possibilities.
