GPL Model Trial and Error and Error and Error

I tried running some of the .gpl files from A Wonderful Life through the previewer program on my iBook.

I attempted to load farm.gpl, since it’s texture configuration is one of the simplest (one tpl + one gpl) amongst the AWL gpl models.

Unfortunately, all of the gpl files from AWL caused a version-mismatch error and I’m not well-versed enough to recompile the program for mac at this point.

Error when attempting to load gpl files from AWL.
Occurs on both SheepShaver and iBook.

Fortunately, after examining the gpl files, I was able to find that the version number can actually be changed in a hex editor by setting the view options to display as decimal, group by double words, and use a big endian byte order. In this case, the version of the gpl was 6012001. I changed the version field to what previewerD requires (version 12012000), and reran previewer.

Changing the gpl library version from 6012001 to 12012000.

This allows the file to open, but leads to a new error:

GXSetVtxAttrFmt(): Only valid scale for 8b pos or texcoord data is 0 on HW1 in “GXGeoVert.c” on line 263.
Occurs on both SheepShaver and iBook.

This is likely due to the gpl being initially exported for HW2 (retail Gamecube) which uses an updated graphics driver compared to HW1 (initial dev kits). Since the mac version of previewer appears to be built on the HW1 code, it leads to the error above.

It might be possible to get around this error by running the HW2 version of previewer.elf via Dolphin (fan emulator) or Swiss (Gamecube homebrew loader), but it would take some time to figure out the proper configuration. Further research will be needed.

I also attempted to load a more complex 3d model (boy_0.gpl, extracted from boy_0.arc). This file has multiple textures associated with it (boy_0_b0.tpl, boy_0_f0_e.tpl, and boy_0_f0_m.tpl).

Unfortunately it seems that the gpl is improperly configured. When loaded through previewer on iBook, it looks for a single nonexistent boy_0.tpl texture.

It’s worth noting that the files from this version of boy_0.arc aren’t actually used in-game (the actual models/textures are loaded from one of the clz archives). These are likely leftovers from some point in the games development.

For now, I’ll be sticking to research on the simpler models first (e.g. farm.gpl, grass.gpl, and various fish models) to see if I can get past the HW1/HW2 limitations.

I also attempted to change encoding of farm.gpl from big to little endian (grouped by double-words).

I ran it through my Windows version of previewerD.exe (recompiled with version-check removed). However, I got a new “component count” error.

This is likely due to some sort of error when I attempted to convert the file’s endianness. Further research will be needed.