Sorry for the wait, it was night time where i live and then took some time to write this response
I feel like you're either misunderstanding something or explaining different things. "I tried making sure there's a polygon in each cut," these extra meshgroups are meant for parts of the hair that will have transparency, why are you creating "empty" meshgroups?
1). Triangulate all of your meshes.
2). Your blend file must have 6 meshgroups: the original 3 that will have the Simskin shader (opaque) and the additional 3 for the Simglass shader ( with transparency).
First hat chop - 0000 (opaque) and 0003 (with transparency);
Second hat chop - 0001 and 0004;
Base shape - 0002 and 0005.
Make sure all meshgroups are visible before saving.
2). File - Save as this blend file as LOD1, reduce the polycount of all meshgroups;
3). Clone the hair of the same length as yours, Tools - Modding - Embed all externally referenced resources;
4). You will see 12 Geometries. Cut numbers do not exist in the game. It is the system S4S uses to determine what 3d models in the blend file will be imported and in what order. So, a meshgroup with 0000 cut number in LOD0 blend file will replace the first Geometry in the list, the one with 0001 will replace the second, and so on;
5). You need to add geometries for Simglass for the first two LODs. On lower LODs it won't be seen from afar. So select the first Geometry, click on Duplicate, change the last number in the Group to 0, for example. Then do this for the other 5 meshgroups while being consistent with numbers ( 0, 1, 2, 3, 4, 5).
6). Click on Region map, then Edit Items. Select the first entry, then Edit items. If you will select the first entry and compare its group number, you'll see that it is 0000 of LOD0. Comparing the rest, you'll understand that HairHatB is for 0000 hat chops of all blends. You need to copy the first entry (LOD0, 0000) and change the last digit of the group numbers of the COPY to 0 (so the same number as LOD0, 0003). Then you need to copy the second entry (LOD1,0000) and change the last digit to 3 (like LOD1, 0003 ). Save;
7). You need to look at all these entries, adding newly created geometry in places where their opaque versions exist. Look at the picture for more instructions;
8). Once done with the region map, save it and save your package.
9). Select CAS Part (if you have more in the package, delete all swatches beside the first one). In the search bar type LODs. Click on LODs, then on Edit items. Select LOD0, next to LODModels click on Edit items. You'll see 0000, 0001,0002 of LOD0. Copy all three entries, change the last digits of the copies to 0, 1, 2. Do the same with LOD1, but change the last digits to 3, 4, 5. Save changes and the package;
10). Import your blend;
11). Change the shaders of the added 6 meshgroups to Simglass. Click on each, type Shader in the search bar, choose it in the drop-down menu. Save the blend.
Here's the package with everything done but
do not import your blend there!!Clone it first.
How to use:
- make sure your blend file has 6 meshgroups and they have the right cut numbers (as i explained above);
- put this package into C:\Users\-----\Documents\
Sims 4 Studio\Mods,
close s4s if it was opened;
- open s4s, CAS - Create 3d mesh - filter content by "Custom" - choose this package, Next, name it;
- you can replace all meshes and textures, there is no need to do anything in the warehouse.
