Alpha sims hairs are always hard to port compared to maxis match hair ones. This is because 9 times out of 10 you're gonna get some sort of transparency issues. We all have our own little tricks to try to fix those issues. I usually edited the alpha channel on hair textures. But it never actually fixed the issues as much as i wanted to. So i decided to get my hands dirty and find a proper workflow on blender using the stuff i learned from other devs like Munchyfly, Padme,and Jenya who i am all grateful for, from extensive researches on the internet to understand how the normals really work and how to fix issues with them, and by doing a lot of trial and error. This is a 5 step workflow and i think it's very easy to replicate on different meshes. I cannot guarantee the perfect mesh look. Because different meshes work in different ways. Sometimes even following the same workflow twice might give you a different result. But i can say it will make your mesh look a lot better than you started with.

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To compare how the workflow worked on a hair mesh i worked with, i took pics of the mesh from before, with the alpha edited look, and after the workflow. I took the pics with lighter colors since darker colors always hides the issues on meshes. I also took them inside the AMM menu since the light of that menu also shows the transparency issues clearly.

Here is how the Anto Empire Mesh from my Morning's Hairstyles for Maleshep looked like without any alpha editing:

It looks pretty bad doesn't it.

Here is how it looked like when i edited the alpha for my mod back when i first released it:

It's a little bit better but it still doesn't look good enough. It might work better with darker colors but the lighter ones show the issues.

And finally here is how it looked when i followed the workflow on the mesh without any alpha editing:

Is it perfect? No, there are still some smaller issues. But compared to rest of them it's miles better.

So now i'm gonna explain my workflow for you. But before i start on that i wanna say this guide assumes you already fitted your mesh to your Shepard's head or at least you know how to do if you wanna do it after the transparency issue fix. Also that you know how to import the hair mesh to your game. This guide only explains how to fix transparency issues. Assumes that you know the other stuff already.

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Fixing Alpha Issues with Hairs

Step 1

First of all i need you to activate the Face orientation option from here:

This is a must for this workflow and gonna make our job so much easier.

This is how my mesh looks like after i choose this option, yours might look similar:

You can see that it's pretty much a mess. Colors are all jumbled, normals look like a mess. So the first thing we're gonna do to start fixing that mess is to go into the edit mode, select the whole mesh which you can do by pressing A on your keyboard. Then go to Mesh -> Normals -> Recalculate Outside like in the pic below.

After you do that make sure no red parts are at the outside. If you see red parts at the outside, then select them with pressing L while your mouse is over them and press alt+N. Then choose flip. Here for example i had some red parts at the side:

After you finish this, i would suggest you to create a save in your blender. There are some rare cases where even just doing this first step fixes the transparency issues. So i would suggest exporting the mesh and trying it in your game. Then take a pic and continue doing the steps anyway, because there might be some small issues left that could be fixed in other steps. But chances are you're gonna see a weird patchy look in your hair. This is because the double faces that are intertwined with each other.

As you can see from the upper pic, blue parts look weird. There are some lighter and darker parts which does make the normals look patchy in the game, which is what we're gonna try to fix in step 2.

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Step 2

In this step we're gonna delete the double faces from the mesh. You might ask how we're gonna do that and how will we even know if it's a double face. But it's actually quite simple. Basically every hair piece that has that patchy look with along with the intertwined vertexes has a double faces. So we're just gonna hover the hair piece that has that look, choose the piece by pressing L, then press Del on our keyboard. Then choose the delete faces from the menu that pops out. Here you can see the double face i selected from the hair piece from the below pic:

Then i press Del on my keyboard and the menu shows up:

And here is how it looks after i delete that piece:

Look how different it looks compared to the rest. This is the tone of blue we want at every piece of that mesh from the outside. From the inside we want a proper non patchy red color. So you need to select all the hair pieces that has that look and delete them, though you only need to select one part of the piece. We don't want any bald parts on the mesh. You can also look at the mesh from the red parts and delete any patchy ones from that side as well. Make sure when you select a hair piece it doesn't select the one near it. In some cases some hair pieces can be connected to one another. So closely monitor how it works when you delete those parts, so that it doesn't delete unnecessary parts. If you see it delete unnecessary parts undo that part and separate the problematic mesh pair from the main mesh, then from each other using the uv map. Then delete the parts you need to delete. In some cases hair piece may not have a patchy look but has a full brighter blue look different than the rest of them. That's also a double face. I would suggest deleting that piece as well.

After it's all done you should have a perfectly blue part on the outside and a red part on the inside like this:

After this step is finished, i would again suggest you to create a save in your blender. In many cases this might just be enough for your mesh. So i would suggest exporting the mesh and trying it in your game. Then take a pic and continue doing the steps anyway like before, because there might be some small issues left that could be fixed in other steps. But having a save protects us if the mesh doesn't like the further steps for some reason.

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Step 3

In this step we're gonna do the merge by distance in our mesh. For that we need to be in the Edit mode and press A to select all of the mesh. Then we open the Mesh Menu from upwards and go Mesh->Clean Up->Merge by distance like in the below pic:

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Step 4

In some cases unapplied transforms might cause some issues on how normals work. We're gonna apply them in this step. For that let's go back to the Object Mode. Then press N so that the sidebar that shows the transform info pops out like this:

Like you can see there are some location, rotation differences there. So what we're gonna do is click the mesh and then press CTRL + A, then choose All Transform from the menu like this:

In case you also have scale issues, we're gonna press CTRL + A again while the mesh is selected and choose Scale this time like this:

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Step 5

The final step is quite easy and quick. We're gonna merge the normals. So first we're gonna go back to the edit mode. Press A to select the whole mesh then choose Mesh from the upwards menu and go Mesh-> Normals->Merge like in the below pic:

Then it is done. Export your mesh and try it in your game. Compare it to the pics you took before. If any of the previous pics look better then go with that one, otherwise use the final mesh and enjoy your game.

I hope this guide helps everyone who is having transparency issues with their Alpha Sims Hair Port. Hopefully it works out for you as much as it did for me. Happy Modding!