Tutorial: Modifying a 3D Model's Texture; Step 3.
Find the Model That Has The Texture You Want To Edit With UE Viewer
Now assuming you've already downloaded UE Viewer, extract the contents of the UE Viewer zip archive you've downloaded anywhere you want. I put it inside of my “extracted” folder that was created in the previous step (that contains all of the game's .uasset files which were extracted from the original .pak files).
Double click on “umodel_64.exe” to open it. For “Path to game files:”, make sure the folder where you've extracted the game's pak files is selected. Check the checkbox for “Override game detection” and select “Unreal engine 4” for the first dropdown and “Unreal engine 4.22” for the second dropdown. Click “OK”.
You will see a folder structure on the left containing all of the .uasset files that were extracted from the .pak file. Now you need to find the model that has the texture you want to edit, and open it. This will be guess and check, in the future we may have a guide on where each model is located.
For this tutorial I'll be modifying the texture on Miriam's head by adding a star on her cheek. This model is located at BloodstainedRotN → Content → Core → Character → P0000 → Mesh. The filename is SK_Pl01_MiriamHead.uasset.
Once you open the file you'll see a preview of the 3D model that has the texture you're about to edit.
Click on Tools → Export Current Object in the menu bar.
You can leave all the settings in this dialog at default, but I suggest changing the export folder in this case to something that's specific to your mod, for organizational purposes. In my case, I'm creating a “BloodstainedMods” folder to contain all of my mods, and for this specific step I'm exporting to a “ModelEdits” folder inside of it, because I will be editing the model in that folder.
Click “OK”, and after it's done you can close the UE Viewer program.
Now if you explore the folder you exported to, you'll notice a lot of files were exported, this includes both the .psk file which is the 3D model you exported, and .tga files which is all of the textures attached to that 3D model.
In my case, the 3D model is located at X:\BloodstainedMods\MiriamHead\ModelEdits\Core\Character\P0000\Mesh\SK_Pl01_MiriamHead.psk.
And the texture I'm going to edit is located at X:\BloodstainedMods\MiriamHead\ModelEdits\Core\Character\P0000\Texture\Face\T_Face01_Color.tga.
You can technically just edit the .tga file directly, and put it in the game hoping your edits worked out, but in the next step I'll show how to edit it while previewing it on the 3D model at the same time.