Copy pasting this from the description of my swimsuit mod. Go to the image gallery there for the mrl3 image explaining the structure of the format.
Information about customizable skin and equip color:
CMM tex defines what parts of a texture are color customizable. Usually red or green. This is usually for equipment.
The game decides which color is customizable on a piece of equipment. I suspect this is defined in common/equip_scolor.esvc
For skin, skin materials have a shader switch in the mrl3 file material index, that tells the game they are a Player or NPC skin material.
Skin materials usually refer to default or common player skin textures. There are also hand textures.
In the case of NPC clothing, sometimes the skin is drawn onto the clothes texture.
But even in the case of a single NPC texture having both clothing and skin, the skin is assigned its own material.
Let's say you have skin materials that aren't changing color. You need to figure out which these are, in the mrl3 file.
"default_tex\skin_BM" seems to be used to change the skin color.
The key to finding the skin materials is searching for the materials that use this texture.
You can do this by counting the number order of textures and then doing a search for materials using that number.
For example, if "default_tex\skin_BM" is 13th in the texture list, its value is 0D. Search for 0D after the material index.
You can figure out where materials start and how long they are, using the mrl3 image I uploaded.
You can also figure out which material is which by what other textures are being used within the same material (they're in the same row).
For example, hand textures being used means it's the material used for the hand.
Note that the bytes for location and size are in reverse. For example, in the top right of the mrl3 image, 4002 is the length. That's 0240 in hex.
Write 0240 into Windows calculator (in hexadecimal mode) and then convert to decimal. The result is 576 bytes. Thus the material size is 576 bytes.
Similarly, if location is 1280, that means it starts at 0x00001280.
Once you figure out which materials are skin materials, simply copy paste the green "skin ID" section from the confirmed skin material of a player mrl3.
Using the image I've uploaded, you should be also able to do things like append materials to the end of the mrl3 file and then edit address and size references for existing materials to point to the appended material. Note that you must keep the material IDs (I'm assuming that's what they are based on a video of a RE6 mod tool by MarioKart64n) so that the model knows which material you are referring to. The game will probably crash otherwise.
I hope my explanation makes sense (I'm tired).
Edited by UberGrainy, 23 August 2018 - 09:02 PM.