Sims 3:0x02019972

MTST
TypeID:	0x02019972
Game Version:	The Sims 3

Overview

This is a Sims 3:RCOL chunk.

The purpose of the MTST (Material Set) is to allow multiple material definitions to be swapped by the game through the function:

ScriptCore.World.ObjectSetMaterial(ObjectGuid objId, string materialSetName, float transitionTime, bool bTransitionToOverlay);

For most objects, this function is often accessed through the function:

Sims3.Gameplay.Abstracts.GameObject.SetMaterial(string materialSetName);

The string argument is FNV32 hashed and matched with the hash name to locate and swap out the object's material.

Format

DWORD 'MTST'
DWORD Version
DWORD FNV32 of MATD Name
DWORD Initial MATD index
DWORD Count
--Count repeats of
	DWORD MATD index
	DWORD FNV32 of MATD Name

Based on all MTST blocks so far seen, 'Count' is >= 1 and there is an entry named "Default", i.e.

DWORD MATD index       // == Initial MATD index
DWORD 0x2EA8FB98       // FNV32 of "default"
DWORD 0xEEAB4327       // FNV32 of "dirty"
DWORD 0x2E5DF9BB       // FNV32 of "verydirty"
DWORD 0xC3867C32       // FNV32 of "burnt"
DWORD 0x257FB026       // FNV32 of "clogged"  

Where the MTST is a MODL block, index is or-d with 0x10000000 and refers to the MODL resource RCOL block number. Where it is a MTST resource, index is or-d with 0x30000000 (not sure what it indexes into, if anything).