find-CDecalGameSystem_UpdateDecals-AND-CDecalGameSystem_ClientPreUpdate

CDecalGameSystem_UpdateDecals & CDecalGameSystem_ClientPreUpdate Location Workflow

Overview

Locate two related functions in CS2 client binary:

• CDecalGameSystem_UpdateDecals — Regular function that handles decal updates
• CDecalGameSystem_ClientPreUpdate — Virtual function that calls UpdateDecals

Location Steps

1. Search for Signature String

Use find_regex to search for the CDecalGameSystem::UpdateDecals string:

mcp__ida-pro-mcp__find_regex(pattern="CDecalGameSystem::UpdateDecals")

2. Find CDecalGameSystem_UpdateDecals via Cross-References

Use xrefs_to on the string address to find the function that references it:

mcp__ida-pro-mcp__xrefs_to(addrs="<string_addr>")

The function referencing this string is CDecalGameSystem_UpdateDecals.

3. Rename CDecalGameSystem_UpdateDecals

mcp__ida-pro-mcp__rename(batch={"func": {"addr": "<UpdateDecals_addr>", "name": "CDecalGameSystem_UpdateDecals"}})

4. Find CDecalGameSystem_ClientPreUpdate via Cross-References

Use xrefs_to on CDecalGameSystem_UpdateDecals to find its caller:

mcp__ida-pro-mcp__xrefs_to(addrs="<UpdateDecals_addr>")

Look for a code xref (type="code"). The calling function is CDecalGameSystem_ClientPreUpdate.

Decompile to verify the pattern:

__int64 __fastcall CDecalGameSystem_ClientPreUpdate(__int64 a1)
{
  __int64 v2; // rcx
  v2 = *(_QWORD *)(a1 + 312);
  if ( v2 )
    (*(void (__fastcall **)(__int64))(*(_QWORD *)v2 + 24LL))(v2);
  return CDecalGameSystem_UpdateDecals(a1);
}

5. Rename CDecalGameSystem_ClientPreUpdate

mcp__ida-pro-mcp__rename(batch={"func": {"addr": "<ClientPreUpdate_addr>", "name": "CDecalGameSystem_ClientPreUpdate"}})

6. Load CDecalGameSystem VTable and Get VTable Index

ALWAYS Use SKILL /get-vtable-from-yaml with class_name=CDecalGameSystem

If the skill returns an error, STOP and report to user.

Find CDecalGameSystem_ClientPreUpdate address in vtable_entries to determine vfunc_index.

7. Generate Signatures

ALWAYS Use SKILL /generate-signature-for-function to generate a robust and unique signature for CDecalGameSystem_UpdateDecals.

ALWAYS Use SKILL /generate-signature-for-function to generate a robust and unique signature for CDecalGameSystem_ClientPreUpdate.

8. Write YAML Output

ALWAYS Use SKILL /write-func-as-yaml to write the analysis results for CDecalGameSystem_UpdateDecals.

Required parameters:

• func_name: CDecalGameSystem_UpdateDecals
• func_addr: The function address from step 2
• func_sig: The validated signature from step 7

ALWAYS Use SKILL /write-vfunc-as-yaml to write the analysis results for CDecalGameSystem_ClientPreUpdate.

Required parameters:

• func_name: CDecalGameSystem_ClientPreUpdate
• func_addr: The function address from step 4
• func_sig: The validated signature from step 7

VTable parameters:

• vtable_name: CDecalGameSystem
• vfunc_offset: calculated from vfunc_index * 8
• vfunc_index: from step 6

Function Characteristics

CDecalGameSystem_UpdateDecals

• Regular function (not virtual)
• References the string CDecalGameSystem::UpdateDecals
• Handles decal update logic

CDecalGameSystem_ClientPreUpdate

• Virtual function in CDecalGameSystem vtable (index 21, offset 0xA8 — may change with game updates)
• Calls a virtual method on a member object at offset +312 (0x138), then tail-calls UpdateDecals
• Small function (~0x28 bytes)

VTable Information

• VTable Name: CDecalGameSystem
• VTable Mangled Name:
  • Windows: ??_7CDecalGameSystem@@6B@
• ClientPreUpdate VTable Index: 21 (may change with game updates)
• ClientPreUpdate VTable Offset: 0xA8 (may change with game updates)

Output YAML Files

• CDecalGameSystem_UpdateDecals.windows.yaml / .linux.yaml
• CDecalGameSystem_ClientPreUpdate.windows.yaml / .linux.yaml