find-CGameSceneNode_GetSkeletonInstance

CGameSceneNode_GetSkeletonInstance Function Location Workflow

Overview

This workflow locates the CGameSceneNode_GetSkeletonInstance virtual function in CS2 server binary. This function is called on CBodyComponentSkeletonInstance::NetworkVar_m_skeletonInstance (a multiple inheritance object: CSkeletonInstance, CGameSceneNode, ISceneAnimatableProceduralBoneTransforms) to retrieve the CSkeletonInstance pointer.

Location Steps

1. Search for Signature String

Use find_regex to search for the DevMsg string:

mcp__ida-pro-mcp__find_regex(pattern="\\[%s\\] playing sequence \\[%s\\] at time \\[%f\\]")

Expected result: Find string address (e.g., 0x1817731b0 for Windows)

2. Find Cross-References

Use xrefs_to to find locations that reference this string:

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

Expected result: Find the function that references the string

3. Decompile and Locate Pattern

Decompile the referencing function and look for this code pattern:

  if ( (unsigned __int8)sub_18119C7E0(*(_QWORD *)(a1 + 16), v14) )
  {
    sub_180878540(&v76, *(unsigned int *)(*(_QWORD *)(a1 + 16) + 56LL));
    sub_18019D560(&v76);
    v15 = &unk_181524F70;
    if ( *a3 )
      v15 = *a3;
    v16 = sub_18119C290(*(_QWORD *)(a2 + 16));
    DevMsg("[%s] playing sequence [%s] at time [%f]\n", v16, v15, v4);
  }
  v17 = CBaseAnimGraph_GetAnimationController(a2);// This is CBaseAnimGraph_GetAnimationController
  if ( *(int *)(v17 + 704) <= 0 && *(_BYTE *)(v17 + 24) == 4 )
  {
    *(_BYTE *)(sub_180A6D880(a2) + 748) = 0;
    v18 = sub_180A6D210(a2);
    v19 = 0LL;

The function called immediately after the DevMsg block is CBaseAnimGraph_GetAnimationController.

4. Analyze CBaseAnimGraph_GetAnimationController

Decompile the identified function. It should have this structure:

__int64 __fastcall CBaseAnimGraph_GetAnimationController(__int64 a1) // CBaseAnimGraph *pEntity
{
  __int64 result; // rax

  // *(_QWORD *)(a1 + 632) = pEntity->m_skeletonInstance
  // Type: CBodyComponentSkeletonInstance::NetworkVar_m_skeletonInstance
  // Multiple inheritance: CSkeletonInstance, CGameSceneNode, ISceneAnimatableProceduralBoneTransforms
  result = (*(__int64 (__fastcall **)(_QWORD))(**(_QWORD **)(a1 + 632) + 64LL))(*(_QWORD *)(a1 + 632));
  if ( result )
    return *(_QWORD *)(result + 928); // CSkeletonInstance->m_animationController
  return result;
}

Key observations:

• a1 + 632 (0x278) = pEntity->m_skeletonInstance
• vtable offset 64 (0x40) = CGameSceneNode_GetSkeletonInstance (vtable index 8)
• result + 928 (0x3A0) = CSkeletonInstance->m_animationController

5. Rename Function

Use rename to give the function a meaningful name:

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

6. Generate Struct Offset Signatures and Write Struct Member YAMLs

For each struct member below, ALWAYS run the workflow independently:

1. Use SKILL /generate-signature-for-structoffset on an instruction that contains the target offset.
2. Use SKILL /write-structoffset-as-yaml with that member's offset_sig.

Member A (CBaseAnimGraph::m_skeletonInstance):

• offset: 0x278 (size 8)
• Typical instruction pattern: *(_QWORD *)(a1 + 632) (632 = 0x278)
• Write YAML parameters:
  • struct_name: CBaseAnimGraph
  • member_name: m_skeletonInstance
  • offset: 0x278
  • size: 8
  • offset_sig: validated signature from /generate-signature-for-structoffset

Member B (CSkeletonInstance::m_animationController):

• offset: 0x3A0 (size 8)
• Typical instruction pattern: *(_QWORD *)(result + 928) (928 = 0x3A0)
• Write YAML parameters:
  • struct_name: CSkeletonInstance
  • member_name: m_animationController
  • offset: 0x3A0
  • size: 8
  • offset_sig: validated signature from /generate-signature-for-structoffset

7. Write Virtual Function as YAML

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

Required parameters:

• func_name: CGameSceneNode_GetSkeletonInstance
• vtable_name: CGameSceneNode
• vfunc_offset: 0x40 (can change on game update)
• vfunc_index: 8 (can change on game update)

Note: func_addr and func_sig are not needed for this virtual function.

Function Characteristics

The CGameSceneNode_GetSkeletonInstance function:

• Is a virtual function at vtable index 8 (offset 0x40)
• Called on CBodyComponentSkeletonInstance::NetworkVar_m_skeletonInstance
• Returns a CSkeletonInstance* pointer

VTable Information

• VTable Name: CGameSceneNode
• VTable Offset: 0x40 (change on game update)
• VTable Index: 8

Related Struct Offsets

Output YAML Files

The output YAML filenames depend on the platform:

• server.dll → *.windows.yaml
• libserver.so / libserver.so → *.linux.yaml

CGameSceneNode_GetSkeletonInstance.{platform}.yaml

Example output:

vtable_name: CGameSceneNode
vfunc_offset: 0x40
vfunc_index: 8

CBaseAnimGraph_m_skeletonInstance.{platform}.yaml

Example output:

struct_name: CBaseAnimGraph
member_name: m_skeletonInstance
offset: 0x278
size: 8
offset_sig: <offset_sig>

CSkeletonInstance_m_animationController.{platform}.yaml

Example output:

struct_name: CSkeletonInstance
member_name: m_animationController
offset: 0x3A0
size: 8
offset_sig: <offset_sig>

Related Functions

• CBaseAnimGraph_GetAnimationController - Wrapper that calls GetSkeletonInstance and returns m_animationController