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LEVEL_FORMAT_INVESTIGATION.md

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EchoVR Level/Scene Format Investigation

Status: Preliminary investigation complete
Date: 2026-01-20
Investigator: AI Assistant

Summary

Level files in EchoVR (e.g., social_2.0) are stored as custom binary formats containing scene/mesh data. This is a complex custom format requiring extensive reverse engineering work.

Findings

File Characteristics

Sample file: _extracted/3b5db8af43546d40/43e2da7914642604

  • Size: 105 KB (107,688 bytes)
  • Type: Binary data (no magic signature detected)
  • Structure: Contains IEEE 754 floats and structured binary data

Binary Structure Observations

From hex analysis (xxd output):

Offset    Pattern                 Interpretation
--------  ----------------------  --------------
0x00      00 00 00 00 ...         Possible header/version
0x80-0xF0 0x3f800000 (repeated)   IEEE 754 float 1.0 (common in 3D math)
0x120+    0x00408043              Float 3.0 (coordinate?)
0x130+    0x3e                    Float 0.x (UV coordinate?)

Float patterns suggest:

  • 3D coordinates (x, y, z)
  • Normal vectors (normalized to 1.0)
  • UV texture coordinates (0.0-1.0 range)
  • Transformation matrices (identity = all 1.0)

Ghidra Analysis

Key Functions Found (echovr.exe @ port 8193):

Function Address Description
LoadLevelSet 0x1402fe430 Level set loading
RenderLevelMeshes 0x140d46c20 Level mesh rendering
RenderLevelLights 0x1404b0800 Level light rendering
CGScene::ActivateGroup 0x1400d3b40 Scene group activation
CGScene::DeactivateGroup 0x1416762f0 Scene group deactivation
UpdateMeshRenderData 0x1401ebb30 Mesh render data update

Key Strings Found:

  • "OlPrEfIxsocial_2.0" @ 0x1416d8d50 - Level identifier
  • "OlPrEfIxsocial_2.0_private" @ 0x1416e303c - Private lobby variant
  • "OlPrEfIxsocial_2.0_npe" @ 0x1416e3068 - NPE (new player experience) variant

LoadLevelSet Function Analysis

Signature:

void __thiscall NRadEngine::CncaGame::LoadLevelSet(
    CncaGame *this,
    ELevelLoadChannel param_1,
    CLevelLoadSet *param_2
)

Key structures:

  • CLevelLoadSet - Level set descriptor
  • ELevelLoadChannel - Loading channel enum
  • Offset +0x150 - Level set count
  • Offset +0x120 - Level set array pointer

Likely Format Structure

Based on float patterns and game engine conventions:

[Header]
- Magic/Version: 8-16 bytes
- Metadata: counts, offsets, sizes

[Vertex Data]
- Position: float3 (x, y, z)
- Normal: float3 (nx, ny, nz)
- UV: float2 (u, v)
- Additional attributes (color, tangent, etc.)

[Index Buffer]
- Triangle indices (uint16 or uint32)

[Material Data]
- Texture GUIDs
- Shader parameters
- Material properties

[Transform Data]
- Matrices (4x4 float)
- Position, rotation, scale

[Scene Graph]
- Object hierarchy
- Bounding volumes
- LOD levels

Next Steps (Future Work)

Priority 1: Binary Format Parsing

  1. Identify header structure

    • Find magic number or version field
    • Parse counts (vertex count, triangle count, etc.)
    • Locate data offsets

  2. Vertex format analysis

    • Determine vertex stride (bytes per vertex)
    • Identify attribute layout
    • Confirm float vs half-float usage

  3. Index buffer location

    • Find index data start
    • Determine index size (16-bit vs 32-bit)
    • Verify triangle list vs strip

Priority 2: Ghidra Deep Dive

  1. LoadLevelSet decomp analysis

    • Trace calls to resource loaders
    • Find format version checks
    • Identify parser functions

  2. CGScene analysis

    • Understand scene graph structure
    • Find mesh loading code path
    • Locate format readers

  3. Resource system

    • LoadResource @ 0x1405bbae0
    • DestroyResource @ 0x1404c85d0
    • Track from file I/O to GPU

Priority 3: Runtime Debugging

  1. Memory inspection

    • Attach debugger to running EchoVR
    • Break on LoadLevelSet
    • Inspect buffer contents after load

  2. File system hooking

    • Intercept level file reads
    • Log raw binary data
    • Compare multiple level files

  3. Mesh extraction

    • Dump loaded meshes from GPU
    • Use tools like RenderDoc or PIX
    • Reverse map GPU data to file format

Known Challenges

  1. Custom format - Not a standard format (FBX, OBJ, GLTF, etc.)
  2. Binary complexity - Multiple sections with internal pointers
  3. Versioning - Format may differ by game version
  4. Compression - Data may be compressed (ZSTD, LZ4, etc.)
  5. Endianness - Likely little-endian (x86-64) but needs confirmation

Estimated Effort

  • Basic parser: 20-40 hours
  • Full format specification: 60-100 hours
  • Mesh extraction tool: 40-60 hours
  • Round-trip (edit & reimport): 80-120 hours

Value vs. Cost

Benefits:

  • Level editing capabilities
  • Custom maps/arenas
  • Asset research & documentation

Costs:

  • High time investment
  • Limited immediate use case
  • Lower priority than texture system

Recommendation: Defer until texture modding workflow is validated with live game testing. Focus on higher-value deliverables first.

References

  • File sample: _extracted/3b5db8af43546d40/43e2da7914642604
  • Ghidra project: EchoVR_6323983201049540 (port 8193)
  • Key function: LoadLevelSet @ 0x1402fe430
  • Related docs: ASSET_TO_MEMORY_PIPELINE.md, ASSET_FORMATS.md

Related Asset Types

Level files likely reference:

  1. Textures (DDS) - Already solved
  2. Materials (asset references) - Already parsed
  3. Audio (audio references) - Already parsed
  4. Animations - Unknown format
  5. Physics meshes - Unknown format
  6. Collision data - Unknown format

Status: Investigation complete. Parser implementation deferred pending use case validation.