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BSPSource offers four different brush modes that control how geometry is reconstructed from compiled BSP data. Each mode has different trade-offs between accuracy and editability.

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BrushMode Options

The decompilation mode is controlled by the brushMode configuration option: 
config.brushMode = BrushMode.BRUSHPLANES; // Default

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BRUSHPLANES

Description: “Brushes and planes” This is the default and recommended mode. It reconstructs the original brush geometry using plane data from the BSP. Advantages:
  • Most accurate reconstruction of original brushes
  • Produces clean, editable geometry
  • Works with Hammer’s brush manipulation tools
  • Best for maps you want to edit further
Use when:
  • You need to edit the decompiled map
  • You want the closest approximation to the original VMF
  • You’re working with standard brush-based geometry

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ORIGFACE

Description: “Original faces” Reconstructs geometry using the original face data before BSP splitting. Advantages:
  • Preserves original face boundaries
  • Good for maps with complex face structures
Limitations:
  • May not reconstruct perfect brushes
  • Some geometry may require manual cleanup
Use when:
  • BRUSHPLANES mode produces incorrect geometry
  • You need to preserve specific face boundaries
  • Working with displacement surfaces

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ORIGFACE_PLUS

Description: “Original plus split faces” Combines original face data with split face information for more complete reconstruction. Advantages:
  • More complete geometry than ORIGFACE alone
  • Handles complex face splitting better
Trade-offs:
  • May produce more complex geometry
  • Can create additional cleanup work
Use when:
  • ORIGFACE produces incomplete results
  • You need both original and split face data
  • Dealing with heavily optimized geometry

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SPLITFACE

Description: “Split faces” Uses only the split face data from BSP compilation. Characteristics:
  • Produces the most fragmented geometry
  • Reflects the actual compiled face splits
  • Least editable output
Use when:
  • Other modes fail to produce valid geometry
  • You’re analyzing compiled face structure
  • You don’t plan to edit the result

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Configuration Example

BspSourceConfig config = new BspSourceConfig();

// Set brush mode
config.brushMode = BrushMode.BRUSHPLANES;

// Related geometry options
config.writeWorldBrushes = true;
config.writeDisp = true;
config.backfaceDepth = 1;

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Mode Selection Guide

Use BRUSHPLANES for the most editable geometry that works well with Hammer’s tools.
Try ORIGFACE first, then ORIGFACE_PLUS if needed.
Use SPLITFACE to see exactly how VBSP split the geometry during compilation.
BRUSHPLANES is the safest default that works for most maps.
The brush mode affects both world brushes and brush entities (func_detail, func_door, etc.).
  • writeWorldBrushes: Enable/disable world brush decompilation
  • writeDisp: Include displacement surfaces
  • backfaceDepth: Depth for backface reconstruction (default: 1)
  • writeBrushEntities: Enable/disable brush entity decompilation
Some heavily protected or optimized maps may not decompile correctly in any mode. See Protection Detection for more information.

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