DoomBSP is the node builder and map compiler originally used by id Software. Like DoomEd, it is a NeXTSTEP application written in Objective-C, complicating the creation of cross-platform ports.

Since it was designed to compile maps created by DoomEd into their binary form, it does not read map lumps such as THINGS, VERTEXES or LINEDEFS. Instead, it parses a text file in DWD format which contains the map information and creates said lumps from it.

The program had its source code released to the public in May 1994, but under no clear licensing scheme: the accompanying text file mentions to contact Jay Wilbur for a licensing agreement instead. id clarified this at some point with the creation of the Doom Data Utility License, which the company asked authors of the leading Doom editor software to sign.

Possibly for all these reasons, no node builders other than IDBSP have been derived from it.

The text file also mentions that there is a bug in the nodebuilder that causes columns to be drawn out of order. The bug described is in fact the slime trail glitch, which is more a consequence of lack of precision than an actual error in the algorithms.


  • Disabled code is present to prevent segment splits on lines comprising a sliding door. Two special linedef flags were to be used to identify them. This code is disabled since sliding doors were never fully implemented in the game engine.
  • Comments indicate the node builder expects all vertices to be placed at coordinates that are multiples of 8.
  • Since sectors are built from linedefs with identical sectordef properties, identical sectors are always merged. To prevent this from happening, Id mappers used dummy sector tags to create artificial differences.


IDBSP is a third-party DOS port of DoomBSP created in 1994 by Ron Rossbach. A converter that turns maps from their binary format to the DWD format used by DoomEd is included with it.

External links[edit]