DoomBSP

DoomBSP, often called idbsp to emphasize its origin, is the node builder and map compiler originally used by Id Software. Like DoomEd, it is a application written in, 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 which contains the map information and creates said lumps from it.

The program had its source code released to the public, but under no clear licensing scheme: the accompanying text file mentions to contact Jay Wilbur for a licensing agreement instead.

Possibly for all these reasons, no other node builders 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.

Trivia

 * 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.