View source for BSPX

{{uncategorized}}{{stub}}
'''BSPX''' is a standard for adding new lumps to {{Idtech2|4.1}}, {{idtech3|4.1}}, and {{goldsrc|4.1}} [[BSP]] files, which are used to add additional features to be used by source ports or [[custom renderer]]s without breaking vanilla compatibility. As BSPX lumps are placed at the end of the BSP file, they are not loaded by vanilla engines, so a BSP with BSPX lumps is backwards compatible.
== Structure ==
<source lang=c>
typedef struct {
	char lumpname[24]; // up to 23 chars, zero-padded
	int fileofs;  // from file start
	int filelen;
} bspx_lump_t;
typedef struct {
	char id[4];  // 'BSPX'
	int numlumps;
	bspx_lump_t lumps[1];
} bspx_header_t;
</source>

== Lumps ==
{{todo|other lumps; see FTE and Ericw-tools source codes}}
=== <tt>DECOUPLED_LM</tt> === 
"Decouples" [[lightmap]] scale, alignment, and rotation from those of [[texel]]s.

Compile with [[ericw-tools]] using {{code|_world_units_per_luxel}} KV in [[worldspawn]] or {{code|-world_units_per_luxel #}} in QBSP, wherein # is the luxel scale (like in {{hammer4|2|addtext='s}} [[Hammer Face Edit Dialog|face edit window]]).

The 2023 {{quake2|4.1}} remaster uses {{mono|DECOUPLED_LM}} with a luxel scale of 8 on all maps except for the Quake II 64 maps. 

=== <tt>LIGHTING_E5BGR9</tt> ===
Used for [[HDR]] [[lightmaps]]. Functions similarly to the [[BSP_(Source)#Lighting|RGBE8 lightmaps]] in {{src|2}}, but with an additional bit of precision per color instead of having the exponent be 8 bits.

=== <tt>ENVMAP</tt> ===
Defines where cubemaps are found (Does not store the cubemaps themselves). Can be generated (alongside <tt>SURFENVMAP</tt>) from {{code|env_cubemap}} entities by loading the BSP in {{fte|4.1}} and running the {{code|mod_findcubemaps}} console command. 

The following FGD entry represents the expected syntax:
<source lang=c>
@PointClass color(0 0 255) iconsprite("sprites/editor/env_cubemap.spr") = env_cubemap : 
	"An entity that creates a sample point for the Cubic Environment Map."
[
	size(choices) : "Cubemap Size" : 0 : "Resolution of the cubemap." =
	[
		0 : "Default"
		1 : "1x1"
		2 : "2x2"
		4 : "4x4"
		8 : "8x8"
		16 : "16x16"
		32 : "32x32"
		64 : "64x64"
		128 : "128x128"
		256 : "256x256"
	]
]
</source>

=== <tt>SURFENVMAP<tt> ===
Used alongside <tt>ENVMAP</tt> lump to store what cubemap index each brush surface should use.

=== <tt>BRUSHLIST</tt> ===
Store actual brush information for collision, like {{quake2|4.1}}, {{quake3|4.1}}, and {{src|4.1}}, allowing for arbitrary hull sizes. This also bypasses 

Only practical for clipnode-based formats like [[BSP29]], [[BSP30]], and [[BSP2]] ([[BSP38]] and derivatives store this information already).

== External links ==
* [https://github.com/fte-team/fteqw/blob/1f9f3635f0aef3b2eed6b40e35fcf6223c6ad533/specs/bspx.txt BSPX spec] in {{fte|2}} repo