BSP flags (Quake and GoldSrc)

Quake and GoldSrc

Quake II

Source Engine

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Note:These aren't actually flags, except for the surface flags; the page title is for consistency so that the tabs work.

Surface flags

Despite having a 32-bit integer available to be used, most flags go unused. Vanilla Quake engines and GoldSrc only use TEX_SPECIAL.

Bit	Name	Dev comment	Notes
0x00000001	TEX_SPECIAL	sky or slime, no lightmap or 256 subdivision	Surface does not have a lightmap. Used by QBSP to tell LIGHT to not generate lightmaps for sky and liquid surfaces, which are not subdivided to account for maximum lightmap size (15x15 luxels, or 240x240 texels). ericw-tools additionally uses this on surfaces textured with TRIGGER. QCSG and HLCSG don't use this, instead always subdividing surfaces regardless of if they need ligthmaps. Therefore, QRAD and HLRAD will always lightmap all textured surfaces, unless they are flagged in some other manner, such as using newbspguy.
0x00000002	TEX_MISSING	johnfitz -- this texinfo does not have a texture	Used by fitzquake and derivatives to indicate a missing texture
0x00000800	???	N/A	Used by VERTEXNORMALS BSPX lump to indicate a face that should have smooth shading based upon its vertex normals.

Contents types

Contents are stored as a signed 32-bit integer, and are always negative.

Clarify: Contents are stored in visleaves somehow, not directly in clipnodes.

Value	Internal name	Dev comment	Notes
-1	CONTENTS_EMPTY
-2	CONTENTS_SOLID
-3	CONTENTS_WATER
-4	CONTENTS_SLIME
-5	CONTENTS_LAVA
-6	CONTENTS_SKY
-7	CONTENTS_ORIGIN		Replaces an entity's origin KV, then is removed by CSG (does not exist in compiled BSP). In GoldSrc, if a brush has this contents at runtime, it will be treated like water.
-8	CONTENTS_CLIP	changed to contents_solid
-9	CONTENTS_CURRENT_0
-10	CONTENTS_CURRENT_90
-11	CONTENTS_CURRENT_180
-12	CONTENTS_CURRENT_270
-13	CONTENTS_UP
-14	CONTENTS_DOWN
-15	CONTENTS_TRANSLUCENT (in all games since goldsrc)		Like water, but never solid
-16	CONTENTS_LADDER (in all games since goldsrc)
-17	CONTENTS_FLYFIELD (in all games since goldsrc)		Zero gravity
-18	CONTENTS_GRAVITY_FLYFIELD (in all games since goldsrc)
-19	CONTENTS_FOG (in all games since goldsrc)

Ambient Types

Ambients are stored as an array of 4 unsigned bytes, indicating volume. Only Quake uses them, and it only uses AMBIENT_SKY and AMBIENT_WATER, which are hardcoded in the engine to play specific sounds when a visleaf containing the given ambient type is in the current PVS.

Index	Header text	Header text
0	AMBIENT_WATER
1	AMBIENT_SKY
2	AMBIENT_SLIME
3	AMBIENT_LAVA