View source for BSP flags (Source)

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{{path|[https://github.com/ValveSoftware/source-sdk-2013/blob/master/mp/src/public/bspflags.h public/bspflags]|h}} defines bitfields used to tell the game engine and compiler how a brush face should be drawn in-game (surface flags), and what should be inside the brush (contents flags). They are descended from the [[WAL#Texture flags|method used by Quake II]].

These are normally defined via [[Material map compile flags]], but they can also be applied directly into a VMF's brush face, using {{code|"contents" "####"}} for contents flags and {{code|"flags" "####"}} for surface flags (wherein {{code|<nowiki>####</nowiki>}} is the bitfield represented in base 10 form). Some values are also defined via other means, such as [[func_detail]] for CONTENTS_DETAIL.
{{modernImportant|{{hammer4|4}} (including {{hammer++|4}}) strips these values! Put applicable geometry in an [[instance]] to avoid issues.}}

Some of the contents flags are also used for MDL models, and are set using the {{cmd|$contents}} [[QC]] command.

== List of flags ==
=== Surface flags ===
Surface flags on different faces of a brush generally do not need to match. If two or more conflicting flags are assigned, then the flag with the lowest bit value will take priority.

Unlike {{quake2|2}}, surface flags are stored as a 16-bit value instead of a 32-bit value. This is because most information about how to draw the surface can be determined instead at runtime via the [[VMT]].
{| class="wikitable"
|-
! Bit !! Flag name !! Dev comment !! Description
|-
| 0x0001
| SURF_LIGHT
| value will hold the light strength
| Normally set on any surface that matches a [[RAD file]] entry; not actually written to the BSP, unlike {{quake2|2}}.
{{modernConfirm|Can the value field be set in a VMF, or does it require regressing to MAP instead?}}
|-
| 0x0002 {{removed|{{src07}}}}
| SURF_SLICK
| effects game physics{{sic}}
| {{modernDeprecated|Legacy {{quake2|2}} flag; deprecated in favor of [[surface properties]].}}
|-
| 0x0002 {{since|{{src07}}}}
| SURF_SKY2D
| don't draw, indicates we should skylight + draw 2d sky but not draw the 3D skybox
| Shows only the 2D skybox. Set via [[$Compile2DSky]]
{{confirm|{{cmd|%Compile2DSky}} assigns both SURF_SKY2D ''and'' SURF_SKY; what happens if a face only has SURF_SKY2D?}}
|-
| 0x0004
| SURF_SKY
| don't draw, but add to skybox
| Shows both the 2D and 3D skybox. Set via [[$CompileSky]]
|-
| 0x0008
| SURF_WARP
| turbulent water warp
| Tells [[VVIS]] and the engine renderer that the surface is water. Set via {{cmd|%CompileWater}}, but not {{cmd|%CompileSlime}}. {{confirm|Why does VVIS read this?}}
|-
| 0x0010
| SURF_TRANS
| (None)
| Surface is translucent, either via {{cmd|$translucent}} or {{cmd|$alpha}}.
{{modernConfirm|Might also apply to {{cmd|$alphatest}}.}}
|-
| 0x0020 {{removed|{{src07}}}}
| SURF_WET
| the surface is wet
| {{modernDeprecated|Legacy {{quake2|2}} flag; deprecated in favor of [[surface properties]].}}
|-
| 0x0020 {{since|{{src07}}}}
| SURF_NOPORTAL
| the surface can not have a portal placed on it
| Set via [[%NoPortal]]
|-
| 0x0040 {{removed|{{hl2xbox}}}}
| SURF_FLOWING
| scroll towards angle
| {{modernDeprecated|Legacy {{quake2|2}} flag; deprecated in favor of [[material proxies]].}}
|-
| 0x0040 {{since|{{hl2xbox}}}}
| SURF_TRIGGER
| FIXME: This is an xbox hack to work around elimination of trigger surfaces, which breaks occluders
| Set via [[%CompileTrigger]]. Doesn't do anything in the PC versions.
|-
| 0x0080
| SURF_NODRAW
| don't bother referencing the texture
| Set via [[%CompileNoDraw]]
|-
| 0x0100
| SURF_HINT
| make a primary bsp splitter
| Set via [[%CompileHint]]
|-
| 0x0200
| SURF_SKIP
| completely ignore, allowing non-closed brushes
| Set via [[%CompileSkip]]. Should never be used on anything except a hint brush.
|-
| 0x0400
| SURF_NOLIGHT
| Don't calculate light
| Face is unlit. Set via [[%CompileNoLight]] if using {{as}} or newer or {{src13}}.
Set automatically on [[UnlitGeneric]] materials.
|-
| 0x0800
| SURF_BUMPLIGHT
| calculate three lightmaps for the surface for bumpmapping
| Implied by [[$bumpmap]] and/or [[$normalmap]]. Actually calculates ''four'' lightmap, with the fourth being used when bumpmapping is disabled.
|-
| 0x1000
| SURF_NOSHADOWS
| Don't receive shadows
| Using {{slammin}} or {{mapbase}} [[VBSP]], set via {{cmd|%CompileNoShadows}}.
{{modernConfirm|How is it used in vanilla compilers? It seems to be unrelated to {{ent|info_no_dynamic_shadow}}.}}
|-
| 0x2000
| SURF_NODECALS
| Don't receive decals
| Set via [[$nodecal]]. Can also set via [[%nopaint]] in {{portal2|2}}.
|-
| 0x4000
| SURF_NOCHOP
| Don't subdivide patches on this surface 
| Set via [[%CompileNoChop]]. Has the side effect of affecting triangulation, as well. 
|-
| 0x8000
| SURF_HITBOX
| surface is part of a hitbox
| {{why}}
|-
|}
{{modernCodenote|{{code|0x0020}} can reliably be used as a custom surface flag on mods not using portals.}}

=== Contents flags ===
Contents flags on different faces of a brush ''almost always need to match''. Mismatched contents will result in compiler errors, and leaves it up to the compiler to decide what contents a brush should have. If two or more conflicting flags are assigned, then the flag with the lowest bit value will take priority.

In addition to brushes, some of these flags can also be set on [[MDL (Source)|MDLs]] using [[$contents]] parameter.
{{todo|Third-party titles}}
{| class="wikitable"
|-
! Bit !! Flag name !! Official description !! Notes
|-
| 0x00000000
| CONTENTS_EMPTY
| No contents
| Technically not a flag, but rather the lack of any flags. This cannot be manually assigned to a surface, as brush faces with the contents field set to zero in the VMF (or MAP) file will be treated as solid{{cn}}. Instead, use [[%CompileNonSolid]], a [[func_illusionary]], or a non-solid [[func_brush]].
|-
| 0x00000001
| CONTENTS_SOLID
| an eye is never valid in a solid
| Default contents
|-
| 0x00000002
| CONTENTS_WINDOW
| translucent, but not watery (glass)
| Affects [[VIS]] testing.
|-
| 0x00000004
| CONTENTS_AUX
| (none)
| Unused.
|-
| 0x00000008
| CONTENTS_GRATE
| alpha-tested "grate" textures. Bullets/sight pass through, but solids don't
| Equivalent to a combination of two brushes: one [[%CompileNonSolid]], and the other [[%CompileClip]]. Set via {{cmd|%CompilePassBullets}} or {{cmd|$contents|"grate"}}.
|-
| 0x00000010
| CONTENTS_SLIME
| (none)
| Set via [[%CompileSlime]]. Unlike Quake II, slime does not do damage; a separate [[trigger_hurt]] should be used for this.
|-
| 0x00000020
| CONTENTS_WATER
| (none)
| Set via [[%CompileWater]].
|-
| 0x00000040 {{src07|removed}}
| CONTENTS_MIST
| (none)
| Unknown purpose; only set by [[%CompilePlayerControlClip]].
|-
| 0x00000040 {{src07|since}}
| CONTENTS_BLOCKLOS
| block AI line of sight
| Only visible to [[NPC]]s and [[bot]]s. Transparent to [[player]]s.
|-
| 0x00000080
| CONTENTS_OPAQUE
| things that cannot be seen through (may be non-solid though)
| Any [[player]]-visible brush that isn't translucent or transparent is opaque.
|-
| 0x00000100
| CONTENTS_TESTFOGVOLUME
| (none)
| 
|-
| 0x00000200
| CONTENTS_UNUSED
| (none)
| 
|-
| 0x00000400 {{as|removed}}
| CONTENTS_UNUSED6
| rowspan=2 | Unused<br>NOTE: If it's visible, grab from the top + update LAST_VISIBLE_CONTENTS<br>if not visible, then grab from the bottom.
| 
|-
| 0x00000400 {{as|since}}
| CONTENTS_BLOCKLIGHT
| Not actually unused; comment is vestigial.
{{modernConfirm|Is this in {{l4dbranch|2}} as well?}}
{{modernConfirm|Can this block dynamic lights, unlike toolsblocklight?}}
|-
| 0x00000800
| CONTENTS_TEAM1
| rowspan=2 | per team contents used to differentiate collisions<br>between players and objects on different teams
| rowspan=2 | Typically to set barriers that prevent one team from entering another team's spawn zone.
Used in multiple games, including {{dods}}{{tf2}}{{l4dseries}}, but only able to be set via [[%CompileTeam]] in {{l4dseries}} and newer.
|-
| 0x00001000
| CONTENTS_TEAM2
|-
| 0x00002000
| CONTENTS_IGNORE_NODRAW_OPAQUE
| ignore CONTENTS_OPAQUE on surfaces that have SURF_NODRAW
| 
|-
| 0x00004000
| CONTENTS_MOVEABLE
| hits entities which are MOVETYPE_PUSH (doors, plats, etc.)
| 
|-
| align=center | ----------------- <!-- Dev comment regarding all subsequent flags -->
| align=center | ----------------- <!-- This space intentionally left blank -->
| remaining contents are non-visible, and don't eat brushes
| align=center | ----------------- <!-- Hyphens used to indicate as such --> 
|-
| 0x00008000
| CONTENTS_AREAPORTAL
| (none)
| Is an [[areaportal]].
|-
| 0x00010000
| CONTENTS_PLAYERCLIP
| (none)
| Solid to [[player]]s, including [[bot]]s.
|-
| 0x00020000
| CONTENTS_MONSTERCLIP
| (none)
| Solid to [[monster]]s, better known in Source as [[NPC]]s. Also solid to [[bot]]s in CSGO, even though they are players.
|-
| 0x00040000 {{portal2|removed}}
| CONTENTS_CURRENT_0
| rowspan=6 | currents can be added to any other contents, and may be mixed
| rowspan=6 | Effectively identical to a [[trigger_push]] traveling the same direction. Mix these to go in diagonals.
|-
| 0x00080000 {{portal2|removed}}
| CONTENTS_CURRENT_90
|-
| 0x00100000 {{portal2|removed}}
| CONTENTS_CURRENT_180
|-
| 0x00200000 {{portal2|removed}}
| CONTENTS_CURRENT_270
|-
| 0x00400000 {{portal2|removed}}
| CONTENTS_CURRENT_UP
|-
| 0x00800000 {{portal2|removed}}
| CONTENTS_CURRENT_DOWN
|-
| 0x00040000 {{portal2|since}}
| CONTENTS_BRUSH_PAINT
| N/A (source code not public)
| 
|-
| 0x00080000 {{csgo|since}}
| CONTENTS_GRENADECLIP
| N/A (source code not public)
|
|-
| 0x00100000 {{since|{{csgo mode|dangerzone}}}}
| CONTENTS_DRONECLIP
| N/A (source code not public)
|
|-
| 0x01000000
| CONTENTS_ORIGIN
| removed before bsping an entity
| Coordinates of enter of the brush is written to the {{code|origin}} [[KV]], to dictate the pivot point of certain entities.{{deprecated}}
|-
| 0x02000000
| CONTENTS_MONSTER
| should never be on a brush, only in game
| Is a [[monster]], better known in Source as an [[NPC]].
|-
| 0x04000000
| CONTENTS_DEBRIS
| (none)
| Solid to point traces (ex [[hitscan]] weapons) and non-debris physics objects{{confirm}}. Non-solid to [[QPhysics]] entities, such as [[player]]s.
|-
| 0x08000000
| CONTENTS_DETAIL
| brushes to be added after vis leafs
| World brushes with these contents don't affect [[VIS]]. Brushes with these contents can be toggled with {{cmd|r_drawfuncdetail}}. Automatically given to any brushes in a [[func_detail]]. This flag [https://github.com/ValveSoftware/source-sdk-2013/blob/master/mp/src/utils/vbsp/map.cpp#L796 is stripped] from brushes which are part of a [[brush entity]].
|-
| 0x10000000
| CONTENTS_TRANSLUCENT
| auto set if any surface has trans
| Used for alpha sorting on (non-detail) worldspawn brushes.
|-
| 0x20000000
| CONTENTS_LADDER
| (none)
| Is a [[ladder]].
|-
| 0x40000000
| CONTENTS_HITBOX
| use accurate hitboxes on trace
| 
|-
| 0x80000000
| N/A
| N/A (not defined)
| Unused
|-
|}
{{modernCodenote|{{code|0x00000200}} and {{code|0x80000000}} can reliably be used for custom contents flags in mods shipping custom DLLs (and preferably custom VBSP).}}

== See also ==
* [[MASK Types]]