View source for WAL

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'''WAL''' is a [[texture]] file format used by {{quake2|4.1}} to store [[brush]] textures. It is a modified version of Quake I's [[miptex]] format, containing four [[mipmaps]], two strings (used for animation), as well as three metadata values. The first two metadata values are [[flags|bitfield]]s, indicating information about a brush's face (surface flags) and a brush's contents (content flags). The third metadata value is an integer value, traditionally used for determining the brightness of [[texlight]]s (although some compilers use it for other purposes on non-emissive surfaces, such as for smoothing groups in [[RAD|Arghrad]]).

The surface flags and contents flags used by Quake II would serve the basis for [[BSP flags (Source)|those used by Source]].

== Technical ==
{{License|type=gpl|version=2}}
The header of a WAL file can be represented by the following C struct (from {{path|qcommon/qfiles|h}} in the Quake II source code release):
<source lang=c>
#define	MIPLEVELS	4
typedef struct miptex_s
{
	char		name[32];			// 31 chars plus null terminator
	unsigned	width, height;
	unsigned	offsets[MIPLEVELS];		// four mip maps stored
	char		animname[32];			// next frame in animation chain
	int			flags;
	int			contents;
	int			value;
} miptex_t;
</source>
{{note|Both {{mono|unsigned}} and {{mono|int}} are 32-bits.}}
It is then followed by raw 8-bit image data for each mipmap, at the offsets relative to the start of the file.

== Texture flags ==
{{tabsBar|main=BSP flags}}
These sections list and describe the various standard surface and content flags used in {{Quake2|4.1}}, as well as the equivalent [[VMT]] parameters to achieve the same or similar result in {{src|4.1|nt=0}}.
=== 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.
{| class="wikitable"
|-
! Bit !! Flag name !! [[VMT]] equivalent !! Description
|-
| {{mono|0x00000001}}
| SURF_LIGHT
| N/A
| Treats this face as a [[texlight]], with brightness dependent upon the surface value.
|-
| {{mono|0x00000002}}
| SURF_SLICK
| N/A
| Makes this face slippery.
|-
| {{mono|0x00000004}}
| SURF_SKY
| {{code|1=[[%Compile2DSky]] 1}}
| Face is is not drawn, and the [[skybox]] is drawn behind all visible faces when this face is in the [[PVS]].
|-
| {{mono|0x00000008}}
| SURF_WARP
| Potentially simulatable using [[List_of_material_proxies#Texture_manipulation|material proxies]]
| "Warp" the texture on this face, like water.
|-
| {{mono|0x00000010}}
| SURF_TRANS33
| {{code|[[$alpha]] "0.33"}}
| rowspan=2 | Render the face as translucent, at 33% or 66% opacity, respectively.
Most source ports, including the remaster, will render any texels using [[palette]] index 255 (or true color images with an alpha of less than 127) as fully transparent.

While these flags can technically be combined, the behavior for such is not standardized. Some engines (such as Yamagi) will prioritize one or the other, others (such as Q2EX) will render the face at 50% opacity, and a small few will instead render the face with binary transparency.
|-
| {{mono|0x00000020}}
| SURF_TRANS66
| {{code|[[$alpha]] "0.66"}}

|-
| {{mono|0x00000040}}
| SURF_FLOWING
| [[List_of_material_proxies#Texture_manipulation|{{mono|TextureScroll}} material proxy]]
| Texture scrolls from top to bottom.
Note that this is different from {{mono|scroll}} textures in {{gldsrc|4.1}}, which scroll from left to right (and require a func_conveyor, which this does not).
|-
| {{mono|0x00000080}}
| SURF_NODRAW
| {{code|1=[[%CompileNoDraw]] 1}}
| Do not render this face in-game.
|-
| {{mono|0x00000100}}
| SURF_HINT
| {{code|1=[[%CompileHint]] 1}}
| Used on [[hint brush]]es.
|-
| {{mono|0x00000200}}
| SURF_SKIP
| {{code|1=[[%CompileSkip]] 1}}
| Completely ignore. Causes unexpected results when applied to anything other than hint brushes; use SURF_NODRAW for other brushes.
|-
| {{mono|0x02000000}}
| SURF_ALPHATEST
| {{code|[[$alphatest]] 1}}
| {{not|Vanilla}} Use binary transparency, using either [[palette]] index 255 of an 8-bit texture or the alpha channel of 32-bit texture as a transparency mask.
|-
| {{mono|0x10000000}}
| SURF_N64_UV
| {{code|<small>[[$basetexturetransform]] "center .5 .5 scale 0.5 0.5 rotate 0 translate 0 0"</small>}}
| {{not|Vanilla}} Halves texture sizes, without requiring setting texture scale in the editor to 2.0.
|-
| {{mono|0x20000000}}
| SURF_N64_SCROLL_X
| [[List_of_material_proxies#Texture_manipulation|{{mono|TextureScroll}} material proxy]]
| {{not|Vanilla}} Scrolls the texture on the X axis. Slower than SURF_FLOWING.
|-
| {{mono|0x40000000}}
| SURF_N64_SCROLL_Y
| [[List_of_material_proxies#Texture_manipulation|{{mono|TextureScroll}} material proxy]]
| {{not|Vanilla}} Scrolls the texture on the Y axis. Slower than SURF_FLOWING.
|-
| {{mono|0x80000000}}
| SURF_N64_SCROLL_FLIP
| [[List_of_material_proxies#Texture_manipulation|{{mono|TextureScroll}} material proxy]]
| {{not|Vanilla}} Inverts the scroll direction.
|-
|}

=== Content flags ===
Content 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.
{| class="wikitable"
|-
! Bit !! Flag name !! [[VMT]] equivalent !! Description
|-
| 0x00000000
| N/A
| N/A
| No contents, sometimes known as "CONTENTS_EMPTY".

This cannot be assigned to a texture or surface via normal means, as brush faces with the contents field set to zero in the WAL and [[MAP]] file will be treated as solid.
|-
| 0x00000001
| CONTENTS_SOLID
| N/A
| Default contents. Generally no need to set manually.
|-
| 0x00000002
| CONTENTS_WINDOW
| N/A
| Prevents the renderer from drawing the backfaces of a brush.
|-
| 0x00000004
| CONTENTS_AUX
| N/A
| No effect (unused).

Some compilers, such as [[ericw-tools]], treat it as an alias for a combination of CONTENTS_MIST and CONTENTS_WINDOW.
|-
| 0x00000008
| CONTENTS_LAVA
| {{code|[[%CompileWater]] 1}}, along with a {{ent|trigger_hurt}} brush
| rowspan=3 | Makes brush swimmable. CONTENTS_LAVA and CONTENTS_SLIME also deal periodic damage to the anyone or anything in them, with lava dealing more damage than slime.
|-
| 0x00000010
| CONTENTS_SLIME
| {{code|[[%CompileSlime]] 1}}, along with a {{ent|trigger_hurt}} brush
|-
| 0x00000020
| CONTENTS_WATER
| {{code|[[%CompileWater]] 1}}
|-
| 0x00000040
| CONTENTS_MIST
| {{codeblock|[[%CompileNonSolid]] 1<br>[[$nocull]] 1}}
| Disables collision, and sometimes disables backface culling.
|-
| 0x00004000
| CONTENTS_PROJECTILECLIP
| N/A
| {{not|Vanilla}} Blocks moving entities using CONTENTS_PROJECTILE. No effect on hitscan weapons.
|-
| 0x00008000
| CONTENTS_AREAPORTAL
| N/A
| Used on [[areaportal]]s.
|-
| 0x00010000
| CONTENTS_PLAYERCLIP
| {{code|[[%PlayerClip]] 1}}
| Blocks player and bot movement.
|-
| 0x00020000
| CONTENTS_MONSTERCLIP
| {{code|[[%CompileNPCClip]] 1}}
| Blocks [[monster]] (NPC) movement.
|-
| 0x00040000
| CONTENTS_CURRENT_0
| N/A
| rowspan=6 | Pushes stuff inside it in the specified direction. These flags can be stacked to go in diagonal directions. Effectively acts like {{ent|trigger_push}}.

[[ZHLT]] and derivatives have [[Tool_textures_(GoldSrc)#Missing_ZHLT_tool_textures|tool textures]] that serve a similar purpose.
|-
| 0x00080000
| CONTENTS_CURRENT_90
| N/A
|-
| 0x00100000
| CONTENTS_CURRENT_180
| N/A
|-
| 0x00200000
| CONTENTS_CURRENT_270
| N/A
|-
| 0x00400000
| CONTENTS_CURRENT_UP
| N/A
|-
| 0x00800000
| CONTENTS_CURRENT_DOWN
| N/A
|-
| 0x1000000
| CONTENTS_ORIGIN
| {{code|[[%CompileOrigin]] 1}}
| Sets the origin of brush entities.
|-
| 0x2000000
| CONTENTS_MONSTER
| N/A
| Internal flag, do not set.
|-
| 0x4000000
| CONTENTS_DEADMONSTER
| N/A
| Internal flag, do not set.
|-
| 0x8000000
| CONTENTS_DETAIL
| {{code|[[%CompileDetail]] 1}}
| Brush does not chop structural brushes, and does not affect [[VIS]]. It may, however, still affect [[visibility]].
|-
| 0x10000000
| CONTENTS_TRANSLUCENT
| N/A
| Marks brush as able to be seen through.

Automatically set by SURF_TRANS33 and SURF_TRANS66, and in some compilers, SURF_ALPHATEST.
|-
| 0x20000000
| CONTENTS_LADDER
| {{code|[[%CompileLadder]] 1}}
| Makes climbable. 
|-
| 0x40000000
| CONTENTS_PLAYER
| N/A
| {{not|Vanilla}} Internal flag, do not set.
|-
| 0x10000000
| CONTENTS_PROJECTILE
| N/A
| {{not|Vanilla}} Internal flag, do not set.
|-
|}

== Variants ==
* '''Daikatana WALs''' are mostly identical to Quake 2 WALs, but have 8 mipmaps instead of 4. This makes them more suitable for hardware renderers than Quake 2's format.
* '''SWL''' files are used by {{sin|2}}.{{elaborate}}
* '''M8''' is a variation of Quake 2 WALs that stores its own palette. Like [[WAD3]], this adds 768 bytes to the file size.
* '''M32''' is a variation of Quake 2 WALs that stores its mipmaps in an uncompressed 32-bit RGBA format, best suited for textures with translucency.
* '''WAL_JSON''' is a JSON file used by [[ericw-tools]] which can store the metadata found in a WAL, allowing compiling maps with textures that use other texture formats ([[TGA]], [[PNG]], or [[JPG]]) without also creating an associated WAL file. It also adds a color value to override the color of [[texlight]]s.

== External links ==
* [http://tastyspleen.net/~panjoo/rust/tutorials/surface_properties/surface_properties.html Surface and content flags documentation from the "Rust" tutorials]
[[Category:File formats]]