WAL

WAL is a texture file format used by Quake II to store brush textures. A single WAL file contains one miptex, as well as three metadata values. The first two metadata values are bitflags, 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 texlights (although some compilers use it for other purposes on non-emissive surfaces, such as for smoothing groups in Arghrad).

The surface flags and content flags found in WAL files would serve the basis for the material map compile flags used by Source 1.

Texture flags

These sections list and describe the various standard surface and content flags used in Quake II, as well as the equivalent VMT parameters to achieve the same result in Source 1.

Surface flags

Surface flags on different faces of a brush generally do not need to match.

Bit	Flag name	VMT equivalent	Description
0x00000001	SURF_LIGHT	N/A	Treats this face as a texlight, with brightness dependent upon the surface value.
0x00000002	SURF_SLICK	N/A	Makes this face slippery.
0x00000004	SURF_SKY	%compile2dsky 1	Face is is not drawn, and the skybox is drawn behind all visible faces when this face is in the PVS.
0x00000008	SURF_WARP	Potentially simulatable using material proxies	"Warp" the texture on this face, like water.
0x00000010	SURF_TRANS33	$alpha "0.33"	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 will even render the face with binary transparency.
0x00000020	SURF_TRANS66	$alpha "0.66"
0x00000040	SURF_FLOWING	TextureScroll material proxy	Texture scrolls from top to bottom. Requires SURF_WARP.
0x00000080	SURF_NODRAW	%compilenodraw 1	Do not render this face in-game.
0x00000100	SURF_HINT	%compilehint 1	Used on hint brushes.
0x00000200	SURF_SKIP	%compileskip 1	Completely ignore. Causes unexpected results when applied to anything other than hint brushes.
0x02000000	SURF_ALPHATEST	$alphatest 1	(not in 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.
0x10000000	SURF_N64_UV	$basetexturetransform "center .5 .5 scale 0.5 0.5 rotate 0 translate 0 0"	(not in Vanilla) Halves texture sizes, without requiring setting texture scale in the editor to 2.0.
0x20000000	SURF_N64_SCROLL_X	TextureScroll material proxy	(not in Vanilla) Scrolls the texture on the X axis. Slower than SURF_FLOWING.
0x40000000	SURF_N64_SCROLL_Y	TextureScroll material proxy	(not in Vanilla) Scrolls the texture on the Y axis. Slower than SURF_FLOWING.
0x80000000	SURF_N64_SCROLL_FLIP	TextureScroll material proxy	(not in 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.

Bit	Flag name	VMT equivalent	Description
0x1	CONTENTS_SOLID	N/A	Default contents. Generally no need to set manually.
0x2	CONTENTS_WINDOW	N/A	Prevents the renderer from drawing the backfaces of a brush.
0x4	CONTENTS_AUX	N/A	No effect. Some compilers treat it as an alias for a combination of of CONTENTS_MIST and CONTENTS_WINDOW.
0x8	CONTENTS_LAVA	%CompileWater 1, along with a trigger_hurt brush	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.
0x10	CONTENTS_SLIME	%CompileSlime 1, along with a trigger_hurt brush
0x20	CONTENTS_WATER	%CompileWater 1
0x40	CONTENTS_MIST	%CompileNonSolid 1 $nocull 1	Disables collision, and sometimes disables backface culling.
0x4000	CONTENTS_PROJECTILECLIP	N/A	(not in Vanilla) Blocks moving entities using CONTENTS_PROJECTILE. No effect on hitscan weapons.
0x8000	CONTENTS_AREAPORTAL	N/A	Used on areaportals.
0x10000	CONTENTS_PLAYERCLIP	%playerclip 1	Blocks player and bot movement.
0x20000	CONTENTS_MONSTERCLIP	%compilenpcclip 1	Blocks monster (NPC) movement.
0x40000	CONTENTS_CURRENT_0	N/A	Pushes stuff inside it in the specified direction. Can be stacked.
0x80000	CONTENTS_CURRENT_90	N/A
0x100000	CONTENTS_CURRENT_180	N/A
0x200000	CONTENTS_CURRENT_270	N/A
0x400000	CONTENTS_CURRENT_UP	N/A
0x800000	CONTENTS_CURRENT_DOWN	N/A
0x1000000	CONTENTS_ORIGIN	%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	%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	%CompileLadder 1	Makes climbable.
0x40000000	CONTENTS_PLAYER	N/A	(not in Vanilla) Internal flag, do not set.
0x10000000	CONTENTS_PROJECTILE	N/A	(not in Vanilla) Internal flag, do not set.