env_bubbles

env_bubbles is a point entity available in all GoldSrc games. It creates an area of rising bubbles.

Key Values

Targetname:

Name (targetname) <string>: The targetname that other entities refer to this entity by.
Bubble density (density) <integer>: This is the density of bubbles spawned.
Bubble frequency (frequency) <integer>: The higher the value here, the greater the frequency bubbles will appear at.
Speed of current (current) <integer>: The higher this value, the more bubbles drift in the direction specified by the entity angle.

ZHLT:

Don't Render (ZHLT 3+) (zhlt_invisible) <boolean>: Treat all faces as if they were textured with NULL.; Tip:Use this on triggers which use custom textures instead of AAATRIGGER or NULL, such as ladders.
Custom Hull 1 (VHLT+) (zhlt_hull1) <targetname>
Custom Hull 2 (VHLT+) (zhlt_hull2) <targetname>
Custom Hull 3 (VHLT+) (zhlt_hull3) <targetname>: Which named info_hullshape entity to use for the specified clipping hull.
Mins/Maxs (VHLT+) (zhlt_minsmaxs) <mins vector + maxs vector>: Override this entity's bounding box.
zhlt_transform (zhlt_transform) <???>
Never visible (VHLT+) (zhlt_hidden) <boolean>: Don't create marksurfaces for this entity, resulting in it being treated by VIS as never visible.; Tip:The _HIDDEN texture suffix does the same thing, but also works on world brushes, which are used for model lighting.
Strip lightmaps after compiling (VHLT+) (zhlt_striprad) <boolean>: Undefines the lightmaps for brushes on this entity after compiling, resulting in the faces being fullbright and not using up allocblock. Unlike TEX_SPECIAL, faces with zhlt_striprad will still affect bounced lighting.

Start off : [1]