halo.Add
halo.Add( table entities, table color, number blurX = 2, number blurY = 2, number passes = 1, boolean additive = true, boolean ignoreZ = false )
Description
Applies a halo glow effect to one or multiple entities.
Using this function outside of the GM:PreDrawHalos hook can cause instability or crashes.
The ignoreZ parameter will cause the halos to draw over the player's viewmodel. You can work around this using render.DepthRange in the GM:PreDrawViewModel, GM:PostDrawViewModel, GM:PreDrawPlayerHands and GM:PostDrawPlayerHands hooks.
Arguments
5 number passes = 1
The number of times the halo should be drawn per frame. Increasing this may hinder player FPS.
Example
Adds a halo around all props in the map using an O(n) operation and iterating through unseen objects which can be extremely expensive to process.
local color_red = Color( 255, 0, 0 )
hook.Add( "PreDrawHalos", "AddPropHalos", function()
halo.Add( ents.FindByClass( "prop_physics*" ), color_red, 5, 5, 2 )
end )
Output:
All the props on the map will be rendered with a red halo, a blur amount of 5, and two passes.

Example
Adds a green halo around all admins.