Glass effect for Garry's Mod; save in lua/autorun.

gm_sublime_glass.lua

---
-- Sublime Glass - Garry's Mod
--
-- Use with the 'Sublime Text Trans' package.
-- https://github.com/vhanla/SublimeTextTrans
--

if SERVER then
	AddCSLuaFile()
	return
end

local UpdateScreenEffectTexture = render.UpdateScreenEffectTexture
local DrawTexturedRect = surface.DrawTexturedRect
local SetMaterial = surface.SetMaterial
local SetDrawColor = surface.SetDrawColor
local EaseInOut = math.EaseInOut
local HasFocus = system.HasFocus
local RealTime = RealTime
local ScrW = ScrW
local ScrH = ScrH
local min = math.min

local GlassCvar = CreateClientConVar( "subl_glass", 1, true, false )

local color_white = color_white
local matBlurScreen = Material( "pp/blurscreen" )
local defaultBlur = 5

local function BackgroundBlur( x, y, w, h, blurAmnt )
	if not blurAmnt then
		blurAmnt = defaultBlur
	end

	SetMaterial( matBlurScreen )
	SetDrawColor( color_white )
	
	for i = 0.33, 1, 0.33 do
		matBlurScreen:SetFloat( "$blur", blurAmnt * i )
		matBlurScreen:Recompute()
		UpdateScreenEffectTexture()   
		DrawTexturedRect( x, y, w, h )
	end
end

local GlassBlur = 8

local TransitionDuration = 0.314
local LastFocus = 0
local CurBlur = 0

local function GlassEffect()
	if not GlassCvar:GetBool() then return end
	if HasFocus() then
		LastFocus = RealTime()
	else
		local progress = min(1, (RealTime() - LastFocus) / TransitionDuration)
		local fade = EaseInOut(progress, 0.8, 0.1)
		BackgroundBlur(0, 0, ScrW(), ScrH(), fade * GlassBlur)
	end
end
hook.Add( "PostRenderVGUI", "Sublime Text Glass Effect", GlassEffect )