quantum/gamemode/engine/core/client/cl_hud.lua

--    __           _        _______        _      __   
--   / /     /\   | |      |__   __|      | |     \ \  
--  / /     /  \  | |_ __ ___ | | ___  ___| |__    \ \ 
-- < <     / /\ \ | | '_ ` _ \| |/ _ \/ __| '_ \    > >
--  \ \   / ____ \| | | | | | | |  __/ (__| | | |  / / 
--   \_\ /_/    \_\_|_| |_| |_|_|\___|\___|_| |_| /_/  

local enabledHUDs = {
	["CHudChat"] = true,
	["CHudGMod"] = true
}

hook.Add( "HUDShouldDraw", "Quantum_RemoveDefualtHUD", function( hudid ) 
	return enabledHUDs[hudid] ~= nil
end)

local scale = Quantum.Client.ResolutionScale
local barW, barH = 400 * scale, 25 * scale
local radius = 1.05 * scale
local padding = 5 * scale
local sw, sh = ScrW(), ScrH()

local client = LocalPlayer()

local function SetAlpha( color, alpha )
	return Color( color.r, color.g, color.b, alpha )
end

local function renderStatHUD()
	local hp = client:Health()
	local lasthp = hp
	local maxhp = client:GetMaxHealth()

	-- Health border
	surface.SetDrawColor( 0, 0, 0, 200 )
	surface.DrawRect( sw/2 - barW/2, sh*0.9, barW, barH )

	-- Health bar
	surface.SetDrawColor( 168, 62, 50, 255 )
	surface.DrawRect( ( sw/2 - barW/2 ) + padding/2, (sh*0.9) + padding/2, math.Clamp( (barW - padding) * hp/maxhp, 0, barW - padding ), barH - padding )

	-- Health Text
	surface.SetFont( "q_HUD" )
	surface.SetTextColor( 255, 255, 255, 255 )
	local hptxt = tostring( 100 * (hp/maxhp) .. "%" )
	local txtW, txtH = surface.GetTextSize( hptxt )
	surface.SetTextPos( ( ( sw/2 - txtW/2 ) + padding/2 ), ( ( sh*0.9 - txtH/3 ) ) )
	surface.DrawText( hptxt )

	-- Crosshair
	if( Quantum.Client.ShowCrosshair ) then
		surface.SetDrawColor( 255, 255, 255, 200 )
		surface.DrawRect( sw/2 - radius, sh/2 - radius, radius*2, radius*2 )
	end
end

local function renderItemInfoHUD()
	local trace = client:GetEyeTraceNoCursor() 
	if( trace.Entity:GetClass() == "q_item" ) then
		local distance = client:GetPos():Distance( trace.Entity:GetPos() )
		local distFrac = Lerp( distance/Quantum.ItemInfoDisplayMaxDistance, 1, 0 )

		if( distance <= Quantum.ItemInfoDisplayMaxDistance ) then
			local item = Quantum.Item.Get( trace.Entity:GetNWString( "q_item_id" ) ) || { name="ERROR" }
			local amount = trace.Entity:GetNWInt( "q_item_amount" ) || 1

			local pos = trace.Entity:GetPos()
			pos.z = pos.z + 20

			local screenPos = pos:ToScreen()

			local txtPadding = 20 * scale
			local itemAmountTxt = ""
			if( amount > 1 ) then itemAmountTxt = amount .. "x " end

			local alphaFrac = distFrac


			draw.SimpleText( itemAmountTxt .. item.name, "q_item_hud_title", screenPos.x, screenPos.y, SetAlpha( item.rarity.color, 255 * alphaFrac ), TEXT_ALIGN_CENTER, TEXT_ALIGN_CENTER )
			draw.SimpleText( "Rarity: " .. item.rarity.txt, "q_item_hud_rarity", screenPos.x, screenPos.y + txtPadding, SetAlpha( item.rarity.color, 255 *alphaFrac ), TEXT_ALIGN_CENTER, TEXT_ALIGN_CENTER )
			if( item.soulbound ) then
				draw.SimpleText( "Soulbound", "q_item_hud_soulbound", screenPos.x, screenPos.y + txtPadding*2, Color( 235, 64, 52, 255 * alphaFrac ), TEXT_ALIGN_CENTER, TEXT_ALIGN_CENTER )
			end
		end
	end
end

function GM:HUDPaint()
	if( !Quantum.Client.IsInMenu ) then
		if( !client:Alive() ) then 
			surface.SetDrawColor( 0, 0, 0, 255 )
			surface.DrawRect( 0, 0, sw, sh )
		end
		
		if( Quantum.Client.Config.EnableHUD ) then
			if( client:Alive() ) then
				renderStatHUD()
				renderItemInfoHUD()
			end
		end
	end
end

function GM:Think()
	if( Quantum.Client.IsInMenu ) then
		if( gui.IsGameUIVisible() ) then gui.HideGameUI() end -- hides the main menu for the player

		if( !LocalPlayer():Alive() ) then
			if( IsValid( Quantum.Client.CurMenu ) ) then 
				Quantum.Client.CurMenu:Close() -- closes the current open menu on death
			end
		end
	end
end

hook.Add( "RenderScreenspaceEffects", "Quantum_HUD_RenderLowHealth", function() 
	if( !Quantum.Client.IsInMenu ) then
		if( LocalPlayer():Health() / LocalPlayer():GetMaxHealth() <= 0.25 ) then 
			DrawMotionBlur( 0.4, 0.8, 0.1 ) 
			DrawColorModify( {
				[ "$pp_colour_addr" ] = 0,
				[ "$pp_colour_addg" ] = 0,
				[ "$pp_colour_addb" ] = 0,
				[ "$pp_colour_brightness" ] = Lerp( LocalPlayer():Health() / LocalPlayer():GetMaxHealth(), -0.25, 0 ),
				[ "$pp_colour_contrast" ] = Lerp( LocalPlayer():Health() / LocalPlayer():GetMaxHealth(), 0.2, 1 ),
				[ "$pp_colour_colour" ] = Lerp( LocalPlayer():Health() / LocalPlayer():GetMaxHealth(), 0.8, 1 ),
				[ "$pp_colour_mulr" ] = 0,
				[ "$pp_colour_mulg" ] = 0,
				[ "$pp_colour_mulb" ] = 0
			} )
		end
	end
end)