Grandfather of Map Mirror

local MirrorRT = GetRenderTarget( "MirrorTexture", ScrW(), ScrH(), false )

local FlippedVertical = CreateConVar( "r_flip_vertical", 1, { FCVAR_ARCHIVE } )
local FlippedHorizontal = CreateConVar( "r_flip_horizontal", 0, { FCVAR_ARCHIVE } )

local function GetBaseTransform()
	return string.format( "center .5 .5 scale %i %i rotate 0 translate 0 0", ( FlippedVertical:GetBool() and -1 or 1 ), ( FlippedHorizontal:GetBool() and -1 or 1 ) )
end

local MirroredMaterial = CreateMaterial(
        "MirroredMaterial",
        "UnlitGeneric",
        {
            [ '$basetexture' ] = MirrorRT,
            [ '$basetexturetransform' ] = GetBaseTransform(),
        }
    )

/*
--Doesn't work :(
local function UpdateTransform()
	MirroredMaterial:SetString( "$basetexturetransform", GetBaseTransform() )
end

cvars.AddChangeCallback( "r_flip_vertical", function( cvar, prev, new )
	UpdateTransform()
end )

cvars.AddChangeCallback( "r_flip_horizontal", function( cvar, prev, new )
	UpdateTransform()
end )
*/

local view = {}

hook.Add( "RenderScene", "Mirror.RenderScene", function( Origin, Angles )

    view.x = 0
    view.y = 0
    view.w = ScrW()
    view.h = ScrH()
    view.origin = Origin
    view.angles = Angles
	view.drawhud = true

    // get the old rendertarget
    local oldrt = render.GetRenderTarget()

    // set the rendertarget
    render.SetRenderTarget( MirrorRT )

        // clear
        render.Clear( 0, 0, 0, 255, true )
        render.ClearDepth()
        render.ClearStencil()
        render.RenderView( view )


    // restore
    render.SetRenderTarget( oldrt )

	MirroredMaterial:SetTexture( "$basetexture", MirrorRT )
    render.SetMaterial( MirroredMaterial )
    render.DrawScreenQuad()
	render.RenderHUD(0,0,view.w,view.h)
    return true
end )

hook.Add( "InputMouseApply", "flipmouse", function( cmd, x, y, angle )

    local pitchchange = y * GetConVar( "m_pitch" ):GetFloat()
    local yawchange = x * -GetConVar( "m_yaw" ):GetFloat()

    angle.p = angle.p + pitchchange * ( FlippedHorizontal:GetBool() and -1 or 1 )
    angle.y = angle.y + yawchange * ( FlippedVertical:GetBool() and -1 or 1 )

    cmd:SetViewAngles( angle )

    return true

end )


hook.Add( "CreateMove", "flipmove", function( cmd ) -- Override player movement

	local forward = 0;
	local right = 0
	local maxspeed = LocalPlayer():GetMaxSpeed() * ( FlippedHorizontal:GetBool() and -1 or 1 )

	if cmd:KeyDown( IN_FORWARD ) then
		forward = forward + maxspeed
	end
	if cmd:KeyDown( IN_BACK ) then
		forward = forward - maxspeed
	end
	if cmd:KeyDown( IN_MOVERIGHT ) then
		right = right - maxspeed
	end
	if cmd:KeyDown( IN_MOVELEFT ) then
		right = right + maxspeed
	end

	cmd:SetForwardMove( forward )
	cmd:SetSideMove( right )

end )