-- normal pp
function normal(shader, t_base, t_second, t_detail)
    shader:begin("null", "postprocess")
        :fog(false)
        :zb(false, false)
    shader:sampler("s_base0"):texture(t_rt):clamp():f_linear()
    shader:sampler("s_base1"):texture(t_rt):clamp():f_linear()
    shader:sampler("s_noise"):texture(t_noise):f_linear()
end