On Balance Volume Analysis [Albert]

//
// @author Albert
// 
// Created on LazyBear's OBV indicator basis
// 
study(title="On Balance Volume Analysis [Albert]", shorttitle="OBV_A")
src = close
length = input(20, minval=1, title="Length")
threshold=input(0, title="threshold for OBV")
lengthema=input(13, title="EMA length")
obv(src) => 
    cum(change(src) > 0 ? volume : change(src) < 0 ? -volume : 0*volume)
    
o=obv(src)
c=cci(src, length)
plot(o, color=c>=threshold?green:red, title="OBV", linewidth=2)
plot(ema(o,lengthema), color=orange, linewidth=2)