// @class Smooth
// @desc contral signal generator for smooth transition
public class Smooth
{
    // audio graph
    Step in => Gain out => blackhole;
    Gain fb => out;
    out => fb;
    
    // init: smoothing coefficient, default no smoothing
    0.0 => float coef;
    initGains();
    
    // initGains()
    fun void initGains() {
        in.gain(1.0 - coef);
        fb.gain(coef);
    }
    
    // setNext(): set target value
    fun void setNext(float value) { 
        in.next(value); 
    }
    
    // getLast(): return current interpolated value
    fun float getLast() {
        1::samp => now; 
        return out.last(); 
    }
    
    // setExpo(): set smoothing directly from exponent
    fun void setExpo(float value) { 
        value => coef;
        initGains();
    }
    
    // setTimeConstant(): set smoothing duration
    fun void setTimeConstant(dur duration) {
        Math.exp(-1.0 / (duration / samp)) => coef;
        initGains();
    }
} // END OF CLASS: Smooth