(load "blit.lisp")

(defun envelope-or-number (in)
  (if (numberp in)
    (list 0 in 1 in)
    in
  ))

(definstrument good-tri (start-time duration frequency &optional (amp 1.0)
				    &key (amp-env '(0 1.0 1.0 1.0))
				    (freq-env '(0 1 1.0 1))
				    (leak .995)
				    (leak2 .9995)
				    (limit .1)  ;attenuation at Nyquist, affects sharpness of waveform, eliminates Gibb's phenomena (!! Must be less than 1.0)
				    (width 0.5) ;morphs the slope to a lag/lead ramp (can be an envelope)
				    (glide 4)   ;exponent of portamento (quartic functions approximate logarithmic behavior)
				    (morph 1.0) ;Morphs even harmonics. 0 = parabola, 1 = triangle. (can be an envelope)
				    (phase 0)   ;initial phase, between 0 and 1
				    )

  
  (multiple-value-bind (beg end) (times->samples start-time duration)
    (let* (
	   (blit1 (make-blit-init :frequency frequency :phase phase :nyquist limit))    ;bipolar BLIT is made by subtracting a phase-offset blit
	   (blit2 (make-blit-init :frequency frequency :phase (+ phase 0.5) :nyquist limit))  ;(in this case duty-cycle is 0.5, but will

	   (integrator (make-one-pole :a0 1
				      :b1 (- leak)))
	   (integrator2 (make-one-pole :a0 1
				      :b1 (- leak2)))
;	   (R (-(- 1 (/ 126 *srate*)))) ; -3 dB at 20 Hz
;	   (dc-block (make-filter :order 2 :xcoeffs '(1 -1) :ycoeffs `(0 ,R) ))
           (amp (make-env :envelope amp-env
                          :scaler amp
                          :duration duration))

	   (width (make-env :envelope (envelope-or-number width)
			    :duration duration))

	   (morph (make-env :envelope (envelope-or-number morph)
			    :duration duration))

	   (freq (make-env :envelope (envelope-exp freq-env glide)
			   :scaler frequency
			   :duration duration))

	   ; initialize variables used in run loop	   
	   f
	   tri
	   duty
	   scale
	   )
      (run
       
       (loop for i from beg below end do
	 (setf f (env freq)
	       tri (env morph)
	       duty (- 1 (env width))
	       (blit-phase blit2) (+ (blit-phase blit1) duty) ;set the duty-cycle / ramp slope
	       scale (/ (* 2 (/ f *srate*)) (- duty (* duty duty))) ;scaling factor from Stilson and Smith
	       scale (+ (* tri scale) (* (- 1 tri) 0.01)) ;??
	       )
	 (if (blit-wrapped blit1)
	     (set-blit-frequency blit1 f)
	   )	 
	 (if (blit-wrapped blit2)
	     (set-blit-frequency blit2 f)
	   )
	 
	 (outa i (* (env amp) 1.1 ;;scale correction
		    (one-pole integrator2
			      (* scale
				  (one-pole integrator
					    (- (blit blit1) (* tri (blit blit2)))
					    )))				 
		    ))

	 ))
      ))
  )



;;(with-sound () (good-tri 0 5 100 0.3 :width '(0 0.2 1 0.8)))
;(with-sound () (good-tri 0 5 50 0.3 :width .995)) ;makes a decent sawtooth