#lang scribble/manual
@(require (for-label racket))

@title{(v-osc3 rate bufpos freq1 freq2 freq3)}


Three variable wavetable oscillators.

A wavetable lookup oscillator which can be swept smoothly across
wavetables. All the wavetables must be allocated to the same
size. Fractional values of table will interpolate between two
adjacent tables. This unit generator contains three oscillators at
different frequencies, mixed together.

This oscillator requires a buffer to be filled with a wavetable
format signal.  This preprocesses the Signal into a form which can
be used efficiently by the oscillator.  The buffer size must be a
power of 2.

This can be acheived by creating a Buffer object and sending it one
of the "b_gen" messages ( sine1, sine2, sine3 ) with the wavetable
flag set to true.

Note about wavetables: Vosc3 requires the b_gen sine1 wavetable
flag to be ON.

Allocate and fill tables 0 to 7 with a generated list of harmonic
amplitudes.


@racketblock[
(with-sc3
 (lambda (fd)
   (let* ((square
	   (lambda (a) (* a a)))
	  (nth
	   (lambda (i)
	     (async fd (b-alloc i 1024 1))
	     (let* ((n (expt (+ i 1) 2))
		    (a (map (lambda (j)
			      (square (/ (- n j) n))) 
			    (enum-from-to 0 (- n 1)))))
	       (async fd (b-gen1 i "sine1" (cons 7 a)))))))
     (for-each nth (enum-from-to 0 7)))))
]

oscillator at buffers 0 through 7.


@racketblock[
(let ((p (mouse-x kr 0 7 0 0.1))
      (f1 (mce2 240 241))
      (f2 (mce2 240.27 241.1))
      (f3 (mce2 240.43 239.71)))
  (audition (out 0 (mul (v-osc3 ar p f1 f2 f3) 0.2))))
]

Reallocate buffers while oscillator is running.


@racketblock[
(with-sc3
 (lambda (fd)
   (for-each
    (lambda (i)
      (async fd (b-gen1  i "sine1" (cons 7 (replicate-m 16 (random 0 1))))))
    (enum-from-to 0 7))))
]