[Fluxus] pfunc question

[gabor papp]

i'm trying to get accustomed to pfunc. i'm trying to use it to
interpolate between two sets of positions ("p0" and "p1"). i guess this
cannot be done with pdata-op. am i right? i had to use 3 pfuncs and 2
temporary pdata fields to do this. "t0" = (1 - t) * "p0", "t1" = t *
"p1", and "p" = "t0" + "t1". is there a simpler way?

best,
gabor

;----------------------------------
(clear)

(define p (build-particles 256))

(with-primitive p
    ; pdata storing positions to interpolate between
    (pdata-add "p0" "v")
    (pdata-add "p1" "v")
    ; random sphere
    (pdata-map! (lambda (p) (srndvec)) "p0")
    ; random cube
    (pdata-map! (lambda (p) (crndvec)) "p1")
    ; temporary data for interpolation
    (pdata-add "t0" "v")
    (pdata-add "t1" "v")
    (pdata-map! (lambda (c) (vector 1 .5)) "c"))

(define p0f (make-pfunc 'arithmetic))
(define p1f (make-pfunc 'arithmetic))
(define pf (make-pfunc 'arithmetic))

; p = t0 + t1
(pfunc-set! pf (list 'operator "add"
                     'src "t0"
                     'other "t1"
                     'dst "p"))

(define (animate)
    (let ([t (+ .5 (* .5 (sin (time))))])
        ; t0 = (1 - t) * p0
        (pfunc-set! p0f (list 'operator "mul"
                              'src "p0"
                              'constant (- 1 t)
                              'dst "t0"))
        ; t1 = t * p1
        (pfunc-set! p1f (list 'operator "mul"
                              'src "p1"
                              'constant t
                              'dst "t1"))
        (with-primitive p
            (pfunc-run p0f)
	    (pfunc-run p1f)
            (pfunc-run pf))))

(every-frame (animate))