Fix fade direction limitation in Crossfade Tracks

plug-ins/crossfadetracks.ny

@@ -7,23 +7,32 @@
 ;author "Steve Daulton"
 ;copyright "Released under terms of the GNU General Public License version 2"
 
-;; crossfadetracks.ny by Steve Daulton Nov 2014.
+;; crossfadetracks.ny by Steve Daulton Nov 2014 / Sep 2015
 ;; Released under terms of the GNU General Public License version 2:
 ;; http://www.gnu.org/licenses/old-licenses/gpl-2.0.html .
 
 ;control type "Fade type" choice "Constant Gain,Constant Power 1,Constant Power 2,Custom Curve" 0
 ;control curve "Custom curve" real "" 0 0 1
+;control direction "Fade direction" choice "Automatic,Alternating Out / In,Alternating In / Out" 0
 
-(defun crossfade (type)
+
+(defun crossfade (type dir curve)
+  (setf fade-out
+    (case dir
+      (0 (equal (guessdirection) 'OUT))   ; auto
+      (1 (oddp (get '*track* 'index)))    ; fade out odd
+      (T (evenp (get '*track* 'index))))) ; fade out even
   (mult *track*
     (cond
-      ((= (get '*track* 'index) 1)  ; fade out.
+      (fade-out
         (case type
           (0 (pwlv 1 1 0))
           (1 (osc (hz-to-step (/ (get-duration 4))) 1 *sine-table* 90))
           (2 (s-sqrt (pwlv 1 1 0)))
           (T (custom curve 0))))
       (T  ; else fade in.
+        ; Control envelope sample rate must match sound so that lengths
+        ; match exactly, otherwise we get a click at the end of the fade.
         (setf *control-srate* *sound-srate*)
         (case type
           (0 (pwlv 0 1 1))
@@ -40,12 +49,24 @@
     (if (= inout 0)
         (setf logcurve (pwev epsilon 1 1))
         (setf logcurve (pwev 1 1 epsilon)))
+    ; Scale and invert curve for 0 to unity gain.
     (sum 1
          (mult (/ -1 (- 1 epsilon))
                (diff logcurve epsilon)))))
+ 
+(defun guessdirection ()
+"If the selection is closer to the start of the
+audio clip, fade in, otherwise fade out."
+  (let* ((start (get '*selection* 'start))
+         (end (get '*selection* 'end))
+         (clips (get '*track* 'clips))
+         (in-dist end)
+         (out-dist end))
+    (if (arrayp clips)
+        (setf clips (append (aref clips 0)(aref clips 1))))
+    (dotimes (i (length clips))
+      (setf in-dist (min in-dist (abs (- start (first (nth i clips))))))
+      (setf out-dist (min out-dist (abs (- end (second (nth i clips)))))))
+    (if (< in-dist out-dist) 'in 'out)))
 
-(let ((tracks (length (get '*selection* 'tracks))))
-  (case tracks
-    (1 "Only 1 track selected.\n'Crossfade Tracks' requires 2 tracks.")
-    (2 (crossfade type))
-    (T "Too many tracks selected.\n'Crossfade Tracks' requires 2 tracks.")))
+(crossfade type direction curve)