From 29c10b0a88b7b9514d4c20d354b7a1e7f76e05c0 Mon Sep 17 00:00:00 2001
From: kevin <kevin@octo.ucsd.edu>
Date: Sun, 3 Nov 2013 11:50:03 -0800
Subject: [PATCH] cmProc3.h/c : Changes to cmXFader to implement equal power
 cross-fade and addition of cmXFaderJumpToDestinationGain().

---
 cmProc3.c | 18 +++++++++++++++++-
 cmProc3.h |  5 +++--
 2 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/cmProc3.c b/cmProc3.c
index 0c01940..0108037 100644
--- a/cmProc3.c
+++ b/cmProc3.c
@@ -2057,7 +2057,7 @@ cmRC_t    cmXfaderExec(  cmXfader* p, unsigned procSmpCnt, const bool* chGateV,
     if( cp->gateFl )
     {
       cp->gain = cmMin(cp->gain + i_dgain,1.0); 
-      cp->ep_gain = sqrt(0.5 + 0.5 * cos(3.14159*cp->gain));
+      cp->ep_gain = sqrt(0.5 - 0.5 * cos(3.14159*cp->gain));
     }
     else
     {
@@ -2133,6 +2133,22 @@ void      cmXfaderAllOff( cmXfader* p )
     p->chArray[i].gateFl = false;
 }
 
+void      cmXfaderJumpToDestinationGain( cmXfader* p )
+{
+  unsigned i = 0;
+  for(i=0; i<p->chCnt; ++i)
+  {
+    if( p->chArray[i].gateFl )
+      p->chArray[i].gain = 1.0;
+    else
+      p->chArray[i].gain = 0.0;
+
+    p->chArray[i].onFl = false;
+    p->chArray[i].offFl = false;
+    p->chArray[i].ep_gain = p->chArray[i].gain;
+  }
+}
+
 //==========================================================================================================================================
 cmFader*  cmFaderAlloc( cmCtx*c, cmFader* p, cmReal_t srate, cmReal_t fadeTimeMs  )
 {
diff --git a/cmProc3.h b/cmProc3.h
index 852d5bc..c1fd407 100644
--- a/cmProc3.h
+++ b/cmProc3.h
@@ -299,8 +299,8 @@ extern "C" {
   // to the audio signal - unless you use cmXfaderExecAudio()
   typedef struct
   {
-    cmReal_t ep_gain;
-    cmReal_t gain;
+    cmReal_t ep_gain; // equal power xfade gain
+    cmReal_t gain;    // linear gain
     bool     gateFl; // true if channel is on
     bool     onFl;   // true if gateFl transitioned to true on this cycle  
     bool     offFl;  // true if gateFl transitioned to false on this cycle
@@ -333,6 +333,7 @@ extern "C" {
   // Set all gates to false except chIdx.
   void      cmXfaderSelectOne( cmXfader* p, unsigned chIdx );
   void      cmXfaderAllOff( cmXfader* p );
+  void      cmXfaderJumpToDestinationGain( cmXfader* p ); // jump to dest. gain based on gate state
 
   //=======================================================================================================================
   // This fader object accepts a gate signal. When the gate is high it increments