Play with curve interpolation.

Timeline/Control_Sequence.C

@@ -319,7 +319,7 @@ Control_Sequence::handle ( int m )
 static inline float
 linear_interpolate ( float y1, float y2, float mu )
 {
-    return y1 * (1 - mu) + y2 * mu;
+    return y1 + mu * ( y2 - y1 );
 }
 
 static inline float
@@ -328,11 +328,21 @@ sigmoid_interpolate ( float y1, float y2, float mu )
     return linear_interpolate( y1, y2, ( 1 - cos( mu * M_PI ) ) / 2 );
 }
 
+static inline float
+quadratic_interpolate ( float y1, float y2, float mu )
+{
+    return ( y1 * y1 ) * ( mu * mu ) + ( 2.0f * y1 * y2 ) * mu * ( y1 * y1 );
+}
+
 /* static inline float */
-/* exponential_interpolate ( float y1, float y2, float mu ) */
+/* quadratic_interpolate ( float y1, float y2, float mu ) */
 /* { */
+/* } */
 
-
+/* static inline float */
+/* exponential_interpolate ( float y1, float y2, float mu ) */
+/* { */
+/* //    return y1 * pow( y2 / y1, mu ); */
 /* } */
 
 /* THREAD: ?? */
@@ -357,7 +367,9 @@ Control_Sequence::play ( sample_t *buf, nframes_t frame, nframes_t nframes )
 
         for ( nframes_t i = frame - p1->when(); i < d; ++i )
         {
-            *(buf++) = 1.0f - ( 2 * sigmoid_interpolate( p1->control(), p2->control(), i / (float)d ) );
+//            *(buf++) = 1.0f - ( 2 * sigmoid_interpolate( p1->control(), p2->control(), i / (float)d ) );
+            *(buf++) = 1.0f - ( 2 * linear_interpolate( p1->control(), p2->control(), i / (float)d ) );
+//            *(buf++) = 1.0f - ( 2 * quadratic_interpolate( p1->control(), p2->control(), i / (float)d ) );
 
             if ( ! n-- )
                 return nframes;

Timeline/Control_Sequence.H

@@ -25,11 +25,18 @@
 
 class Control_Sequence : public Sequence
 {
+public:
+
+    enum curve_type_e { Linear, Quadratic };
+
+private:
 
     Port *_output;
 
     bool _highlighted;
 
+    curve_type_e _type;
+
     void init ( void );
 
 

Timeline/Region.C

@@ -766,86 +766,6 @@ Region::Fade::apply ( sample_t *buf, Region::Fade::fade_dir_e dir, long start, n
             *(buf++) *= gain( fi );
 }
 
-
-#if 0
-/** Compute the gain value (0 to 1f) for a fade-in/out curve of /type/
- * (LINEAR, QUADRAIC, CUBIC), of /nframes/ in length at point
- * /offset/ */
-static inline
-float gain_on_curve ( int type, int dir, nframes_t nframes, nframes_t offset, nframes_t length )
-{
-    float a, b;
-
-    /* FIXME: these first two sections should *definitely* be cached */
-
-    /* calculate coefficients */
-    if ( dir == FADE_OUT )
-    {
-        a = -1.0f / (double)nframes;
-        /* fixme why would we need to know the clip length? */
-        b = length / (double)nframes;
-//        b = nframes;
-    }
-    else
-    {
-        a = 1.0f / (double)nframes;
-        b = 0.0f;
-    }
-
-    float c[4];
-
-    /* interpolate points */
-    switch ( type )
-    {
-        case Linear:
-            c[1] = a;
-            c[0] = b;
-            break;
-        case Quadratic:
-            c[2] = a * a;
-            c[1] = 2.0f * a * b;
-            c[0] = b * b;
-            break;
-        case Cubic:
-        {
-            const float a2 = a * a;
-            const float b2 = b * b;
-            c[3] = a * a2;
-            c[2] = 3.0f * a2 * b;
-            c[1] = 3.0f * a * b2;
-            c[0] = b * b2;
-            break;
-        }
-        default:
-            printf( "unknown curve order\n" );
-    }
-
-    /* now get the gain for the given point */
-
-    const float f  = offset;
-    const float f2 = f * f;
-
-    float g = 1.0f;
-
-    switch ( type )
-    {
-        case Linear:
-            g *= c[1] * f + c[0];
-            break;
-        case Quadratic:
-            g *= c[2] * f2 + c[1] * f + c[0];
-            break;
-        case Cubic:
-            g *= c[3] * f2 * f + c[2] * f2 + c[1] * f + c[0];
-            break;
-    }
-
-    printf( "gain for %lu is %f\n", offset, g );
-
-    return g;
-}
-#endif
-
 /* THREAD: IO */
 /** read the overlapping part of /channel/ at /pos/ for /nframes/ of
     this region into /buf/, where /pos/ is in timeline frames */