engine: client: use alternative ease-in ease-out function in sound fade

engine/client/s_main.c

@@ -159,7 +159,7 @@ void S_UpdateSoundFade( void )
 	}
 
 	// spline it.
-	f = SimpleSpline( f );
+	f = -( cos( M_PI * f ) - 1 ) / 2;
 	f = bound( 0.0f, f, 1.0f );
 
 	soundfade.percent = soundfade.initial_percent * f;

public/xash3d_mathlib.c

@@ -53,24 +53,6 @@ float anglemod( float a )
 	return a;
 }
 
-/*
-=================
-SimpleSpline
-
-NOTE: ripped from hl2 source
-hermite basis function for smooth interpolation
-Similar to Gain() above, but very cheap to call
-value should be between 0 & 1 inclusive
-=================
-*/
-float SimpleSpline( float value )
-{
-	float	valueSquared = value * value;
-
-	// nice little ease-in, ease-out spline-like curve
-	return (3.0f * valueSquared - 2.0f * valueSquared * value);
-}
-
 word FloatToHalf( float v )
 {
 	unsigned int	i = FloatAsUint( v );

public/xash3d_mathlib.h

@@ -177,7 +177,6 @@ float rsqrt( float number );
 float anglemod( float a );
 word FloatToHalf( float v );
 float HalfToFloat( word h );
-float SimpleSpline( float value );
 void RoundUpHullSize( vec3_t size );
 int SignbitsForPlane( const vec3_t normal );
 int PlaneTypeForNormal( const vec3_t normal );