"haste" mod

stepmania/src/ScreenGameplay.cpp

@@ -1588,6 +1588,35 @@ void ScreenGameplay::Update( float fDeltaTime )
 		}
 	}
 
+	if( GAMESTATE->m_SongOptions.GetCurrent().m_fHaste != 0.0f )
+	{
+		float fLife = 0;
+		FOREACH_EnabledPlayerInfo( m_vPlayerInfo, pi )
+		{
+			if( !GAMESTATE->IsHumanPlayer(pi->m_pn) )
+				continue;
+			fLife = max( fLife, pi->m_pLifeMeter->GetLife() );
+		}
+
+		/* Scale the music nonlinearly.  Only slow the song down below 0.25, so we
+		 * don't drag the music out too long.  Stick at 1x up to 0.5, so we start
+		 * at 1x if the life meter defaults to 0.5.  Increase gradually up to 0.9.
+		 * Accelerate sharply above 0.9. */
+		float fSpeed = 1.0f;
+		if( fLife < 0.25f )
+			fSpeed = SCALE( fLife, 0.0f, 0.25f, 0.5f, 1.0f );
+		else if( fLife > 0.5f && fLife < 0.9f )
+			fSpeed = SCALE( fLife, 0.5f, 0.9f, 1.0f, 1.25f );
+		else if( fLife >= 0.9f )
+			fSpeed = SCALE( fLife, 0.9f, 1.0f, 1.25f, 2.5f );
+
+		fSpeed *= GAMESTATE->m_SongOptions.GetCurrent().m_fHaste;
+		fSpeed *= GAMESTATE->m_SongOptions.GetCurrent().m_fMusicRate;
+
+		RageSoundParams p = m_pSoundMusic->GetParams();
+		p.m_fSpeed = fSpeed;
+		m_pSoundMusic->SetParams( p );
+	}
 
 	switch( m_DancingState )
 	{