Method setPosition

Engine/source/sfx/sfxVoice.cpp:293–352

//-----------------------------------------------------------------------------

void SFXVoice::setPosition( U32 inSample )
{
   // Clamp to sample range.
   const U32 sample = inSample % ( mBuffer->getFormat().getSampleCount( mBuffer->getDuration() ) - 1 );
   
   // Don't perform a seek when we already are at the
   // given position.  Especially avoids a costly stream
   // clone when seeking on a streamed voice.
   
   if( getPosition() == sample )
      return;

   if( !mBuffer->isStreaming() )
   {
      // Non-streaming sound.  Just seek in the device buffer.

      _seek( sample );
   }
   else
   {
      // Streaming sound.  Reset the stream and playback.
      //
      // Unfortunately, the logic here is still prone to subtle timing dependencies
      // in relation to the buffer updates.  In retrospect, I feel that solving all issues
      // of asynchronous operation on a per-voice/buffer level has greatly complicated
      // the system.  It seems now that it would have been a lot simpler to have a single
      // asynchronous buffer/voice manager that manages the updates of all voices and buffers
      // currently in the system in one spot.  Packet reads could still be pushed out to
      // the thread pool but queue updates would all be handled centrally in one spot.  This
      // would do away with problems like those (mostly) solved by the multi-step procedure
      // here.

      // Go into transition.

      SFXStatus oldStatus;
      while( true )
      {
         oldStatus = mStatus;
         if( oldStatus != SFXStatusTransition &&
             dCompareAndSwap( ( U32& ) mStatus, oldStatus, SFXStatusTransition ) )
            break;
      }

      // Switch the stream.

      _resetStream( sample, false );

      // Come out of transition.

      SFXStatus newStatus = oldStatus;
      if( oldStatus == SFXStatusPlaying )
         newStatus = SFXStatusBlocked;

      dCompareAndSwap( ( U32& ) mStatus, SFXStatusTransition, newStatus );

      // Trigger an update.

      SFXInternal::TriggerUpdate();