Shenmue 3D audio, sample decompilation

3DAudio.cpp

unsigned int Shenmue::CalculateAngleBetweenAngles(float firstFloat, float secondFloat)
{
  if ( secondFloat < firstFloat )
  {
    if ( secondFloat < -firstFloat )
    {
      if ( secondFloat == 0.0 )
        return 32768;                           // -180 degrees
      else
        return ((((atanf(firstFloat / secondFloat) * 65536.0) / 6.2831855) + 0.5) + 32768);
    }
    else if ( firstFloat == 0.0 )
    {
      return 16384;                             // 90 degrees
    }
    else
    {
      return (16384 - (((atanf(secondFloat / firstFloat) * 65536.0) / 6.2831855) + 0.5));
    }
  }
  else if ( secondFloat < -firstFloat )
  {
    if ( firstFloat == 0.0 )
      return 49152;                             // 270 degrees
    else
      return (49152 - (((atanf(secondFloat / firstFloat) * 65536.0) / 6.2831855) + 0.5));
  }
  else if ( secondFloat == 0.0 )
  {
    return 0;
  }
  else
  {
    return (((atanf(firstFloat / secondFloat) * 65536.0) / 6.2831855) + 0.5);
  }
}

void Shenmue::Execute3DSoundCommand(
        uint32_t base_command,
        uint32_t bank,
        Vector3 *position,
        float min_distance,
        float max_distance)
{

  z_1 = position->z;
  x_1 = position->x;
  mag = sqrtf(((x - x_1) * (x - x_1)) + ((z - z_1) * (z - z_1)));
  if ( min_distance <= mag )
  {
    if ( mag <= (min_distance + max_distance) )
    {
      first_cmd_vol = ((max_distance - (mag - min_distance)) * (127.0 / max_distance));
    }
    else if ( base_command != -1 )
    {
      return;
    }
  }
  else
  {
    first_cmd_vol = 127;
  }
  angle_degrees = Shenmue::CalculateAngleBetweenAngles(-(x_1 - x), -(z_1 - z));
  direction_flag = (16384 - v6 + angle_degrees) < 0;
  angle = 16384 - v6 + angle_degrees;
  dir = ~angle;
  if ( !direction_flag )
    dir = angle;
  second_cmd_vol = -((dir - 16384) << 6 >> 14);
  if ( second_cmd_vol <= 40 )
  {
    if ( second_cmd_vol < -40 )
      second_cmd_vol = -40;
  }
  else
  {
    second_cmd_vol = 40;
  }
  if ( base_command == -1 )
  {
    Shenmue::ExecuteAICACommand(0x10A5i64, bank, first_cmd_vol);
    if ( !first_cmd_vol )
      return;

    Shenmue::ExecuteAICACommand(0x20A5i64, bank, second_cmd_vol);
    volume = last_cmd_vol;
    command = 0xA6i64;
  }
  else
  {
    Shenmue::ExecuteAICACommand(0x27B0i64, bank, first_cmd_vol);
    Shenmue::ExecuteAICACommand(0x2AB0i64, bank, second_cmd_vol);
    Shenmue::ExecuteAICACommand(base_command, 0, 0i64);
    Shenmue::ExecuteAICACommand(0x2AB0i64, bank, 0i64);
    volume = 127i64;
    command = 0x27B0i64;
  }
  Shenmue::ExecuteAICACommand(command, bank, volume);
}