C++ ThreeDPoint::Normalize方法代码示例

// This algorithm is specicied in the webaudio spec.
void
PannerNodeEngine::ComputeAzimuthAndElevation(float& aAzimuth, float& aElevation)
{
  ThreeDPoint sourceListener = mPosition - mListenerPosition;

  if (sourceListener.IsZero()) {
    aAzimuth = 0.0;
    aElevation = 0.0;
    return;
  }

  sourceListener.Normalize();

  // Project the source-listener vector on the x-z plane.
  ThreeDPoint& listenerFront = mListenerOrientation;
  ThreeDPoint listenerRightNorm = listenerFront.CrossProduct(mListenerUpVector);
  listenerRightNorm.Normalize();

  ThreeDPoint listenerFrontNorm(listenerFront);
  listenerFrontNorm.Normalize();

  ThreeDPoint up = listenerRightNorm.CrossProduct(listenerFrontNorm);

  double upProjection = sourceListener.DotProduct(up);

  ThreeDPoint projectedSource = sourceListener - up * upProjection;
  projectedSource.Normalize();

  // Actually compute the angle, and convert to degrees
  double projection = projectedSource.DotProduct(listenerRightNorm);
  aAzimuth = 180 * acos(projection) / M_PI;

  // Compute whether the source is in front or behind the listener.
  double frontBack = projectedSource.DotProduct(listenerFrontNorm);
  if (frontBack < 0) {
    aAzimuth = 360 - aAzimuth;
  }
  // Rotate the azimuth so it is relative to the listener front vector instead
  // of the right vector.
  if ((aAzimuth >= 0) && (aAzimuth <= 270)) {
    aAzimuth = 90 - aAzimuth;
  } else {
    aAzimuth = 450 - aAzimuth;
  }

  aElevation = 90 - 180 * acos(sourceListener.DotProduct(up)) / M_PI;

  if (aElevation > 90) {
    aElevation = 180 - aElevation;
  } else if (aElevation < -90) {
    aElevation = -180 - aElevation;
  }
}

// This algorithm is described in the WebAudio spec.
float
PannerNodeEngine::ComputeConeGain()
{
  // Omnidirectional source
  if (mOrientation.IsZero() || ((mConeInnerAngle == 360) && (mConeOuterAngle == 360))) {
    return 1;
  }

  // Normalized source-listener vector
  ThreeDPoint sourceToListener = mListenerPosition - mPosition;
  sourceToListener.Normalize();

  ThreeDPoint normalizedSourceOrientation = mOrientation;
  normalizedSourceOrientation.Normalize();

  // Angle between the source orientation vector and the source-listener vector
  double dotProduct = sourceToListener.DotProduct(normalizedSourceOrientation);
  double angle = 180 * acos(dotProduct) / M_PI;
  double absAngle = fabs(angle);

  // Divide by 2 here since API is entire angle (not half-angle)
  double absInnerAngle = fabs(mConeInnerAngle) / 2;
  double absOuterAngle = fabs(mConeOuterAngle) / 2;
  double gain = 1;

  if (absAngle <= absInnerAngle) {
    // No attenuation
    gain = 1;
  } else if (absAngle >= absOuterAngle) {
    // Max attenuation
    gain = mConeOuterGain;
  } else {
    // Between inner and outer cones
    // inner -> outer, x goes from 0 -> 1
    double x = (absAngle - absInnerAngle) / (absOuterAngle - absInnerAngle);
    gain = (1 - x) + mConeOuterGain * x;
  }

  return gain;
}

void
PannerNodeEngine::HRTFPanningFunction(const AudioBlock& aInput,
                                      AudioBlock* aOutput,
                                      StreamTime tick)
{
  // The output of this node is always stereo, no matter what the inputs are.
  aOutput->AllocateChannels(2);

  float azimuth, elevation;

  ThreeDPoint position = ConvertAudioParamTimelineTo3DP(mPositionX, mPositionY, mPositionZ, tick);
  ThreeDPoint orientation = ConvertAudioParamTimelineTo3DP(mOrientationX, mOrientationY, mOrientationZ, tick);
  if (!orientation.IsZero()) {
    orientation.Normalize();
  }
  ComputeAzimuthAndElevation(position, azimuth, elevation);

  AudioBlock input = aInput;
  // Gain is applied before the delay and convolution of the HRTF.
  input.mVolume *= ComputeConeGain(position, orientation) * ComputeDistanceGain(position);

  mHRTFPanner->pan(azimuth, elevation, &input, aOutput);
}

void
PannerNodeEngine::EqualPowerPanningFunction(const AudioBlock& aInput,
                                            AudioBlock* aOutput,
                                            StreamTime tick)
{
  float azimuth, elevation, gainL, gainR, normalizedAzimuth, distanceGain, coneGain;
  int inputChannels = aInput.ChannelCount();

  // Optimize the case where the position and orientation is constant for this
  // processing block: we can just apply a constant gain on the left and right
  // channel
  if (mPositionX.HasSimpleValue() &&
      mPositionY.HasSimpleValue() &&
      mPositionZ.HasSimpleValue() &&
      mOrientationX.HasSimpleValue() &&
      mOrientationY.HasSimpleValue() &&
      mOrientationZ.HasSimpleValue()) {

    ThreeDPoint position = ConvertAudioParamTimelineTo3DP(mPositionX, mPositionY, mPositionZ, tick);
    ThreeDPoint orientation = ConvertAudioParamTimelineTo3DP(mOrientationX, mOrientationY, mOrientationZ, tick);
    if (!orientation.IsZero()) {
      orientation.Normalize();
    }

    // If both the listener are in the same spot, and no cone gain is specified,
    // this node is noop.
    if (mListenerPosition ==  position &&
        mConeInnerAngle == 360 &&
        mConeOuterAngle == 360) {
      *aOutput = aInput;
      return;
    }

    // The output of this node is always stereo, no matter what the inputs are.
    aOutput->AllocateChannels(2);

    ComputeAzimuthAndElevation(position, azimuth, elevation);
    coneGain = ComputeConeGain(position, orientation);

    // The following algorithm is described in the spec.
    // Clamp azimuth in the [-90, 90] range.
    azimuth = min(180.f, max(-180.f, azimuth));

    // Wrap around
    if (azimuth < -90.f) {
      azimuth = -180.f - azimuth;
    } else if (azimuth > 90) {
      azimuth = 180.f - azimuth;
    }

    // Normalize the value in the [0, 1] range.
    if (inputChannels == 1) {
      normalizedAzimuth = (azimuth + 90.f) / 180.f;
    } else {
      if (azimuth <= 0) {
        normalizedAzimuth = (azimuth + 90.f) / 90.f;
      } else {
        normalizedAzimuth = azimuth / 90.f;
      }
    }

    distanceGain = ComputeDistanceGain(position);

    // Actually compute the left and right gain.
    gainL = cos(0.5 * M_PI * normalizedAzimuth);
    gainR = sin(0.5 * M_PI * normalizedAzimuth);

    // Compute the output.
    ApplyStereoPanning(aInput, aOutput, gainL, gainR, azimuth <= 0);

    aOutput->mVolume = aInput.mVolume * distanceGain * coneGain;
  } else {
    float positionX[WEBAUDIO_BLOCK_SIZE];
    float positionY[WEBAUDIO_BLOCK_SIZE];
    float positionZ[WEBAUDIO_BLOCK_SIZE];
    float orientationX[WEBAUDIO_BLOCK_SIZE];
    float orientationY[WEBAUDIO_BLOCK_SIZE];
    float orientationZ[WEBAUDIO_BLOCK_SIZE];

    // The output of this node is always stereo, no matter what the inputs are.
    aOutput->AllocateChannels(2);

    if (!mPositionX.HasSimpleValue()) {
      mPositionX.GetValuesAtTime(tick, positionX, WEBAUDIO_BLOCK_SIZE);
    } else {
      positionX[0] = mPositionX.GetValueAtTime(tick);
    }
    if (!mPositionY.HasSimpleValue()) {
      mPositionY.GetValuesAtTime(tick, positionY, WEBAUDIO_BLOCK_SIZE);
    } else {
      positionY[0] = mPositionY.GetValueAtTime(tick);
    }
    if (!mPositionZ.HasSimpleValue()) {
      mPositionZ.GetValuesAtTime(tick, positionZ, WEBAUDIO_BLOCK_SIZE);
    } else {
      positionZ[0] = mPositionZ.GetValueAtTime(tick);
    }
    if (!mOrientationX.HasSimpleValue()) {
      mOrientationX.GetValuesAtTime(tick, orientationX, WEBAUDIO_BLOCK_SIZE);
    } else {
//.........这里部分代码省略.........