UnrealEngineUWP/Engine/Plugins/Runtime/Metasound/Source/MetasoundStandardNodes/Private/MetasoundSampleAndHoldNode.cpp

// Copyright Epic Games, Inc. All Rights Reserved.

#include "Internationalization/Text.h"
#include "MetasoundExecutableOperator.h"
#include "MetasoundNodeRegistrationMacro.h"
#include "MetasoundPrimitives.h"
#include "MetasoundStandardNodesNames.h"
#include "MetasoundTrigger.h"
#include "MetasoundTime.h"
#include "MetasoundAudioBuffer.h"
#include "DSP/Delay.h"
#include "MetasoundStandardNodesCategories.h"
#include "MetasoundFacade.h"
#include "MetasoundParamHelper.h"

#define LOCTEXT_NAMESPACE "MetasoundStandardNodes_SampleAndHold"

namespace Metasound
{
	namespace SampleAndHoldVertexNames
	{
		METASOUND_PARAM(InputTriggerSampleAndHold, "Sample And Hold", "Trigger to sample and hold the input audio.");
		METASOUND_PARAM(InputAudio, "In", "The audio input to sample.");

		METASOUND_PARAM(OutputOnSampleAndHold, "On Sample And Hold", "Triggers when the input sample and hold is triggered.");
		METASOUND_PARAM(OutputAudio, "Out", "Sampled output value.");
	}

	class FSampleAndHoldOperator : public TExecutableOperator<FSampleAndHoldOperator>
	{
	public:

		static const FNodeClassMetadata& GetNodeInfo()
		{
			auto CreateNodeClassMetadata = []() -> FNodeClassMetadata
			{
				FVertexInterface NodeInterface = GetVertexInterface();

				FNodeClassMetadata Metadata
				{
					FNodeClassName { "SampleAndHold", "Sample And Hold", StandardNodes::AudioVariant },
					1, // Major Version
					0, // Minor Version
					METASOUND_LOCTEXT("SampleAndHoldDisplayName", "Sample And Hold"),
					METASOUND_LOCTEXT("SampleAndHoldDesc", "Will output a single value of the input audio signal when triggered."),
					PluginAuthor,
					PluginNodeMissingPrompt,
					NodeInterface,
					{ NodeCategories::Filters },
					{ },
					FNodeDisplayStyle()
				};

				return Metadata;
			};

			static const FNodeClassMetadata Metadata = CreateNodeClassMetadata();
			return Metadata;
		}

		static const FVertexInterface& GetVertexInterface()
		{
			using namespace SampleAndHoldVertexNames;

			static const FVertexInterface Interface(
				FInputVertexInterface(
					TInputDataVertex<FTrigger>(METASOUND_GET_PARAM_NAME_AND_METADATA(InputTriggerSampleAndHold)),
					TInputDataVertex<FAudioBuffer>(METASOUND_GET_PARAM_NAME_AND_METADATA(InputAudio))
				),
				FOutputVertexInterface(
					TOutputDataVertex<FTrigger>(METASOUND_GET_PARAM_NAME_AND_METADATA(OutputOnSampleAndHold)),
					TOutputDataVertex<FAudioBuffer>(METASOUND_GET_PARAM_NAME_AND_METADATA(OutputAudio))
				)
			);

			return Interface;
		}
		
		static TUniquePtr<IOperator> CreateOperator(const FCreateOperatorParams& InParams, FBuildErrorArray& OutErrors)
		{
			using namespace SampleAndHoldVertexNames;
			const FDataReferenceCollection& Inputs = InParams.InputDataReferences;

			FTriggerReadRef InputTriggerSampleAndHold = Inputs.GetDataReadReferenceOrConstruct<FTrigger>(METASOUND_GET_PARAM_NAME(InputTriggerSampleAndHold), InParams.OperatorSettings);
			FAudioBufferReadRef InputAudio = Inputs.GetDataReadReferenceOrConstruct<FAudioBuffer>(METASOUND_GET_PARAM_NAME(InputAudio), InParams.OperatorSettings);

			return MakeUnique<FSampleAndHoldOperator>(InParams.OperatorSettings, InputTriggerSampleAndHold, InputAudio);
		}

		FSampleAndHoldOperator(const FOperatorSettings& InSettings, const FTriggerReadRef& InTriggerSampleAndHold, const FAudioBufferReadRef& InAudioInput)
			: AudioInput(InAudioInput)
			, TriggerSampleAndHold(InTriggerSampleAndHold)
			, AudioOutput(FAudioBufferWriteRef::CreateNew(InSettings))
		{
			// Init the hold value to the first sample in the audio buffer
			HoldValue = AudioInput->GetData()[0];
		}

		virtual FDataReferenceCollection GetInputs() const override
		{
			using namespace SampleAndHoldVertexNames;

			FDataReferenceCollection InputDataReferences;
			InputDataReferences.AddDataReadReference(METASOUND_GET_PARAM_NAME(InputAudio), AudioInput);
			InputDataReferences.AddDataReadReference(METASOUND_GET_PARAM_NAME(InputTriggerSampleAndHold), TriggerSampleAndHold);

			return InputDataReferences;

		}

		virtual FDataReferenceCollection GetOutputs() const override
		{
			using namespace SampleAndHoldVertexNames;
			FDataReferenceCollection OutputDataReferences;
			OutputDataReferences.AddDataReadReference(METASOUND_GET_PARAM_NAME(OutputOnSampleAndHold), TriggerSampleAndHold);
			OutputDataReferences.AddDataReadReference(METASOUND_GET_PARAM_NAME(OutputAudio), AudioOutput);
			return OutputDataReferences;
		}
		
		void Execute()
		{
			// Lambda is used for both pre and post trigger frames
			auto SetToHoldLambda = [this](int32 StartFrame, int32 EndFrame)
			{
				check(AudioOutput->Num() >= EndFrame);
				float* OutputBufferPtr = AudioOutput->GetData();
				float* CurrOutputPtr = &OutputBufferPtr[StartFrame];

				const int32 NumSamples = EndFrame - StartFrame;

				// non-SIMD version
				for (int32 i = 0; i < NumSamples; ++i)
				{
					CurrOutputPtr[i] = HoldValue;
				}
			};

			TriggerSampleAndHold->ExecuteBlock(
				// On Pre-Trigger, continue outputting the held value
				SetToHoldLambda, 
				// On Trigger, get a new hold value, then output for the rest of the block
				[this, &SetToHoldLambda](int32 StartFrame, int32 EndFrame)
				{
					// Get a new value to sample and hold
					HoldValue = AudioInput->GetData()[StartFrame];
					SetToHoldLambda(StartFrame, EndFrame);
				}
			);
		}

	private:

		FAudioBufferReadRef AudioInput;
		FTriggerReadRef TriggerSampleAndHold;

		FAudioBufferWriteRef AudioOutput;

		float HoldValue = 0.0f;
	};

	class FSampleAndHoldNode : public FNodeFacade
	{
	public:
		FSampleAndHoldNode(const FNodeInitData& InitData)
			: FNodeFacade(InitData.InstanceName, InitData.InstanceID, TFacadeOperatorClass<FSampleAndHoldOperator>())
		{
		}
	};


	METASOUND_REGISTER_NODE(FSampleAndHoldNode)
}

#undef LOCTEXT_NAMESPACE