WaveTableOsc.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
 
namespace Audio
{
    // Wavetable oscillator types
    namespace EWaveTable
    {
        enum Type
        {
            None,
            SineWaveTable,
            SawWaveTable,
            TriangleWaveTable,
            SquareWaveTable,
            BandLimitedSawWaveTable,
            BandLimitedTriangleWaveTable,
            BandLimitedSquareWaveTable,
            Custom
        };
    }
 
    class FWaveTableOsc;
 
 
    // A wave table oscillator class
    class FWaveTableOsc
    {
    public:
        // Constructor
        SIGNALPROCESSING_API FWaveTableOsc();
 
        // Virtual Destructor
        SIGNALPROCESSING_API virtual ~FWaveTableOsc();
 
        // Initialize the wave table oscillator
        SIGNALPROCESSING_API void Init(const float InSampleRate, const float InFrequencyHz);
 
        // Sets the sample rate of the oscillator.
        SIGNALPROCESSING_API void SetSampleRate(const float InSampleRate);
 
        // Resets the wave table read indices.
        SIGNALPROCESSING_API void Reset();
 
        // Sets the amount to scale and add to the output of the wave table
        SIGNALPROCESSING_API void SetScaleAdd(const float InScale, const float InAdd);
 
        // Returns the type of the wave table oscillator.
        EWaveTable::Type GetType() const { return WaveTableType; }
 
        // Sets the frequency of the wave table oscillator.
        SIGNALPROCESSING_API void SetFrequencyHz(const float InFrequencyHz);
 
        // Returns the frequency of the wave table oscillator.
        float GetFrequencyHz() const { return FrequencyHz; }
 
        // Returns the internal table used in the wave table.
        SIGNALPROCESSING_API TArray<float>& GetTable();
        SIGNALPROCESSING_API const TArray<float>& GetTable() const;
 
        // Processes the wave table, outputs the normal and quad phase (optional) values 
        SIGNALPROCESSING_API void Generate(float* OutputNormalPhase, float* OutputQuadPhase = nullptr);
 
        // Creates a wave table using internal factories for standard wave tables or uses custom wave table factor if it exists.
        static SIGNALPROCESSING_API TSharedPtr<FWaveTableOsc> CreateWaveTable(const EWaveTable::Type WaveTableType, const int32 WaveTableSize = 1024);
 
    protected:
        SIGNALPROCESSING_API void UpdateFrequency();
 
        // The wave table buffer
        TArray<float> WaveTableBuffer;
 
        // The frequency of the output (given the sample rate)
        float FrequencyHz;
 
        // The sample rate of the oscillator
        float SampleRate;
 
        // Normal phase read index
        float NormalPhaseReadIndex;
 
        // The quad-phase read index
        float QuadPhaseReadIndex;
 
        // The phase increment (based on frequency)
        float PhaseIncrement;
 
        // Amount to scale the output by
        float OutputScale;
 
        // Amount to add to the output
        float OutputAdd;
 
        // The wave table oscillator type
        EWaveTable::Type WaveTableType;
    };
 
}