IESLoader.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
 
#pragma once
 
#include "CoreMinimal.h"
 
//class Error;
 
enum class EIESPhotometricType;
 
class FIESLoader
{
public:
    FIESLoader(const uint8* Buffer, uint32 BufferLength);
 
    // @return Multiplier as the texture is normalized
    float ExtractInRGBA16F(TArray<uint8>& OutData);
 
    bool IsValid() const;
 
    uint32 GetWidth() const;
    uint32 GetHeight() const;
 
    float GetBrightness() const;
 
    const TCHAR* GetError() const
    {
        return Error.IsEmpty() ? nullptr : *Error;
    }
 
private:
 
    TArray<float> HAngles;
    TArray<float> VAngles;
    TArray<float> CandelaValues;
 
    float Brightness;
 
    float CachedIntegral;
 
    EIESPhotometricType PhotometricType;
 
    // will set Error to 0 on success
    void Load(const uint8* Buffer);
 
    // 0 if no error, otherwise points to an ASCII error string
    FString Error;
 
    float ComputeMax() const;
 
    // integrate over the unit sphere
    // @return in Candela
    float ComputeFullIntegral();
 
    static float ComputeFilterPos(float Value, const TArray<float>& SortedValues);
 
    // low level code, only used by InterpolateBilinear
    // @param X 0..HAngles.size()-1
    // @param Y 0..VAngles.size()-1
    float InterpolatePoint(int X, int Y) const;
 
    // low level code, used by Interpolate2D() and Interpolate1D()
    // @param fX 0..HAngles.size()-1
    // @param fY 0..VAngles.size()-1
    float InterpolateBilinear(float fX, float fY) const;
 
    // high level code to compute the Candela value for a given direction
    // @param HAngle n degrees e.g. 0..360
    // @param VAngle n degrees e.g. 0..180
    float Interpolate2D(float HAngle, float VAngle) const;
 
    // like Interpolate2D but also integrates over HAngle
    // @param VAngle n degrees e.g. 0..180
    float Interpolate1D(float VAngle) const;
};