DensityField.h

#pragma once

#include "CoreMinimal.h"
#include "DensityField.generated.h"

class APointCloud;

USTRUCT(BlueprintType)
struct FVoxel
{
    GENERATED_BODY()

private:
    FVector WorldPosition;
	FIntVector3 GridPosition;
    double VoxelDensity;
    FVector VoxelGradient;
	double ClosePointsNumber;

public:
    FVoxel() : WorldPosition(FVector::ZeroVector), GridPosition(FIntVector3::ZeroValue), VoxelDensity(0.0), VoxelGradient(FVector::ZeroVector), ClosePointsNumber(0.0) {}
    FVoxel(const FVector &InPosition, const FIntVector3 &InGridPos) : WorldPosition(InPosition), GridPosition(InGridPos), VoxelDensity(0.0), VoxelGradient(FVector::ZeroVector), ClosePointsNumber(0.0) {}
	
    double GetVoxelDensity() const { return VoxelDensity; }
	FIntVector3 GetVoxelGridPos() const { return GridPosition; }
    FVector GetVoxelPosition() const { return WorldPosition; }
    FVector GetVoxelGradient() const { return VoxelGradient; }
	double GetClosePointsNumber() const { return ClosePointsNumber; }
	
	void SetVoxelDensity(const double Density) { this->VoxelDensity = Density; }
    void SetVoxelGradient(const FVector &Gradient) { this->VoxelGradient = Gradient; }
	void SetClosePointsNumber(const double Dis) { ClosePointsNumber = Dis; }
    void AddToVoxelDensity(const double Dis) { VoxelDensity += Dis; }
};

USTRUCT(BlueprintType)
struct FLUTUnit
{
    GENERATED_BODY()

    TArray<int32> LUTUnit;

    void AddToLUT(const int32 TargetInt)
    {
        LUTUnit.Add(TargetInt);
    }

    TArray<int32> GetLTUnit() const
    {
        return LUTUnit;
    }
};

class FDensityField
{
	//	VARIABLES
    TArray<FVoxel> VoxelList;
    int32 XNum, YNum, ZNum;
    float XStep, YStep, ZStep;
	FVector GridOrigin;
	
public:
	mutable FCriticalSection DataGuard;
	// CONSTRUCTOR
	FDensityField();

	// INITIALIZATION FUNCTIONS
	void InitializeDensityField(const FVector& MinBounds, const FVector& MaxBounds, const int32 XAxisNum, const int32 YAxisNum, const int32 ZAxisNum);
    void CalculateVoxelDensities(const APointCloud* PointCloud, float InfluenceRadius, float Sigma);
	void CalculateVoxelDensitiesByNumber(const APointCloud* PointCloud, float InfluenceRadius);
	void CalculateAndStoreGradients();

	//	DEBUG FUNCTIONS
    void DrawDebugVoxelDensity(const UWorld* World, const AActor* Actor, float Duration, float Scale, float DensityThreshold) const;

	// CONVERSION FUNCTIONS
	int32 WorldPositionToIndex(const FVector& Position) const;
	FIntVector3 WorldToGridPosition(const FVector& Position) const;
	bool IsValidGridPosition(int32 XBin, int32 YBin, int32 ZBin) const;
	int32 GridPositionToIndex(int32 X, int32 Y, int32 Z) const;
	TArray<FVector> IndexToVoxelCornersWorld(const int32 Index) const;
	
	// GETTER AND SETTER FUNCTIONS
	FVector GetGridOrigin() const;
    FVector IndexToVoxelGradient(int32 Index) const;
    FVector IndexToVoxelPosition(int32 Index) const;
	FIntVector3 IndexToGridPosition(int32 Index) const;
	int32 GetVoxelNumber() const;
    double IndexToVoxelDensity(int32 Index) const;
	void IndexToVoxelBounds(int32 Index, FVector& OutMinBounds, FVector& OutMaxBounds) const;
	double GridPositionToVoxelDensity(int32 XBin, int32 YBin, int32 ZBin) const;
	FVector GridPositionToVoxelGradient(int32 XBin, int32 YBin, int32 ZBin) const;
	FVector GetStep() const;
	int32 GetXNum() const;
	int32 GetYNum() const;
	int32 GetZNum() const;
	bool IsValidWorldPosition(const FVector& Position) const;
	TArray<int32> IndexToVoxelNeighbors(const int32 Index) const;
	bool IsValidIndex(int32 Index) const;
	bool IsValid();
	void SetVoxelDensityByIndex(int32 Index, double Density);
    void SetVoxelGradientByIndex(int32 Index, const FVector& Gradient);
};