ProceduralFoliageTile.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
#include "UObject/ObjectMacros.h"
#include "UObject/Object.h"
#include "Math/RandomStream.h"
#include "InstancedFoliage.h"
#include "ProceduralFoliageInstance.h"
#include "ProceduralFoliageBroadphase.h"
#include "ProceduralFoliageTile.generated.h"
 
class UFoliageType;
class UProceduralFoliageSpawner;
struct FBodyInstance;
 
UCLASS(MinimalAPI)
class UProceduralFoliageTile : public UObject
{
    GENERATED_UCLASS_BODY()
 
    
    FOLIAGE_API void Simulate(const UProceduralFoliageSpawner* InFoliageSpawner, const int32 RandomSeed, const int32 MaxNumSteps, const int32 InLastCancel);
    
    FOLIAGE_API void ExtractDesiredInstances(TArray<FDesiredFoliageInstance>& OutDesiredInstances, const FTransform& WorldTM, const FVector2D& ActorVolumeLocation, FVector::FReal ActorVolumeMaxExtent, const FGuid& ProceduralGuid, const FVector::FReal HalfHeight, const FBodyInstance* VolumeBodyInstance, bool bEmptyTileInfo = true);
    
    FOLIAGE_API void CopyInstancesToTile(UProceduralFoliageTile* ToTile, const FBox2D& LocalAABB, const FTransform& RelativeTM, const float Overlap) const;
 
    FOLIAGE_API void RemoveInstance(FProceduralFoliageInstance* Inst);
 
    FOLIAGE_API void RemoveInstances();
 
    FOLIAGE_API void Empty();
 
    FOLIAGE_API void InitSimulation(const UProceduralFoliageSpawner* InFoliageSpawner, const int32 InRandomSeed);
 
    // UObject interface
    FOLIAGE_API virtual void GetResourceSizeEx(FResourceSizeEx& CumulativeResourceSize) override;
    FOLIAGE_API virtual void BeginDestroy() override;
 
private:
    
    void GetInstancesInAABB(const FBox2D& LocalAABB, TArray<FProceduralFoliageInstance* >& OutInstances, bool bFullyContainedOnly = true) const;
 
    void AddInstances(const TArray<FProceduralFoliageInstance*>& NewInstances, const FTransform& ToLocalTM, const FBox2D& InnerLocalAABB);
 
    void InstancesToArray();
 
    void RunSimulation(const int32 MaxNumSteps, bool bOnlyInShade);
 
    void StepSimulation();
 
    void AddRandomSeeds(TArray<FProceduralFoliageInstance*>& OutInstances);
 
    bool HandleOverlaps(FProceduralFoliageInstance* Instance);
 
    FProceduralFoliageInstance* NewSeed(const FVector& Location, float Scale, const UFoliageType* Type, float InAge, bool bBlocker = false);
 
    void SpreadSeeds(TArray<FProceduralFoliageInstance*>& NewSeeds);
    void AgeSeeds();
 
    void MarkPendingRemoval(FProceduralFoliageInstance* ToRemove);
    void FlushPendingRemovals();
 
    bool UserCancelled() const;
    
private:
 
    UPROPERTY()
    TObjectPtr<const UProceduralFoliageSpawner> FoliageSpawner;
 
    TSet<FProceduralFoliageInstance*> PendingRemovals;
    TSet<FProceduralFoliageInstance*> InstancesSet;
 
    UPROPERTY()
    TArray<FProceduralFoliageInstance> InstancesArray;
 
    int32 SimulationStep;
    FProceduralFoliageBroadphase Broadphase;    
 
    int32 RandomSeed;
    FRandomStream RandomStream;
    bool bSimulateOnlyInShade;
 
    int32 LastCancel;
 
private:
    float GetRandomGaussian();
    FVector GetSeedOffset(const UFoliageType* Type, float MinDistance);
};