PropActorFactory.h

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// Copyright (c) 2026 Computer Vision Center (CVC) at the Universitat Autonoma
// de Barcelona (UAB).
//
// This work is licensed under the terms of the MIT license.
// For a copy, see <https://opensource.org/licenses/MIT>.
 
#pragma once
 
#include "Carla/Actor/ActorSpawnResult.h"
#include "Carla/Actor/CarlaActorFactory.h"
#include "Carla/Actor/PropParameters.h"
 
#include <util/ue-header-guard-begin.h>
#include "Json.h"
#include "JsonUtilities.h"
#include <util/ue-header-guard-end.h>
 
#include "PropActorFactory.generated.h"
 
UCLASS()
class CARLA_API APropActorFactory : public ACarlaActorFactory
{
    GENERATED_BODY()
 
    /// Retrieve the definitions of the static mesh actor
    virtual TArray<FActorDefinition> GetDefinitions() override;
 
    virtual FActorSpawnResult SpawnActor(
        const FTransform &SpawnAtTransform,
        const FActorDescription &ActorDescription) override;
 
public:
    UFUNCTION(BlueprintCallable, Category = "PropActorFactory")
    static void SavePropParametersArrayToFile(const TArray<FPropParameters> &PropParamsArray, const FString &FileName);
    UFUNCTION(BlueprintCallable, Category = "PropActorFactory")
    static void LoadPropParametersArrayFromFile(const FString &FileName, TArray<FPropParameters> &OutPropParamsArray);
 
    UFUNCTION(BlueprintImplementableEvent, Category = "PropActorFactory")
    bool PostProcessProp(AActor* SpawnedActor, const FActorDescription& PropParams);
 
private:
    static TSharedPtr<FJsonObject> FPropParametersToJsonObject(const FPropParameters& PropParams);
    static FString FPropParametersArrayToJson(const TArray<FPropParameters>& PropParamsArray);
    static bool JsonToFPropParameters(const TSharedPtr<FJsonObject> JsonObject, FPropParameters& OutPropParams);
    static bool JsonToFPropParametersArray(const FString& JsonString, TArray<FPropParameters>& OutPropParamsArray);
 
    virtual void ReleaseContentPack(const FString &MountPoint) override;
 
protected:
    // Transient: GetDefinitions() rebuilds these from the JSON catalogs every
    // episode, and a saved copy bakes a stale catalog into the map.
    UPROPERTY(EditAnywhere, Transient)
    TArray<FActorDefinition> Definitions;
    UPROPERTY(EditAnywhere, BlueprintReadWrite, Transient)
    TArray<FPropParameters> PropsParams;
 
private:
    /// Mesh cache keyed by mesh path (same string stored in
    /// ActorDescription.Variations["mesh_path"]). Populated from PropsParams in
    /// GetDefinitions() so that SpawnActor() avoids the per-spawn
    /// synchronous LoadObject on the game thread. Cache-miss fall back to
    /// LoadObject with a warning log.
    UPROPERTY(Transient, DuplicateTransient)
    TMap<FString, TObjectPtr<UStaticMesh>> MeshCacheByPath;
};