FRigVMCodeConverter

Converts RigVM bytecode into a JSON representation for template rendering.

API > API/Plugins > API/Plugins/RigVMDeveloper

Converts RigVM bytecode into a JSON representation for template rendering.

FRigVMCodeConverter is the core of the nativization pipeline. It parses a compiled RigVM's bytecode and produces a comprehensive JSON structure that Inja templates can use to generate C++ source code.Conversion Pipeline

Construction: Parses the VM's bytecode in a 14-step process:

  • External variables, memory layouts (literal/work)
  • Property paths, callables, blocks, entries
  • Instructions with operand resolution
  • Dependency tracking (includes, libraries)

Render: Combines the JSON with an Inja template to produce C++ code.JSON Structure Overview

The generated JSON contains:

  • `AssetName_: Name of the source asset
  • `VMHash_: Hash for validation
  • `Variables_: External variable definitions
  • `Memory.Literal_: Constant/default values
  • `Memory.Work_: Runtime temporaries
  • `Functions_: Unit functions and dispatch factories
  • `Blocks_: Control flow blocks (branches)
  • `Callables_: User-defined callable functions
  • `Entries_: Entry points into the VM
  • `Instructions_: Bytecode instructions with resolved operands
  • `Includes_: Required C++ header files
  • `Libraries_: Required UE module dependencies Usage

FRigVMCodeConversionSettingsSettings;Settings.TargetModule=TEXT("MyGame");Settings.OutputFolder=TEXT("Source/MyGame/Generated");autoConverter=MakeShared(EditorAsset,Settings);if(Converter->HasError()){//Handleconversionfailurereturn;}//UsewithFRigVMCodeGeneratortoproduceoutputfilesFRigVMCodeGeneratorGenerator(ERigVMCodeLanguage::CPlusPlus);autoOutputs=Generator.GenerateAll(Converter);

   
Name FRigVMCodeConverter
Type class
Header File /Engine/Plugins/Runtime/RigVM/Source/RigVMDeveloper/Public/RigVMCompiler/RigVMCodeConverter.h
Include Path #include "RigVMCompiler/RigVMCodeConverter.h"

Syntax

class FRigVMCodeConverter

Constructors

Name Remarks Include Path Unreal Specifiers

FRigVMCodeConverter ( IRigVMEditorAssetInterface* InEditorAsset,
const FRigVMCodeConversionSettings& InSettings
)

 Constructs a converter and parses the VM's bytecode into JSON. RigVMCompiler/RigVMCodeConverter.h  

Variables

Protected

Name Type Remarks Include Path Unreal Specifiers
bHasError bool True if an error occurred during conversion. RigVMCompiler/RigVMCodeConverter.h  
BlockIndexPerInstruction TArray< int32 > Maps instruction index -> containing block index. RigVMCompiler/RigVMCodeConverter.h  
Blocks TArray< FRigVMBranchInfo > All blocks (branches) including synthesized RunInstruction blocks. RigVMCompiler/RigVMCodeConverter.h  
ByteCode const FRigVMByteCode * Direct reference to VM's bytecode. RigVMCompiler/RigVMCodeConverter.h  
CallableArgumentMap TMap< TTuple< int32, int32 >, TTuple< int32, int32, FName > > Maps (memory type, register index) -> (callable index, argument index, argument name). RigVMCompiler/RigVMCodeConverter.h  
CallableIndexPerInstruction TArray< int32 > Maps instruction index -> containing callable index. RigVMCompiler/RigVMCodeConverter.h  
EditorAsset IRigVMEditorAssetInterface * ============================================================================ State RigVMCompiler/RigVMCodeConverter.h  
FunctionIndexMap TMap< const void *, int32 > Maps function pointer -> function index (for deduplication). RigVMCompiler/RigVMCodeConverter.h  
HashToCustomFunction TMap< uint32, TSharedPtr< FRigVMFunction > > Maps type hash -> custom function (for dispatch permutations). RigVMCompiler/RigVMCodeConverter.h  
Includes TArray< FString > Accumulated include paths for generated code. RigVMCompiler/RigVMCodeConverter.h  
Instructions FRigVMInstructionArray All instructions from bytecode. RigVMCompiler/RigVMCodeConverter.h  
InstructionToCustomFunction TMap< int32, TSharedPtr< FRigVMFunction > > Maps instruction index -> custom function (for dispatch permutations). RigVMCompiler/RigVMCodeConverter.h  
Json inja::json The complete JSON representation of the VM. RigVMCompiler/RigVMCodeConverter.h  
KnownDependencies TSet< const UObject * > Set of already-processed dependencies (avoids duplicates). RigVMCompiler/RigVMCodeConverter.h  
LazyFunctionArguments TSet< TTuple< int32, int32 > > Set of (function index, argument index) pairs that are lazy values. RigVMCompiler/RigVMCodeConverter.h  
LazyProperties TArray< TTuple< FString, FString > > Accumulated lazy property definitions. RigVMCompiler/RigVMCodeConverter.h  
Libraries TArray< FString > Accumulated library/module dependencies. RigVMCompiler/RigVMCodeConverter.h  
NativePathMap TMap< FString, const UObject * > Cache: native path string -> UObject. RigVMCompiler/RigVMCodeConverter.h  
NativeTypeMap TMap< FString, FString > Cache: original type -> sanitized type (for 2D array remapping). RigVMCompiler/RigVMCodeConverter.h  
PackageName FString Sanitized package name (used for class naming). RigVMCompiler/RigVMCodeConverter.h  
PropertyMap TMap< TTuple< int32, int32 >, int32 > Maps (memory type, register index) -> exported property index. RigVMCompiler/RigVMCodeConverter.h  
PropertyPathMap TMap< uint32, int32 > Maps property path hash -> property path index. RigVMCompiler/RigVMCodeConverter.h  
RunInstructionBranches TMap< TTuple< int32, int32 >, int32 > Maps (first instruction, last instruction) -> branch info index for RunInstruction blocks. RigVMCompiler/RigVMCodeConverter.h  
Settings FRigVMCodeConversionSettings Conversion settings. RigVMCompiler/RigVMCodeConverter.h  
UniquePropertyNames TSet< TTuple< int32, FString > > Tracks unique property names per memory type for deduplication. RigVMCompiler/RigVMCodeConverter.h  
VM URigVM * The RigVM being converted. RigVMCompiler/RigVMCodeConverter.h  

Functions

Public

Name Remarks Include Path Unreal Specifiers

FString GetAssetName()

 Returns the sanitized asset name used for generated class names. RigVMCompiler/RigVMCodeConverter.h  

const inja::json & GetJson()

 Returns the parsed JSON representation of the VM (for debugging/inspection). RigVMCompiler/RigVMCodeConverter.h  

bool HasError()

 Returns true if an error occurred during construction or rendering. RigVMCompiler/RigVMCodeConverter.h  

TSharedPtr< FRigVMCodeOutput > Render ( const TSharedPtr< FRigVMCodeTemplate >& InTemplate
)

 Renders a template using the parsed JSON data. RigVMCompiler/RigVMCodeConverter.h  

Static

Name Remarks Include Path Unreal Specifiers

static FString FromJson ( const std::string& InJson
)

 Converts std::string to FString. RigVMCompiler/RigVMCodeConverter.h  

static FString FromJson ( const inja::json& InJson
)

 Converts inja::json to FString. RigVMCompiler/RigVMCodeConverter.h  

static uint32 GetPropertyPathHash ( const FRigVMPropertyPath& InPropertyPath
)

 ============================================================================ Type/Path Resolution RigVMCompiler/RigVMCodeConverter.h  

static FString SanitizeName ( const FString& InString
)

 ============================================================================ Name Sanitization RigVMCompiler/RigVMCodeConverter.h  

static inja::json ToJson ( const FString& InString
)

 Converts FString to inja::json (UTF-8 encoded). RigVMCompiler/RigVMCodeConverter.h  

static inja::json ToJson ( int64 InEnumValue,
bool bTrimWhiteSpace
)

 ============================================================================ Enum/Primitive JSON Conversion RigVMCompiler/RigVMCodeConverter.h  

static inja::json ToJson ( const FText& InText
)

 Converts FText to inja::json. RigVMCompiler/RigVMCodeConverter.h  

static inja::json ToJson ( const FName& InName
)

 Converts FName to inja::json. RigVMCompiler/RigVMCodeConverter.h  

static inja::json ToJson ( const UEnum* InEnum,
int64 InEnumValue,
bool bTrimWhiteSpace
)

 Converts an enum value to its display name as JSON. RigVMCompiler/RigVMCodeConverter.h  

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