Implementation:CARLA simulator Carla ActorBlueprint Class

Knowledge Sources	CARLA
Domains	Client Library, Actor Spawning, Blueprint System
Last Updated	2026-02-15 05:00 GMT

Overview

ActorBlueprint contains all the necessary information for spawning an actor in CARLA, including its identifier, tags, and configurable attributes.

Description

The ActorBlueprint class in the carla::client namespace wraps an rpc::ActorDefinition and provides methods for querying and configuring actor blueprints before spawning.

Construction

The constructor takes an rpc::ActorDefinition and:

• Stores the _uid (unique identifier) and _id (string identifier, e.g., vehicle.tesla.model3).
• Splits the definition's comma-separated tags into an _tags set using StringUtil::Split.
• Fills the _attributes map from the definition's attributes using the FillMap helper.

Tag Operations

• ContainsTag(tag) -- Checks if a specific tag exists in the tag set.
• MatchTags(wildcard_pattern) -- Tests if the blueprint ID or any tag matches a Unix shell-style wildcard pattern using StringUtil::Match.
• GetTags() -- Returns all tags as a vector of strings.

Attribute Operations

• ContainsAttribute(id) -- Checks if an attribute exists by ID.
• GetAttribute(id) -- Returns a const reference to the ActorAttribute; throws std::out_of_range if not found.
• SetAttribute(id, value) -- Sets an attribute value; throws std::out_of_range if the attribute does not exist, or InvalidAttributeValue if the attribute is not modifiable or the format does not match.
• size() / begin() / end() -- Iteration over attributes using iterator::make_map_values_const_iterator.

Actor Description

• MakeActorDescription() -- Creates an rpc::ActorDescription from the current blueprint state, collecting the UID, ID, and all current attribute values for submission to the simulator for spawning.

Private Members

• _uid -- uint32_t unique identifier
• _id -- std::string blueprint identifier
• _tags -- std::unordered_set<std::string> of tags
• _attributes -- std::unordered_map<std::string, ActorAttribute> of configurable attributes

Usage

Retrieve blueprints from the BlueprintLibrary, optionally modify their attributes (e.g., color, number of wheels), then pass to World::SpawnActor or World::TrySpawnActor.

Code Reference

Source Location

• Repository: CARLA
• Files:
  • LibCarla/source/carla/client/ActorBlueprint.h (124 lines)
  • LibCarla/source/carla/client/ActorBlueprint.cpp (66 lines)

Signature

namespace carla {
namespace client {

class ActorBlueprint {
public:
  explicit ActorBlueprint(rpc::ActorDefinition actor_definition);

  const std::string &GetId() const;

  bool ContainsTag(const std::string &tag) const;
  bool MatchTags(const std::string &wildcard_pattern) const;
  std::vector<std::string> GetTags() const;

  bool ContainsAttribute(const std::string &id) const;
  const ActorAttribute &GetAttribute(const std::string &id) const;
  void SetAttribute(const std::string &id, std::string value);

  size_t size() const;
  auto begin() const;
  auto end() const;

  rpc::ActorDescription MakeActorDescription() const;

private:
  uint32_t _uid;
  std::string _id;
  std::unordered_set<std::string> _tags;
  std::unordered_map<std::string, ActorAttribute> _attributes;
};

} // namespace client
} // namespace carla

Import

#include "carla/client/ActorBlueprint.h"

I/O Contract

Inputs

Name	Type	Required	Description
actor_definition	rpc::ActorDefinition	Yes	Server-provided actor definition with uid, id, tags, and attributes
id	std::string	Yes (for Get/SetAttribute)	Attribute identifier string
value	std::string	Yes (for SetAttribute)	New attribute value as string
wildcard_pattern	std::string	Yes (for MatchTags)	Unix shell-style wildcard pattern

Outputs

Name	Type	Description
id	const std::string&	Blueprint identifier (e.g., "vehicle.tesla.model3")
tags	std::vector<std::string>	List of tags associated with the blueprint
attribute	const ActorAttribute&	Attribute value for a given id
description	rpc::ActorDescription	Complete actor description ready for spawning

Usage Examples

// Get a blueprint from the library
auto blueprint_library = world.GetBlueprintLibrary();
auto bp = blueprint_library->Find("vehicle.tesla.model3");

// Check tags
if (bp->MatchTags("vehicle.*")) {
    // Configure attributes
    if (bp->ContainsAttribute("color")) {
        bp->SetAttribute("color", "255,0,0");
    }

    // Spawn the actor
    auto actor = world.SpawnActor(*bp, spawn_transform);
}

Related Pages

• Environment:CARLA_simulator_Carla_Simulation_Runtime
• CARLA_simulator_Carla_BlueprintLibrary_Class - Collection that contains ActorBlueprints
• CARLA_simulator_Carla_Actor_Class - Actor class spawned from blueprints