C + + game engine real-time hot reloading and editing environment integration method and system
By introducing XML serialization and DLL replacement into the C++ game engine, the problems of hot reloading instability and insufficient iteration efficiency during structural modifications of the C++ game engine are solved, achieving efficient and stable editor state migration and rapid verification.
Patent Information
- Application Number
- CN202511644362.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-11
- Publication Date
- 2026-02-10
AI Technical Summary
Existing C++ game engines suffer from instability due to hot reloading and insufficient iteration efficiency when undergoing structural modifications. In particular, they cannot safely handle changes in object memory layout and rely on external runtime environments, making them difficult to promote in native high-performance C++ engines.
A unified XML serialization mechanism is adopted to convert the game scene state into memory data blocks. The complete saving and restoration of the editor state is achieved through DLL replacement and deserialization operations, ensuring the correctness of memory layout and virtual function table when C++ class structure changes, and avoiding memory corruption.
It achieves an efficient and stable hot reload process in the C++ game engine, which greatly improves the iteration efficiency of development and debugging, reduces the time from code modification to verification results, and solves the problems of runtime errors and frequent compilation restarts in the traditional mode.
Smart Images
Figure CN121490401A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of game engine development technology, and in particular to a method and system for integrating a real-time hot reload and editing environment for a C++ game engine. Background Technology
[0002] In traditional C++ game development, code modifications often require a complete cycle of compiling > running > debugging > modifying > recompiling. For resource-intensive and logically complex projects, a single restart can take several minutes, and developers cannot dynamically adjust parameters or intuitively modify resources during runtime. Even minor adjustments to values (such as character jump height) require interrupting the game, modifying the code, and recompiling and restarting, severely impacting debugging and iteration efficiency.
[0003] To improve development efficiency, mainstream game engines have generally introduced a hot reload mechanism:
[0004] Unity uses C# and .NET reflection to implement assembly field overloading, which can preserve object state to a certain extent. However, this approach is highly dependent on the external runtime environment and is difficult to reuse directly in native C++ architectures.
[0005] Unreal Engine (UE) provides Live Coding, which supports hot reloading of C++ code through binary patches. It is highly efficient when only function body logic is modified. However, once structural modifications occur (such as adding types, member variables, or virtual functions), the memory layout changes, which can easily lead to crashes or memory corruption, ultimately requiring recompilation and a restart. In summary, the existing solution still has the following shortcomings:
[0006] Structural modifications are unstable: They cannot safely handle changes in object memory layout, which can easily lead to runtime errors.
[0007] Strong runtime dependency: It depends on external runtime or reflection mechanisms, making it difficult to promote in native high-performance C++ engines.
[0008] Insufficient iteration efficiency: Traditional development requires frequent compilation and restart processes, which cannot meet the needs of high-frequency debugging, visual modification, and rapid verification. Summary of the Invention
[0009] To overcome the above problems, the purpose of this invention is to provide a method for real-time hot reloading of a C++ game engine and integration of the editing environment. By introducing a unified XML serialization mechanism, it is possible to achieve complete saving and accurate restoration of the editor state, thereby significantly improving the iterative efficiency of development and debugging while ensuring operational stability.
[0010] This invention is implemented using the following scheme:
[0011] A method for integrating a real-time hot reload and editing environment for a C++ game engine, the method comprising the following steps:
[0012] Step S1: Safely convert the EditingSceneState to the PlayingState, initialize the settings required for game runtime, identify and remove nodes used only for the editor view, serialize all current critical runtime data into data blocks in memory using XML format, and create a brand new playback scene;
[0013] Step S2: Switch from PlayingState to EditingSceneState, delete the currently running playback scene, the engine accesses the XML serialized data block in memory, performs deserialization, and restores the editor scene state before playback.
[0014] Step S3: The developer modifies the C++ script source code and compiles the script. After successful compilation, a dynamic link library file HotReload.dll containing the new code logic is generated. The engine switches to ReloadingScriptsState to reload the script state. The engine serializes the current editor scene state into memory using XML format, deletes the old editor scene object, unloads the dynamic link library HotReload.dll containing the old code logic, loads the newly compiled dynamic link library HotReload.dll, and uses the XML data block stored in memory to perform a deserialization operation on the newly loaded scene. The deserialization operation uses the C++ class structure in the compiled dynamic link library HotReload.dll to create objects and populate the state data; the scene state switches to EditingSceneState.
[0015] Furthermore, step S1 further comprises:
[0016] Step S11: Upon receiving the "Play" command triggered by the user, the engine switches the scene state from EditingSceneState to PlayingState, preparing for the game to run.
[0017] Step S12: Initialize the settings required for the game to run;
[0018] Step S13: Identify and remove nodes used only in the editor view;
[0019] Step S14: The engine traverses all scene entities that need to be saved and uses XML as a unified standard to serialize the runtime data of these entities into a memory data block in XML format. The memory data block serves as a snapshot of the restored editor scene.
[0020] Step S15: After the data snapshot is securely stored, delete the original scene object in the editor and release resources;
[0021] Step S16: Ensure that player commands are processed correctly and start or reset the physics engine. The engine uses XML-formatted serialized data to create a completely new playback scene.
[0022] Furthermore, step S2 further comprises:
[0023] Step S21: Upon receiving the "Stop" command triggered by the user, switch the engine state from PlayingState back to EditingSceneState to prepare for entering the editing environment.
[0024] Step S22: Delete the currently running playback scene and release all memory and resources occupied by the game during runtime;
[0025] Step S23: The engine accesses the XML serialized data block stored in memory, performs deserialization based on the data block, creates a brand new editor scene, clears the shortcut keys registered at runtime, and restores the editor environment to the standard editing state.
[0026] Furthermore, the compilation script in step S3 is further as follows:
[0027] The engine automatically detects file changes through background tools, starts a dedicated thread (not the main thread) to handle compilation tasks, avoids blocking editor operations, and uses the compilation tools CMake and MS build for compilation scripts.
[0028] A real-time hot reload and editing environment integration system for a C++ game engine, the system including a PIE playback module, a PIE stop module, and a script hot reload module;
[0029] The PIE playback module: safely converts the EditingSceneState scene editing state to the PlayingState scene playback state, initializes the settings required for game runtime, identifies and removes nodes used only for the editor view, serializes all current critical runtime data into data blocks in memory using XML format, and creates a completely new playback scene;
[0030] The PIE stop module: switches from the PlayingState playback scene state back to the EditingSceneState scene editing state, deletes the currently running playback scene, the engine accesses the XML serialized data block in memory, performs deserialization operation, and restores the editor scene state before playback;
[0031] The script hot reload module works as follows: Developers modify the C++ script source code, compile the script, and upon successful compilation, generate a dynamic link library file HotReload.dll containing the new code logic. The engine switches to ReloadingScriptsState to reload the script state. The engine serializes the current editor scene state into memory using XML format, deletes the old editor scene object, unloads the dynamic link library HotReload.dll containing the old code logic, loads the newly compiled dynamic link library HotReload.dll, and uses the XML data blocks stored in memory to perform a deserialization operation on the newly loaded scene. The deserialization operation uses the C++ class structure in the compiled dynamic link library HotReload.dll to create objects and populate the state data; the scene state then switches to EditingSceneState for scene editing.
[0032] Furthermore, the PIE playback module further comprises:
[0033] State switching module: Upon receiving the "Play" command triggered by the user, the engine switches the scene state from EditingSceneState to PlayingState, preparing the game to run;
[0034] Application initialization module: Initializes the settings required for the game to run;
[0035] Remove unserialized nodes module: Identifies and removes nodes used only in the editor view;
[0036] XML Serialization Module: The engine traverses all scene entities that need to be saved and uses XML as a unified standard to serialize the runtime data of these entities into a memory data block using XML format. The memory data block serves as a snapshot of the editor scene.
[0037] Scene deletion module: After the data snapshot is safely stored, delete the original scene object in the editor and release resources;
[0038] Scene creation module: Ensures that player commands are processed correctly and starts or resets the physics engine. The engine uses data serialized in XML format to create a brand new playback scene.
[0039] Furthermore, the PIE stop module further comprises:
[0040] State switching module: Receives the "Stop" command triggered by the user and switches the engine state from PlayingState back to EditingSceneState, preparing to enter the editing environment;
[0041] Scene deletion module: Deletes the currently running playback scene, releasing all memory and resources used by the game during runtime;
[0042] Scene restoration module: The engine accesses the XML serialized data block stored in memory, performs deserialization operation based on the data block, creates a brand new editor scene, clears the shortcut keys registered at runtime, and restores the editor environment to the standard editing state.
[0043] Furthermore, the compilation script in the script hot reload module is further as follows:
[0044] The engine automatically detects file changes through background tools, starts a dedicated thread (not the main thread) to handle compilation tasks, avoids blocking editor operations, and uses the compilation tools CMake and MS build for compilation scripts.
[0045] The beneficial effects of this invention are as follows: This invention fundamentally solves the stability problem of hot reloading for C++ structural changes: This solution completely abandons the unstable and restrictive binary hot patching technology. By adopting a serialization-DLL replacement-deserialization process, it ensures that when structural changes such as adding new member variables or new virtual functions to a C++ class occur, the newly created object instance has the correct new memory layout and virtual function table, while the editor state data is losslessly migrated via XML, avoiding the memory corruption and crash phenomena common in solutions such as UE Live Coding.
[0046] Precise and rapid state synchronization: Serialization and deserialization operations are completed at high speed in engine memory, ensuring that PIE playback / stop and hot reload processes are completed in a very short time. Even if it is necessary to exit PIE to replace a DLL, the entire process can still be completed within seconds, greatly reducing the time required for developers to go from code modification to verification results, which has an overwhelming efficiency advantage compared to traditional methods. Attached Figure Description
[0047] Figure 1 This is a schematic diagram of the method flow of the present invention;
[0048] Figure 2 This is a system principle block diagram of the present invention;
[0049] Figure 3 This is the flowchart of the PIE playback module;
[0050] Figure 4 This is the flowchart for stopping the engine PIE module;
[0051] Figure 5 This is a flowchart of the script hot reload module. Detailed Implementation
[0052] The invention will now be further described with reference to the accompanying drawings.
[0053] Please see Figure 1 As shown, the present invention provides a method for integrating a real-time hot reload and editing environment for a C++ game engine, the method comprising the following steps:
[0054] Step S1: Safely convert the EditingSceneState to the PlayingState, initialize the settings required for game runtime, identify and remove nodes used only for the editor view, serialize all current critical runtime data into data blocks in memory using XML format, and create a brand new playback scene;
[0055] Step S2: Switch from PlayingState to EditingSceneState, delete the currently running playback scene, the engine accesses the XML serialized data block in memory, performs deserialization, and restores the editor scene state before playback.
[0056] Step S3: The developer modifies the C++ script source code, compiles the script, and after successful compilation, generates a dynamic link library file HotReload.dll containing the new code logic. The engine switches to ReloadingScriptsState to reload the script state. The engine serializes the current editor scene state into memory using XML format, deletes the old editor scene object, unloads the dynamic link library HotReload.dll containing the old code logic, loads the newly compiled dynamic link library HotReload.dll, and uses the XML data block stored in memory to perform a deserialization operation on the newly loaded scene. The deserialization operation uses the C++ class structure in the compiled dynamic link library HotReload.dll to create objects and populate the state data; the scene state switches to EditingSceneState.
[0057] The present invention will be further described below with reference to a specific embodiment:
[0058] A method for integrating real-time hot reloading of a C++ game engine with an editing environment.
[0059] 1. Safely convert the EditingSceneState to the PlayingState, initialize the settings required for game runtime, identify and remove nodes used only for the editor view, serialize all current critical runtime data into in-memory data blocks using XML format, and create a completely new playback scene; see [link / reference]. Figure 3 The PIE playback process is responsible for safely transitioning a scene from the editing state to the running state;
[0060] 11. Receive Playback Command: Receive the "Play" command triggered by the user; State Switching: The engine switches the scene state from EditingSceneState to PlayingState, preparing for the game to run;
[0061] 12. Application Initialization: Initializes the settings required for the game to run, including registering runtime shortcut keys and establishing a physics simulation environment.
[0062] 13. Remove non-serialized nodes: Identify and remove nodes that are only used in the editor view; such as the GameCamera in the editor's Game window, and the EnvNode that stores environment information in the editor state; these nodes are not related to the PlayingState runtime.
[0063] 14. Serialize the editor scene into memory: The engine traverses all scene entities that need to be saved and uses XML as a unified standard to serialize the runtime data of these entities into a memory data block in XML format. The memory data block serves as a snapshot of the restored editor scene. This is one of the core steps of the PIE function. The runtime data includes the state of all variables in the script instance.
[0064] 15. Delete editor scene: After the data snapshot is safely stored, delete the original scene object in the editor to release resources;
[0065] 16. Initialize Input / Start Physics: Ensures correct handling of player commands and starts or resets the physics engine; Create Playback Scene: The engine creates a completely new playback scene using data serialized in XML format. Object instances in the new scene load their initial states via deserialization and begin executing the game logic scripts.
[0066] 2. Switching from PlayingState to EditingSceneState deletes the currently running playback scene. The engine accesses the XML serialized data block in memory, performs deserialization, and restores the editor scene state before playback. (See also...) Figure 4The PIE stop process is responsible for restoring the editor environment without loss when exiting game mode.
[0067] 21. Receive Stop Command: Receive the "Stop" command triggered by the user; State Switch: Switch the engine state from PlayingState back to EditingSceneState, preparing to enter the editing environment;
[0068] 22. Delete playback scene: Delete the currently running playback scene, releasing all memory and resources used by the game during runtime;
[0069] 23. Restore Game Settings and Editing Environment: The engine accesses XML serialized data blocks stored in memory, performs deserialization based on the data blocks, creates a completely new editor scene, clears runtime-registered shortcuts, and restores the editor environment to a standard editing state. This is the core step of PIE restoration. Because it is based on precise XML snapshot restoration, all objects, components, and parameters in the scene will be precisely restored to their state before PIE started.
[0070] 3. Modify C++ script: The developer modifies the C++ script source code; compiles the script to generate HotReload.dll: After successful compilation, a dynamic link library file HotReload.dll containing the new code logic is generated; switch to reload state: the engine switches to ReloadingScriptsState to reload the script. ReloadingScriptsState represents switching from EditingSceneState to ReloadingScriptsState. In this state, the old HotReload.dll is unloaded and the new HotReload.dll is loaded; serialize the editor scene data into memory and delete the scene: the engine uses XML format to serialize the current editor scene state (i.e., the scene design data before playback). The scene is serialized into memory, and the old editor scene object is deleted. The old DLL is unloaded: the dynamic link library HotReload.dll containing the old code logic is unloaded, and a newly generated DLL is loaded: the newly compiled dynamic link library HotReload.dll is loaded (at this point, the new C++ class definitions, memory layout, and virtual function table (VTable) take effect), and scene data is restored: using the XML data blocks saved in memory, a deserialization operation is performed on the newly loaded scene (the deserialization mechanism uses the C++ class structure in the new DLL to create objects and populate state data). The deserialization operation uses the C++ class structure in the compiled dynamic link library HotReload.dll to create objects and populate state data; the scene state switches to EditingSceneState, where developers can continue editing or restart the PIE session. See also... Figure 5 This process is an innovative solution for addressing the stability and structural change support issues of C++ hot reloading. The unloading and loading of DLLs can only be performed after exiting PIE (PlayingState) or while in editor mode to ensure memory operation safety. If currently running, you must first exit the current PlayingState and then switch the engine to ReloadingScriptsState.
[0071] The compilation script is further as follows:
[0072] The engine automatically detects file changes through background tools, starts a dedicated thread (not the main thread) to handle compilation tasks, avoids blocking editor operations, and uses the compilation tools CMake and MS build for compilation scripts.
[0073] Please see Figure 2 As shown, the present invention also provides a C++ game engine real-time hot reload and editing environment integrated system, the system including a PIE playback module, a PIE stop module, and a script hot reload module;
[0074] The PIE playback module: safely converts the EditingSceneState scene editing state to the PlayingState scene playback state, initializes the settings required for game runtime, identifies and removes nodes used only for the editor view, serializes all current critical runtime data into data blocks in memory using XML format, and creates a completely new playback scene;
[0075] The PIE playback module is further configured as follows:
[0076] State switching module: Receive playback command: Receives the "Play" command triggered by the user; State switching: The engine switches the scene state from EditingSceneState to PlayingState to prepare for game execution;
[0077] Application initialization module: Application initialization: Initializes the settings required for the game to run;
[0078] Remove Deserialized Nodes module: Remove Deserialized Nodes: Identifies and removes nodes used only in the editor view;
[0079] XML Serialization Module: Serializes the editor scene into memory: The engine traverses all scene entities that need to be saved and uses XML as a unified standard to serialize the runtime data of these entities into a memory data block using XML format. The memory data block serves as a snapshot of the restored editor scene.
[0080] Scene deletion module: Delete editor scene: After the data snapshot is safely stored, delete the original scene object in the editor and release resources;
[0081] Scene Creation Module: Initialize Input / Start Physics: Ensures that player commands can be processed correctly and starts or resets the physics engine. Create Playback Scene: The engine uses XML-formatted serialized data to create a brand new playback scene.
[0082] The PIE stop module: switches from the PlayingState playback scene state back to the EditingSceneState scene editing state, deletes the currently running playback scene, the engine accesses the XML serialized data block in memory, performs deserialization operation, and restores the editor scene state before playback;
[0083] The PIE stop module is further configured to:
[0084] State switching module: Receive stop command: Receive the "Stop" command triggered by the user, switch the state from PlayingState back to EditingSceneState, and prepare to enter the editing environment;
[0085] Scene deletion module: Delete playback scene: Delete the currently running playback scene, releasing all memory and resources occupied by the game during runtime;
[0086] Scene Restoration Module: Restores the game settings and editing environment state. The engine accesses XML serialized data blocks stored in memory, performs deserialization operations based on the data blocks, creates a completely new editor scene, clears runtime registered shortcuts, and restores the editor environment to a standard editing state. This is the core step of PIE restoration. Because it is based on precise XML snapshot restoration, all objects, components, and parameters in the scene will be precisely restored to their state before PIE started.
[0087] The script hot reload module works as follows: Modifying the C++ script: Developers modify the C++ script source code, compile the script, and generate HotReload.dll: After successful compilation, a dynamic link library file HotReload.dll containing the new code logic is generated; Switching to reload state: The engine switches to ReloadingScriptsState to reload the script state, serializes the editor scene data into memory, and deletes the scene: The engine serializes the current editor scene state (i.e., the scene design data before playback) into memory using XML format and deletes the old editor scene object; Unloading the old DLL: Unloading the dynamic link library HotReload.dll containing the old code logic. (At this point, the new C++ class definitions, memory layout, and virtual function tables (WTable) take effect.) The newly generated DLL is loaded: the newly compiled dynamic link library HotReload.dll is loaded. Scene data is restored: using the XML data blocks stored in memory, a deserialization operation is performed on the newly loaded scene (the deserialization mechanism uses the C++ class structure in the new DLL to create objects and populate state data). The deserialization operation uses the C++ class structure in the compiled dynamic link library HotReload.dll to create objects and populate state data. The scene state switches to EditingSceneState, where developers can continue editing or restart the PIE session. See also... Figure 5This process is an innovative solution for addressing the stability and structural change support issues of C++ hot reloading. The unloading and loading of deep learning can only be performed after exiting the PIE (PlayingState) or while in editor mode to ensure memory operation safety. If it is currently running, you must first exit the current PlayingState and then switch the engine to ReloadingScriptsState.
[0088] The compilation script in the script hot reload module is further as follows:
[0089] The engine automatically detects file changes through background tools, starts a dedicated thread (not the main thread) to handle compilation tasks, avoids blocking editor operations, and uses the compilation tools CMake and MS build for compilation scripts.
[0090] This solution utilizes the synergy of C++ and XML to achieve a high degree of decoupling between data and code structure while ensuring native performance.
[0091] High-efficiency hot reloading in C++: The mechanism itself is implemented in C++, utilizing native DLL unloading and loading capabilities with minimal performance overhead. This ensures that newly compiled code can be activated in the shortest possible time, meeting the speed requirements of high-performance game engines.
[0092] XML as a serialization bridge: It offers tremendous flexibility by using XML instead of relying on C++ runtime type information (RTTI) or reflection.
[0093] Structural robustness: XML is a structured text format whose data blocks are independent of the specific memory layout of C++ objects. This means that when the structure of a C++ class changes (such as adding or changing the order of fields), the new class instance can accurately extract and populate the corresponding state values from the data blocks by parsing the XML tags, without becoming invalid due to changes in memory offsets, unlike binary patches.
[0094]
[0095]
[0096] Engine PIE Core Process and Data Operation Table
[0097] Referring to the table above showing the core process and data operation of the engine's PIE, this invention provides a stable and efficient Play-in-Editor (PIE) function capable of supporting arbitrary structural modifications within a high-performance game engine based on C++. This solution introduces a unified XML serialization mechanism to achieve complete saving and precise restoration of the editor's state, thereby significantly improving the iterative efficiency of development and debugging while ensuring operational stability. It completely decouples the runtime state of scene objects from their underlying C++ class definitions and memory layout. Unlike methods that attempt to patch binary code during runtime, this invention employs a three-stage approach—runtime snapshot, dynamic library update, and state reconstruction—when the engine performs hot reload or PIE state switching.
[0098] Runtime snapshot: Before code replacement, all current critical runtime data (e.g., attribute values of all game objects and their script components in the scene) are serialized into data blocks in memory using XML format.
[0099] Dynamic library update: At the operational level, the engine unloads the old dynamic link library (DLL) and then loads a new DLL containing the new code logic. Because the unloading operation ensures that the old memory layout and class definitions are completely removed, the newly loaded DLL brings the latest and correct C++ class structure.
[0100] State restructuring: The newly loaded scene is deserialized using XML data blocks in memory. The deserialization mechanism creates object instances based on the new C++ class definition and populates the corresponding attribute values from the XML data.
[0101] This mechanism fundamentally avoids the memory address misalignment and data corruption problems caused by underlying binary patches when handling structural changes, ensuring that even when adding new member variables or virtual functions, stable and lossless state migration can be achieved.
[0102] This invention consists of three core processes: PIE playback, PIE stop, and C++ script hot reload. All processes rely on XML serialization to save and restore the state. Specific Implementation Example 1:
[0104] Adjusting high-frequency character movement parameters (simple modifications)
[0105] Development goal: To precisely tune the movement physics parameters of the PlayerCharacterComponent, such as ground friction, air acceleration, and jump speed.
[0106] 1. Initial Testing and State Capture: Developers set up a test scenario containing ramps and obstacles in the editor.
[0107] The developer modified the private variable float m_JumpVelocityFactor in the PlayerCharacterComponent.cpp script in the IDE, setting it to the initial value 600.0f.
[0108] Click "Play" to launch PIE. The engine executes the PIE playback process. Figure 3 As shown), the current editor scene state (positions of all obstacles, lighting settings, initial character position, etc.) is serialized to a memory snapshot.
[0109] After entering the game, the developers controlled the character to conduct a jump test and found that the jump height was slightly low.
[0110] 2. Hot reload triggering and state transition:
[0111] The developer modified the value of m_JumpVelocityFactor to 750.0f in the IDE.
[0112] The background monitoring tool detected changes to C++ files and automatically started the compilation process. Figure 5 (See steps 2-5 in the text).
[0113] After successful compilation, execute the safe hot reload process. Figure 5 (See steps 6-10).
[0114] Exit playback: If PIE is still running, the PIE stop process will be triggered first. Figure 4 As shown), destroy the current Play scene.
[0115] Capture Editor State: Serializes the current editor's scene data into memory, ensuring that all non-code states (such as camera position and scene object modifications) are saved.
[0116] DLL replacement: The engine unloads the DLL containing the old code from memory and then loads the newly generated HotReload.dll.
[0117] Scene restoration: The engine uses the saved XML data to deserialize and restore the editor scene.
[0118] Revalidation: Developers do not need to restart the editor; they can immediately click Play again. A new PIE session starts, and a PlayerCharacterComponent instance is created based on the definition in the new DLL, with its m_JumpVelocityFactor updated to 750.0f. Developers can immediately validate the new jump height; the entire iteration cycle takes only a few seconds, several times faster than the traditional mode. Specific Implementation Example 2:
[0120] Weapon core logic and structural changes (complex modifications)
[0121] Development goal: To add a new mechanism to the core weapon class (BaseWeaponComponent) to control the recoil curve during continuous firing. This involves adding new member variables and virtual functions.
[0122] 1. Structural code modifications: Developers need to make the following structural modifications to the BaseWeaponComponent class:
[0123] Add a new private member variable m_RecoilSpreadCurve; to define the spread curve of recoil over time.
[0124] A new virtual function, `virtual void CalculateNextRecoil(float DeltaTime)`, is added to update the recoil state in each frame.
[0125] At the same time, the logic in the FireWeapon() function body was modified to introduce recoil calculation.
[0126] 2. Hot overload execution:
[0127] 1. Developers save the code, and the compilation starts in the background. Figure 5 (See steps 2-5 in the text).
[0128] 2. After successful compilation, the hot reload process will begin.
[0129] 3. Serializing Editor State: The engine saves the current editor scene (including the positions of all weapon objects, but only serializes declared properties such as FireRate) to an in-memory XML stream.
[0130] 4. Critical DLL replacement: The engine performs DLL unloading / loading ( Figure 5 (See steps 8 and 9 in the diagram). This is the core innovation of this solution: by replacing the DLL, the old C++ class definitions and the old memory layout are completely eliminated.
[0131] 5. Safe Object Reconstruction: After the engine loads the new DLL, which contains a new definition of BaseWeaponComponent (with m_RecoilSpreadCurve and a new VTable), the deserialization mechanism reads the XML data and reconstructs all scene object instances under the new DLL definition.
[0132] The values of old attributes (such as FireRate) are accurately restored from the XML.
[0133] Newly added attributes (such as m_RecoilSpreadCurve) are correctly initialized (e.g., to empty curves or default values), and new virtual functions are correctly added to the VTable.
[0134] 2. Results and Advantages: The scene is restored to edit mode. Developers can re-enter the game by clicking "Play," and the character's equipped weapons now have a new, fully functional recoil system. Compared to the UE Live Coding solution, this solution successfully avoids the risks of memory layout misalignment and runtime crashes caused by structural C++ modifications (adding members and virtual functions) by forcibly serializing / deserializing the scene state and replacing DLLs. Developers can make significant structural modifications to the C++ core architecture and quickly verify them with extremely high stability, completely solving the efficiency and stability bottlenecks of native C++ development.
[0135] In summary, this invention fundamentally solves the stability problem of hot reloading for structural changes in C++: this solution completely abandons the unstable and restrictive binary hot patching technology. By adopting a serialization-DLL replacement-deserialization process, it ensures that when structural changes such as adding new member variables or virtual functions to C++ classes occur, the newly created object instances have the correct new memory layout and virtual function table, while editor state data is losslessly migrated via XML, avoiding memory corruption and crashes common in solutions such as UE Live Coding.
[0136] Precise and rapid state synchronization: Serialization and deserialization operations are completed at high speed in engine memory, ensuring that PIE playback / stop and hot reload processes are completed in a very short time. Even if it is necessary to exit PIE to replace a DLL, the entire process can still be completed within seconds, greatly reducing the time required for developers to go from code modification to verification results, which has an overwhelming efficiency advantage compared to traditional methods.
[0137] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.
Claims
1. A method for integrating a real-time hot reload and editing environment for a C++ game engine, characterized in that, The method includes the following steps: Step S1: Safely convert the EditingSceneState to the PlayingState, initialize the settings required for game runtime, identify and remove nodes used only for the editor view, serialize all current critical runtime data into data blocks in memory using XML format, and create a brand new playback scene; Step S2: Switch from PlayingState (playing scene state) back to EditingSceneState (scene editing state). The currently running playback scene is deleted. The engine accesses the XML serialized data block in memory, performs deserialization, and restores the editor scene state before playback. Step S3: The developer modifies the C++ script source code and compiles the script. After successful compilation, a dynamic link library file HotReload.dll containing the new code logic is generated. The engine switches to ReloadingScriptsState to reload the script state. The engine serializes the current editor scene state into memory using XML format, deletes the old editor scene object, unloads the dynamic link library HotReload.dll containing the old code logic, loads the newly compiled dynamic link library HotReload.dll, uses the XML data blocks stored in memory, and performs deserialization using the C++ class structure in the compiled dynamic link library HotReload.dll to create objects and populate the state data. The newly loaded scene is deserialized, and the scene state switches to EditingSceneState.
2. The method for integrating a real-time hot reload and editing environment for a C++ game engine according to claim 1, characterized in that, Step S1 further comprises: Step S11: Upon receiving the "Play" command triggered by the user, the engine switches the scene state from EditingSceneState to PlayingState, preparing for the game to run. Step S12: Initialize the settings required for the game to run; Step S13: Identify and remove nodes used only in the editor view; Step S14: The engine traverses all scene entities that need to be saved and uses XML as a unified standard to serialize the runtime data of these entities into a memory data block in XML format. The memory data block serves as a snapshot of the restored editor scene. Step S15: After the data snapshot is securely stored, delete the original scene object in the editor and release resources; Step S16: Ensure that player commands are processed correctly and start or reset the physics engine. The engine uses XML-formatted serialized data to create a completely new playback scene.
3. The method for integrating a real-time hot reload and editing environment for a C++ game engine according to claim 1, characterized in that, Step S2 further comprises: Step S21: Receive the "Stop" command triggered by the user, switch the engine state from PlayingState back to EditingSceneState, and prepare to enter the editing environment; Step S22: Delete the currently running playback scene and release all memory and resources occupied by the game during runtime; Step S23: The engine accesses the XML serialized data block stored in memory, performs deserialization based on the data block, creates a brand new editor scene, clears the shortcut keys registered at runtime, and restores the editor environment to the standard editing state.
4. The method for integrating a real-time hot reload and editing environment for a C++ game engine according to claim 1, characterized in that, The compilation script in step S3 is further as follows: The engine automatically detects file changes through background tools, starts a dedicated thread (not the main thread) to handle compilation tasks, avoids blocking editor operations, and uses the compilation tools CMake and MS build for compilation scripts.
5. A real-time hot reload and editing environment integration system for a C++ game engine, characterized in that, The system includes a PIE playback module, a PIE stop module, and a script hot reload module. The PIE playback module: safely converts the EditingSceneState scene editing state to the PlayingState scene playback state, initializes the settings required for game runtime, identifies and removes nodes used only for the editor view, serializes all current critical runtime data into data blocks in memory using XML format, and creates a completely new playback scene; The PIE stop module: switches from the PlayingState playback scene state back to the EditingSceneState scene editing state, deletes the currently running playback scene, the engine accesses the XML serialized data block in memory, performs deserialization operation, and restores the editor scene state before playback; The script hot reload module works as follows: Developers modify the C++ script source code, compile the script, and upon successful compilation, generate a dynamic link library file HotReload.dll containing the new code logic. The engine switches to ReloadingScriptsState to reload the script state. The engine serializes the current editor scene state into memory using XML format, deletes the old editor scene object, unloads the dynamic link library HotReload.dll containing the old code logic, loads the newly compiled dynamic link library HotReload.dll, and uses the XML data blocks stored in memory to perform a deserialization operation on the newly loaded scene. The deserialization operation uses the C++ class structure in the compiled dynamic link library HotReload.dll to create objects and populate the state data; the scene state then switches to EditingSceneState for scene editing.
6. The integrated system for real-time hot reloading and editing environment of a C++ game engine according to claim 1, characterized in that, The PIE playback module is further configured as follows: State switching module: Upon receiving the "Play" command triggered by the user, the engine switches the scene state from EditingSceneState to PlayingState, preparing the game to run; Application initialization module: Initializes the settings required for the game to run; Remove unserialized nodes module: Identifies and removes nodes used only in the editor view; XML Serialization Module: The engine traverses all scene entities that need to be saved and uses XML as a unified standard to serialize the runtime data of these entities into a memory data block using XML format. The memory data block serves as a snapshot of the editor scene. Scene deletion module: After the data snapshot is safely stored, delete the original scene object in the editor and release resources; Scene creation module: Ensures that player commands are processed correctly and starts or resets the physics engine. The engine uses data serialized in XML format to create a brand new playback scene.
7. The integrated system for real-time hot reloading and editing environment of a C++ game engine according to claim 5, characterized in that, The PIE stop module is further configured to: State switching module: Receives the "Stop" command triggered by the user and switches the engine state from PlayingState back to EditingSceneState, preparing to enter the editing environment; Scene deletion module: Deletes the currently running playback scene, releasing all memory and resources used by the game during runtime; Scene restoration module: The engine accesses the XML serialized data block stored in memory, performs deserialization operation based on the data block, creates a brand new editor scene, clears the shortcut keys registered at runtime, and restores the editor environment to the standard editing state.
8. The integrated system for real-time hot reloading and editing environment of a C++ game engine according to claim 5, characterized in that, The compilation script in the script hot reload module is further as follows: The engine automatically detects file changes through background tools, starts a dedicated thread (not the main thread) to handle compilation tasks, avoids blocking editor operations, and uses the compilation tools CMake and MS build for compilation scripts.