Overview

In CRYENGINE, it is possible to create a custom Flow Graph node by using C++ to generate a .dll file that can be introduced to CRYENGINE as a plugin. This technique offers another solution for the users who prefer creating a custom node without having to create it from scratch. For more information about creating a Flow Graph node, please refer to the Creating a New Flow Node section.

Prerequisites

The following applications will need to be installed in order to compile projects and the Engine itself.

Steps

1. Create a Plugin CPP project and open the project folder.
   For more information about creating a project, please refer to the Creating, Importing & Upgrading Projects page.

   The project files are stored separately from the engine. A .cryproject file will be generated for you; this can be right-clicked to reveal helper functionality or opened with a text editor to reveal JSON detailing the project.

2. Next, in the project folder, right-click on the Plugin.cryproject file and choose Generate solution;
   
   Go to the solution file that has been generated and open the Plugin.sln file; e.g: \MyProject\solutions\win64\Plugin.sln

3. In the Solution Explorer, open project\Plugin\Plugin.cpp and paste the class & macro shown below just before the last line of the code block, which is CRYREGISTER_SINGLETON_CLASS(CPlugin):
   

   // This is the class that is going to be registered by the REGISTER_FLOW_NODE macro at the bottom
   class CFlowSubstringNode : public CFlowBaseNode<eNCT_Singleton>
   {
   public:
       CFlowSubstringNode(SActivationInfo* pActInfo) {};
   
       virtual void GetConfiguration(SFlowNodeConfig& config)
       {
           static const SInputPortConfig in_config[] = {
               InputPortConfig_Void("Get",        _HELP("Substring, retrieves letters from defined string.")),
               InputPortConfig<string>("String", _HELP("String to retrieve letters from")),
               InputPortConfig<int>("Int1", _HELP("Start retrieving from")),
               InputPortConfig<int>("Int2", _HELP("Number of letters to retrieve")),
           { 0 }
           };
           static const SOutputPortConfig out_config[] = {
               OutputPortConfig<string>("Out"),
           { 0 }
           };
           config.sDescription = _HELP("Substring");
           config.pInputPorts = in_config;
           config.pOutputPorts = out_config;
           config.SetCategory(EFLN_APPROVED);
       }
       virtual void ProcessEvent(EFlowEvent evt, SActivationInfo* pActInfo)
       {
           switch (evt)
           {
           case eFE_Activate:
               if (IsPortActive(pActInfo, 0))
               {
                   string str1 = GetPortString(pActInfo, 1);
                   int int1 = GetPortInt(pActInfo, 2);
                   int int2 = GetPortInt(pActInfo, 3);
   
                   if (int1 + int2 > str1.length())
                   {
                       CryWarning(
                           VALIDATOR_MODULE_FLOWGRAPH,
                           VALIDATOR_WARNING,
                           "Failed to get %d characters starting from %d in a string %d characters long.",
                           int2, int1, str1.length());
                   }
                   ActivateOutput(pActInfo, 0, str1.substr(int1, int2));
               }
               break;
           }
       };
   
       virtual void GetMemoryUsage(ICrySizer* s) const
       {
           s->Add(*this);
       }
   };
   //Register Flownode (you will need to do this for every FlowNode once)
   //The REGISTER_FLOW_NODE Macro takes 2 parameters, the name as first and the class as second parameter.
   REGISTER_FLOW_NODE("String:Substring", CFlowSubstringNode)

   In this example, the node will be called String:Substring, as indicated in the last line of the code block above.

   The last line of this block should be CRYREGISTER_SINGLETON_CLASS(CPlugin).

4. After copying the code, go to the Plugin.h → CPlugin class on the Solution Explorer and paste the following two lines at the bottom of the public section:
   

   PLUGIN_FLOWNODE_REGISTER

   PLUGIN_FLOWNODE_UNREGISTER

   When the process is finished, the code block should look as follows:

   #pragma once
   
   #include <CrySystem/ICryPlugin.h>
   
   #include <CryGame/IGameFramework.h>
   
   #include <CryEntitySystem/IEntityClass.h>
   
   class CPlugin
                   : public Cry::IEnginePlugin
                   , public ISystemEventListener
   {
   public:
                   CRYINTERFACE_SIMPLE(Cry::IEnginePlugin)
                   CRYGENERATE_SINGLETONCLASS_GUID(CPlugin, "MyPlugin", "2711a23d-3848-4cdd-a95b-e9d88ffa23b0"_cry_guid)
   
                   virtual ~CPlugin();
                  
                   // Cry::IEnginePlugin
                   virtual bool Initialize(SSystemGlobalEnvironment& env, const SSystemInitParams& initParams) override;
                   // ~Cry::IEnginePlugin
                  
                   // ISystemEventListener
                   virtual void OnSystemEvent(ESystemEvent event, UINT_PTR wparam, UINT_PTR lparam) override;
                   // ~ISystemEventListener
   
                   //Include Flownode Registering and unregistering (just needs to be included once in total)
                   PLUGIN_FLOWNODE_REGISTER
                   PLUGIN_FLOWNODE_UNREGISTER
   };

   These two lines will make sure that the Flow Graph node is registered/unregistered and they only need to be included once in total.
   After confirming the code position is correct, proceed to the next steps:

5. Build the solution by choosing Build → Build Solution on the Visual Studio menu bar. This will generate a .dll file in the MyPlugin\bin\win_x64 folder;
6. Copy that .dll file to the \bin\win_x64 folder of any existing CRYENGINE project in which you want to use your plugin.
   In this example, the GameSDK project is being used, so the .dll file is coped to \GameSDK\bin\win_x64;

7. Right-click on the GameSDK.cryproject file and Edit it in a plain text editor to add the following reference of the .dll file in the plugins section; keep in mind that the reference code shown below can be different based on the path of the project's bin folder:
   {
   "type": "EPluginType::Native",
   "path": "bin/win_x64/plugin.dll"
   }.

   If the new line is not the last line of the plug-in, make sure it ends with a comma.

8. Open the GameSDK.cryproject file in the Sandbox editor. Then proceed to Flow Graph to use the new node;
   

   You may also want to use visual panels to communicate related information, tips or things users need to be aware of.