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Core messages are sent around Cinema 4D to inform various parts of the application about events and changes. This is happens so different parts of the interface can update their status (e.g. Attribute Manager, Viewport, etc.).

Note: Other important message types are messages sent to C4DAtom based elements (see C4DAtom Manual and NodeData::Message() Manual) and GUI messages (GUI and Interaction Messages Manual).

EventAdd

When the active document is changed by some operation one must inform Cinema 4D about this, so Cinema 4D can update the GUI.

EventAdd(): Adds a global event to Cinema 4D's event queue. It triggers the core message EVMSG_CHANGE.

Valid flags are:

EVENT::FORCEREDRAW : Force a complete redraw. Currently not used.
EVENT::ANIMATE : Animate the document.
EVENT::NOEXPRESSION : Do not execute expressions.
EVENT::CAMERAEXPRESSION : If set (and not EVENT::NOEXPRESSION), the event will only update camera dependent expressions (for faster speed).
EVENT::ENQUEUE_REDRAW : Do not stop the current redraw if DrawViews() is running at the moment. In that case enqueue the redraw after the current draw is done.

Note: This is only needed when the active document is changed. It is not needed when a virtual or internal document is edited or when objects are handled that are not part of a document.; Events are not sent if no GUI exists (if CINEMAINFO::FORBID_GUI is true).

Warning: Do not use EventAdd() in a threaded context.

  // This example shows how to create a new "Cube" object and how to insert it into the document.
 
  BaseDocument* const document = GetActiveDocument();
  if (document == nullptr)
    return maxon::UnexpectedError(MAXON_SOURCE_LOCATION);
 
  BaseObject* const cubeObject = BaseObject::Alloc(Ocube);
  if (cubeObject == nullptr)
    return maxon::OutOfMemoryError(MAXON_SOURCE_LOCATION);
 
  cubeObject->SetName("This is a new object"_s);
 
  document->InsertObject(cubeObject, nullptr, nullptr);
 
  EventAdd();

Catching Messages

Core messages are sent to update the GUI so it is possible to catch core messages in custom GUI elements:

GeDialog::CoreMessage(): Receives core messages in a custom GeDialog.
GeUserArea::CoreMessage(): Receives core messages in a custom GeUserArea.

When EVMSG_CHANGE is received, GeDialog based custom panels typically re-initialize their values by calling GeDialog::InitValues().

It is also possible to catch core messages with a MessageData plugin:

MessageData::CoreMessage(): Receives core messages in a custom MessageData plugin.

  // This example MessageData::CoreMessage() catches EVMSG_CHANGE to detect any change.
  Bool CoreMessage(Int32 id, const BaseContainer& bc)
  {
    if (id == EVMSG_CHANGE)
    {
      if (g_printMessage)
        ApplicationOutput("Something was changed.");
    }
 
    return true;
  }

A core message can contain a BaseContainer argument. This container may store these values:

BFM_CORE_ID: The core message ID.
BFM_CORE_UNIQUEID: Time stamp.
BFM_CORE_PAR1: Parameter 1.
BFM_CORE_PAR2: Parameter 2.
BFM_CORE_SPECIALCOREID: Special manager ID for synchronization messages.

Message Types

These are Cinema 4D's core messages:

EVMSG_CHANGE: Sent by EventAdd(). The optional flags are stored in BFM_CORE_PAR1.
EVMSG_DOCUMENTRECALCULATED: Sent while drawing after the animation, expressions and cache building have been done. It allows that certain managers (e.g. Attribute Manager) update their values to the changes done by the expressions etc.
EVMSG_TOOLCHANGED: A tool setting has changed (local event).
EVMSG_GRAPHVIEWCHANGED: Something in XPresso has been changed (local event).
EVMSG_AUTKEYMODECHANGED: The autokey mode was changed.
EVMSG_UPDATEHIGHLIGHT: Sent in the case that only the highlighting changes.
EVMSG_TIMELINESELECTION: A timeline selection has been changed (local event).
EVMSG_BROWSERCHANGE: Something in the content browser has been changed (local event).
EVMSG_MATERIALSELECTION: A material selection has been changed (local event).
EVMSG_TAKECHANGED: Sent by the Take System when the current Take ID changed to let all managers react to the new status.
EVMSG_UPDATEBASEDRAW: Sent to update the viewport (invokes DrawViews()).
EVMSG_ASYNCEDITORMOVE: The user moved something in the editor window. Managers should update things like position fields.
- MOVE_START: Move started.
- MOVE_CONTINUE: Move continued.
- MOVE_END: Move ended.

      // This example catches EVMSG_ASYNCEDITORMOVE in a GeDialog.
 
      case EVMSG_ASYNCEDITORMOVE:
      {
        // check if this core message is new
        if (CheckCoreMessage(bc))
        {
          const Int movement = (Int)bc.GetVoid(BFM_CORE_PAR1);
 
          switch (movement)
          {
            case MOVE_START: { ApplicationOutput("Start Movement"); break; }
            case MOVE_CONTINUE: { ApplicationOutput("Continue Movement"); break; }
            case MOVE_END: { ApplicationOutput("End Movement"); break; }
          }
        }
        break;
      }

EVMSG_UPDATESCHEME: Scheme has been updated.
- ::SCHEME_LIGHT: Light.
- SCHEME_DARK: Dark.
- SCHEME_OTHER: Other.

      // This example catches EVMSG_UPDATESCHEME in a GeDialog
      // to be informed when the scheme is changed.
 
      case EVMSG_UPDATESCHEME:
      {
        // check if this core message is new
        if (CheckCoreMessage(bc))
        {
          const Int scheme = (Int)bc.GetVoid(BFM_CORE_PAR1);
 
          switch (scheme)
          {
            case SCHEME_DARK: { ApplicationOutput("Dark Scheme"); break; }
            case SCHEME_OTHER: { ApplicationOutput("Other Scheme"); break; }
          }
        }
        break;
      }

Custom Messages

It is possible to send custom, asynchronous core messages. This can be used to send a message from a custom thread into the main thread.

SpecialEventAdd(): Adds a custom event.

  // This example sends a custom core message.
 
  SpecialEventAdd(ID_CUSTOMEVENT, 123, 456);

      // This example catches a custom core message.
 
      case ID_CUSTOMEVENT:
      {
        const Int value1 = (Int)bc.GetVoid(BFM_CORE_PAR1);
        const Int value2 = (Int)bc.GetVoid(BFM_CORE_PAR2);
 
        const String value1String = String::IntToString(value1);
        const String value2String = String::IntToString(value2);
        ApplicationOutput("Value 1: " + value1String + ", value 2: " + value2String);
 
        break;
      }

Other Functions

Other functions to send core messages are:

SendCoreMessage(): Typically used to send Command related messages. Alternatively functions like CallCommand() etc. can be used.
GeSyncMessage(): Sends a synchronous event message.

// This example forces an update of the attribute manager.
 
SendCoreMessage(COREMSG_CINEMA, BaseContainer(COREMSG_CINEMA_FORCE_AM_UPDATE));

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