Core Messages Manual


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.).

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).


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

Valid flags are:

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).
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);
BaseDocument * GetActiveDocument(void)
void EventAdd(EVENT eventflag=EVENT::NONE)
Definition: c4d_basedocument.h:498
void InsertObject(BaseObject *op, BaseObject *parent, BaseObject *pred, Bool checknames=false)
void SetName(const maxon::String &name)
Definition: c4d_baselist.h:2369
Definition: c4d_baseobject.h:225
static BaseObject * Alloc(Int32 type)
#define Ocube
Definition: ge_prepass.h:1095
Definition: memoryallocationbase.h:67

Catching Messages

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

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:

// 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;
Definition: c4d_basecontainer.h:47
maxon::Bool Bool
Definition: ge_sys_math.h:55
maxon::Int32 Int32
Definition: ge_sys_math.h:60
Sent by EventAdd().
Definition: ge_prepass.h:2751
#define ApplicationOutput(formatString,...)
Definition: debugdiagnostics.h:210

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

Message Types

These are Cinema 4D's core messages:

// This example catches EVMSG_ASYNCEDITORMOVE in a GeDialog.
// 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; }
void * GetVoid(Int32 id, void *preset=nullptr) const
Definition: c4d_basecontainer.h:343
maxon::Int Int
Definition: ge_sys_math.h:64
ANY Parameter 1.
Definition: gui.h:893
#define MOVE_END
Move ended. par2 == ESC.
Definition: ge_prepass.h:2790
The user moved something in the editor window. Managers should update things like position fields.
Definition: ge_prepass.h:2784
Move continued.
Definition: ge_prepass.h:2789
#define MOVE_START
Move started.
Definition: ge_prepass.h:2788
// This example catches EVMSG_UPDATESCHEME in a GeDialog
// to be informed when the scheme is changed.
// 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; }
Scheme has been updated.
Definition: ge_prepass.h:2794
Definition: ge_prepass.h:2796
Definition: ge_prepass.h:2797

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.

// This example sends a custom core message.
SpecialEventAdd(ID_CUSTOMEVENT, 123, 456);
void SpecialEventAdd(Int32 messageid, UInt p1=0, UInt p2=0)
// This example catches a custom core message.
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);
Definition: c4d_string.h:39
static String IntToString(Int32 v)
Definition: c4d_string.h:495
ANY Parameter 2.
Definition: gui.h:894

Other Functions

Other functions to send core messages are:

// This example forces an update of the attribute manager.
GeData SendCoreMessage(Int32 coreid, const BaseContainer &msg, Int32 eventid=0)
Requests to Cinema 4D core.
Definition: c4d_general.h:1518
Forces an Attribute Manager update.
Definition: c4d_gui.h:94

Further Reading