Maya 中的事件 Api 以捕获当前时间/帧变化

Question

我目前正在开发一个 Maya 插件。我如何设置每次在场景中更改帧号/当前时间时触发的回调？
我查看了 MSceneMessage Class，但它似乎不包含我要查找的内容。
谢谢

Answer 1

您可以使用 MEventMessage 设置每次 frame/current 时间更改时的回调。代码胜于雄辩，所以这里有一些代码和注释穿插以说明如何设置它：（首先为不耐烦的TLDR，下一节将提供完整的代码摘录）

TLDR:

不耐烦的代码摘要：

    // ...

    // Our callback Id array to 
    // store the Ids of all our callbacks
    // for later removal    
    MCallbackIdArray myCallbackIds;

    // This is where the actual adding callback happens
    // We register our callback to the "timeChanged" event
    MCallbackId callbackId = MEventMessage::addEventCallback("timeChanged",  (MMessage::MBasicFunction) MySampleCmd::userCB);

    // ...

    if(myCallbackIds.length() != 0)
        // Make sure we remove all the callbacks we added
        stat = MEventMessage::removeCallbacks(myCallbackIds);

参考 MEventMessage from the docs。
列出的事件 here（在 scriptJob 命令中）可以与 MEventMessage 一起使用。

带有注释的完整（大概）代码：

MySampleCommand.h

class MySampleCmd : public MPxCommand {
public:
                MySampleCmd();
    virtual     ~MySampleCmd();

    // Our callback - implemented as a static method
    static      void userCB(void* clientData);

    MStatus     doIt( const MArgList& );
    MStatus     redoIt();
    MStatus     undoIt();   
    bool        isUndoable() const;
    static      void* creator();

public:

    // Our callback Id array to 
    // store the Ids of all our callbacks
    // for later removal
    MCallbackIdArray myCallbackIds;
};

MySampleCommand.cpp（摘录）

// Constructor
MySampleCmd::MySampleCmd() {

    // Clearing our callback Id array
    // for housekeeping    
    myCallbackIds.clear();
}

// Destructor
MySampleCmd::~MySampleCmd() {

    // Make sure we remove all the callbacks we added
    // Failing to do so will result in fatal error    
    if(myCallbackIds.length() != 0)

        // Remove the MEventMessage callback
        MEventMessage::removeCallbacks(myCallbackIds);
}

MStatus MySampleCmd::redoIt() {

    // This is where the actual adding callback happens
    // We register our callback to the "timeChanged" event
    MCallbackId callbackId = MEventMessage::addEventCallback("timeChanged",  (MMessage::MBasicFunction) MySampleCmd::userCB);

    // Append the newly added callback's ID to our list of callback ids
    // for future removal
    myCallbackIds.append(callbackId);
    return MS::kSuccess;
}

MStatus MySampleCmd::undoIt() {
    MStatus stat;
    if(myCallbackIds.length() != 0)
        // Make sure we remove all the callbacks we added
        stat = MEventMessage::removeCallbacks(myCallbackIds);
    return stat;
}

// Our callback function
void SafeSelect::userCB(void* clientData) {
    MGlobal::displayInfo( "Callback userCB called!\n" );
    return;
}

Answer 2

此外，根据应用程序，您可以只创建一个调用任意 python/mel 的表达式（包括插件中的 NPX 命令）。

Maya 中的事件 Api 以捕获当前时间/帧变化

Event in Maya Api to capture currentTime / frame change

c++

events

message

callback

maya

TLDR:

带有注释的完整（大概）代码：

MySampleCommand.h

MySampleCommand.cpp（摘录）