Maya插件(五): 自定义Dependency Node

前言

       在插件(三)中，我们使用了自定义的Locator结点，它也是个DG Node，本文目的是学习和理解Mplug && Attribute。

MyDGNode是我们自定义的结点, 有输入、输出Attribute，下图是一个用法：

       将时间结点time1的输出-->MyDGNode1-->sphere1(Transform结点).

      

 

 

MyDGNode的实现

       从MPxNode继承。MyDGNode.h

#ifndef __MYDGNODE_H__#define __MYDGNODE_H__#ifdef WIN32 #ifdef NT_PLUGIN #define NT_PLUGIN #endif#endif#include <maya/MIOStream.h>#include <maya/MString.h>#include <maya/MGlobal.h>#include <maya/MFnDependencyNode.h>#include <maya/MTime.h>#include <maya/MPlug.h>#include <maya/MDagModifier.h>#include <maya/MDataBlock.h>#include <maya/MDataHandle.h>#include <maya/MFnNumericAttribute.h>#include <maya/MFnUnitAttribute.h>#include <maya/MPxNode.h>#include <maya/MSelectionList.h>/// MyDGNodeclass MyDGNode : public MPxNode{public: MyDGNode(); virtual ~MyDGNode(); /// /brief /// to calculate the value of a specific output attribute. virtual MStatus compute(const MPlug &outPlug, MDataBlock &dataBlock); /// /brief /// create this-self static void *creator(); /// /brief /// initialize the node, to append the addtional attributes. static MStatus initialize(); public: const static MTypeId m_typeId; const static MString m_typeName;private: static MObject m_inTime; /// attribute inTime for in static MObject m_outValue; /// attribute outValue to out};#endif /// __MYDGNODE_H__

1. virtual MStatus compute(const MPlug &outPlug, MDataBlock &dataBlock);

    当DG网络出现脏数据时，该函数将被调用，用于更新数据.

2. static MStatus initialize();

    初始化该结点，创建Attributes（相当于动态添加类成员变量）.

3. static MObject m_inTime;  static MObject m_outValue;

    新的Attribute标识符(句柄).

实现代码MyDGNode.cpp

#include "MyDGNode.h"#include <iostream>#include <math.h>const MTypeId MyDGNode::m_typeId = 0x10001;const MString MyDGNode::m_typeName = "MyDGNode";MObject MyDGNode::m_inTime;MObject MyDGNode::m_outValue;/// construction && destructionMyDGNode::MyDGNode(){ std::cout << "MyDGNode()" << std::endl;}MyDGNode::~MyDGNode(){ std::cout << "~MyDGNode()" << std::endl;}void *MyDGNode::creator(){ std::cout << "MyDGNode::creator()" << std::endl; return new MyDGNode();}MStatus MyDGNode::initialize(){ /// attribute "time" 将连接到全局时间结点的attribute上 MFnUnitAttribute uAttr; m_inTime = uAttr.create("time", "t", MFnUnitAttribute::kTime); uAttr.setStorable(false); uAttr.setKeyable(false); MFnNumericAttribute nAttr; m_outValue = nAttr.create("output", "o", MFnNumericData::kFloat, 0.0f); nAttr.setReadable(true); nAttr.setKeyable(false); // 必须为false,否则compute将不会被调用,不明白. addAttribute(m_inTime); addAttribute(m_outValue); /// 设置依赖 attributeAffects(m_inTime, m_outValue); return MS::kSuccess;}MStatus MyDGNode::compute(const MPlug &plug, MDataBlock &data){std::cout << "MyDGNode::compute() begin " << std::endl; if (plug != m_outValue) return MS::kUnknownParameter; /// 获取inTime MDataHandle timeData = data.inputValue(m_inTime); MDataHandle outData = data.outputValue(m_outValue); MTime time = timeData.asTime();std::cout << "time.as(MTime::kSeconds): " << time.as(MTime::kSeconds) << std::endl; outData.set((float)sin(time.as(MTime::kSeconds))); data.setClean(plug); return MS::kSuccess;}

注册MyDGNode, pluginMain.cpp

#include <maya/MFnPlugin.h>#include <iostream>#include "MyDGNode.h"#ifdef WIN32 #define MLL_EXPORT __declspec(dllexport)#else #define MLL_EXPORT#endifMLL_EXPORT MStatus initializePlugin(MObject obj){ std::cout << "initializePlugin" << std::endl; MStatus status; MFnPlugin plugin(obj, "Jett Huang", "1.0", "Any"); status = plugin.registerNode(MyDGNode::m_typeName, MyDGNode::m_typeId, MyDGNode::creator, MyDGNode::initialize, MPxNode::kDependNode); return status;}MLL_EXPORT MStatus uninitializePlugin(MObject obj){ std::cout << "uninitializePlugin" << std::endl; MStatus status; MFnPlugin plugin(obj); status = plugin.deregisterNode(MyDGNode::m_typeId); return status;}

Attribute Editor模板MEL

/// /brief/// Attribute Editor Template./////////global proc AEMyDGNodeTemplate ( string $nodeName ){ print("DEBUG: AEMyDGNodeTemplate is Invokded: " + $nodeName);editorTemplate -beginScrollLayout;// 加入我们的属性编辑控件editorTemplate -beginLayout "MyDGNode Input" -collapse 0;editorTemplate -addControl "time";editorTemplate -endLayout;AEdependNodeTemplate $nodeName;// This will add the standard UI controls for the nodeeditorTemplate -addExtraControls;editorTemplate -endScrollLayout;}

放在Maya用户目录的Scripts下面。

编译工程.....

加载插件后，在MEL窗口中执行如下脚本

// run this MEL to test the MyDGNode

{
     $myNode = `createNode "MyDGNode"`;
    
     // create a polygon sphere
     string $psphere[] = `polySphere -r 1 -sx 20 -sy 20 -ax 0 1 0 -tx 1 -ch 1`;

 

     // connect the output of the node to the x-scale of the ploy sphere
     string $plugName = `connectAttr ($myNode + ".output") ($psphere[0] + ".sx")`;
     print $plugName;
     print("/n");
    
     // connect the time1 output to the "time" of myNode
     $plugName = `connectAttr "time1.outTime" ($myNode + ".time")`;
     print $plugName;
     print("/n");
}

然后开启时间滑块，你会发现球体的缩放动画。

 

做个实验

       在MEL命令中继续输入如下命令：

connectAttr "time1.outTime"  "MyDGNode1.output";

 

直接将time1连接到MyDGNode1的ouput， 发现对显示无影响，看看连接图如下：

 

如果输入的命令是：

connectAttr "pSphere1.sy"  "MyDGNode1.time"；

将出现错误, Error: line 1: 'MyDGNode1.time' already has an incoming connection from 'time1.outTime'.

说明incoming的来源只能是一个!