Maya插件(二): Context 交互式命令插件

前言

上一篇中讲述了如何编写Mel命令插件， 即用户通过命令行与Maya交互。本篇介绍如何通过鼠标和键盘操作Maya。

如下图所示，用户通过点击工具栏按钮选择某个功能(如移动模型、框选模型、创建模型). 

 

在这个例子中，我们在Shelf/Custom的Tab页下添加一个Tool Button. 并且用于框选。如下图：

Tool Button截图

框选截图

 

MPxContext && MPxContextCommand

MPxContext用于负责于用户的交互处理，它接手了原有的鼠标、键盘输入事件，MPxContextCommand用于创建MPxContext对象。

1. MyContext.h MyContext.cpp 实现了自定义的MyContext类:

#ifndef __MYCONTEXT_H__ #define __MYCONTEXT_H__ #ifdef WIN32 #ifndef NT_PLUGIN #define NT_PLUGIN #endif #endif #include <maya/MIOStream.h> #include <maya/MGlobal.h> #include <maya/MStatus.h> #include <maya/MPxContext.h> #include <maya/MEvent.h> #include <maya/M3dView.h> /// Context is an object can receive user's input class MyContext : public MPxContext { public: MyContext(); virtual ~MyContext(); /// /brief /// This is used to setup any user interface things you need when the tool is actived. /// /param /// event (in) information on the input event /// virtual void toolOnSetup(MEvent &event); /// /brief /// handle a mouse press event /// virtual MStatus doPress(MEvent &event); /// /brief /// handle a mouse drag event /// virtual MStatus doDrag(MEvent &event); /// /brief /// handle a mouse release event /// virtual MStatus doRelease(MEvent &event); private: /// The location of the cursor when mouse pressed short m_start[2]; /// The location of the cursor when mouse released short m_end[2]; /// THe View we are doing the selection in M3dView m_View; /// A flag to indicate that this tool is currently selecting things... bool m_isSelecting; }; #endif /// __MYCONTEXT_H__ 

 MyContext继承自MPxContext，并重写了鼠标响应代码。

#include <iostream> #include "MyContext.h" const char *g_helpText = "Click and drag a rectangular region to select"; MyContext::MyContext() { std::cout << "MyContext construction" << std::endl; } MyContext::~MyContext() { std::cout << "~MyContext destruction" << std::endl; } void MyContext::toolOnSetup(MEvent &event) { /// initialize the value m_isSelecting = false; /// set the help text in the maya help boxes setHelpString(g_helpText); /// set the title in the Tool Options setTitleString("MyContextTool"); /// set the icon in the toolbox setImage("cloud.xpm", MPxContext::kImage1); } MStatus MyContext::doPress(MEvent &event) { /// log the mouse location && curretn view if (event.mouseButton() == MEvent::kLeftMouse) { m_View = M3dView::active3dView(); event.getPosition(m_start[0], m_start[1]); m_end[0] = m_start[0]; m_end[1] = m_start[1]; /// set the working state m_isSelecting = true; /// return MS::kSuccess; } /// just let the base class handle this event return MPxContext::doPress(event); } MStatus MyContext::doDrag(MEvent &event) { /// if the working state is true if (m_isSelecting) { /// get current location event.getPosition(m_end[0], m_end[1]); /// draw the rectangle m_View.beginOverlayDrawing(); /// clear the overlay planes m_View.clearOverlayPlane(); /// set up the orthographic projection matrix glMatrixMode(GL_PROJECTION); glLoadIdentity(); glOrtho(0.0f, m_View.portWidth(), 0.0f, m_View.portHeight(), 1.0f, -1.0f); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); /// set line width glLineWidth(1.0f); glColor3f(1.0f, 0.0f, 0.0f); /// draw the rectangle glBegin(GL_LINE_LOOP); glVertex2i(m_start[0], m_start[1]); glVertex2i(m_end[0], m_start[1]); glVertex2i(m_end[0], m_end[1]); glVertex2i(m_start[0], m_end[1]); glEnd(); /// done drawing our overlay on the viewport m_View.endOverlayDrawing(); /// return MS::kSuccess; } return MPxContext::doDrag(event); } MStatus MyContext::doRelease(MEvent &event) { if (event.mouseButton() != MEvent::kLeftMouse) { return MPxContext::doRelease(event); } /// reset the working state m_isSelecting = false; /// clear the overlay plane m_View.beginOverlayDrawing(); m_View.clearOverlayPlane(); m_View.endOverlayDrawing(); /// set the selection region short minx, miny; short maxx, maxy; /// if the selection went left if (m_end[0] < m_start[0]) { minx = m_end[0]; maxx = m_start[0]; } else { maxx = m_end[0]; minx = m_start[0]; } /// if the selection went down if (m_end[1] < m_start[1]) { miny = m_end[1]; maxy = m_start[1]; } else { maxy = m_end[1]; miny = m_start[1]; } /// Use the selection mechanism within MGlobal MGlobal::selectFromScreen(minx, miny, maxx, maxy, MGlobal::kReplaceList); /// reset location m_start[0] = m_start[1] = m_end[0] = m_end[1] = 0; return MPxContext::doRelease(event); } 

具体的代码不多解释。

 

2. MyContextCommand.h MyContextCommand.cpp实现了ContextCommand，用于创建上面的MyContext。

#ifndef __MYCONTEXTCMD_H__ #define __MYCONTEXTCMD_H__ #ifdef WIN32 #ifndef NT_PLUGIN #define NT_PLUGIN #endif #pragma comment(lib, "opengl32.lib") #endif #include <maya/MIOStream.h> #include <maya/MStatus.h> #include <maya/MPxContext.h> #include <maya/MPxContextCommand.h> #include <maya/MEvent.h> #include <maya/M3dView.h> #include "MyContext.h" /// MyContextCommand class MyContextCommand : public MPxContextCommand { public: MyContextCommand(); virtual ~MyContextCommand(); /// /brief /// create the context derived from MPxContext virtual MPxContext* makeObj(); /// /brief /// return a new instance of MyContextCommand for maya static void* creator(); }; #endif /// __MYCONTEXTCMD_H__ 

当我们点击Tool Button时，MyContextCommand对象将调用makeObj()获取一个MyContext，并设定该MyContext为当前Context.

 

#include <iostream> #include "MyContextCmd.h" MyContextCommand::MyContextCommand() { std::cout << "MyContextCommand construction" << std::endl; } MyContextCommand::~MyContextCommand() { std::cout << "~MyContextCommand destruction" << std::endl; } /// /brief /// create the context derived from MPxContext MPxContext* MyContextCommand::makeObj() { return new MyContext; } /// /brief /// return a new instance of MyContextCommand for maya void* MyContextCommand::creator() { return new MyContextCommand; } 

 

接下来，要向Maya注册上述两个对象，在plugMain.cpp实现DLL的导出函数。

#include <maya/MIOStream.h> #include <maya/MFnPlugin.h> #include <iostream> #include "MyContextCmd.h" #ifdef WIN32 #define MLL_EXPORT __declspec(dllexport) #else #define MLL_EXPORT #endif /// /brief /// initialize plugin /// /param /// obj (in) the plugin handle /// /ret /// return MS::kSuccess if OK. /// /NOTE: /// invoked only once by Maya when DLL is loaded. MLL_EXPORT MStatus initializePlugin(MObject obj) { MFnPlugin plugin(obj, "Jett Huang", "1.0", "Any"); /// register the command MStatus status = plugin.registerContextCommand("MyContextCmd", MyContextCommand::creator); if (!status) { status.perror("Failed to register /"MyContextCmd/"/n"); return status; } else { /// the MEL procedure will be invoked when load / unload plugin.registerUI("NewMyContextToolUI", "DelMyContextToolUI"); std::cout << "initializePlugin" << std::endl; } return status; } /// /brief /// unintializePlugin /// /param /// obj (in) the plugin handle to un-register /// /ret /// MS::kSuccess if OK. MLL_EXPORT MStatus uninitializePlugin(MObject obj) { MFnPlugin plugin(obj); /// deregister the PxCommand MStatus status = plugin.deregisterContextCommand("MyContextCmd"); if (!status) { status.perror("failed to deregister /"MyContextCmd/"/n"); return status; } else { std::cout << "uninitializePlugin" << std::endl; } return status; } 

暂时我们先不创建Tool Button来启动自定义的Context, 用命令行来启动之。 请注释掉initializePlugin(MObject obj)中的语句 plugin.registerUI("NewMyContextToolUI", "DelMyContextToolUI"); 

 

编译连接运行， 打开plug-ins Manager窗口，加载插件。在底部的MEL窗口中输入命令：

MyContextCmd  按Enter键, 会在该窗口的右边窗口中看到执行结果。接着输入命令：

setToolTo MyContextCmd1 按Enter键

 

OK! 使用鼠标在View上进行操作试试吧！

 

Tool Button界面

接下来不用过Mel命令进行激活MyContext, 首先打开刚才的语句    plugin.registerUI("NewMyContextToolUI", "DelMyContextToolUI");  然后将脚本文件NewMyContextToolUI.MEL和DelMyContextToolUI.MEL拷贝到Maya用户目录下的

scripts文件夹下。 将cloud.pxm拷贝到安装目录的icons下。

 

OK！重行运行程序，在plugins Manager窗口中加载我们的插件。我们将会在Custom Tab页下看到一个按钮了，点击按钮，使用鼠标

在View上进行操作吧！

 

下面分析脚本文件，解释在代码中。

global proc NewMyContextToolUI() { /// check if exists one if (`optionVar -exists MyContextToolName`) { print("MyContextTool has exist/n"); optionVar -rm MyContextToolName; return; } /// create the tool string $MyContextToolName = `eval "MyContextCmd"`; /// crate a bottom on the "Custom" shelf string $MyContextToolBtnName = `toolButton -doubleClickCommand "toolPropertyWindow" -cl toolCluster -p Custom -t $MyContextToolName -i1 "cloud.xpm"`; /// save the name to the Env-Variable optionVar -sv MyContextToolName $MyContextToolName -sv MyContextToolBtnName $MyContextToolBtnName; print("Button: " + $MyContextToolBtnName); print("NewMyContextToolUI()"); } global proc DelMyContextToolUI() { // restore the control to the main Context setToolTo selectSuperContext; // do check if (`optionVar -exists MyContextToolName`) { // query the varible value string $MyContextToolName = `optionVar -q MyContextToolName`; print("MyContextToolName: " + $MyContextToolName); // remove the Env-Variable optionVar -rm MyContextToolName; // delete it $res = `deleteUI -tc $MyContextToolName`; } // do the same for the tool button if (`optionVar -exists MyContextToolBtnName`) { print("MyContextToolBtnName exists/n"); // query the varible value string $MyContextToolBtnName = `optionVar -q MyContextToolBtnName`; // remove the Env-Variable optionVar -rm MyContextToolBtnName; // delete it print("Delete Button: " + $MyContextToolBtnName); $res = `deleteUI $MyContextToolBtnName`; } print("DelMyContextToolUI()"); }

NewMyContextToolUI()函数在加载插件后被调用；

DelMyContextToolUI()函数在卸载插件时被调用。

 

完整的vs2005代码URL:http://download.youkuaiyun.com/source/2700431

 

问题列表(郁闷！)

1. m_View.clearOverlayPlane()不能有效地清屏；

2. 没有看到MyContext和MyContextCommand的析构函数被调用；