Force Compute On Node

[shredder]

I know this has been discussed at length, but I still cant seem to figure it out.

My situation is this..

I have a node that has a lot of int attrs. This node is communicating with servos in my robot, so it connects to the robots controller and sends it serial commands. I have all that working. The problem comes when I adjust the values of the ints, the compute doesnt get called (because I am sure I have to force it somehow), so the servos dont move. I used the affects.cpp as a basis for this node, and just added my communication code to it. If I do what the comments say, which is add a "A" and a "B" attr to it and do the getAttr on B it does update and the servo moves! So I guess I am having trouble understanding hoe "setDependantsDirty" works. Is there an easy way to set the dirty bit for a nodes attr so its forced to compute?

CODE
#include
#include
#include
//#include
#include
#include
#include "dynamixel.h"

#pragma comment(lib, "dynamixel.lib")

#include
#include
#include
#include
#include

#include
#include
#include
#include
#include
#include
#include
#include

//bioloid specific address
// Control table address
#define P_GOAL_POSITION_L           30
#define P_GOAL_POSITION_H           31
#define P_PRESENT_POSITION_L  36
#define P_PRESENT_POSITION_H  37
#define P_MOVING                    46

#define P_MODEL_NUMBER_L      0     // Model number low byte
#define P_MODEL_NUMBER_H      1     // Model number high byte
#define P_VERSION             2     // Firmware version

//void //ErrorDisplay();
int index = 0;

class robotisCom : public MPxNode
{
public:
                                    robotisCom();
      virtual                       ~robotisCom();

      virtual MStatus         compute( const MPlug& plug, MDataBlock& data );
      virtual MStatus         setDependentsDirty( const MPlug& plugBeingDirtied,
                                                MPlugArray &affectedPlugs );

      static  void*           creator();
      static  MStatus         initialize();

      static      MTypeId           id;                     // The IFF type id
      static MObject oConnect;
      static MObject oDisconnect;
      static MObject oScanDynamixels;
      static MObject oServoOne;
      static MObject oServoTwentyEight;
};

MObject robotisCom::oConnect;
MObject robotisCom::oDisconnect;
MObject robotisCom::oScanDynamixels;
MObject robotisCom::oServoOne;
MObject robotisCom::oServoTwentyEight;

//TEMP ID FOR NOW
MTypeId robotisCom::id( 0x00019 );

// This node does not need to perform any special actions on creation or
// destruction
//
robotisCom::robotisCom() {}
robotisCom::~robotisCom() {}

// The compute() method does the actual work of the node using the inputs
// of the node to generate its output.
//
// Compute takes two parameters: plug and data.
// - Plug is the the data value that needs to be recomputed
// - Data provides handles to all of the nodes attributes, only these
//   handles should be used when performing computations.
//
MStatus robotisCom::compute( const MPlug& plug, MDataBlock& data )
{
      MStatus status;
      MObject thisNode = thisMObject();
      MFnDependencyNode fnThisNode( thisNode );
      MFnDagNode dagFn( thisNode  );

      int baudnum = 1;
      char buffer[256];

            sprintf( buffer, "robotisCom::compute() on ", fnThisNode.name().asChar() , "\n" );
            MGlobal::displayInfo( buffer );

//GET ALL THE DATA FROM THE NODE FOR COMPUTING

                               MPlug servoTwentyEightPlug = fnThisNode.findPlug( "servoTwentyEight", &status );

                               sprintf( buffer, "servoTwentyEightValue status is ", status );
                               MGlobal::displayInfo( buffer );

            short servoTwentyEightValue;
            servoTwentyEightPlug.getValue( servoTwentyEightValue );
                                          sprintf( buffer, "servoTwentyEightValue is ", servoTwentyEightValue, " and status is ", status );
                               MGlobal::displayInfo( buffer );
                                          sprintf( buffer, "trying to get value 28 from plug ", servoTwentyEightPlug.name().asChar(), " and status is ", status );
                               MGlobal::displayInfo( buffer );

//if the connect box is checked connect to usb2dynamixel
MPlug connectPlug = fnThisNode.findPlug( "connect", &status );
      short connectValue;
      connectPlug.getValue( connectValue );

//if the connect box is checked connect to usb2dynamixel
MPlug disconnectPlug = fnThisNode.findPlug( "disconnect", &status );
      short disconnectValue;
      disconnectPlug.getValue( disconnectValue );

//if the connect box is checked connect to usb2dynamixel
MPlug scanDynamixelsPlug = fnThisNode.findPlug( "scanDynamixels", &status );
      short scanDynamixelsValue;
      scanDynamixelsPlug.getValue( scanDynamixelsValue );
//DONE GETING DATA

//NOW USE THE DATA
//INIT THE CONNECTION TO THE USB2DYNAMIXEL

      if (connectValue)
      {
        sprintf( buffer, "TRYING to open USB2Dynamixel!\n" );
        MGlobal::displayInfo( buffer );

            int dxlInit = dxl_initialize();
                  if( dxlInit == 0 )
                        {
                              cout << ( "Failed to open USB2Dynamixel!\n" );
                              sprintf( buffer, "Failed to open USB2Dynamixel!\n" );
                               MGlobal::displayInfo( buffer );
                              ////goto END_MAIN;
                        }
                  if( dxlInit == 1 )
                        {
                              cout <<( "Succeed to open USB2Dynamixel!\n" );
                              //printf( "Succeed to open USB2Dynamixel!\n" );
                              sprintf( buffer, "Succeed to open USB2Dynamixel!\n" );
                               MGlobal::displayInfo( buffer );
                  }
                              dxl_set_baud( baudnum );

      //set it back to 0
            connectPlug.setValue( 0 );
}

      if (disconnectValue)
      {

      dxl_terminate();

                  disconnectPlug.setValue( 0 );
}
//////////// Scan Dynamixel //////////////
      if (scanDynamixelsValue)
      {
      int i, j, n;
      int bValue;
      int wValue;

      //printf( "Scan start!(Quit to press ESC key)\n" );
                              sprintf( buffer, "Scan start!(Quit to press ESC key)\n" );
                          MGlobal::displayInfo( buffer );
      for( i=1; i<2; i++ )
      {
            dxl_set_baud( i );
            //printf( "==== Baudrate number: %d =====\n", i );
                        sprintf( buffer, "==== Baudrate number: %d =====\n", i );
                          MGlobal::displayInfo( buffer );

            for( j=0, n=0; j<BROADCAST_ID; j++ )
            {
                  dxl_ping( j );
                  if( dxl_get_result() == COMM_RXSUCCESS )
                  {
                        n++;
                        //printf( "-ID:%d (", j );
                        sprintf( buffer, "-ID:%d (", j );
                          MGlobal::displayInfo( buffer );

                        wValue = dxl_read_word( j, P_MODEL_NUMBER_L );
                        if( dxl_get_result() == COMM_RXSUCCESS )
                        {     //printf( "Model number:%d, ", wValue );
                        sprintf( buffer, "Model number:%d, ", wValue );
                          MGlobal::displayInfo( buffer );
                        }
                        else
                        {
                              //ErrorDisplay();
                              printf( ", " );
                        }

                        bValue = dxl_read_byte( j, P_VERSION );
                        if( dxl_get_result() == COMM_RXSUCCESS )
                        {     //printf( "Version:%d", bValue );
                        sprintf( buffer, "Version:%d", bValue );
                          MGlobal::displayInfo( buffer );
                        }
                        else
                              //ErrorDisplay();

                        printf( ")\n" );
                  }

                  // key check
                  if( _kbhit() > 0 )
                  {
                        if( getch() == 0x1b )
                        {
                              printf( "Scan break!\n" );
                              //goto END_MAIN;
                        }
                  }
            }

            printf( "Total found number: %d\n", n );
                        sprintf( buffer, "Total found number: %d\n", n );
                          MGlobal::displayInfo( buffer );
      }

scanDynamixelsPlug.setValue( 0 );
      }

//HACK TO COMPUTE THE NODE FOR NOW
      if ( plug.partialName() == "B" ) {
            // Plug "B" is being computed. Assign it the value on plug "A"
            // if "A" exists.
            //
            MPlug pA = fnThisNode.findPlug( "A", &status );
            if ( MStatus::kSuccess == status ) {
                  fprintf(stderr,"\t\t... found dynamic attribute \"A\", copying its value to \"B\"\n");
                  MDataHandle inputData = data.inputValue( pA, &status );
                  CHECK_MSTATUS( status );
                  int value = inputData.asInt();

                  MDataHandle outputHandle = data.outputValue( plug );
                  outputHandle.set( value );
                  data.setClean(plug);
            }
      } else {
            return MS::kUnknownParameter;
      }

            //move the dynamixel
            int Moving, PresentPos;

            dxl_set_baud( 1 );

            Moving = dxl_read_byte( 28, P_MOVING );
            if( dxl_get_result() == COMM_RXSUCCESS )
             {
                  dxl_write_word( 28, P_GOAL_POSITION_L, servoTwentyEightValue );
             }

      return( MS::kSuccess );
}

void* robotisCom::creator()
{
      return( new robotisCom() );
}

MStatus robotisCom::initialize()
{
      MStatus status;
      MFnNumericAttribute           numFn;

            //buffer for printing to script editor
            char buffer[256];

            oConnect = numFn.create( "connect", "cdm", MFnNumericData::kBoolean );
                  numFn.setKeyable( true );
                  numFn.setDefault( 0 );
                  status = addAttribute( oConnect );
                  if (!status)
                        {
                        status.perror( "Unable to add \"disconnect\" attribute" );
                        return status;
                        }

            oDisconnect = numFn.create( "disconnect", "ddm", MFnNumericData::kBoolean );
                  numFn.setKeyable( true );
                  numFn.setDefault( 0 );
                  status = addAttribute( oDisconnect );
                  if (!status)
                        {
                        status.perror( "Unable to add \"disconnect\" attribute" );
                        return status;
                        }

            oScanDynamixels = numFn.create( "scanDynamixels", "sdm", MFnNumericData::kBoolean );
                  numFn.setKeyable( true );
                  numFn.setDefault( 0 );
                  status = addAttribute( oScanDynamixels );
                  if (!status)
                        {
                        status.perror( "Unable to add \"scanDynamixels\" attribute" );
                        return status;
                        }

      oServoOne = numFn.create( "servoOne", "son", MFnNumericData::kShort );
            numFn.setDefault( 512 );
            numFn.setMin( 0 );
            numFn.setMax( 1023 );
            numFn.setKeyable( true );
            status = addAttribute( oServoOne );
            if (!status)
                  {
                  status.perror( "Unable to add \"servoOne\" attribute" );
                  return status;
                  }

      oServoTwentyEight = numFn.create( "servoTwentyEight", "ste", MFnNumericData::kShort );
            numFn.setDefault( 512 );
            numFn.setMin( 0 );
            numFn.setMax( 1023 );
            numFn.setKeyable( true );
            status = addAttribute( oServoTwentyEight );
            if (!status)
                  {
                  status.perror( "Unable to add \"servoTwentyEight\" attribute" );
                  return status;
                  }

      return( MS::kSuccess );
}

MStatus robotisCom::setDependentsDirty( const MPlug &plugBeingDirtied,
            MPlugArray &affectedPlugs )
{
      MStatus     status;
      MObject thisNode = thisMObject();
      MFnDependencyNode fnThisNode( thisNode );

      if ( plugBeingDirtied.partialName() == "A" ) {
            // "A" is dirty, so mark "B" dirty if "B" exists.
            // This implements the relationship "A robotisCom B".
            //
            fprintf(stderr,"robotisCom::setDependentsDirty, \"A\" being dirtied\n");
            MPlug pB = fnThisNode.findPlug( "B", &status );
            if ( MStatus::kSuccess == status ) {
                  fprintf(stderr,"\t\t... dirtying \"B\"\n");
                  CHECK_MSTATUS( affectedPlugs.append( pB ) );
            }
      }

/////////////////////////////////////////////////
//tried this, and it didnt seem to do anything//
///////////////////////////////////////////////
            if ( plugBeingDirtied.partialName() == "servoTwentyEight" ) {
            MPlug pSte = fnThisNode.findPlug( "servoTwentyEight", &status );
            if ( MStatus::kSuccess == status ) {
                  CHECK_MSTATUS( affectedPlugs.append( pSte ) );
            }
      }
      return( MS::kSuccess );
}

// These methods load and unload the plugin, registerNode registers the
// new node type with maya
//
MStatus initializePlugin( MObject obj )
{
      MStatus   status;

      MFnPlugin plugin( obj, PLUGIN_COMPANY , "6.0", "Any");

      status = plugin.registerNode( "robotisCom", robotisCom::id, robotisCom::creator,
                                                  robotisCom::initialize );
      if (!status) {
            status.perror("registerNode");
            return( status );
      }

      return( status );
}

MStatus uninitializePlugin( MObject obj)
{
      MStatus   status;
      MFnPlugin plugin( obj );

      status = plugin.deregisterNode( robotisCom::id );
      if (!status) {
            status.perror("deregisterNode");
            return( status );
      }

      return( status );
}

with it written like this, it still doesnt work UNLESS I plug something into both sides of the attr "servoTwentyEight" So I connect anything into it, then its output to something else.. and it updates

connectAttr locator1.translateX robotisCom.servoTwentyEight;
connectAttr robotisCom.servoTwentyEight locator2.translateX;

now move locator1 and it updates the server.. would rather not have to plug things in everywhere to just get it to update.

[uiron]

where's your attributeAffects() mappings?

you should not be forcing compute in any way. compute is not called when input is changed. when you change value of an input, whatever output is mapped to be affected by this attribute, is marked dirty. next time that particular output is requested, because it's dirty, compute() is called first.

edit: nevermind me, never done that in setDependsDirty() way. anyway, that's where you should start looking for bugs.

[shredder]

QUOTE(uiron @ 08/20/09, 10:09 PM) [snapback]313141[/snapback]
where's your attributeAffects() mappings?

you should not be forcing compute in any way. compute is not called when input is changed. when you change value of an input, whatever output is mapped to be affected by this attribute, is marked dirty. next time that particular output is requested, because it's dirty, compute() is called first.
edit: nevermind me, never done that in setDependsDirty() way. anyway, that's where you should start looking for bugs.

Ok I'll look into attributeAffects().. this is the first node like this that I have written.

[deane]

A node computes output attribute values based on input attribute values. The compute() method only executes when an output attribute value is requested. So it doesn't matter how often the inputs change, if the output is never requested then the compute() will never run.

So you have a bunch of int input attributes. What output attribute depends on them? When/how does the value of that output attribute get requested?

Under normal conditions the two main drivers of node evaluation are rendering and drawing the 3D views. Both need to know lots of information about the scene and thus request lots of values from nodes.

Often when people run into this sort of a problem it is because they are using a node when they should be using a command which is triggered by events. For example, let's say that those input values that you talked about are coming joint rotations on a skeleton in the scene. When the scene plays back you want your robot to replicate the pose. In that case you should really be using a command which is using 'scriptJob -timeChange' to ensure that it changes every time the frame changes.

If you want your robot to respond every time one of the joints moves, even when not playing back (e.g. when the user manipulates the joint) then you should place an attribute changed callback on the joint's rotations and have the callback execute your command.