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Maya API: want to create a new input slot if the first(preceding) slot has been created.

Hi, i am writing a plugin which takes multiple inputs and based on a condition outputs one of those..!

I am stuck at creating the next input slot as the first one's connected

can someone point me in the right direction..????????

Thanks. Iceboxx

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2 answers

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manny [ Editor ]

Just query the value of the next slot. It gets automatically created.

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jagadish kumar
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i am creating a MFnNumericAttribute, and i am only creating one attribute in my init function how do i query the next input..?

Pardon me i’m just learning to do mayaAPI

jagadish kumar
-

Do i have to create a compound attribute and then add my normal float attribute as a child, then to create a new child attribute i just need to query the next element in the array..?

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  • 1

julian [ Admin ]

They are called multi attributes (many plugs), in order to distinguish them from array attributes (an array of values in one plug)

But just to confuse you, when you create a multi attribute in the initialize function you need to call setArray(true)

aBlender  = nAttr.create( "blender", "bl", MFnNumericData::kDouble);
nAttr.setKeyable(true);
nAttr.setArray(true);
addAttribute( aBlender );

That will allow you to make indexed plugs for the attribute:

myNode.blender[0] , myNode.blender[1] ... myNode.blender[n]

The attribute editor for that node should set up an "Add Item" button. Or you can just use setAttr or connectAttr in a script.

To get the data from those indexed plugs in your compute function, you have a couple of choices. It depends whether you want them all, or just the one that matches the index of an output attribute.

If you want them all:

MArrayDataHandle hInArray = data.inputArrayValue(aBlender);
const unsigned nStartElement = hInArray.elementIndex();
do {
    MDataHandle hIn = hInArray.inputValue();
    double bVal = hIn.asDouble();
    // do stuff
} while(hInArray.next() == MS::kSuccess);

Or if you want the plug index relating to the index of the output plug being requested:

MStatus myNode::compute (const MPlug& plug, MDataBlock& data) 
{
    unsigned multiIndex = plug.logicalIndex( );
    MArrayDataHandle hInArray = data.inputArrayValue(aBlender);
    hInputArray.jumpToElement( multiIndex );
    MDataHandle hIn = hInArray.inputValue();
    double bVal = hIn.asDouble();
    // do stuff and set output etc.
}

Well I left out all the error checking etc. Hope it helps

j

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