output attr array

[3dsman]

hi i've made an output array attribute to output colors.

aOutColor = nAttr.createColor("outColor", "oc");
MAKE_OUTPUT(nAttr);
nAttr.setArray(true);

but my problem is that in the compute function i want to update the output that's calling the function and i can't
i've triing lots of solution but without result!
the last one of these is here:

MDataHandle outColorHandle = block.outputValue( aOutColor ).child(plug);
MFloatVector& outColor = outColorHandle.asFloatVector();
outColor = resultColor;
outColorHandle.setClean();

please help me i've found nothing on internet to help me and the maya documentation have no exemple
thanks in advance for any help!
(sory for my poor english )

[jiann]

I think the following function solve the prob,

outColorHandle.set(resultColor);

The below codes only obtain the value of the attribute. Changing its value in your function doesn't change the value of the attribute. You have to use the .set() function.
MFloatVector& outColor = outColorHandle.asFloatVector();
outColor = resultColor;

[3dsman]

no it don't work!
the output is random
is anybody have any other solution?

[jiann]

Sorry, just noticed that your attribute is an array.

You should use the MArrayDataHandle and MArrayDataBuilder to obtain and set the attribute value.

check up the documentation to see how to use them.

[3dsman]

i tried to use the array builder but it didn't work (but may be i didn't understand how to do )

i obtain the input value (i've another array attr for the input) with this code (and that's work):

MArrayDataHandle arrayinDataHandle = block.inputArrayValue(aInColor);
arrayinDataHandle.jumpToElement(plug.logicalIndex());
MDataHandle incolor = arrayinDataHandle.inputValue();
MFloatVector& inCol = incolor.asFloatVector();

so i tried to do same thing for the output:

MArrayDataHandle arrayOutDataHandle = block.outputArrayValue(aOutColor);
arrayOutDataHandle.jumpToElement(plug.logicalIndex());
MDataHandle outColor = arrayOutDataHandle.inputValue();
outColor.set(resultColor);

and here the shader connected to the output is always black and my node doesn't work.

if you think that databuilder is a solution can you send me exemple of code to do output attr please?!

thanks in advance.

[jiann]

Try the following codes, hopefully this time it works for you...

MArrayDataHandle arrayOutDataHandle = block.outputArrayValue( aOutColor );
MArrayDataBuilder arrayOutBuilder = arrayOutDataHandle.builder();
MDataHandle outColor = arrayOutBuilder.addElement( i );

outColor.set( resultColor );
arrayOutDataHandle.set( arrayOutBuilder );

[alexbetts]

I've been using multi attributes a lot lately, & have been doing what's in Jiann's post. Also, in the initialize method, I call the setUsesArrayDataBuilder() member function on the attribute:

aOutColor = nAttr.createColor("outColor","oc");
nAttr.setArray(true);
nAttr.setUsesArrayDataBuilder(true);

I'd had some trouble with this & basically looked at multiCurveNode.cpp and apiMeshShape.cpp which both output multi attributes.

• Alex

[3dsman]

with the ArrayDataBuilder it work now but only for 3 output.
the array is initialised by:

if (arrayOutDataHandle.elementCount() == 0) {
MArrayDataBuilder tempBuilder(aOutColor, 2);

		for (int i=0; i<2; i++)
			tempBuilder.addElement(i);

		arrayOutDataHandle.set(tempBuilder);
	}

(thanks to jiann for this code)
but i can't have more output than 3.
if i increase the value of the initialisation i increase the number of possible output. But i whant to have anny number of output so i think i must update it at any compute...
So how can i do?
i dont understand how the ArrayDataBuilder work!

is anyone can help me?
thanks