The frameCache Node is pretty good if you want to get a translation or
rotation from a previous frame but you can only use it on a single
attribute so if you if you need it to do it on translation and rotation
together you would need six frameCache nodes. It's a pretty easy node to
use, just plug your driver attribute into the frameCache stream attribute
and use the varyTime attribute for your offset (it can be positive or
negative). Plug the varying attribute into the driven attribute and hey
presto!
On Sunday, 30 April 2017 19:50:34 UTC+1, David DeJuan wrote:
>
> Hi,
> I'm trying to do a Node, where the input is a mesh and get the translation
> matrix of it in the previous frame. But I don't get it.
> I have tried using the MPlug getValue setting the MDGContext one frame
> before, but it doesn't work.
> This is the code, it is in C++
>
> MStatus node::compute(const MPlug& plug, MDataBlock& data){
>
> if (plug == dirX) {
> MDataHandle dirXHandle = data.outputValue(dirX);
> MDataHandle dirXHandleOld = data.outputValue(dirXOld);
> MTime time = MAnimControl::currentTime();
>
> MDGContext timeContextOld(time - 1);
>
> MObject inputMeshObj = inputMeshHandle.asMesh();
> MFnMesh meshFn(inputMeshObj);
>
> MDagPath dagPath;
> dagPath = meshFn.dagPath();
> MFnDagNode transFn(dagPath);
>
> MPlug matrixPlugArray = transFn.findPlug("worldMatrix");
> matrixPlugArray.evaluateNumElements();
> MPlug matrixPlug = matrixPlugArray.elementByPhysicalIndex(0);
>
> MObject matrixO;
> matrixPlug.getValue(matrixO, timeContextOld);
> MFnMatrixData fnMat(matrixO);
> MVector res = fnMat.transformation().getTranslation(MSpace::kWor ld);
>
> // Set the output data.
> dirXHandle.setFloat(0.0);
> dirXHandleOld.setFloat(res.x);
> }else {
> return MS::kUnknownParameter;
> }
>
> return MS::kSuccess;
> }
>
>
> I am wondering also how the cacheFrame node works.
> Can anyone help me?
> Thanks
>
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