Maya API: My own mesh deformer node isn't "live" enough

Coding
1

I’ve built an MPxNode in maya 2009 API, (based of maya 2009 devkit’s SplitUVNode), which takes an input mesh, modifies its UVs, and outputs an output mesh.

I have a float value which affects how the UVs are modified when I change it.
So in the channel box, when i set the float value, the meshes UVs are changed.
However, my problem is that this isn’t “live” - as in, the change happens ONLY when i release the mouse from the float slider in the AttributeEditor/ChannelBox. This is different from, say, a bend deformer on a mesh which you can drag the Curvature slider and see results in maya dynamically before releasing the mouse.

When i drag my slider, I can see that my node’s float value is changing and that my node’s Compute() method is firing as I drag. But I dont see any changes in the UV Editor (which DO happen when I release the mouse, or type a number into the floatField)

I’m fairly sure everything is done “properly” with regards to the API, i.e. setting up input/output attributes, my mesh and float attributes have attributeAffects on my outputMesh. A hugely simplified psuedo-code version of my compute() method is as follows:



if (plug == outMesh)
{
  MDataHandle inputData = data.inputValue( inMesh, &status );
  MDataHandle inputDataFloat = data.inputValue( floatScaler, &status );
  MDataHandle outputData = data.outputValue( outMesh, &status );

  // Copy the inMesh to the outMesh, and now you can
  // perform operations in-place on the outMesh (from devkit code)
  outputData.set(inputData.asMesh());

  float scaler = inputDataFloat.asFloat();
  MObject mesh = outputData.asMesh();
  MFnMesh meshFn( mesh );

  for uv in uvs:
      # Do stuff with float scaler to modify uvs here. Details unimportant.Then set uvs:
      meshFn.setUV(uv);

  outputData.setClean();
}

Perhaps the UV Editor is not designed to refresh dynamically in this way? Any ideas?

2

You might want to try converting your MPxNode to a MPxDeformerNode and setting the deformation details in the post constructor like:


void yourDeformer::postConstructor()
{
    setDeformationDetails(MPxDeformerNode::kDeformsUVs);
}

Hopefully that helps!!

Tony

3

Good idea! I’ll give it a try whenever I get some spare R&D time

Edit: Damn. Looks like that guy only works for 2011 (not 2009)…