I was wondering if it's possible to output curves from HDA modifiers in Max? I can use them as inputs for HDAs that output geometry, but if the output is supposed to be a curve, then I get nothing in the viewport.
Are they supported? The docs mention linear and CV curves, but doesn't specify if that's only inputs or outputs too.
Output curves are only supported for geometry HDAs at the moment. You can apply a modifier HDA to a curve in 3ds Max but the output of the HDA must be a mesh for it to work.
I will update the docs to be more clear about supported inputs/outputs.