Vellum reads SOP point attributes once at sim init, then runs entirely in DOP space with no link back to the source SOP. Animated Cd, animated stiffness masks, time-varying pin weights — all silently dropped from frame 2 onward. The standard fixes (hand-rolled popwrangle microsolver, separate cache + Geometry Wrangle DOP, learning that microsolvers don’t run on the creation frame) are nontrivial plumbing.

This HDA is that plumbing in one click. Same popwrangle-in-Pre-Solve pattern SideFX uses internally for muscleupdatevellum.

What it does: - This DOP HDA inserts a popwrangle microsolver into the Vellum Solver’s popsolver Pre-Solve chain — fires every substep, copies listed point attributes from the upstream SOP onto the live sim points - SOP-level init wrangle seeds frame 1 (microsolvers skip the creation frame in Houdini) - Channel-referenced parms keep the SOP wrangle and DOP streamer in sync — edit one, both update

Setup: select Vellum Solver, File > Run Script..., pick the .cmd. Three files (.cmd, .py, .hda) sit in one folder. No shelf install, no copying into prefs, no restart.

Supported attribute types: float scalar/vec3/vec4 and integer scalar. Match by id (topology-safe) or ptnum.

Free download: https://kleer001.github.io/funkworks/vellum_attr_stream [kleer001.github.io]

Houdini 19.5+, any edition.

FX users: a build script is included to compile the HDA clean under your own license.

🐜 More free tools at https://github.com/kleer001/funkworks [github.com]