sheet_child

Run by a fresh hython for render_sheet: render frames once, tile them, exit.

Not imported by the server. On Houdini 22.0.368 an OpenGL ROP renders once per hython: the second render in the same process segfaults, and a render off the main thread (as in a serving hython) crashes creating Qt's platform. So each sheet is one process, one render call, on its main thread.

argv[1] is a JSON object: hip (the snapshot), hip_file (the session's own path, for $HIP), camera, start, end, step, resolution, columns, output. The last stdout line is "MCP_RESULT " + JSON.