houdini-animation

name	houdini-animation
description	Pipeline skill — typed timeline, keyframe, channel, and cache-baking tools. Query/set time, FPS and ranges; set/get/delete/list keyframes; inspect channels and expressions; validate bounded transform-loop continuity; export/import channel JSON; bake channels and trigger bounded simulation/cache renders. The canonical timeline API.
license	MIT
compatibility	dcc-mcp-houdini 0.1+, Houdini 20.5+, dcc-mcp-core 0.19.45+
allowed-tools	Bash Read Write Edit
metadata	{"dcc-mcp":{"dcc":"houdini","layer":"domain","stage":"pipeline","version":"1.0.0","tags":["houdini","animation","keyframe","channel","timeline","loop","seam","validation","fps","bake","simulation","cache","pipeline"],"search-hint":"keyframe channel timeline frame range fps animation loop seam continuity validate bake simulation cache expression","tools":"tools.yaml"}}

houdini-animation

Typed animation tools for agents. All tools are affinity: main.

Tool groups

• timeline: get_timeline, set_timeline — the canonical timeline query/setter. For interactive timeline edits prefer set_timeline over houdini_automation__set_frame_range (which remains for file-based batch flows).
• keyframes: set_keyframe, get_keyframes, delete_keyframes (destructive).
• channels: list_animated_parms, get_channel_info, export_channels, import_channels (JSON round-trip).
• validation: validate_loop_contract — bounded, read-only OBJ world- transform continuity checks with driver summaries. It never inspects or cooks geometry and restores the original frame in finally.
• bake (async): bake_channels (per-frame sample → constant keys, hard frame cap), cache_simulation (render a filecache/DOP/geometry ROP, report a background job in interactive Houdini or written_files + elapsed_secs in headless/explicit foreground mode).

Tracer-bullet flow

1. set_timeline(frame_range=[1,48], fps=24)
2. set_keyframe(node_path="/obj/geo1", parm_name="tx", frame=1, value=0)
3. set_keyframe(node_path="/obj/geo1", parm_name="tx", frame=48, value=10)
4. get_keyframes("/obj/geo1", "tx") → verify two keys
5. validate_loop_contract(["/obj/geo1"], 1, 48) → verify the periodic seam
6. export_channels("/obj/geo1", ["tx"], "/tmp/tx.json") → import_channels to retarget
7. bake_channels("/obj/geo1", ["tx"], frame_range=[1,48]) to flatten expressions

For numeric keys, set_keyframe accepts optional interpolation: bezier, linear, or constant. It controls the segment starting at that key; omit it to preserve Houdini's default. Use constant for discrete one-frame switches.

Loop range contract

validate_loop_contract treats [start_frame, end_frame] as N unique playback samples. For the default step of one frame it temporarily samples start, start+1, start+2, end-1, end, and the virtual continuation end+1.

• endpoint_duplicate_delta reports end vs start for diagnosing assets authored with a duplicated endpoint; it is informational and does not decide pass/fail.
• duplicate_endpoint_hold_risk becomes true when that duplicated endpoint is within transform tolerances but the first linear or angular step is nontrivial. This diagnostic stays false for static nodes and is not a gate.
• periodic_delta compares virtual end+1 vs start and drives positional, angular, scale, and matrix continuity checks.
• Velocity residuals compare the end → end+1 step with start → start+1; acceleration residuals compare the neighboring three-sample stencils.

This avoids the one-frame hold caused by requiring end == start in a range whose endpoints are both played. Supply tolerances to override the documented defaults; requests remain bounded to 64 unique /obj paths and six transform samples per resolved node.

cache_simulation is async with a 1-hour timeout hint. Interactive Houdini defaults to isolated hython; poll its job_id with houdini_render__get_render_job and cancel it with houdini_render__cancel_render_job. Pass background=false for intentional foreground execution. Interactive background launch requires an explicitly saved, clean HIP and never auto-saves the GUI scene. Explicit headless background launch requires an existing HIP and captures its current state in a job-owned temporary snapshot without saving the source scene. Output-path parm names are probed defensively so File Cache, DOP I/O, and Geometry ROPs are all tolerated.