Generate Scene

When to Use

• User describes a scene in words and wants the generator to produce it (scene.usda + scene_info.json + layout graph).
• User has an LLM_RESULT.py (hand-written or LLM-produced) and wants to compile / preview it.
• User wants a quick one-shot scene without standing up Open WebUI / MCP — Claude writes the DSL program directly (Path B below).

Prerequisite only for Path A (the Open WebUI agent loop): the MCP stack + Open WebUI are running (deploy-generator first). Path B needs just the package importable + ASSETS_INDEX available — no servers.

Do not use for:

• Standing up the servers → deploy-generator skill.
• Just browsing assets → search-assets skill.

The pipeline (what actually happens)

NL request
  │  ── Path A: Open WebUI "geniesimscenegen" agent (uses search_assets/get_interactions)
  │  ── Path B: Claude writes the DSL program directly (no WebUI / no MCP server)
  ▼
Python program:  from helper import *  →  @register()… def root_scene() -> Shape
  │  written to → src/geniesim_generator/LLM_RESULT.py
  ▼
cd src/geniesim_generator && python app.py  (imports LLM_RESULT.root_scene, runs it)
  │  gen_scene_layout_info → (scene_info, networkx graph)
  │  gen_scene_usda        → scene.usda
  ▼
benchmark/config/llm_task/<scene_id>/<n>/{scene.usda, scene_info.json, graph.dot, graph.svg, LLM_RESULT.py}

The program is the only handoff between "write" and "compile" — so Path A and Path B differ only in who writes it. Path B (Claude writes it directly) needs neither Open WebUI nor the MCP servers running; it only needs the package importable and ASSETS_INDEX available.

Workflow

Step 1 — Produce LLM_RESULT.py from the request

Two ways; pick by whether the WebUI/MCP stack is up.

Path A — via the Open WebUI agent (the deployed loop)

Drive the geniesimscenegen agent (import config/geniesimscenegen.json; MCP tools wired via config/openwebui.json). Describe the scene; the agent searches the asset library, writes a DSL program, and its "save to file" action drops it at generator/LLM_RESULT.py. Requires deploy-generator first.

Path B — Claude writes the program directly (no WebUI, no MCP)

When the servers aren't up (or you just want a one-shot scene), write LLM_RESULT.py yourself and run the compiler. This is the lightweight path.

1. Get real asset ids. The program must reference ids that exist in ASSETS_INDEX — guessed ids raise KeyError in helper.usd(). Options:

   • If the MCP server is up, use the search-assets skill.

   • Otherwise query the index directly in Python:

     python -c "from geniesim_assets import ASSETS_INDEX; \
       import re; pat=re.compile('bottle', re.I); \
       print([k for k in ASSETS_INDEX if pat.search(k)][:20])"
     

2. Write the program to src/geniesim_generator/LLM_RESULT.py following the contract below. Build every object through usd(oid, keywords) / library_call("usd", …) and place with the DSL helpers (transform_shape, translation_matrix, rotation_matrix, attach, align_with_*, concat_shapes).

   Minimal real example (mirrors the shipped template):

   from helper import *
   
   @register()
   def place_bottle(oid: str, position) -> Shape:
       shape = library_call("usd", oid=oid, keywords=["bottle", "drink"])
       # drop it so its center lands on `position`
       center = get_object_info(shape)["center"]
       return transform_shape(shape, translation_matrix(np.array(position) - center))
   
   @register()
   def root_scene() -> Shape:                 # REQUIRED entry point — app.py imports this name
       a = place_bottle("genie_beverage_bottle_007", (-0.32, -0.96, 1.11))
       b = place_bottle("genie_beverage_bottle_008", (-0.32, -0.70, 1.11))
       return concat_shapes(a, b)
   

   Keep one @register() on each builder (the decorator pushes the layout stack frame gen_scene_layout_info walks) and exactly one root_scene().

3. Proceed to Step 2 to compile.

The program must follow the contract (see the shipped LLM_RESULT.py template):

from helper import *

@register()
def place_mug() -> Shape:
    ...                       # build from usd(asset_id) + transform/concat helpers

@register()
def root_scene() -> Shape:    # REQUIRED entry point — app.py imports this name
    return place_mug()

If the user supplies their own program, overwrite the live slot src/geniesim_generator/LLM_RESULT.py with it (back up the original first). This is the one reliable way to feed a program in — see the --template_path caveat in Step 2.

Step 2 — Compile the scene

# Run from the package dir — app.py uses script-relative imports
# (`from helper import *`, `from LLM_RESULT import root_scene`), so it is NOT
# launchable as `python -m geniesim_generator.app`.
cd source/geniesim_generator/src/geniesim_generator
PYTHONPATH=../.. python app.py --scene_id <my_scene>

Flags:

Outputs land in benchmark/config/llm_task/<scene_id>/<n>/ (<n> auto-increments per run): scene.usda, scene_info.json, graph.dot, graph.svg, and a snapshot of the LLM_RESULT.py that produced it. On success it prints step3: save scene to <path>....

Step 3 — Preview live in Isaac Sim (optional)

python src/geniesim_generator/scene_viewer.py [--auto-play]

scene_viewer watches LLM_RESULT.py; on every save it re-runs the generator (via run_generator.sh, alongside app.py), parses the printed scene path, and reloads scene.usda under /World. Edit the program → save → watch it update. Needs Isaac Sim available in the environment.

Tips

• root_scene() is the hard entry point — app.py always imports that exact name. Keep it.
• Always compile via app.py, never python LLM_RESULT.py directly. primitive_call is an unimplemented Hole until app.py runs import geniesim_generator.scene_language.mi_helper (its line 18) — that call is what implements the primitives. Run the program any other way and primitive_call silently degrades to a placeholder that drops info["stack"], giving KeyError: 'stack'. If you ever execute a DSL program outside app.py (e.g. a quick unit check), import geniesim_generator.scene_language.mi_helper first.
• Build objects through usd(asset_id, keywords) so positions/bboxes resolve against ASSETS_INDEX — don't hand-pin coordinates. Use attach / align_with_* (in scene_language/calc_utils.py) for relative placement.
• Get real asset_ids from the search-assets skill before writing the program; guessed ids won't resolve in ASSETS_INDEX.
• Only ENGINE_MODE="exposed" primitives exist (cube / sphere / cylinder); everything else is composed from those + asset USDs.
• Inspect graph.svg to sanity-check the object relationship DAG the layout produced.

Resources

• App entry: src/geniesim_generator/app.py
• DSL surface (from helper import *): src/geniesim_generator/helper.py
• Program template / slot: src/geniesim_generator/LLM_RESULT.py
• Live preview: src/geniesim_generator/scene_viewer.py
• Scene-Language DSL: src/geniesim_generator/scene_language/
• Scene-gen agent: config/geniesimscenegen.json