Scenario Maya Modeling

Maya modeling (hard surface, organic, props)

Expert modeling is purposeful topology: every loop exists for the silhouette, a highlight, a bake, a UV seam or a joint, and the model arrives downstream with nothing the next person has to clean. The agent works big to small, measures each stage with the toolkit, and looks at a metal highlight render before believing a surface. If a sibling skill named here is missing from your available skills, ask the user to install it (npx skills add scenario-labs/skills --skill <name>); unattended, proceed from tool schemas and flag the gap.

REQUIRED BACKGROUND: scenario-maya-expert (execution channel, review loop, 2027 version traps). Toolkit: scripts/mx_modeling.py (sys.path[:0] = ["<skills>/scenario-maya-modeling/scripts", "<skills>/scenario-maya-expert/scripts"]; import mx_modeling as MM), used with mx_audit, mx_validate, mx_review, mx_run. Not yet run in Maya: its pure-Python layer passed offline tests; every Maya call is pending tests/code/maya-modeling/run_all.sh.

Stance (the expert delta)

• Purpose first, then density. A still from CAD or booleans can skip clean topology; games, animation and close-ups cannot (Mario Elementza [00:00:32]). Minimum density is the narrowest feature, "the shortest distance between the two edges" [00:17:19]; then camera distance decides: low density needs redirected edges and pinches slightly (background), high density needs none (hero close-up) [01:09:20] [01:39:46]. Vertex count is the real cost: UV seams, hard edges and materials split vertices; a hard edge on a UV seam is free (Polycount).
• Clean uncut form, then cut. On flats, offset before cutting: the offset ring becomes the support loop; on curved parts, cut the support loop before the detail (Mario [00:16:13] [00:38:16] [01:19:49]).
• Even grid, never double; loops are the proof. Neighbor quads under 2:1 (Mario [00:08:31]); a breaking loop is an unsolved area, a loop that stops dead is a hidden double extrude [00:18:57] [00:39:22].
• Triangles: remove, solve, reinstate; n-gons never. On a cage, take triangles out, solve the rest, put one back only where the metal test holds; flats forgive, curves and deforming areas do not (Mario [00:20:36] [00:29:59]; Jessica Dru Johnson [01:12:33]). On a game low, triangles end loops locally (On Mars [00:10:29]). Cleanup fixes only lamina, non-manifold and zero-length geometry; n-gons by hand (FlippedNormals ToWRH4IXF7A [00:11:15] [00:11:50]).
• Cylinders in quarters, quad caps, ring loops only (Mario [00:57:43] [01:12:04] [01:14:16]; Pixar OpenSubdiv: no high-valence fans).
• The destination picks the edge-holding method, and subdivision lives in one place: Arnold renders Smooth Mesh Preview's state on top of its own iterations, so every save goes out with preview off (Arnold subdivision doc; FlippedNormals [00:24:00]). Creases are lost on export (antCGi RlNnp4qQIrU [00:28:12]).
• Deformation topology is the modeler's job. One control plus two support loops per joint (Jessica [01:15:51]), isolation loops bound controls [01:14:11], no pole on a deforming surface (antCGi QW8w15J00Ok [00:09:58]); prove a fix by bending two topologies with identical settings (antCGi x07USYlvu2o [00:16:24]).
• Hygiene is a delivery contract. Rebuild beats repair, unique short names, render stats at defaults; two-sided lighting hides flipped faces (FlippedNormals [00:08:31] [00:18:16] [00:02:35] [00:20:47]).

Establish first

Workflow

Every stage is a headless mx_run job that saves a new version with preview off; the GUI bridge is for playblasts and interactive tools (substitutes in references/procedures.md). Component lists cross stages only through MM.component_record and MM.carry_components, never by name or by an index read before a topology edit (P18).

1. Session and brief. cmds.about(version=True) (Smart Bevel changed in 2027.1 and 2027.2), units cm, Y up, brief in numbers (P1). GATE: assumptions written.
2. Blockout at real size. Primitives named at creation, stand on the grid, pivot per convention, freeze, delete history (P2). GATE: mx_audit frozen, no default_name or duplicate_short_name, dimensions within 2% [added]; silhouette and clay sheets compared to reference.
3. Primary form, clean grid. Write down the narrowest feature (groove, recess wall, gap) and its width: the grid near it takes that spacing, the rest balances to it; decide density or redirection per corner from the camera distance. Close the biggest quads, balance, stress-test by adding loops (Mario [00:10:11]); curves with Edit Edge Flow (antCGi [00:16:04]). GATE: MM.balance(m)["edges_over_limit"] == 0 before support loops; MM.cage_report(m): n-gons 0, every curved triangle removed or proven by the highlight review; loops continuous on the wire sheet.
4. Secondary forms. MM.extrude(faces, offset_cm=...) then recess (P3; refuses the empty extrude); openings from one quad; cylinders with MM.cylinder_sides_for and MM.build_quad_cylinder (P4), support loops cut before the opening; or polyCBoolOp on manifold meshes, then Smart Bevel (P5). GATE: zero-length edges, coincident pairs, non-manifold all 0.
5. Edge holding, per destination:
   • SubD hero or bake high, portable: support loops (offset rings, beveled-cube corner routing, Mario [00:44:24]).
   • SubD staying in Maya, Arnold or USD: creases, one method, values at or below render levels (MM.crease, MM.crease_report, P6).
   • Game low: chamfers with MM.bevel (Smart Bevel after booleans, legacy Fractional on clean quads) plus MM.weighted_normals, or hard edges on UV seams and a baked normal map (Polycount).
   • Still only from CAD or booleans: Smart Bevel, no retopology. GATE: MM.cage_report(cage)["ready_to_smooth"] (hard edges 0, since a faceted patch is a hard edge, Mario [01:28:38]; no fan caps; 6+ poles justified); MM.highlight_review(..., subdiv=n) stripes continuous across every cut; bevel problems empty; crease_report clean.
6. Game low and bake prep (P10). MM.smooth_copy the high; duplicate the cage and reach the low only by deleting edges (MM.flat_edges off the silhouette, loops ended with triangles); radius edges on round corners, evenly spaced, one on the crest (On Mars [00:12:50] [00:26:34]); parts touching the body welded in or their hidden faces deleted (Polycount: contiguous low); MM.shrink_wrap; MM.set_hard_by_angle(low, 45); MM.triangulated_copy(low, toward=high) for bake and export. GATE: MM.deviation recorded, silhouettes overlap, tris in budget, engine vertices reported, each separate shell (polyEvaluate(shell=True)) justified, diagonals_wrong_after == 0.
7. Characters: deformation check (P13). Loops across wrist and ankle, lids and lips with matching counts, mouth-corner loop under the cheek, neutral face (antCGi; Jessica [01:00:30]). GATE: MM.bend_test shows no flips and no regression against the previous topology; restored true.
8. Hygiene and handoff (P14, P15). MM.cleanup_technical, MM.inverted_shells, MM.handoff_report(roots, out, to=...), mx_validate.validate(profile="model", fix=SAFE_FIXES + ("render_stats",)), report again, save a new version. GATE: report ok; cleanup ok; 0 inverted shells; preview off; pending items named; sheets opened.