/retopology

name: retopology
description: Production retopology for animation-ready, low-poly, quad-dominant meshes with proper edge loops and efficient polygon flow. Use after sculpting or high-poly modeling before rigging and UV work in Blender via MCP.
license: MIT
metadata:
  author: https://github.com/arjun988
  version: "1.0.0"
  domain: blender
  role: specialist
  triggers: retopo, retopology, edge loop, quad, topology, animation ready, poly reduction, remesh
  related-skills: character-artist, creature-artist, sculpting, uv-workflow

Retopology

Clean, purposeful topology for deformation, UVs, and performance. Quad-dominant. Animation-ready.

When to Use

• After sculpting high-poly characters/creatures
• Before rigging any deforming mesh
• Poly reduction while preserving silhouette
• Fixing topology from boolean or scan cleanup

Workflow

High-Poly Reference → Guide Setup → Block Retopo → Loop Refinement
    → Pole Placement → Triangle Cleanup → Validation → UV Handoff

Retopology Methods

| Method | Best For | Speed | |--------|----------|-------| | Manual (Poly Build tool) | Hero characters | Slow, best quality | | Shrinkwrap retopo | Creatures, organic | Medium | | Quad Remesh (voxel) | Quick blockout retopo | Fast, needs cleanup | | Instant Meshes (external) | Background assets | Fast | | Symmetry retopo | Bilateral characters | Medium |

**Production default:** Manual with shrinkwrap for hero; Quad Remesh + cleanup for background.

Edge Loop Rules

• Loops follow muscle/deformation direction
• One loop per major form change
• Maintain even edge length in deformation zones
• Redirect loops at poles (minimum 3 edges meeting)
• Hide poles at back of head, armpits, groin

Pole Management

| Location | Acceptable | Avoid | |----------|------------|-------| | Top of head | 3–5 pole | — | | Inner eye corner | Redirect pole | Pole directly at corner | | Shoulder | 3-edge pole hidden | Star pattern on deltoid | | Back of knee | Pole in crease | Pole on front of knee |

Triangle Policy

• Triangles OK on non-deforming static mesh
• Convert tris to quads on face, joints, fingers
• No n-gons on deforming surfaces
• Tris at hidden areas (scalp under hair, mouth interior)

Polycount Targets

See `../references/polycount-budgets.md`. Retopo is where budget is enforced.

Shrinkwrap Retopo Setup

1. Duplicate high-poly to reference collection (hidden in render)
2. Create retopo mesh with Poly Build / manual extrude
3. Shrinkwrap modifier → Target: high-poly
4. Snap to face with project individual elements
5. Validate shrinkwrap distance (no intersection)

Validation Checklist

• [ ] Quad-dominant on all deformation areas
• [ ] Edge loops support planned rig joints
• [ ] No non-manifold geometry
• [ ] Silhouette matches high-poly reference
• [ ] Polycount within budget
• [ ] Poles placed at acceptable locations
• [ ] Mesh manifold and watertight (if required)

MCP Integration

1. Create retopo mesh object via MCP 2. Apply shrinkwrap modifier via MCP 3. Query face/edge count during retopo 4. Compare silhouette via MCP render/query 5. Transfer to `COL_Geo_LowPoly` collection

Constraints

MUST DO

• Retopo before rigging deforming meshes
• Preserve silhouette vs high-poly reference
• Plan loops for facial expressions (characters)
• Enforce polycount budget
• Validate manifold before UV pass

MUST NOT DO

• Auto-retopo without manual cleanup (hero assets)
• Leave n-gons on deformation surfaces
• Skip validation against reference
• Retopo without knowing rig requirements
• Uniform density (more density at face/hands)

Reference Guide

| Topic | Reference | Load When | |-------|-----------|-----------| | Facial retopo | `references/facial-retopo.md` | Character faces | | Game vs cinematic | `references/game-cinematic-topo.md` | Budget decisions |