Retopology

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

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

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