contour-to-mesh

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Build Blender mesh surfaces directly from extracted 2D contours/masks instead of approximate primitives. Use for 1:1 mascot/logo reconstruction, exact leaf/petal silhouettes, filled wireframe shapes, shallow bas-relief forms, or when the model outline must match a front template before adding depth.

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Sourceroble3/cc-blender-skill

Added on2026-08-30

NPX Install

npx skill4agent add roble3/cc-blender-skill contour-to-mesh

SKILL.md Content

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Contour to Mesh

Use this when a reference silhouette is the contract. The mesh starts as a filled 2D contour in front-view X/Z, then gets shallow Y depth/crown after validation.

Workflow

Extract or select a clean contour/mask for one structural part.
Generate a triangulated mesh recipe with
```
scripts/mask_to_mesh_recipe.py
```
.
Run the generated Blender Python to create a named
```
GEO_*
```
mesh.
Assign front-projected UVs immediately.
Add depth only as a modifier or vertex displacement that preserves X/Z boundary positions.
Validate the front render against the source mask.

Hard rules

Do not use radial duplication unless the manifest says the source is symmetric.
Do not use a generic ellipse if a contour exists.
Boundary vertices must keep source X/Z coordinates.
Depth deformation may move Y and inner vertices, but must not alter front silhouette.
One structural source part should become one named structural mesh.

Blender pattern

Generated mesh coordinates should map image

to Blender

and image

to Blender

with vertical flip. Use

only for thickness/depth.

Front-plane rotation rule

In this Blender coordinate convention, the front camera looks along the Y axis and the reference silhouette lives in the X/Z plane. Therefore 2D rotations inside the front view are rotations around the Y axis, not around Z. Use

rotation_euler = (0, angle, 0)

for 2D component orientation in the front projection. Z rotation spins objects into/out of screen-space incorrectly for X/Z-plane meshes.

Sources distilled

Blender Mesh API: create meshes from vertices/faces using
```
from_pydata
```
.
Blender BMesh: use for cleanup, triangulation, normals, smoothing.
OpenCV contours: detect and simplify boundaries.
Delaunay triangulation: useful for filled interior meshes when filtered by mask containment.

Part-inventory handoff

When masks come from

source-part-segmentation

, preserve the

part_inventory.json

names in Blender:

GEO_<part_name>

,

MAT_<part_name>

, and UV layer names. Mesh generation must record:

source image size;
source mask path;
contour boundary point count;
boundary landmark points (tip, base-left, base-right, centroid/extrema) when detectable;
atlas UV rectangle or projection mode.

For exact mascot/logo work, generate boundary vertices from the contour and add interior vertices only for surface support. The boundary is a contract: bevels, solidify, subdivision, shrinkwrap, or sculpt passes must not move front-view X/Z boundary vertices unless a new source mask is produced.

Hole and stroke policy

Filled structural masks become meshes.
Wireframe strokes guide boundaries/landmarks; they are not structural meshes unless the manifest classifies them as decorative linework.
Holes/negative regions should be kept as separate cut masks when they affect silhouette; otherwise implement them as decals/material masks.

Source-locked front-skin fallback

When a design sheet is painterly/stylized and separate orthographic views are not CAD-consistent, use a front-skin pass before sculptural interpretation:

choose the canonical front/master source;
extract the visible subject mask as a filled contour;
create a shallow 2.5D mesh whose X/Z boundary is that contour;
assign full-image front-projected UVs so the rendered front matches the source pixels;
add depth only along Y and behind the front surface;
optionally add separate relief/backing parts for side plausibility, but keep the front skin as the visual acceptance gate.

This is a generic fallback for logos/mascots where a faithful front read is more important than speculative volume. Mark it as

front_locked_visual_skin

, not as a fully solved turntable model.

Script

```
scripts/source_locked_skin_recipe.py
```
extracts a largest/canonical foreground component and emits a mask + contour mesh recipe using full-image front-projected UV coordinates.