Blender Stylized Npr skill

Stylized / NPR

The execution model is in blender-core. Base colors still come from blender-pbr-materials/blender-texturing. This skill replaces how they're lit.

One call each

scripts/toon_setup.py -- --objects Hero Sword --bands 2 --rim 0.4 --outline 0.004
scripts/toon_setup.py -- --objects Hero --bands 3 --spec 0.3 --smooth-normals      # + engine outline data
scripts/toon_setup.py -- --objects Hero --lighting scene                           # EEVEE: all lights + cast shadows
scripts/toon_setup.py -- --line-art --outline 0                                    # scene-wide Line Art
scripts/toon_setup.py -- --objects Hero Sword --remove --line-art                  # exact restore

toon_setup.py

• Inserts an NPR_Toon emission group between each material's Principled base color and the output, and records the original surface link for --remove. Re-running updates values in place.
• --lighting key (default, Cycles + EEVEE): shading = N·L against one sun (--light; NPR_Key is created if there's none). Drivers follow the sun's rotation, so rotate the sun to art-direct the shadow shape. This is how engine toon shaders work, and the look matches after export.
• --lighting scene: Shader to RGB on a white diffuse, so every light and cast shadow shapes the bands. EEVEE only. Measured: in Cycles, Shader to RGB returns a constant regardless of light (identical render at 0, 3 and 10 W/m² sun).
• Bands: 2 (lit/shadow, classic anime) or 3 (adds a mid band 0.45 above --threshold). --softness (0.02) is the half-width of the band edge, so 0 aliases. --shadow-tint multiplies the base color: use cool and saturated (0.6, 0.55, 0.75), never grey/black, because grey shadows read as dirty.
• --rim (0–1) adds a lit-side rim, and --spec (0–1) a hard Blinn highlight disc (0.2–0.4 for hair/metal, 0 for skin).
• Sets view transform Standard: AgX/Filmic desaturate and compress flat colors, so the albedo you pick is the pixel you get only under Standard. The original is restored on --remove.

Outlines (pros use several at once)

Method	Where it works	Notes
Inverted hull (--outline, m)	Cycles, EEVEE, engines	Solidify outward, flipped normals, outline slot, Backfacing→transparent. Width 2–6 mm on a 1.75 m character. --outline-group = vertex group for width (taper toward tips, 0 inside the mouth)
--smooth-normals	engine outline shaders	NPR_OutlineNormal corner color = position-welded normal in tangent space (0.5 + 0.5n). Hard edges/UV splits no longer open gaps. Decode n = TBN·(c·2−1)
Line Art (--line-art, Grease Pencil)	renders	contour + crease + intersection from the camera. Needs a scene camera. --line-radius (m)
Freestyle	renders	scene.render.use_freestyle = True, line_thickness px. Slowest, most options
Known hull limits: lines at intersections and inner creases are missing (use Line Art for those in renders), and hard-edged meshes split the hull. In Blender, merge by distance before the Solidify. In engines, use --smooth-normals.

Anime faces and hair

• Face shadows from real normals look blotchy. Transfer custom normals from a simple ellipsoid proxy: a Data Transfer modifier with use_loop_data=True, data_types_loops={'CUSTOM_NORMAL'}, loop_mapping='POLYINTERP_NEAREST' (no auto smooth needed since 4.1), masked by a face vertex group. Engines import the custom normals (FBX/glTF export normals).
• For a stylized nose/cheek shadow, many games use an SDF face shadow texture sampled with the light angle in-engine. Author it as a grayscale threshold map, not in the node tree.
• Hair: a strong --spec plus a hand-painted highlight band ("angel ring") in the base color texture.

Grease Pencil (5.x API)

gp = bpy.data.grease_pencils.new("Ink"); ob = bpy.data.objects.new("Ink", gp); scene.collection.objects.link(ob)
mat = bpy.data.materials.new("Ink"); bpy.data.materials.create_gpencil_data(mat); gp.materials.append(mat)
drawing = gp.layers.new("Lines").frames.new(1).drawing
drawing.add_strokes([3]); s = drawing.strokes[0]
for i, p in enumerate(s.points): p.position, p.radius = (i * 0.5, 0, 0), 0.01   # radius in m

Strokes expose cyclic, material_index, fill_id, hide_stroke. Raw attributes: drawing.attributes (position, radius). GreasePencilv3/grease_pencils_v3 are gone (5.0). 5.2 Line Art can emit fill strokes (fill_strokes).

To game engines

Node toon shading doesn't export. Export the base color textures and rebuild the toon ramp in the engine (UE material/post-process, Unity URP toon shader, Godot ShaderMaterial), driven by the same sun direction. Ship the hull as a second material slot (apply the modifier), or as NPR_OutlineNormal for a shader outline pass. For flat, unlit assets in glTF, use a Background shader, or Light Path Is Camera Ray mixing Transparent→Background: both export as KHR_materials_unlit. Emission exports as emissive on a black base, not unlit (measured).

Gotchas

• Apply scale before --outline: Solidify thickness is in object space.
• Bloom and AO fight the flat look. Keep the world dim and uniform, and use one key light plus maybe a rim light.
• --lighting scene bands shift with light energy (luminance 0.3 ≈ threshold 0). Raise/lower --threshold instead of the light power.