blender-uv-texturing

Blender UV Texturing

This skill fills the gap between “assign a material” and “the supplied texture pack actually fits the model.” It is mandatory for template/atlas-driven assets.

Decision tree

What does the texture represent?
├── Whole object from front/reference → Project-from-View style UVs from the validation camera
├── Atlas with separate parts         → crop/map each part to its own UV island/rectangle
├── Repeating material                → generated/object coords or tiled UVs
├── Face/expression decal             → alpha material plane or projected UV island; no black background
├── Roughness/bump/normal map         → Non-Color data, correct node type
└── Lightmap                          → separate UV/lightmap channel or optional multiply helper; not emission

Non-negotiable rules

1. Image textures need a material node setup to render/export; viewport UV display alone is not enough.
2. Basecolor/albedo = sRGB. Roughness, metallic, bump, normal, AO/lightmap = Non-Color.
3. Atlas textures must be mapped by region. Never apply a full atlas to every mesh part.
4. Alpha decals must use alpha-connected material settings (BLEND, Alpha Hashed, or Alpha Clip) and a keyed/correct PNG. Do not leave black planes.
5. For GLB, keep to exporter-recognized nodes where possible: Principled BSDF with Image Texture inputs, UVs, normals, tangents.
6. Validate with a checker texture or overlay render before final material tuning.

Recipes

Create front-projected UVs from world X/Z bounds

import bpy

def assign_front_projected_uv(obj_name, uv_name='UV_front_projected'):
    obj = bpy.data.objects[obj_name]
    mesh = obj.data
    uv = mesh.uv_layers.get(uv_name) or mesh.uv_layers.new(name=uv_name)
    mesh.uv_layers.active = uv
    xs = [v.co.x for v in mesh.vertices]
    zs = [v.co.z for v in mesh.vertices]
    minx, maxx = min(xs), max(xs)
    minz, maxz = min(zs), max(zs)
    dx = max(maxx - minx, 1e-8)
    dz = max(maxz - minz, 1e-8)
    for poly in mesh.polygons:
        for li in poly.loop_indices:
            co = mesh.vertices[mesh.loops[li].vertex_index].co
            uv.data[li].uv = ((co.x - minx) / dx, (co.z - minz) / dz)
    mesh.update()