What the studio does automatically
How non-jewellery parts get their materials
Open a car and the windows are glass, the tyres are rubber and the seats are leather before you have touched anything. That is not a material library shipped with the model — most CAD exports carry no usable materials — it is the studio reading the part names the author wrote and dressing each part from what they say.
The category sets the default
Tell the studio what the file is and every part starts as what that thing is mostly made of: furniture opens in leather, interiors in wood, household objects in ceramic, industrial parts in steel, buildings in stone, cars in car paint, and anything unclassified in a matte plastic that reads as a placeholder rather than a finished product. Jewellery is the exception — it gets the stone-finding pass instead.
Then the name overrides it, part by part
A list of rules runs against each part's name, in a fixed order, and the first match wins. Glass leads, because a car with painted-over windows reads as a toy: window, windscreen, glazing, lens. Then smoked and frosted for obscured glass. Tyre, rubber, wheel for rubber. Lamp, headlight, indicator for the coloured glass a light actually is. Carbon fibre. Cloth, fabric, upholstery, alcantara for fabric. Seat and leather for leather. Rim, alloy, hub, spoke and aluminium for aluminium. Steel. Chrome, bumper, grille, mirror, handle, exhaust for chrome.
Two subtleties. 'Body' and 'door' only mean paint on something that is painted — on a villa the door reaches the timber rule instead of stopping at bodywork. And a rule for matte, rough or satin black runs before the paint rule, because a car's seals, vents and grille mesh are matte black and would otherwise turn glossy.
Colours come from names too
When a file carries no colour — OBJ materials are discarded, and many exports write none — a colour word in the part name is used: white, black, grey, beige, brown, red, blue, green, gold. This is sometimes the only colour information in the file, and it was written by the author: a villa's 01_wall_white and 02_wall_gray render as different walls because the names say so. Automotive glass gets a tint, because every reference photograph of a car has tinted windows and clear glass makes the interior sit in open air; glass on a building stays clear.
Why word boundaries matter
Trim contains rim. An unanchored rule for rim once matched all 108 of a car's trim parts and turned the whole thing into one aluminium mass. The rules match whole words, and names are split on underscores, hyphens and the boundary between letters and digits first — so Rim_1 and glass003 match, and Trim does not.
- Category → default material for everything
- Part name → per-part override, first rule wins
- Colour word in the name → tint, when the file has none
- Click any part to change it — a rule is a starting point
Naming for the rules
If you export for rendering, name parts for what they are made of, not for where they are: Window_Left not Panel_3, Tyre_FR not Wheel_Assembly_2. Every rule above is a whole word, so Glass_Roof and roof_glass both land. Everything here happens on your own machine: the file is converted and rendered in the browser through your GPU and is never uploaded, so an unreleased design stays unreleased.
Questions
My car's windows rendered as paint. Why?
The parts are not named as glass — perhaps Panel or Surface. Rename them with window, glass or windscreen and re-open, or click each and choose clear glass. The glass rule runs first precisely so this does not happen when names are ordinary.
Does the studio read the materials in my file?
glTF materials are read as physically based materials. OBJ and FBX materials are set aside, because their shading models predate physically based rendering. For those, the category default and the part names decide.
Can I change what a rule chose?
Yes, for any part, by clicking it and picking a material. The rules choose a starting point; nothing is locked.
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