PBR Materials
PBR — physically based rendering — is the shading model most 3D tools share. Instead of describing a surface with ad-hoc highlight settings, you describe what it's made of: how rough it is, whether it's metal, and which texture maps carry that detail per-pixel. The renderer works out how light should behave.
In Spline this lives in the Lighting Layer of a material. Set that layer's mode to Physical and you're working with a PBR surface.
PBR materials need something to reflect. A metal in a scene with no environment has nothing to pick up and reads as flat grey — pair these materials with an environment or HDRi.
The two dials that matter most
| Control | What it does |
|---|---|
| Roughness | How scattered reflections are. Low is a mirror or polished metal; high is chalk, rubber or unfinished wood |
| Metalness | Whether the surface behaves like metal. Metals take their color from what they reflect; non-metals keep their own color and reflect the environment on top |
Most real-world looks come from these two alone. Reflectivity tunes how strongly a non-metal surface reflects — or use IOR (index of refraction) with Specular for the physically-stated version of the same thing, which is what glass, water and gemstone values are usually quoted as.
Texture maps
Any of the dials above can be driven per-pixel by an image instead of a single value. That's what a downloaded or authored material set gives you:
| Map | What it carries |
|---|---|
| Rough Map | Per-pixel roughness — worn patches, polished edges, smudges |
| Metal Map | Which parts of the surface are metal |
| Normal Map | Surface detail as direction data, for dents and grain that catch light without extra geometry. Normal Scale adjusts the strength |
| Bump Map | The simpler height-based alternative to a normal map |
| AO Map | Baked ambient occlusion — contact shadows in crevices. AO Intensity dials it back |
| Emissive Map | Which parts glow, with Emissive for the color and Emissive Power for the strength. Push it past 1 and it blooms |
Packed textures
Material sets often pack three maps into one image — occlusion in red, roughness in green, metalness in blue. Each map has a Channel selector (Luminance, Red, Green, Blue, Alpha) so you can point all three at the same image and read a different channel for each, with no need to split it into separate files first.
Beyond the basics
Some surfaces need more than roughness and metalness, and the Physical mode has dedicated lobes for them:
- Clearcoat and Coat Rough — a thin glossy layer over the base, like car paint, lacquered wood or a screen behind glass.
- Sheen and Sheen Rough — the soft rim of light on fabric: velvet, satin, brushed cloth.
- Iridescence — color that shifts with viewing angle, like a soap bubble, beetle shell or oil slick.
Each stays inactive until you touch it, so a material only carries what it actually uses.
PBR texture maps and the extended lobes above render on the WebGPU pipeline. Set your scene's Renderer accordingly before publishing — see Play Settings.
Bringing materials in from other tools
If you import a glTF or GLB whose materials are already metallic-roughness — what Blender, Substance, Houdini and most asset libraries export — Spline recognizes it and wires the maps up for you, packed channels included. You land on a Physical lighting layer with the base color, roughness, metalness, normal and occlusion already connected.
How to Import Content, CAD to Spline: optimization best practices
Where to go next
Creating Material Layers, Lighting Layer, Bump Map & Roughness Map, Reflection Layer, Environment & HDRi, AI Textures