🏠 A PBR sphere, live
A sphere lit by a microfacet BRDF (GGX + Fresnel-Schlick) right in the browser, no code. Turn the sliders and watch the material change. One light source plus a weak ambient for the Fresnel rim.
What to notice:
- Roughness 0 → 1: a sharp bright highlight spreads into a wide dull patch. That is microfacet spread: flat facets → a narrow beam, rough ones → a cone.
- Metallic 0 → 1 (at low roughness): a diffuse ball with a white highlight turns into polished metal — the diffuse term disappears and the highlight goes colored (it takes the base color).
- The silhouette rim is always a little brighter — that is Fresnel: at grazing angles (N·V→0) reflectance climbs toward 1. Easiest to see on smooth surfaces and metal.
- Light angle: on a dielectric the highlight is white and narrow, on metal it is colored; slide the light toward the edge and you'll catch the moment the highlight and the Fresnel rim merge.