PBR Advanced Surface Properties Guide

Base material lock

Before advanced controls are touched, freeze albedo range, normal intensity, roughness or Glossiness Map convention, and metalness policy. Clearcoat cannot rescue a base layer that is already too bright, and Transmission will exaggerate any wrong color management. Capture a neutral studio render and an engine render under the same HDRI so differences are visible.

Clearcoat layer behavior

Clearcoat is a second specular lobe. Use it for varnish, automotive paint, lacquered plastic, wet sealant, or coated carbon; do not use it as a generic shine slider. Record coat weight, coat roughness, normal source, and whether the coat shares or overrides the base normal.

Failure symptoms include double highlights on cloth, oily skin on plastic, and mip shimmer on curved surfaces. Fix by lowering coat weight, increasing coat roughness, or removing coat normals that fight the base normal.

Fresnel and IOR decisions

Fresnel controls view-angle reflectance. Index of Refraction controls how strong that behavior should be for dielectrics and transparent surfaces. Keep IOR plausible: water near 1.33, glass around 1.45-1.52, many plastics around 1.45. If art direction needs stronger rim light, write it as a deliberate style override.

Transmission and subsurface limits

Transmission is for light passing through thin or transparent material. It needs thickness, absorption color, refraction behavior, and shadow policy. Scattering Color belongs to subsurface or volume decisions, not to every translucent texture by default.

A leaf, wax seal, frosted glass panel, and potion bottle require different evidence. Show backlight, shadow, and grazing angle screenshots before approving the channel.

Opacity mask and sorting

Opacity Mask should be binary or intentionally dithered for leaves, decals, grates, and torn fabric. Semi-transparent glass belongs in a transparent blend path, not in a masked shader. Record alpha cutoff, mip behavior, two-sided setting, and whether the asset casts masked shadows.

Symptoms: halos around TGA cutouts, disappearing hair cards, noisy distant foliage, and bad depth sorting. Fix alpha padding, cutoff value, mip alpha coverage, or move the material to a proper transparency mode.

Triplanar projection use

Triplanar Projection hides UV seams on rocks, terrain cuts, scan cleanup, and large blended surfaces. It should not replace UVs on assets that need decals, wear direction, or authored trim. Write projection scale, blend softness, object/world space, and normal blending method.

Texture sampler and packing constraints

Texture Sampler count matters on realtime targets. Combine compatible grayscale channels, keep Specular Map use intentional, and document which channels are sRGB or linear. A packed ORM texture with a stray sRGB import will change roughness and occlusion at once.

Acrylic transmission decision

Example: a clear acrylic display case with polished edges should use base color near neutral, Transmission enabled, IOR around glass or acrylic, low roughness for front panels, and a separate Opacity Mask only for labels or ventilation holes. Do not add Clearcoat unless there is a coated surface above the transparent body.

The acceptance render needs front view, grazing angle, backlit view, and engine screenshot with the same environment reflection.

Shader artifact evidence

Collect material instance values, texture import settings, shader model, channel packing diagram, studio render, engine render, and one close crop of the artifact. Mark whether the issue is physical mismatch, engine limitation, or intentional style.