Add support for anisotropy, reflectance to metal rough material (Request in QGIS)

[qgis-bot]

Request for documentation

From pull request qgis/QGIS#66254
Author: @nyalldawson
QGIS version: 4.2

Add support for anisotropy, reflectance to metal rough material

PR Description:

Description

Fixes missing scattering energy compensation for metallic materials, which caused rough metals to incorrectly darken. Adds additional parameters for the metal rough material to allow creation of a wider range of materials representing real-world objects.

See https://google.github.io/filament/images/material_chart.jpg for a visual representation on what these parameters actually mean.

Shader math was adapted from https://google.github.io/filament/Filament.md.html (And by inspecting the filament source)

AI tool usage

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Commits tagged with [need-docs] or [FEATURE]