* The 'precision' factor controls the discretization of the normal. * Higher values mean more discretization steps mean more precision. * * 2 is

* 'internal' functions are just so that 'principled_bsdf_eval' looks nicer */

* The "glossy base" is the combination of a specular GGX layer * on top of a diffuse BRDF. */

* Returns -1 if there is no valid temporal neighbor. * The linear buffer index of the temporal neighbor otherwise */

* Reference: * * https://stackoverflow.com/questions/12435671/quaternion-lookat-function */

References: * * [1] [Foundations of Game Engine Development: Rendering - Tangent/Bitangent calculation] http://foundationsofgameenginedev.com/#fged

* Returns true if the two given points pass the plane distance check, false otherwise */

* Reference: * * [1] [Open PBR Specification - Coat Darkening] https://academysoftwarefoundation.github.io/OpenPBR/#model/coat/darkening * * 're

* The sampled direction is returned in the local shading frame of the basis used for 'local_view_direction' */

* The sampled direction is returned in world space */

* The sampled direction is returned in the local shading frame of the basis used for 'local_view_direction' */