calibNormalTest

A procedural normal-mapping test pattern for the materialLibraryKit calibration shelf. The surface stays geometrically flat while the shader writes an analytic, perturbed shading normal: the top three quarters hold a 4 x 3 grid of true hemispheres alternating raised bumps and sunken dents (the (0,0) top-left cell is a bump), and the bottom quarter holds a raised ridge with 45-degree bevels running along U and a sunken bevelled groove below it, all on mid grey (base_color, roughness). A bump must light on the side facing the light and darken on the far side, a dent the reverse; if they swap, the tangent frame or the green-channel convention is wrong (the green channel follows the OpenGL / glTF convention the engine uses, +Y = image up; flip_y = 1 gives the DirectX convention to compare). strength scales every tilt. Engine-lit surface() body with no textures, so the normal capture pass shows the perturbed normal per pixel. Used by the normalTest material.