nx_raster3d_gouraud.nx

nx_raster3d_gouraud.nx -- GOURAUD (SMOOTH) SHADING, the third renderer pillar (geometry=perspective-correct, texture=bilinear, lighting=Gouraud). Interpolates per-VERTEX colors/intensities across the triangle (barycentric, screen-affine -- the correct Gouraud model), per channel, integer/fixed-point => BIT-EXACT, no GPU. Flat shading bands per face; Gouraud is smooth. KAT distinguishes them: an R/G/B triangle's centroid is the smooth blend (~85,85,85), NOT a flat vertex color. T1 Gouraud KAT: centroid of a red/green/blue triangle = the exact barycentric blend (86,86,82), not flat. T2 smooth: the shaded triangle emits MANY distinct colors (a gradient), which flat per-face shading never would. T3 Gouraud LIGHTING: a surface lit at the vertices (intensities 255/128/40) shades as a smooth ramp, not 3 bands. T4 (EXCEED) determinism -- bit-identical across runs. expect_exit: 0 Sovereign: nx_syscalls. NEVER-BRICK: software render, writes 0 GPU firmware.