nx_raster_triangle.nx

nx_raster_triangle.nx -- software triangle rasterizer with Z-buffer. LINEAGE (per [[feedback-no-tool-proliferation-consolidate-or-justify]] cardinal landed 2026-05-20): Distinct from [[nx_raster.nx]] because: nx_raster.nx ships Bresenham lines + Pineda triangles + shaded triangles on the *Image abstraction; this file is the *i64-framebuffer + Z-buffer variant for 3D rendering with depth occlusion. Distinct from [[nx_raster_sw.nx]] because: nx_raster_sw.nx is the 2D strict-interior coverage variant for perceptual-render demos without depth; this file adds Z-buffer for 3D occlusion. The two compose: this file CALLS nx_raster_sw's edge function in its Pineda inner loop. HONEST PROLIFERATION NOTE: three rasterizer primitives exist in the substrate by 2026-05-20. Future raster work MUST extend one of these three; consolidate if the substrate hits four. Generic 3D substrate primitive per the placement cardinal `feedback-nishi-lang-vs-nishi-engine-placement-discipline`. Any program that renders 3D triangles uses this; not voxel- specific. Lives in nishi-core/nxc2/runtime/. Algorithm: edge-function rasterization (Pineda 1988). Per-pixel: compute three signed edge values from the triangle's three edges; pixel is inside the triangle if all three have the same sign. Barycentric interpolation gives the per-pixel Z-depth used for depth-buffered occlusion. No sub-pixel precision (integer coordinates only) -- chunky pixels are the aesthetic for the software-rendered /voxels path. Vertex layout (matches nx_voxel_mesh): verts[3*i + 0] = x_pixel (integer screen X) verts[3*i + 1] = y_pixel (integer screen Y) verts[3*i + 2] = z_q14_depth (Q14; smaller = closer) verts[3*i + 3] = packed_color (u32 RGBA in low 32 bits) Triangle list: vertices [0..3) are triangle 0, [3..6) are